The Tor Browser: layout/base/nsLayoutUtils.cpp@b8a032363ba2 (annotated)

layout/base/nsLayoutUtils.cpp@b8a032363ba2 (annotated)

layout/base/nsLayoutUtils.cpp

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=2 sw=2 et tw=78: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "nsLayoutUtils.h"
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/BasicEvents.h"
 #include "mozilla/MemoryReporting.h"
 #include "nsPresContext.h"
 #include "nsIContent.h"
 #include "nsIDOMHTMLDocument.h"
 #include "nsIDOMHTMLElement.h"
 #include "nsFrameList.h"
 #include "nsGkAtoms.h"
 #include "nsIAtom.h"
 #include "nsCSSPseudoElements.h"
 #include "nsCSSAnonBoxes.h"
 #include "nsCSSColorUtils.h"
 #include "nsView.h"
 #include "nsPlaceholderFrame.h"
 #include "nsIScrollableFrame.h"
 #include "nsIDOMEvent.h"
 #include "nsDisplayList.h"
 #include "nsRegion.h"
 #include "nsFrameManager.h"
 #include "nsBlockFrame.h"
 #include "nsBidiPresUtils.h"
 #include "imgIContainer.h"
 #include "ImageOps.h"
 #include "gfxRect.h"
 #include "gfxContext.h"
 #include "nsRenderingContext.h"
 #include "nsIInterfaceRequestorUtils.h"
 #include "nsCSSRendering.h"
 #include "nsThemeConstants.h"
 #include "nsPIDOMWindow.h"
 #include "nsIDocShell.h"
 #include "nsIWidget.h"
 #include "gfxMatrix.h"
 #include "gfxPoint3D.h"
 #include "gfxPrefs.h"
 #include "gfxTypes.h"
 #include "nsTArray.h"
 #include "mozilla/dom/HTMLCanvasElement.h"
 #include "nsICanvasRenderingContextInternal.h"
 #include "gfxPlatform.h"
 #include <algorithm>
 #include "mozilla/dom/HTMLVideoElement.h"
 #include "mozilla/dom/HTMLImageElement.h"
 #include "mozilla/dom/DOMRect.h"
 #include "imgIRequest.h"
 #include "nsIImageLoadingContent.h"
 #include "nsCOMPtr.h"
 #include "nsCSSProps.h"
 #include "nsListControlFrame.h"
 #include "mozilla/dom/Element.h"
 #include "nsCanvasFrame.h"
 #include "gfxDrawable.h"
 #include "gfxUtils.h"
 #include "nsDataHashtable.h"
 #include "nsTextFrame.h"
 #include "nsFontFaceList.h"
 #include "nsFontInflationData.h"
 #include "nsSVGUtils.h"
 #include "SVGTextFrame.h"
 #include "nsStyleStructInlines.h"
 #include "nsStyleTransformMatrix.h"
 #include "nsIFrameInlines.h"
 #include "ImageContainer.h"
 #include "nsComputedDOMStyle.h"
 #include "ActiveLayerTracker.h"
 #include "mozilla/gfx/2D.h"
 #include "gfx2DGlue.h"
 #include "mozilla/LookAndFeel.h"
 #include "UnitTransforms.h"
 #include "TiledLayerBuffer.h" // For TILEDLAYERBUFFER_TILE_SIZE
 #include "mozilla/Preferences.h"
 #include "mozilla/LookAndFeel.h"
 #ifdef MOZ_XUL
 #include "nsXULPopupManager.h"
 #endif
 #include "GeckoProfiler.h"
 #include "nsAnimationManager.h"
 #include "nsTransitionManager.h"
 #include "RestyleManager.h"
 // Additional includes used on B2G by code in GetOrMaybeCreateDisplayPort().
 #ifdef MOZ_WIDGET_GONK
 #include "mozilla/layers/AsyncPanZoomController.h"
 #endif
 using namespace mozilla;
 using namespace mozilla::css;
 using namespace mozilla::dom;
 using namespace mozilla::layers;
 using namespace mozilla::layout;
 using namespace mozilla::gfx;
 using mozilla::image::Angle;
 using mozilla::image::Flip;
 using mozilla::image::ImageOps;
 using mozilla::image::Orientation;
 #define GRID_ENABLED_PREF_NAME "layout.css.grid.enabled"
 #define STICKY_ENABLED_PREF_NAME "layout.css.sticky.enabled"
 #define TEXT_ALIGN_TRUE_ENABLED_PREF_NAME "layout.css.text-align-true-value.enabled"
 #ifdef DEBUG
 // TODO: remove, see bug 598468.
 bool nsLayoutUtils::gPreventAssertInCompareTreePosition = false;
 #endif // DEBUG
 typedef FrameMetrics::ViewID ViewID;
 /* static */ uint32_t nsLayoutUtils::sFontSizeInflationEmPerLine;
 /* static */ uint32_t nsLayoutUtils::sFontSizeInflationMinTwips;
 /* static */ uint32_t nsLayoutUtils::sFontSizeInflationLineThreshold;
 /* static */ int32_t  nsLayoutUtils::sFontSizeInflationMappingIntercept;
 /* static */ uint32_t nsLayoutUtils::sFontSizeInflationMaxRatio;
 /* static */ bool nsLayoutUtils::sFontSizeInflationForceEnabled;
 /* static */ bool nsLayoutUtils::sFontSizeInflationDisabledInMasterProcess;
 /* static */ bool nsLayoutUtils::sInvalidationDebuggingIsEnabled;
 /* static */ bool nsLayoutUtils::sCSSVariablesEnabled;
 /* static */ bool nsLayoutUtils::sInterruptibleReflowEnabled;
 static ViewID sScrollIdCounter = FrameMetrics::START_SCROLL_ID;
 typedef nsDataHashtable<nsUint64HashKey, nsIContent*> ContentMap;
 static ContentMap* sContentMap = nullptr;
 static ContentMap& GetContentMap() {
   if (!sContentMap) {
     sContentMap = new ContentMap();
   }
   return *sContentMap;
 }
 // When the pref "layout.css.grid.enabled" changes, this function is invoked
 // to let us update kDisplayKTable, to selectively disable or restore the
 // entries for "grid" and "inline-grid" in that table.
 static void
 GridEnabledPrefChangeCallback(const char* aPrefName, void* aClosure)
 {
   MOZ_ASSERT(strncmp(aPrefName, GRID_ENABLED_PREF_NAME,
                      ArrayLength(GRID_ENABLED_PREF_NAME)) == 0,
              "We only registered this callback for a single pref, so it "
              "should only be called for that pref");
   static int32_t sIndexOfGridInDisplayTable;
   static int32_t sIndexOfInlineGridInDisplayTable;
   static bool sAreGridKeywordIndicesInitialized; // initialized to false
   bool isGridEnabled =
     Preferences::GetBool(GRID_ENABLED_PREF_NAME, false);
   if (!sAreGridKeywordIndicesInitialized) {
     // First run: find the position of "grid" and "inline-grid" in
     // kDisplayKTable.
     sIndexOfGridInDisplayTable =
       nsCSSProps::FindIndexOfKeyword(eCSSKeyword_grid,
                                      nsCSSProps::kDisplayKTable);
     MOZ_ASSERT(sIndexOfGridInDisplayTable >= 0,
                "Couldn't find grid in kDisplayKTable");
     sIndexOfInlineGridInDisplayTable =
       nsCSSProps::FindIndexOfKeyword(eCSSKeyword_inline_grid,
                                      nsCSSProps::kDisplayKTable);
     MOZ_ASSERT(sIndexOfInlineGridInDisplayTable >= 0,
                "Couldn't find inline-grid in kDisplayKTable");
     sAreGridKeywordIndicesInitialized = true;
   }
   // OK -- now, stomp on or restore the "grid" entries in kDisplayKTable,
   // depending on whether the grid pref is enabled vs. disabled.
   if (sIndexOfGridInDisplayTable >= 0) {
     nsCSSProps::kDisplayKTable[sIndexOfGridInDisplayTable] =
       isGridEnabled ? eCSSKeyword_grid : eCSSKeyword_UNKNOWN;
   }
   if (sIndexOfInlineGridInDisplayTable >= 0) {
     nsCSSProps::kDisplayKTable[sIndexOfInlineGridInDisplayTable] =
       isGridEnabled ? eCSSKeyword_inline_grid : eCSSKeyword_UNKNOWN;
   }
 }
 // When the pref "layout.css.sticky.enabled" changes, this function is invoked
 // to let us update kPositionKTable, to selectively disable or restore the
 // entry for "sticky" in that table.
 static void
 StickyEnabledPrefChangeCallback(const char* aPrefName, void* aClosure)
 {
   MOZ_ASSERT(strncmp(aPrefName, STICKY_ENABLED_PREF_NAME,
                      ArrayLength(STICKY_ENABLED_PREF_NAME)) == 0,
              "We only registered this callback for a single pref, so it "
              "should only be called for that pref");
   static int32_t sIndexOfStickyInPositionTable;
   static bool sIsStickyKeywordIndexInitialized; // initialized to false
   bool isStickyEnabled =
     Preferences::GetBool(STICKY_ENABLED_PREF_NAME, false);
   if (!sIsStickyKeywordIndexInitialized) {
     // First run: find the position of "sticky" in kPositionKTable.
     sIndexOfStickyInPositionTable =
       nsCSSProps::FindIndexOfKeyword(eCSSKeyword_sticky,
                                      nsCSSProps::kPositionKTable);
     MOZ_ASSERT(sIndexOfStickyInPositionTable >= 0,
                "Couldn't find sticky in kPositionKTable");
     sIsStickyKeywordIndexInitialized = true;
   }
   // OK -- now, stomp on or restore the "sticky" entry in kPositionKTable,
   // depending on whether the sticky pref is enabled vs. disabled.
   nsCSSProps::kPositionKTable[sIndexOfStickyInPositionTable] =
     isStickyEnabled ? eCSSKeyword_sticky : eCSSKeyword_UNKNOWN;
 }
 // When the pref "layout.css.text-align-true-value.enabled" changes, this
 // function is called to let us update kTextAlignKTable & kTextAlignLastKTable,
 // to selectively disable or restore the entries for "true" in those tables.
 static void
 TextAlignTrueEnabledPrefChangeCallback(const char* aPrefName, void* aClosure)
 {
   NS_ASSERTION(strcmp(aPrefName, TEXT_ALIGN_TRUE_ENABLED_PREF_NAME) == 0,
                "Did you misspell " TEXT_ALIGN_TRUE_ENABLED_PREF_NAME " ?");
   static bool sIsInitialized;
   static int32_t sIndexOfTrueInTextAlignTable;
   static int32_t sIndexOfTrueInTextAlignLastTable;
   bool isTextAlignTrueEnabled =
     Preferences::GetBool(TEXT_ALIGN_TRUE_ENABLED_PREF_NAME, false);
   if (!sIsInitialized) {
     // First run: find the position of "true" in kTextAlignKTable.
     sIndexOfTrueInTextAlignTable =
       nsCSSProps::FindIndexOfKeyword(eCSSKeyword_true,
                                      nsCSSProps::kTextAlignKTable);
     // First run: find the position of "true" in kTextAlignLastKTable.
     sIndexOfTrueInTextAlignLastTable =
       nsCSSProps::FindIndexOfKeyword(eCSSKeyword_true,
                                      nsCSSProps::kTextAlignLastKTable);
     sIsInitialized = true;
   }
   // OK -- now, stomp on or restore the "true" entry in the keyword tables,
   // depending on whether the pref is enabled vs. disabled.
   MOZ_ASSERT(sIndexOfTrueInTextAlignTable >= 0);
   nsCSSProps::kTextAlignKTable[sIndexOfTrueInTextAlignTable] =
     isTextAlignTrueEnabled ? eCSSKeyword_true : eCSSKeyword_UNKNOWN;
   MOZ_ASSERT(sIndexOfTrueInTextAlignLastTable >= 0);
   nsCSSProps::kTextAlignLastKTable[sIndexOfTrueInTextAlignLastTable] =
     isTextAlignTrueEnabled ? eCSSKeyword_true : eCSSKeyword_UNKNOWN;
 }
 template <class AnimationsOrTransitions>
 static AnimationsOrTransitions*
 HasAnimationOrTransitionForCompositor(nsIContent* aContent,
                                       nsIAtom* aAnimationProperty,
                                       nsCSSProperty aProperty)
 {
   AnimationsOrTransitions* animations =
     static_cast<AnimationsOrTransitions*>(aContent->GetProperty(aAnimationProperty));
   if (animations) {
     bool propertyMatches = animations->HasAnimationOfProperty(aProperty);
     if (propertyMatches &&
         animations->CanPerformOnCompositorThread(
           CommonElementAnimationData::CanAnimate_AllowPartial)) {
       return animations;
     }
   }
   return nullptr;
 }
 bool
 nsLayoutUtils::HasAnimationsForCompositor(nsIContent* aContent,
                                           nsCSSProperty aProperty)
 {
   if (!aContent->MayHaveAnimations())
     return false;
   return HasAnimationOrTransitionForCompositor<ElementAnimations>
             (aContent, nsGkAtoms::animationsProperty, aProperty) ||
          HasAnimationOrTransitionForCompositor<ElementTransitions>
             (aContent, nsGkAtoms::transitionsProperty, aProperty);
 }
 template <class AnimationsOrTransitions>
 AnimationsOrTransitions*
 mozilla::HasAnimationOrTransition(nsIContent* aContent,
                          nsIAtom* aAnimationProperty,
                          nsCSSProperty aProperty)
 {
   AnimationsOrTransitions* animations =
     static_cast<AnimationsOrTransitions*>(aContent->GetProperty(aAnimationProperty));
   if (animations) {
     bool propertyMatches = animations->HasAnimationOfProperty(aProperty);
     if (propertyMatches) {
       return animations;
     }
   }
   return nullptr;
 }
 template ElementAnimations*
 mozilla::HasAnimationOrTransition<ElementAnimations>(nsIContent* aContent,
                          nsIAtom* aAnimationProperty,
                          nsCSSProperty aProperty);
 template ElementTransitions*
 mozilla::HasAnimationOrTransition<ElementTransitions>(nsIContent* aContent,
                          nsIAtom* aAnimationProperty,
                          nsCSSProperty aProperty);
 bool
 nsLayoutUtils::HasAnimations(nsIContent* aContent,
                              nsCSSProperty aProperty)
 {
   if (!aContent->MayHaveAnimations())
     return false;
   return HasAnimationOrTransition<ElementAnimations>
             (aContent, nsGkAtoms::animationsProperty, aProperty) ||
          HasAnimationOrTransition<ElementTransitions>
             (aContent, nsGkAtoms::transitionsProperty, aProperty);
 }
 static gfxSize
 GetScaleForValue(const nsStyleAnimation::Value& aValue,
                  nsIFrame* aFrame)
 {
   if (!aFrame) {
     NS_WARNING("No frame.");
     return gfxSize();
   }
   if (aValue.GetUnit() != nsStyleAnimation::eUnit_Transform) {
     NS_WARNING("Expected a transform.");
     return gfxSize();
   }
   nsCSSValueSharedList* list = aValue.GetCSSValueSharedListValue();
   MOZ_ASSERT(list->mHead);
   if (list->mHead->mValue.GetUnit() == eCSSUnit_None) {
     // There is an animation, but no actual transform yet.
     return gfxSize();
   }
   nsRect frameBounds = aFrame->GetRect();
   bool dontCare;
   gfx3DMatrix transform = nsStyleTransformMatrix::ReadTransforms(
                             list->mHead,
                             aFrame->StyleContext(),
                             aFrame->PresContext(), dontCare, frameBounds,
                             aFrame->PresContext()->AppUnitsPerDevPixel());
   gfxMatrix transform2d;
   bool canDraw2D = transform.CanDraw2D(&transform2d);
   if (!canDraw2D) {
     return gfxSize();
   }
   return transform2d.ScaleFactors(true);
 }
 float
 GetSuitableScale(float aMaxScale, float aMinScale)
 {
   // If the minimum scale >= 1.0f, use it; if the maximum <= 1.0f, use it;
   // otherwise use 1.0f.
   if (aMinScale >= 1.0f) {
     return aMinScale;
   }
   else if (aMaxScale <= 1.0f) {
     return aMaxScale;
   }
   return 1.0f;
 }
 gfxSize
 nsLayoutUtils::ComputeSuitableScaleForAnimation(nsIContent* aContent)
 {
   gfxSize maxScale(1.0f, 1.0f);
   gfxSize minScale(1.0f, 1.0f);
   ElementAnimations* animations = HasAnimationOrTransitionForCompositor<ElementAnimations>
     (aContent, nsGkAtoms::animationsProperty, eCSSProperty_transform);
   if (animations) {
     for (uint32_t animIdx = animations->mAnimations.Length(); animIdx-- != 0; ) {
       mozilla::StyleAnimation& anim = animations->mAnimations[animIdx];
       for (uint32_t propIdx = anim.mProperties.Length(); propIdx-- != 0; ) {
         AnimationProperty& prop = anim.mProperties[propIdx];
         if (prop.mProperty == eCSSProperty_transform) {
           for (uint32_t segIdx = prop.mSegments.Length(); segIdx-- != 0; ) {
             AnimationPropertySegment& segment = prop.mSegments[segIdx];
             gfxSize from = GetScaleForValue(segment.mFromValue,
                                             aContent->GetPrimaryFrame());
             maxScale.width = std::max<float>(maxScale.width, from.width);
             maxScale.height = std::max<float>(maxScale.height, from.height);
             minScale.width = std::min<float>(minScale.width, from.width);
             minScale.height = std::min<float>(minScale.height, from.height);
             gfxSize to = GetScaleForValue(segment.mToValue,
                                           aContent->GetPrimaryFrame());
             maxScale.width = std::max<float>(maxScale.width, to.width);
             maxScale.height = std::max<float>(maxScale.height, to.height);
             minScale.width = std::min<float>(minScale.width, to.width);
             minScale.height = std::min<float>(minScale.height, to.height);
           }
         }
       }
     }
   }
   ElementTransitions* transitions = HasAnimationOrTransitionForCompositor<ElementTransitions>
     (aContent, nsGkAtoms::transitionsProperty, eCSSProperty_transform);
   if (transitions) {
     for (uint32_t i = 0, i_end = transitions->mPropertyTransitions.Length();
          i < i_end; ++i){
       ElementPropertyTransition &pt = transitions->mPropertyTransitions[i];
       if (pt.IsRemovedSentinel()) {
         continue;
       }
       MOZ_ASSERT(pt.mProperties.Length() == 1,
         "Should have one animation property for a transition");
       MOZ_ASSERT(pt.mProperties[0].mSegments.Length() == 1,
         "Animation property should have one segment for a transition");
       const AnimationPropertySegment& segment = pt.mProperties[0].mSegments[0];
       if (pt.mProperties[0].mProperty == eCSSProperty_transform) {
         gfxSize start = GetScaleForValue(segment.mFromValue,
                                          aContent->GetPrimaryFrame());
         maxScale.width = std::max<float>(maxScale.width, start.width);
         maxScale.height = std::max<float>(maxScale.height, start.height);
         minScale.width = std::min<float>(minScale.width, start.width);
         minScale.height = std::min<float>(minScale.height, start.height);
         gfxSize end = GetScaleForValue(segment.mToValue,
                                        aContent->GetPrimaryFrame());
         maxScale.width = std::max<float>(maxScale.width, end.width);
         maxScale.height = std::max<float>(maxScale.height, end.height);
         minScale.width = std::min<float>(minScale.width, end.width);
         minScale.height = std::min<float>(minScale.height, end.height);
       }
     }
   }
   return gfxSize(GetSuitableScale(maxScale.width, minScale.width),
       GetSuitableScale(maxScale.height, minScale.height));
 }
 bool
 nsLayoutUtils::AreAsyncAnimationsEnabled()
 {
   static bool sAreAsyncAnimationsEnabled;
   static bool sAsyncPrefCached = false;
   if (!sAsyncPrefCached) {
     sAsyncPrefCached = true;
     Preferences::AddBoolVarCache(&sAreAsyncAnimationsEnabled,
                                  "layers.offmainthreadcomposition.async-animations");
   }
   return sAreAsyncAnimationsEnabled &&
     gfxPlatform::OffMainThreadCompositingEnabled();
 }
 bool
 nsLayoutUtils::IsAnimationLoggingEnabled()
 {
   static bool sShouldLog;
   static bool sShouldLogPrefCached;
   if (!sShouldLogPrefCached) {
     sShouldLogPrefCached = true;
     Preferences::AddBoolVarCache(&sShouldLog,
                                  "layers.offmainthreadcomposition.log-animations");
   }
   return sShouldLog;
 }
 bool
 nsLayoutUtils::UseBackgroundNearestFiltering()
 {
   static bool sUseBackgroundNearestFilteringEnabled;
   static bool sUseBackgroundNearestFilteringPrefInitialised = false;
   if (!sUseBackgroundNearestFilteringPrefInitialised) {
     sUseBackgroundNearestFilteringPrefInitialised = true;
     sUseBackgroundNearestFilteringEnabled =
       Preferences::GetBool("gfx.filter.nearest.force-enabled", false);
   }
   return sUseBackgroundNearestFilteringEnabled;
 }
 bool
 nsLayoutUtils::GPUImageScalingEnabled()
 {
   static bool sGPUImageScalingEnabled;
   static bool sGPUImageScalingPrefInitialised = false;
   if (!sGPUImageScalingPrefInitialised) {
     sGPUImageScalingPrefInitialised = true;
     sGPUImageScalingEnabled =
       Preferences::GetBool("layout.gpu-image-scaling.enabled", false);
   }
   return sGPUImageScalingEnabled;
 }
 bool
 nsLayoutUtils::AnimatedImageLayersEnabled()
 {
   static bool sAnimatedImageLayersEnabled;
   static bool sAnimatedImageLayersPrefCached = false;
   if (!sAnimatedImageLayersPrefCached) {
     sAnimatedImageLayersPrefCached = true;
     Preferences::AddBoolVarCache(&sAnimatedImageLayersEnabled,
                                  "layout.animated-image-layers.enabled",
                                  false);
   }
   return sAnimatedImageLayersEnabled;
 }
 bool
 nsLayoutUtils::CSSFiltersEnabled()
 {
   static bool sCSSFiltersEnabled;
   static bool sCSSFiltersPrefCached = false;
   if (!sCSSFiltersPrefCached) {
     sCSSFiltersPrefCached = true;
     Preferences::AddBoolVarCache(&sCSSFiltersEnabled,
                                  "layout.css.filters.enabled",
                                  false);
   }
   return sCSSFiltersEnabled;
 }
 bool
 nsLayoutUtils::UnsetValueEnabled()
 {
   static bool sUnsetValueEnabled;
   static bool sUnsetValuePrefCached = false;
   if (!sUnsetValuePrefCached) {
     sUnsetValuePrefCached = true;
     Preferences::AddBoolVarCache(&sUnsetValueEnabled,
                                  "layout.css.unset-value.enabled",
                                  false);
   }
   return sUnsetValueEnabled;
 }
 bool
 nsLayoutUtils::IsTextAlignTrueValueEnabled()
 {
   static bool sTextAlignTrueValueEnabled;
   static bool sTextAlignTrueValueEnabledPrefCached = false;
   if (!sTextAlignTrueValueEnabledPrefCached) {
     sTextAlignTrueValueEnabledPrefCached = true;
     Preferences::AddBoolVarCache(&sTextAlignTrueValueEnabled,
                                  TEXT_ALIGN_TRUE_ENABLED_PREF_NAME,
                                  false);
   }
   return sTextAlignTrueValueEnabled;
 }
 void
 nsLayoutUtils::UnionChildOverflow(nsIFrame* aFrame,
                                   nsOverflowAreas& aOverflowAreas,
                                   FrameChildListIDs aSkipChildLists)
 {
   // Iterate over all children except pop-ups.
   FrameChildListIDs skip = aSkipChildLists |
       nsIFrame::kSelectPopupList | nsIFrame::kPopupList;
   for (nsIFrame::ChildListIterator childLists(aFrame);
        !childLists.IsDone(); childLists.Next()) {
     if (skip.Contains(childLists.CurrentID())) {
       continue;
     }
     nsFrameList children = childLists.CurrentList();
     for (nsFrameList::Enumerator e(children); !e.AtEnd(); e.Next()) {
       nsIFrame* child = e.get();
       nsOverflowAreas childOverflow =
         child->GetOverflowAreas() + child->GetPosition();
       aOverflowAreas.UnionWith(childOverflow);
     }
   }
 }
 static void DestroyViewID(void* aObject, nsIAtom* aPropertyName,
                           void* aPropertyValue, void* aData)
 {
   ViewID* id = static_cast<ViewID*>(aPropertyValue);
   GetContentMap().Remove(*id);
   delete id;
 }
 /**
  * A namespace class for static layout utilities.
  */
 bool
 nsLayoutUtils::FindIDFor(const nsIContent* aContent, ViewID* aOutViewId)
 {
   void* scrollIdProperty = aContent->GetProperty(nsGkAtoms::RemoteId);
   if (scrollIdProperty) {
     *aOutViewId = *static_cast<ViewID*>(scrollIdProperty);
     return true;
   }
   return false;
 }
 ViewID
 nsLayoutUtils::FindOrCreateIDFor(nsIContent* aContent)
 {
   ViewID scrollId;
   if (!FindIDFor(aContent, &scrollId)) {
     scrollId = sScrollIdCounter++;
     aContent->SetProperty(nsGkAtoms::RemoteId, new ViewID(scrollId),
                           DestroyViewID);
     GetContentMap().Put(scrollId, aContent);
   }
   return scrollId;
 }
 nsIContent*
 nsLayoutUtils::FindContentFor(ViewID aId)
 {
   NS_ABORT_IF_FALSE(aId != FrameMetrics::NULL_SCROLL_ID,
                     "Cannot find a content element in map for null IDs.");
   nsIContent* content;
   bool exists = GetContentMap().Get(aId, &content);
   if (exists) {
     return content;
   } else {
     return nullptr;
   }
 }
 nsIScrollableFrame*
 nsLayoutUtils::FindScrollableFrameFor(ViewID aId)
 {
   nsIContent* content = FindContentFor(aId);
   if (!content) {
     return nullptr;
   }
   nsIFrame* scrolledFrame = content->GetPrimaryFrame();
   if (scrolledFrame && content->OwnerDoc()->GetRootElement() == content) {
     // The content is the root element of a subdocument, so return the root scrollable
     // for the subdocument.
     scrolledFrame = scrolledFrame->PresContext()->PresShell()->GetRootScrollFrame();
   }
   return scrolledFrame ? scrolledFrame->GetScrollTargetFrame() : nullptr;
 }
 bool
 nsLayoutUtils::GetDisplayPort(nsIContent* aContent, nsRect *aResult)
 {
   DisplayPortPropertyData* rectData =
     static_cast<DisplayPortPropertyData*>(aContent->GetProperty(nsGkAtoms::DisplayPort));
   DisplayPortMarginsPropertyData* marginsData =
     static_cast<DisplayPortMarginsPropertyData*>(aContent->GetProperty(nsGkAtoms::DisplayPortMargins));
   if (!rectData && !marginsData) {
     return false;
   }
   if (aResult) {
     if (rectData && marginsData) {
       // choose margins if equal priority
       if (rectData->mPriority > marginsData->mPriority) {
         marginsData = nullptr;
       } else {
         rectData = nullptr;
       }
     }
     if (rectData) {
       *aResult = rectData->mRect;
     } else {
       nsRect* baseData =
         static_cast<nsRect*>(aContent->GetProperty(nsGkAtoms::DisplayPortBase));
       nsRect base;
       if (baseData) {
         base = *baseData;
       }
       nsIFrame* frame = aContent->GetPrimaryFrame();
       if (frame) {
         bool isRoot = false;
         if (aContent->OwnerDoc()->GetRootElement() == aContent) {
           // We want the scroll frame, the root scroll frame differs from all
           // others in that the primary frame is not the scroll frame.
           frame = frame->PresContext()->PresShell()->GetRootScrollFrame();
           isRoot = true;
         }
         // first convert the base rect to layer pixels
         nsPresContext* presContext = frame->PresContext();
         int32_t auPerDevPixel = presContext->AppUnitsPerDevPixel();
         gfxSize res = presContext->PresShell()->GetCumulativeResolution();
         gfxSize parentRes = res;
         if (isRoot) {
           // the base rect for root scroll frames is specified in the parent document
           // coordinate space, so it doesn't include the local resolution.
           gfxSize localRes = presContext->PresShell()->GetResolution();
           parentRes.width /= localRes.width;
           parentRes.height /= localRes.height;
         }
         LayerRect rect;
         rect.x = parentRes.width * NSAppUnitsToFloatPixels(base.x, auPerDevPixel);
         rect.y = parentRes.height * NSAppUnitsToFloatPixels(base.y, auPerDevPixel);
         rect.width =
           parentRes.width * NSAppUnitsToFloatPixels(base.width, auPerDevPixel);
         rect.height =
           parentRes.height * NSAppUnitsToFloatPixels(base.height, auPerDevPixel);
         rect.Inflate(marginsData->mMargins);
         nsIScrollableFrame* scrollableFrame = frame->GetScrollTargetFrame();
         nsPoint scrollPos(
           scrollableFrame ? scrollableFrame->GetScrollPosition() : nsPoint(0,0));
         if (marginsData->mAlignmentX > 0 || marginsData->mAlignmentY > 0) {
           // Avoid division by zero.
           if (marginsData->mAlignmentX == 0) {
             marginsData->mAlignmentX = 1;
           }
           if (marginsData->mAlignmentY == 0) {
             marginsData->mAlignmentY = 1;
           }
           LayerPoint scrollPosLayer(
             res.width * NSAppUnitsToFloatPixels(scrollPos.x, auPerDevPixel),
             res.height * NSAppUnitsToFloatPixels(scrollPos.y, auPerDevPixel));
           rect += scrollPosLayer;
           // Inflate the rectangle by 1 so that we always push to the next tile
           // boundary. This is desirable to stop from having a rectangle with a
           // moving origin occasionally being smaller when it coincidentally lines
           // up to tile boundaries.
           rect.Inflate(1);
           float left =
             marginsData->mAlignmentX * floor(rect.x / marginsData->mAlignmentX);
           float top =
             marginsData->mAlignmentY * floor(rect.y / marginsData->mAlignmentY);
           float right =
             marginsData->mAlignmentX * ceil(rect.XMost() / marginsData->mAlignmentX);
           float bottom =
             marginsData->mAlignmentY * ceil(rect.YMost() / marginsData->mAlignmentY);
           rect = LayerRect(left, top, right - left, bottom - top);
           rect -= scrollPosLayer;
         }
         nsRect result;
         result.x = NSFloatPixelsToAppUnits(rect.x / res.width, auPerDevPixel);
         result.y = NSFloatPixelsToAppUnits(rect.y / res.height, auPerDevPixel);
         result.width =
           NSFloatPixelsToAppUnits(rect.width / res.width, auPerDevPixel);
         result.height =
           NSFloatPixelsToAppUnits(rect.height / res.height, auPerDevPixel);
         // Finally, clamp the display port to the expanded scrollable rect.
         nsRect expandedScrollableRect = CalculateExpandedScrollableRect(frame);
         result = expandedScrollableRect.Intersect(result + scrollPos) - scrollPos;
         *aResult = result;
       }
     }
   }
   return true;
 }
 void
 nsLayoutUtils::SetDisplayPortMargins(nsIContent* aContent,
                                      nsIPresShell* aPresShell,
                                      const LayerMargin& aMargins,
                                      uint32_t aAlignmentX,
                                      uint32_t aAlignmentY,
                                      uint32_t aPriority,
                                      RepaintMode aRepaintMode)
 {
   DisplayPortMarginsPropertyData* currentData =
     static_cast<DisplayPortMarginsPropertyData*>(aContent->GetProperty(nsGkAtoms::DisplayPortMargins));
   if (currentData && currentData->mPriority > aPriority) {
     return;
   }
   aContent->SetProperty(nsGkAtoms::DisplayPortMargins,
                         new DisplayPortMarginsPropertyData(
                             aMargins, aAlignmentX, aAlignmentY, aPriority),
                         nsINode::DeleteProperty<DisplayPortMarginsPropertyData>);
   nsIFrame* rootScrollFrame = aPresShell->GetRootScrollFrame();
   if (rootScrollFrame && aContent == rootScrollFrame->GetContent()) {
     // We are setting a root displayport for a document.
     // The pres shell needs a special flag set.
     aPresShell->SetIgnoreViewportScrolling(true);
   }
   if (aRepaintMode == RepaintMode::Repaint) {
     nsIFrame* rootFrame = aPresShell->FrameManager()->GetRootFrame();
     if (rootFrame) {
       rootFrame->SchedulePaint();
     }
   }
 }
 void
 nsLayoutUtils::SetDisplayPortBase(nsIContent* aContent, const nsRect& aBase)
 {
   aContent->SetProperty(nsGkAtoms::DisplayPortBase, new nsRect(aBase),
                         nsINode::DeleteProperty<nsRect>);
 }
 void
 nsLayoutUtils::SetDisplayPortBaseIfNotSet(nsIContent* aContent, const nsRect& aBase)
 {
   if (!aContent->GetProperty(nsGkAtoms::DisplayPortBase)) {
     SetDisplayPortBase(aContent, aBase);
   }
 }
 bool
 nsLayoutUtils::GetCriticalDisplayPort(nsIContent* aContent, nsRect* aResult)
 {
   void* property = aContent->GetProperty(nsGkAtoms::CriticalDisplayPort);
   if (!property) {
     return false;
   }
   if (aResult) {
     *aResult = *static_cast<nsRect*>(property);
   }
   return true;
 }
 nsIFrame*
 nsLayoutUtils::LastContinuationWithChild(nsIFrame* aFrame)
 {
   NS_PRECONDITION(aFrame, "NULL frame pointer");
   aFrame = aFrame->LastContinuation();
   while (!aFrame->GetFirstPrincipalChild() &&
          aFrame->GetPrevContinuation()) {
     aFrame = aFrame->GetPrevContinuation();
   }
   return aFrame;
 }
 /**
  * GetFirstChildFrame returns the first "real" child frame of a
  * given frame.  It will descend down into pseudo-frames (unless the
  * pseudo-frame is the :before generated frame).
  * @param aFrame the frame
  * @param aFrame the frame's content node
  */
 static nsIFrame*
 GetFirstChildFrame(nsIFrame*       aFrame,
                    nsIContent*     aContent)
 {
   NS_PRECONDITION(aFrame, "NULL frame pointer");
   // Get the first child frame
   nsIFrame* childFrame = aFrame->GetFirstPrincipalChild();
   // If the child frame is a pseudo-frame, then return its first child.
   // Note that the frame we create for the generated content is also a
   // pseudo-frame and so don't drill down in that case
   if (childFrame &&
       childFrame->IsPseudoFrame(aContent) &&
       !childFrame->IsGeneratedContentFrame()) {
     return GetFirstChildFrame(childFrame, aContent);
   }
   return childFrame;
 }
 /**
  * GetLastChildFrame returns the last "real" child frame of a
  * given frame.  It will descend down into pseudo-frames (unless the
  * pseudo-frame is the :after generated frame).
  * @param aFrame the frame
  * @param aFrame the frame's content node
  */
 static nsIFrame*
 GetLastChildFrame(nsIFrame*       aFrame,
                   nsIContent*     aContent)
 {
   NS_PRECONDITION(aFrame, "NULL frame pointer");
   // Get the last continuation frame that's a parent
   nsIFrame* lastParentContinuation =
     nsLayoutUtils::LastContinuationWithChild(aFrame);
   nsIFrame* lastChildFrame =
     lastParentContinuation->GetLastChild(nsIFrame::kPrincipalList);
   if (lastChildFrame) {
     // Get the frame's first continuation. This matters in case the frame has
     // been continued across multiple lines or split by BiDi resolution.
     lastChildFrame = lastChildFrame->FirstContinuation();
     // If the last child frame is a pseudo-frame, then return its last child.
     // Note that the frame we create for the generated content is also a
     // pseudo-frame and so don't drill down in that case
     if (lastChildFrame &&
         lastChildFrame->IsPseudoFrame(aContent) &&
         !lastChildFrame->IsGeneratedContentFrame()) {
       return GetLastChildFrame(lastChildFrame, aContent);
     }
     return lastChildFrame;
   }
   return nullptr;
 }
 //static
 FrameChildListID
 nsLayoutUtils::GetChildListNameFor(nsIFrame* aChildFrame)
 {
   nsIFrame::ChildListID id = nsIFrame::kPrincipalList;
   if (aChildFrame->GetStateBits() & NS_FRAME_IS_OVERFLOW_CONTAINER) {
     nsIFrame* pif = aChildFrame->GetPrevInFlow();
     if (pif->GetParent() == aChildFrame->GetParent()) {
       id = nsIFrame::kExcessOverflowContainersList;
     }
     else {
       id = nsIFrame::kOverflowContainersList;
     }
   }
   // See if the frame is moved out of the flow
   else if (aChildFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW) {
     // Look at the style information to tell
     const nsStyleDisplay* disp = aChildFrame->StyleDisplay();
     if (NS_STYLE_POSITION_ABSOLUTE == disp->mPosition) {
       id = nsIFrame::kAbsoluteList;
     } else if (NS_STYLE_POSITION_FIXED == disp->mPosition) {
       if (nsLayoutUtils::IsReallyFixedPos(aChildFrame)) {
         id = nsIFrame::kFixedList;
       } else {
         id = nsIFrame::kAbsoluteList;
       }
 #ifdef MOZ_XUL
     } else if (NS_STYLE_DISPLAY_POPUP == disp->mDisplay) {
       // Out-of-flows that are DISPLAY_POPUP must be kids of the root popup set
 #ifdef DEBUG
       nsIFrame* parent = aChildFrame->GetParent();
       NS_ASSERTION(parent && parent->GetType() == nsGkAtoms::popupSetFrame,
                    "Unexpected parent");
 #endif // DEBUG
       id = nsIFrame::kPopupList;
 #endif // MOZ_XUL
     } else {
       NS_ASSERTION(aChildFrame->IsFloating(), "not a floated frame");
       id = nsIFrame::kFloatList;
     }
   } else {
     nsIAtom* childType = aChildFrame->GetType();
     if (nsGkAtoms::menuPopupFrame == childType) {
       nsIFrame* parent = aChildFrame->GetParent();
       MOZ_ASSERT(parent, "nsMenuPopupFrame can't be the root frame");
       if (parent) {
         if (parent->GetType() == nsGkAtoms::popupSetFrame) {
           id = nsIFrame::kPopupList;
         } else {
           nsIFrame* firstPopup = parent->GetFirstChild(nsIFrame::kPopupList);
           MOZ_ASSERT(!firstPopup || !firstPopup->GetNextSibling(),
                      "We assume popupList only has one child, but it has more.");
           id = firstPopup == aChildFrame
                  ? nsIFrame::kPopupList
                  : nsIFrame::kPrincipalList;
         }
       } else {
         id = nsIFrame::kPrincipalList;
       }
     } else if (nsGkAtoms::tableColGroupFrame == childType) {
       id = nsIFrame::kColGroupList;
     } else if (nsGkAtoms::tableCaptionFrame == childType) {
       id = nsIFrame::kCaptionList;
     } else {
       id = nsIFrame::kPrincipalList;
     }
   }
 #ifdef DEBUG
   // Verify that the frame is actually in that child list or in the
   // corresponding overflow list.
   nsIFrame* parent = aChildFrame->GetParent();
   bool found = parent->GetChildList(id).ContainsFrame(aChildFrame);
   if (!found) {
     if (!(aChildFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW)) {
       found = parent->GetChildList(nsIFrame::kOverflowList)
                 .ContainsFrame(aChildFrame);
     }
     else if (aChildFrame->IsFloating()) {
       found = parent->GetChildList(nsIFrame::kOverflowOutOfFlowList)
                 .ContainsFrame(aChildFrame);
       if (!found) {
         found = parent->GetChildList(nsIFrame::kPushedFloatsList)
                   .ContainsFrame(aChildFrame);
       }
     }
     // else it's positioned and should have been on the 'id' child list.
     NS_POSTCONDITION(found, "not in child list");
   }
 #endif
   return id;
 }
 // static
 nsIFrame*
 nsLayoutUtils::GetBeforeFrame(nsIFrame* aFrame)
 {
   NS_PRECONDITION(aFrame, "NULL frame pointer");
   NS_ASSERTION(!aFrame->GetPrevContinuation(),
                "aFrame must be first continuation");
   nsIFrame* cif = aFrame->GetContentInsertionFrame();
   nsIFrame* firstFrame = GetFirstChildFrame(cif, aFrame->GetContent());
   if (firstFrame && IsGeneratedContentFor(nullptr, firstFrame,
                                           nsCSSPseudoElements::before)) {
     return firstFrame;
   }
   return nullptr;
 }
 // static
 nsIFrame*
 nsLayoutUtils::GetAfterFrame(nsIFrame* aFrame)
 {
   NS_PRECONDITION(aFrame, "NULL frame pointer");
   nsIFrame* cif = aFrame->GetContentInsertionFrame();
   nsIFrame* lastFrame = GetLastChildFrame(cif, aFrame->GetContent());
   if (lastFrame && IsGeneratedContentFor(nullptr, lastFrame,
                                          nsCSSPseudoElements::after)) {
     return lastFrame;
   }
   return nullptr;
 }
 // static
 nsIFrame*
 nsLayoutUtils::GetClosestFrameOfType(nsIFrame* aFrame, nsIAtom* aFrameType)
 {
   for (nsIFrame* frame = aFrame; frame; frame = frame->GetParent()) {
     if (frame->GetType() == aFrameType) {
       return frame;
     }
   }
   return nullptr;
 }
 // static
 nsIFrame*
 nsLayoutUtils::GetStyleFrame(nsIFrame* aFrame)
 {
   if (aFrame->GetType() == nsGkAtoms::tableOuterFrame) {
     nsIFrame* inner = aFrame->GetFirstPrincipalChild();
     NS_ASSERTION(inner, "Outer table must have an inner");
     return inner;
   }
   return aFrame;
 }
 nsIFrame*
 nsLayoutUtils::GetStyleFrame(const nsIContent* aContent)
 {
   nsIFrame *frame = aContent->GetPrimaryFrame();
   if (!frame) {
     return nullptr;
   }
   return nsLayoutUtils::GetStyleFrame(frame);
 }
 nsIFrame*
 nsLayoutUtils::GetFloatFromPlaceholder(nsIFrame* aFrame) {
   NS_ASSERTION(nsGkAtoms::placeholderFrame == aFrame->GetType(),
                "Must have a placeholder here");
   if (aFrame->GetStateBits() & PLACEHOLDER_FOR_FLOAT) {
     nsIFrame *outOfFlowFrame =
       nsPlaceholderFrame::GetRealFrameForPlaceholder(aFrame);
     NS_ASSERTION(outOfFlowFrame->IsFloating(),
                  "How did that happen?");
     return outOfFlowFrame;
   }
   return nullptr;
 }
 // static
 bool
 nsLayoutUtils::IsGeneratedContentFor(nsIContent* aContent,
                                      nsIFrame* aFrame,
                                      nsIAtom* aPseudoElement)
 {
   NS_PRECONDITION(aFrame, "Must have a frame");
   NS_PRECONDITION(aPseudoElement, "Must have a pseudo name");
   if (!aFrame->IsGeneratedContentFrame()) {
     return false;
   }
   nsIFrame* parent = aFrame->GetParent();
   NS_ASSERTION(parent, "Generated content can't be root frame");
   if (parent->IsGeneratedContentFrame()) {
     // Not the root of the generated content
     return false;
   }
   if (aContent && parent->GetContent() != aContent) {
     return false;
   }
   return (aFrame->GetContent()->Tag() == nsGkAtoms::mozgeneratedcontentbefore) ==
     (aPseudoElement == nsCSSPseudoElements::before);
 }
 // static
 nsIFrame*
 nsLayoutUtils::GetCrossDocParentFrame(const nsIFrame* aFrame,
                                       nsPoint* aExtraOffset)
 {
   nsIFrame* p = aFrame->GetParent();
   if (p)
     return p;
   nsView* v = aFrame->GetView();
   if (!v)
     return nullptr;
   v = v->GetParent(); // anonymous inner view
   if (!v)
     return nullptr;
   if (aExtraOffset) {
     *aExtraOffset += v->GetPosition();
   }
   v = v->GetParent(); // subdocumentframe's view
   return v ? v->GetFrame() : nullptr;
 }
 // static
 bool
 nsLayoutUtils::IsProperAncestorFrameCrossDoc(nsIFrame* aAncestorFrame, nsIFrame* aFrame,
                                              nsIFrame* aCommonAncestor)
 {
   if (aFrame == aAncestorFrame)
     return false;
   return IsAncestorFrameCrossDoc(aAncestorFrame, aFrame, aCommonAncestor);
 }
 // static
 bool
 nsLayoutUtils::IsAncestorFrameCrossDoc(const nsIFrame* aAncestorFrame, const nsIFrame* aFrame,
                                        const nsIFrame* aCommonAncestor)
 {
   for (const nsIFrame* f = aFrame; f != aCommonAncestor;
        f = GetCrossDocParentFrame(f)) {
     if (f == aAncestorFrame)
       return true;
   }
   return aCommonAncestor == aAncestorFrame;
 }
 // static
 bool
 nsLayoutUtils::IsProperAncestorFrame(nsIFrame* aAncestorFrame, nsIFrame* aFrame,
                                      nsIFrame* aCommonAncestor)
 {
   if (aFrame == aAncestorFrame)
     return false;
   for (nsIFrame* f = aFrame; f != aCommonAncestor; f = f->GetParent()) {
     if (f == aAncestorFrame)
       return true;
   }
   return aCommonAncestor == aAncestorFrame;
 }
 // static
 int32_t
 nsLayoutUtils::DoCompareTreePosition(nsIContent* aContent1,
                                      nsIContent* aContent2,
                                      int32_t aIf1Ancestor,
                                      int32_t aIf2Ancestor,
                                      const nsIContent* aCommonAncestor)
 {
   NS_PRECONDITION(aContent1, "aContent1 must not be null");
   NS_PRECONDITION(aContent2, "aContent2 must not be null");
   nsAutoTArray<nsINode*, 32> content1Ancestors;
   nsINode* c1;
   for (c1 = aContent1; c1 && c1 != aCommonAncestor; c1 = c1->GetParentNode()) {
     content1Ancestors.AppendElement(c1);
   }
   if (!c1 && aCommonAncestor) {
     // So, it turns out aCommonAncestor was not an ancestor of c1. Oops.
     // Never mind. We can continue as if aCommonAncestor was null.
     aCommonAncestor = nullptr;
   }
   nsAutoTArray<nsINode*, 32> content2Ancestors;
   nsINode* c2;
   for (c2 = aContent2; c2 && c2 != aCommonAncestor; c2 = c2->GetParentNode()) {
     content2Ancestors.AppendElement(c2);
   }
   if (!c2 && aCommonAncestor) {
     // So, it turns out aCommonAncestor was not an ancestor of c2.
     // We need to retry with no common ancestor hint.
     return DoCompareTreePosition(aContent1, aContent2,
                                  aIf1Ancestor, aIf2Ancestor, nullptr);
   }
   int last1 = content1Ancestors.Length() - 1;
   int last2 = content2Ancestors.Length() - 1;
   nsINode* content1Ancestor = nullptr;
   nsINode* content2Ancestor = nullptr;
   while (last1 >= 0 && last2 >= 0
          && ((content1Ancestor = content1Ancestors.ElementAt(last1)) ==
              (content2Ancestor = content2Ancestors.ElementAt(last2)))) {
     last1--;
     last2--;
   }
   if (last1 < 0) {
     if (last2 < 0) {
       NS_ASSERTION(aContent1 == aContent2, "internal error?");
       return 0;
     }
     // aContent1 is an ancestor of aContent2
     return aIf1Ancestor;
   }
   if (last2 < 0) {
     // aContent2 is an ancestor of aContent1
     return aIf2Ancestor;
   }
   // content1Ancestor != content2Ancestor, so they must be siblings with the same parent
   nsINode* parent = content1Ancestor->GetParentNode();
 #ifdef DEBUG
   // TODO: remove the uglyness, see bug 598468.
   NS_ASSERTION(gPreventAssertInCompareTreePosition || parent,
                "no common ancestor at all???");
 #endif // DEBUG
   if (!parent) { // different documents??
     return 0;
   }
   int32_t index1 = parent->IndexOf(content1Ancestor);
   int32_t index2 = parent->IndexOf(content2Ancestor);
   if (index1 < 0 || index2 < 0) {
     // one of them must be anonymous; we can't determine the order
     return 0;
   }
   return index1 - index2;
 }
 // static
 nsIFrame*
 nsLayoutUtils::FillAncestors(nsIFrame* aFrame,
                              nsIFrame* aStopAtAncestor,
                              nsTArray<nsIFrame*>* aAncestors)
 {
   while (aFrame && aFrame != aStopAtAncestor) {
     aAncestors->AppendElement(aFrame);
     aFrame = nsLayoutUtils::GetParentOrPlaceholderFor(aFrame);
   }
   return aFrame;
 }
 // Return true if aFrame1 is after aFrame2
 static bool IsFrameAfter(nsIFrame* aFrame1, nsIFrame* aFrame2)
 {
   nsIFrame* f = aFrame2;
   do {
     f = f->GetNextSibling();
     if (f == aFrame1)
       return true;
   } while (f);
   return false;
 }
 // static
 int32_t
 nsLayoutUtils::DoCompareTreePosition(nsIFrame* aFrame1,
                                      nsIFrame* aFrame2,
                                      int32_t aIf1Ancestor,
                                      int32_t aIf2Ancestor,
                                      nsIFrame* aCommonAncestor)
 {
   NS_PRECONDITION(aFrame1, "aFrame1 must not be null");
   NS_PRECONDITION(aFrame2, "aFrame2 must not be null");
   nsAutoTArray<nsIFrame*,20> frame2Ancestors;
   nsIFrame* nonCommonAncestor =
     FillAncestors(aFrame2, aCommonAncestor, &frame2Ancestors);
   return DoCompareTreePosition(aFrame1, aFrame2, frame2Ancestors,
                                aIf1Ancestor, aIf2Ancestor,
                                nonCommonAncestor ? aCommonAncestor : nullptr);
 }
 // static
 int32_t
 nsLayoutUtils::DoCompareTreePosition(nsIFrame* aFrame1,
                                      nsIFrame* aFrame2,
                                      nsTArray<nsIFrame*>& aFrame2Ancestors,
                                      int32_t aIf1Ancestor,
                                      int32_t aIf2Ancestor,
                                      nsIFrame* aCommonAncestor)
 {
   NS_PRECONDITION(aFrame1, "aFrame1 must not be null");
   NS_PRECONDITION(aFrame2, "aFrame2 must not be null");
   nsPresContext* presContext = aFrame1->PresContext();
   if (presContext != aFrame2->PresContext()) {
     NS_ERROR("no common ancestor at all, different documents");
     return 0;
   }
   nsAutoTArray<nsIFrame*,20> frame1Ancestors;
   if (aCommonAncestor &&
       !FillAncestors(aFrame1, aCommonAncestor, &frame1Ancestors)) {
     // We reached the root of the frame tree ... if aCommonAncestor was set,
     // it is wrong
     return DoCompareTreePosition(aFrame1, aFrame2,
                                  aIf1Ancestor, aIf2Ancestor, nullptr);
   }
   int32_t last1 = int32_t(frame1Ancestors.Length()) - 1;
   int32_t last2 = int32_t(aFrame2Ancestors.Length()) - 1;
   while (last1 >= 0 && last2 >= 0 &&
          frame1Ancestors[last1] == aFrame2Ancestors[last2]) {
     last1--;
     last2--;
   }
   if (last1 < 0) {
     if (last2 < 0) {
       NS_ASSERTION(aFrame1 == aFrame2, "internal error?");
       return 0;
     }
     // aFrame1 is an ancestor of aFrame2
     return aIf1Ancestor;
   }
   if (last2 < 0) {
     // aFrame2 is an ancestor of aFrame1
     return aIf2Ancestor;
   }
   nsIFrame* ancestor1 = frame1Ancestors[last1];
   nsIFrame* ancestor2 = aFrame2Ancestors[last2];
   // Now we should be able to walk sibling chains to find which one is first
   if (IsFrameAfter(ancestor2, ancestor1))
     return -1;
   if (IsFrameAfter(ancestor1, ancestor2))
     return 1;
   NS_WARNING("Frames were in different child lists???");
   return 0;
 }
 // static
 nsIFrame* nsLayoutUtils::GetLastSibling(nsIFrame* aFrame) {
   if (!aFrame) {
     return nullptr;
   }
   nsIFrame* next;
   while ((next = aFrame->GetNextSibling()) != nullptr) {
     aFrame = next;
   }
   return aFrame;
 }
 // static
 nsView*
 nsLayoutUtils::FindSiblingViewFor(nsView* aParentView, nsIFrame* aFrame) {
   nsIFrame* parentViewFrame = aParentView->GetFrame();
   nsIContent* parentViewContent = parentViewFrame ? parentViewFrame->GetContent() : nullptr;
   for (nsView* insertBefore = aParentView->GetFirstChild(); insertBefore;
        insertBefore = insertBefore->GetNextSibling()) {
     nsIFrame* f = insertBefore->GetFrame();
     if (!f) {
       // this view could be some anonymous view attached to a meaningful parent
       for (nsView* searchView = insertBefore->GetParent(); searchView;
            searchView = searchView->GetParent()) {
         f = searchView->GetFrame();
         if (f) {
           break;
         }
       }
       NS_ASSERTION(f, "Can't find a frame anywhere!");
     }
     if (!f || !aFrame->GetContent() || !f->GetContent() ||
         CompareTreePosition(aFrame->GetContent(), f->GetContent(), parentViewContent) > 0) {
       // aFrame's content is after f's content (or we just don't know),
       // so put our view before f's view
       return insertBefore;
     }
   }
   return nullptr;
 }
 //static
 nsIScrollableFrame*
 nsLayoutUtils::GetScrollableFrameFor(const nsIFrame *aScrolledFrame)
 {
   nsIFrame *frame = aScrolledFrame->GetParent();
   nsIScrollableFrame *sf = do_QueryFrame(frame);
   return sf;
 }
 /* static */ void
 nsLayoutUtils::SetFixedPositionLayerData(Layer* aLayer,
                                          const nsIFrame* aViewportFrame,
                                          const nsRect& aAnchorRect,
                                          const nsIFrame* aFixedPosFrame,
                                          nsPresContext* aPresContext,
                                          const ContainerLayerParameters& aContainerParameters) {
   // Find out the rect of the viewport frame relative to the reference frame.
   // This, in conjunction with the container scale, will correspond to the
   // coordinate-space of the built layer.
   float factor = aPresContext->AppUnitsPerDevPixel();
   Rect anchorRect(NSAppUnitsToFloatPixels(aAnchorRect.x, factor) *
                     aContainerParameters.mXScale,
                   NSAppUnitsToFloatPixels(aAnchorRect.y, factor) *
                     aContainerParameters.mYScale,
                   NSAppUnitsToFloatPixels(aAnchorRect.width, factor) *
                     aContainerParameters.mXScale,
                   NSAppUnitsToFloatPixels(aAnchorRect.height, factor) *
                     aContainerParameters.mYScale);
   // Need to transform anchorRect from the container layer's coordinate system
   // into aLayer's coordinate system.
   Matrix transform2d;
   if (aLayer->GetTransform().Is2D(&transform2d)) {
     transform2d.Invert();
     anchorRect = transform2d.TransformBounds(anchorRect);
   } else {
     NS_ERROR("3D transform found between fixedpos content and its viewport (should never happen)");
     anchorRect = Rect(0,0,0,0);
   }
   // Work out the anchor point for this fixed position layer. We assume that
   // any positioning set (left/top/right/bottom) indicates that the
   // corresponding side of its container should be the anchor point,
   // defaulting to top-left.
   LayerPoint anchor(anchorRect.x, anchorRect.y);
   // Make sure the layer is aware of any fixed position margins that have
   // been set.
   nsMargin fixedMargins = aPresContext->PresShell()->GetContentDocumentFixedPositionMargins();
   LayerMargin fixedLayerMargins(NSAppUnitsToFloatPixels(fixedMargins.top, factor) *
                                   aContainerParameters.mYScale,
                                 NSAppUnitsToFloatPixels(fixedMargins.right, factor) *
                                   aContainerParameters.mXScale,
                                 NSAppUnitsToFloatPixels(fixedMargins.bottom, factor) *
                                   aContainerParameters.mYScale,
                                 NSAppUnitsToFloatPixels(fixedMargins.left, factor) *
                                   aContainerParameters.mXScale);
   if (aFixedPosFrame != aViewportFrame) {
     const nsStylePosition* position = aFixedPosFrame->StylePosition();
     if (position->mOffset.GetRightUnit() != eStyleUnit_Auto) {
       if (position->mOffset.GetLeftUnit() != eStyleUnit_Auto) {
         anchor.x = anchorRect.x + anchorRect.width / 2.f;
       } else {
         anchor.x = anchorRect.XMost();
       }
     }
     if (position->mOffset.GetBottomUnit() != eStyleUnit_Auto) {
       if (position->mOffset.GetTopUnit() != eStyleUnit_Auto) {
         anchor.y = anchorRect.y + anchorRect.height / 2.f;
       } else {
         anchor.y = anchorRect.YMost();
       }
     }
     // If the frame is auto-positioned on either axis, set the top/left layer
     // margins to -1, to indicate to the compositor that this layer is
     // unaffected by fixed margins.
     if (position->mOffset.GetLeftUnit() == eStyleUnit_Auto &&
         position->mOffset.GetRightUnit() == eStyleUnit_Auto) {
       fixedLayerMargins.left = -1;
     }
     if (position->mOffset.GetTopUnit() == eStyleUnit_Auto &&
         position->mOffset.GetBottomUnit() == eStyleUnit_Auto) {
       fixedLayerMargins.top = -1;
     }
   }
   aLayer->SetFixedPositionAnchor(anchor);
   aLayer->SetFixedPositionMargins(fixedLayerMargins);
 }
 bool
 nsLayoutUtils::ViewportHasDisplayPort(nsPresContext* aPresContext, nsRect* aDisplayPort)
 {
   nsIFrame* rootScrollFrame =
     aPresContext->PresShell()->GetRootScrollFrame();
   return rootScrollFrame &&
     nsLayoutUtils::GetDisplayPort(rootScrollFrame->GetContent(), aDisplayPort);
 }
 bool
 nsLayoutUtils::IsFixedPosFrameInDisplayPort(const nsIFrame* aFrame, nsRect* aDisplayPort)
 {
   // Fixed-pos frames are parented by the viewport frame or the page content frame.
   // We'll assume that printing/print preview don't have displayports for their
   // pages!
   nsIFrame* parent = aFrame->GetParent();
   if (!parent || parent->GetParent() ||
       aFrame->StyleDisplay()->mPosition != NS_STYLE_POSITION_FIXED) {
     return false;
   }
   return ViewportHasDisplayPort(aFrame->PresContext(), aDisplayPort);
 }
 static nsIFrame*
 GetAnimatedGeometryRootForFrame(nsIFrame* aFrame,
                                 const nsIFrame* aStopAtAncestor)
 {
   nsIFrame* f = aFrame;
   nsIFrame* stickyFrame = nullptr;
   while (f != aStopAtAncestor) {
     if (nsLayoutUtils::IsPopup(f))
       break;
     if (ActiveLayerTracker::IsOffsetOrMarginStyleAnimated(f))
       break;
     if (!f->GetParent() &&
         nsLayoutUtils::ViewportHasDisplayPort(f->PresContext())) {
       // Viewport frames in a display port need to be animated geometry roots
       // for background-attachment:fixed elements.
       break;
     }
     nsIFrame* parent = nsLayoutUtils::GetCrossDocParentFrame(f);
     if (!parent)
       break;
     nsIAtom* parentType = parent->GetType();
 #ifdef ANDROID
     // Treat the slider thumb as being as an active scrolled root
     // on mobile so that it can move without repainting.
     if (parentType == nsGkAtoms::sliderFrame)
       break;
 #endif
     // Sticky frames are active if their nearest scrollable frame
     // is also active, just keep a record of sticky frames that we
     // encounter for now.
     if (f->StyleDisplay()->mPosition == NS_STYLE_POSITION_STICKY &&
         !stickyFrame) {
       stickyFrame = f;
     }
     if (parentType == nsGkAtoms::scrollFrame) {
       nsIScrollableFrame* sf = do_QueryFrame(parent);
       if (sf->IsScrollingActive() && sf->GetScrolledFrame() == f) {
         // If we found a sticky frame inside this active scroll frame,
         // then use that. Otherwise use the scroll frame.
         if (stickyFrame) {
           return stickyFrame;
         }
         return f;
       } else {
         stickyFrame = nullptr;
       }
     }
     // Fixed-pos frames are parented by the viewport frame, which has no parent
     if (nsLayoutUtils::IsFixedPosFrameInDisplayPort(f)) {
       return f;
     }
     f = parent;
   }
   return f;
 }
 nsIFrame*
 nsLayoutUtils::GetAnimatedGeometryRootFor(nsDisplayItem* aItem,
                                           nsDisplayListBuilder* aBuilder)
 {
   nsIFrame* f = aItem->Frame();
   if (aItem->GetType() == nsDisplayItem::TYPE_SCROLL_LAYER) {
     nsDisplayScrollLayer* scrollLayerItem =
       static_cast<nsDisplayScrollLayer*>(aItem);
     nsIFrame* scrolledFrame = scrollLayerItem->GetScrolledFrame();
     return GetAnimatedGeometryRootForFrame(scrolledFrame,
         aBuilder->FindReferenceFrameFor(scrolledFrame));
   }
   if (aItem->ShouldFixToViewport(aBuilder)) {
     // Make its active scrolled root be the active scrolled root of
     // the enclosing viewport, since it shouldn't be scrolled by scrolled
     // frames in its document. InvalidateFixedBackgroundFramesFromList in
     // nsGfxScrollFrame will not repaint this item when scrolling occurs.
     nsIFrame* viewportFrame =
       nsLayoutUtils::GetClosestFrameOfType(f, nsGkAtoms::viewportFrame);
     NS_ASSERTION(viewportFrame, "no viewport???");
     return GetAnimatedGeometryRootForFrame(viewportFrame,
         aBuilder->FindReferenceFrameFor(viewportFrame));
   }
   return GetAnimatedGeometryRootForFrame(f, aItem->ReferenceFrame());
 }
 // static
 nsIScrollableFrame*
 nsLayoutUtils::GetNearestScrollableFrameForDirection(nsIFrame* aFrame,
                                                      Direction aDirection)
 {
   NS_ASSERTION(aFrame, "GetNearestScrollableFrameForDirection expects a non-null frame");
   for (nsIFrame* f = aFrame; f; f = nsLayoutUtils::GetCrossDocParentFrame(f)) {
     nsIScrollableFrame* scrollableFrame = do_QueryFrame(f);
     if (scrollableFrame) {
       ScrollbarStyles ss = scrollableFrame->GetScrollbarStyles();
       uint32_t directions = scrollableFrame->GetPerceivedScrollingDirections();
       if (aDirection == eVertical ?
           (ss.mVertical != NS_STYLE_OVERFLOW_HIDDEN &&
            (directions & nsIScrollableFrame::VERTICAL)) :
           (ss.mHorizontal != NS_STYLE_OVERFLOW_HIDDEN &&
            (directions & nsIScrollableFrame::HORIZONTAL)))
         return scrollableFrame;
     }
   }
   return nullptr;
 }
 // static
 nsIScrollableFrame*
 nsLayoutUtils::GetNearestScrollableFrame(nsIFrame* aFrame, uint32_t aFlags)
 {
   NS_ASSERTION(aFrame, "GetNearestScrollableFrame expects a non-null frame");
   for (nsIFrame* f = aFrame; f; f = (aFlags & SCROLLABLE_SAME_DOC) ?
        f->GetParent() : nsLayoutUtils::GetCrossDocParentFrame(f)) {
     nsIScrollableFrame* scrollableFrame = do_QueryFrame(f);
     if (scrollableFrame) {
       ScrollbarStyles ss = scrollableFrame->GetScrollbarStyles();
       if ((aFlags & SCROLLABLE_INCLUDE_HIDDEN) ||
           ss.mVertical != NS_STYLE_OVERFLOW_HIDDEN ||
           ss.mHorizontal != NS_STYLE_OVERFLOW_HIDDEN)
         return scrollableFrame;
     }
   }
   return nullptr;
 }
 // static
 nsRect
 nsLayoutUtils::GetScrolledRect(nsIFrame* aScrolledFrame,
                                const nsRect& aScrolledFrameOverflowArea,
                                const nsSize& aScrollPortSize,
                                uint8_t aDirection)
 {
   nscoord x1 = aScrolledFrameOverflowArea.x,
           x2 = aScrolledFrameOverflowArea.XMost(),
           y1 = aScrolledFrameOverflowArea.y,
           y2 = aScrolledFrameOverflowArea.YMost();
   if (y1 < 0) {
     y1 = 0;
   }
   if (aDirection != NS_STYLE_DIRECTION_RTL) {
     if (x1 < 0) {
       x1 = 0;
     }
   } else {
     if (x2 > aScrollPortSize.width) {
       x2 = aScrollPortSize.width;
     }
     // When the scrolled frame chooses a size larger than its available width (because
     // its padding alone is larger than the available width), we need to keep the
     // start-edge of the scroll frame anchored to the start-edge of the scrollport.
     // When the scrolled frame is RTL, this means moving it in our left-based
     // coordinate system, so we need to compensate for its extra width here by
     // effectively repositioning the frame.
     nscoord extraWidth = std::max(0, aScrolledFrame->GetSize().width - aScrollPortSize.width);
     x2 += extraWidth;
   }
   return nsRect(x1, y1, x2 - x1, y2 - y1);
 }
 //static
 bool
 nsLayoutUtils::HasPseudoStyle(nsIContent* aContent,
                               nsStyleContext* aStyleContext,
                               nsCSSPseudoElements::Type aPseudoElement,
                               nsPresContext* aPresContext)
 {
   NS_PRECONDITION(aPresContext, "Must have a prescontext");
   nsRefPtr<nsStyleContext> pseudoContext;
   if (aContent) {
     pseudoContext = aPresContext->StyleSet()->
       ProbePseudoElementStyle(aContent->AsElement(), aPseudoElement,
                               aStyleContext);
   }
   return pseudoContext != nullptr;
 }
 nsPoint
 nsLayoutUtils::GetDOMEventCoordinatesRelativeTo(nsIDOMEvent* aDOMEvent, nsIFrame* aFrame)
 {
   if (!aDOMEvent)
     return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
   WidgetEvent* event = aDOMEvent->GetInternalNSEvent();
   if (!event)
     return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
   return GetEventCoordinatesRelativeTo(event, aFrame);
 }
 nsPoint
 nsLayoutUtils::GetEventCoordinatesRelativeTo(const WidgetEvent* aEvent,
                                              nsIFrame* aFrame)
 {
   if (!aEvent || (aEvent->eventStructType != NS_MOUSE_EVENT &&
                   aEvent->eventStructType != NS_MOUSE_SCROLL_EVENT &&
                   aEvent->eventStructType != NS_WHEEL_EVENT &&
                   aEvent->eventStructType != NS_DRAG_EVENT &&
                   aEvent->eventStructType != NS_SIMPLE_GESTURE_EVENT &&
                   aEvent->eventStructType != NS_POINTER_EVENT &&
                   aEvent->eventStructType != NS_GESTURENOTIFY_EVENT &&
                   aEvent->eventStructType != NS_TOUCH_EVENT &&
                   aEvent->eventStructType != NS_QUERY_CONTENT_EVENT))
     return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
   return GetEventCoordinatesRelativeTo(aEvent,
            LayoutDeviceIntPoint::ToUntyped(aEvent->AsGUIEvent()->refPoint),
            aFrame);
 }
 nsPoint
 nsLayoutUtils::GetEventCoordinatesRelativeTo(const WidgetEvent* aEvent,
                                              const nsIntPoint aPoint,
                                              nsIFrame* aFrame)
 {
   if (!aFrame) {
     return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
   }
   nsIWidget* widget = aEvent->AsGUIEvent()->widget;
   if (!widget) {
     return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
   }
   return GetEventCoordinatesRelativeTo(widget, aPoint, aFrame);
 }
 nsPoint
 nsLayoutUtils::GetEventCoordinatesRelativeTo(nsIWidget* aWidget,
                                              const nsIntPoint aPoint,
                                              nsIFrame* aFrame)
 {
   if (!aFrame || !aWidget) {
     return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
   }
   nsView* view = aFrame->GetView();
   if (view) {
     nsIWidget* frameWidget = view->GetWidget();
     if (frameWidget && frameWidget == aWidget) {
       // Special case this cause it happens a lot.
       // This also fixes bug 664707, events in the extra-special case of select
       // dropdown popups that are transformed.
       nsPresContext* presContext = aFrame->PresContext();
       nsPoint pt(presContext->DevPixelsToAppUnits(aPoint.x),
                  presContext->DevPixelsToAppUnits(aPoint.y));
       return pt - view->ViewToWidgetOffset();
     }
   }
   /* If we walk up the frame tree and discover that any of the frames are
    * transformed, we need to do extra work to convert from the global
    * space to the local space.
    */
   nsIFrame* rootFrame = aFrame;
   bool transformFound = false;
   for (nsIFrame* f = aFrame; f; f = GetCrossDocParentFrame(f)) {
     if (f->IsTransformed()) {
       transformFound = true;
     }
     rootFrame = f;
   }
   nsView* rootView = rootFrame->GetView();
   if (!rootView) {
     return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
   }
   nsPoint widgetToView = TranslateWidgetToView(rootFrame->PresContext(),
                                                aWidget, aPoint, rootView);
   if (widgetToView == nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE)) {
     return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
   }
   // Convert from root document app units to app units of the document aFrame
   // is in.
   int32_t rootAPD = rootFrame->PresContext()->AppUnitsPerDevPixel();
   int32_t localAPD = aFrame->PresContext()->AppUnitsPerDevPixel();
   widgetToView = widgetToView.ConvertAppUnits(rootAPD, localAPD);
   /* If we encountered a transform, we can't do simple arithmetic to figure
    * out how to convert back to aFrame's coordinates and must use the CTM.
    */
   if (transformFound || aFrame->IsSVGText()) {
     return TransformRootPointToFrame(aFrame, widgetToView);
   }
   /* Otherwise, all coordinate systems are translations of one another,
    * so we can just subtract out the difference.
    */
   return widgetToView - aFrame->GetOffsetToCrossDoc(rootFrame);
 }
 nsIFrame*
 nsLayoutUtils::GetPopupFrameForEventCoordinates(nsPresContext* aPresContext,
                                                 const WidgetEvent* aEvent)
 {
 #ifdef MOZ_XUL
   nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
   if (!pm) {
     return nullptr;
   }
   nsTArray<nsIFrame*> popups;
   pm->GetVisiblePopups(popups);
   uint32_t i;
   // Search from top to bottom
   for (i = 0; i < popups.Length(); i++) {
     nsIFrame* popup = popups[i];
     if (popup->PresContext()->GetRootPresContext() == aPresContext &&
         popup->GetScrollableOverflowRect().Contains(
           GetEventCoordinatesRelativeTo(aEvent, popup))) {
       return popup;
     }
   }
 #endif
   return nullptr;
 }
 gfx3DMatrix
 nsLayoutUtils::ChangeMatrixBasis(const gfxPoint3D &aOrigin,
                                  const gfx3DMatrix &aMatrix)
 {
   gfx3DMatrix result = aMatrix;
   /* Translate to the origin before aMatrix */
   result.Translate(-aOrigin);
   /* Translate back into position after aMatrix */
   result.TranslatePost(aOrigin);
   return result;
 }
 static void ConstrainToCoordValues(float& aStart, float& aSize)
 {
   MOZ_ASSERT(aSize >= 0);
   // Here we try to make sure that the resulting nsRect will continue to cover
   // as much of the area that was covered by the original gfx Rect as possible.
   // We clamp the bounds of the rect to {nscoord_MIN,nscoord_MAX} since
   // nsRect::X/Y() and nsRect::XMost/YMost() can't return values outwith this
   // range:
   float end = aStart + aSize;
   aStart = clamped(aStart, float(nscoord_MIN), float(nscoord_MAX));
   end = clamped(end, float(nscoord_MIN), float(nscoord_MAX));
   aSize = end - aStart;
   // We must also clamp aSize to {0,nscoord_MAX} since nsRect::Width/Height()
   // can't return a value greater than nscoord_MAX. If aSize is greater than
   // nscoord_MAX then we reduce it to nscoord_MAX while keeping the rect
   // centered:
   if (aSize > nscoord_MAX) {
     float excess = aSize - nscoord_MAX;
     excess /= 2;
     aStart += excess;
     aSize = nscoord_MAX;
   }
 }
 /**
  * Given a gfxFloat, constrains its value to be between nscoord_MIN and nscoord_MAX.
  *
  * @param aVal The value to constrain (in/out)
  */
 static void ConstrainToCoordValues(gfxFloat& aVal)
 {
   if (aVal <= nscoord_MIN)
     aVal = nscoord_MIN;
   else if (aVal >= nscoord_MAX)
     aVal = nscoord_MAX;
 }
 static void ConstrainToCoordValues(gfxFloat& aStart, gfxFloat& aSize)
 {
   gfxFloat max = aStart + aSize;
   // Clamp the end points to within nscoord range
   ConstrainToCoordValues(aStart);
   ConstrainToCoordValues(max);
   aSize = max - aStart;
   // If the width if still greater than the max nscoord, then bring both
   // endpoints in by the same amount until it fits.
   if (aSize > nscoord_MAX) {
     gfxFloat excess = aSize - nscoord_MAX;
     excess /= 2;
     aStart += excess;
     aSize = nscoord_MAX;
   } else if (aSize < nscoord_MIN) {
     gfxFloat excess = aSize - nscoord_MIN;
     excess /= 2;
     aStart -= excess;
     aSize = nscoord_MIN;
   }
 }
 nsRect
 nsLayoutUtils::RoundGfxRectToAppRect(const Rect &aRect, float aFactor)
 {
   /* Get a new Rect whose units are app units by scaling by the specified factor. */
   Rect scaledRect = aRect;
   scaledRect.ScaleRoundOut(aFactor);
   /* We now need to constrain our results to the max and min values for coords. */
   ConstrainToCoordValues(scaledRect.x, scaledRect.width);
   ConstrainToCoordValues(scaledRect.y, scaledRect.height);
   /* Now typecast everything back.  This is guaranteed to be safe. */
   return nsRect(nscoord(scaledRect.X()), nscoord(scaledRect.Y()),
                 nscoord(scaledRect.Width()), nscoord(scaledRect.Height()));
 }
 nsRect
 nsLayoutUtils::RoundGfxRectToAppRect(const gfxRect &aRect, float aFactor)
 {
   /* Get a new gfxRect whose units are app units by scaling by the specified factor. */
   gfxRect scaledRect = aRect;
   scaledRect.ScaleRoundOut(aFactor);
   /* We now need to constrain our results to the max and min values for coords. */
   ConstrainToCoordValues(scaledRect.x, scaledRect.width);
   ConstrainToCoordValues(scaledRect.y, scaledRect.height);
   /* Now typecast everything back.  This is guaranteed to be safe. */
   return nsRect(nscoord(scaledRect.X()), nscoord(scaledRect.Y()),
                 nscoord(scaledRect.Width()), nscoord(scaledRect.Height()));
 }
 nsRegion
 nsLayoutUtils::RoundedRectIntersectRect(const nsRect& aRoundedRect,
                                         const nscoord aRadii[8],
                                         const nsRect& aContainedRect)
 {
   // rectFullHeight and rectFullWidth together will approximately contain
   // the total area of the frame minus the rounded corners.
   nsRect rectFullHeight = aRoundedRect;
   nscoord xDiff = std::max(aRadii[NS_CORNER_TOP_LEFT_X], aRadii[NS_CORNER_BOTTOM_LEFT_X]);
   rectFullHeight.x += xDiff;
   rectFullHeight.width -= std::max(aRadii[NS_CORNER_TOP_RIGHT_X],
                                  aRadii[NS_CORNER_BOTTOM_RIGHT_X]) + xDiff;
   nsRect r1;
   r1.IntersectRect(rectFullHeight, aContainedRect);
   nsRect rectFullWidth = aRoundedRect;
   nscoord yDiff = std::max(aRadii[NS_CORNER_TOP_LEFT_Y], aRadii[NS_CORNER_TOP_RIGHT_Y]);
   rectFullWidth.y += yDiff;
   rectFullWidth.height -= std::max(aRadii[NS_CORNER_BOTTOM_LEFT_Y],
                                  aRadii[NS_CORNER_BOTTOM_RIGHT_Y]) + yDiff;
   nsRect r2;
   r2.IntersectRect(rectFullWidth, aContainedRect);
   nsRegion result;
   result.Or(r1, r2);
   return result;
 }
 // Helper for RoundedRectIntersectsRect.
 static bool
 CheckCorner(nscoord aXOffset, nscoord aYOffset,
             nscoord aXRadius, nscoord aYRadius)
 {
   NS_ABORT_IF_FALSE(aXOffset > 0 && aYOffset > 0,
                     "must not pass nonpositives to CheckCorner");
   NS_ABORT_IF_FALSE(aXRadius >= 0 && aYRadius >= 0,
                     "must not pass negatives to CheckCorner");
   // Avoid floating point math unless we're either (1) within the
   // quarter-ellipse area at the rounded corner or (2) outside the
   // rounding.
   if (aXOffset >= aXRadius || aYOffset >= aYRadius)
     return true;
   // Convert coordinates to a unit circle with (0,0) as the center of
   // curvature, and see if we're inside the circle or outside.
   float scaledX = float(aXRadius - aXOffset) / float(aXRadius);
   float scaledY = float(aYRadius - aYOffset) / float(aYRadius);
   return scaledX * scaledX + scaledY * scaledY < 1.0f;
 }
 bool
 nsLayoutUtils::RoundedRectIntersectsRect(const nsRect& aRoundedRect,
                                          const nscoord aRadii[8],
                                          const nsRect& aTestRect)
 {
   if (!aTestRect.Intersects(aRoundedRect))
     return false;
   // distances from this edge of aRoundedRect to opposite edge of aTestRect,
   // which we know are positive due to the Intersects check above.
   nsMargin insets;
   insets.top = aTestRect.YMost() - aRoundedRect.y;
   insets.right = aRoundedRect.XMost() - aTestRect.x;
   insets.bottom = aRoundedRect.YMost() - aTestRect.y;
   insets.left = aTestRect.XMost() - aRoundedRect.x;
   // Check whether the bottom-right corner of aTestRect is inside the
   // top left corner of aBounds when rounded by aRadii, etc.  If any
   // corner is not, then fail; otherwise succeed.
   return CheckCorner(insets.left, insets.top,
                      aRadii[NS_CORNER_TOP_LEFT_X],
                      aRadii[NS_CORNER_TOP_LEFT_Y]) &&
          CheckCorner(insets.right, insets.top,
                      aRadii[NS_CORNER_TOP_RIGHT_X],
                      aRadii[NS_CORNER_TOP_RIGHT_Y]) &&
          CheckCorner(insets.right, insets.bottom,
                      aRadii[NS_CORNER_BOTTOM_RIGHT_X],
                      aRadii[NS_CORNER_BOTTOM_RIGHT_Y]) &&
          CheckCorner(insets.left, insets.bottom,
                      aRadii[NS_CORNER_BOTTOM_LEFT_X],
                      aRadii[NS_CORNER_BOTTOM_LEFT_Y]);
 }
 nsRect
 nsLayoutUtils::MatrixTransformRectOut(const nsRect &aBounds,
                                       const gfx3DMatrix &aMatrix, float aFactor)
 {
   nsRect outside = aBounds;
   outside.ScaleRoundOut(1/aFactor);
   gfxRect image = aMatrix.TransformBounds(gfxRect(outside.x,
                                                   outside.y,
                                                   outside.width,
                                                   outside.height));
   return RoundGfxRectToAppRect(image, aFactor);
 }
 nsRect
 nsLayoutUtils::MatrixTransformRect(const nsRect &aBounds,
                                    const gfx3DMatrix &aMatrix, float aFactor)
 {
   gfxRect image = aMatrix.TransformBounds(gfxRect(NSAppUnitsToDoublePixels(aBounds.x, aFactor),
                                                   NSAppUnitsToDoublePixels(aBounds.y, aFactor),
                                                   NSAppUnitsToDoublePixels(aBounds.width, aFactor),
                                                   NSAppUnitsToDoublePixels(aBounds.height, aFactor)));
   return RoundGfxRectToAppRect(image, aFactor);
 }
 nsPoint
 nsLayoutUtils::MatrixTransformPoint(const nsPoint &aPoint,
                                     const gfx3DMatrix &aMatrix, float aFactor)
 {
   gfxPoint image = aMatrix.Transform(gfxPoint(NSAppUnitsToFloatPixels(aPoint.x, aFactor),
                                               NSAppUnitsToFloatPixels(aPoint.y, aFactor)));
   return nsPoint(NSFloatPixelsToAppUnits(float(image.x), aFactor),
                  NSFloatPixelsToAppUnits(float(image.y), aFactor));
 }
 gfx3DMatrix
 nsLayoutUtils::GetTransformToAncestor(nsIFrame *aFrame, const nsIFrame *aAncestor)
 {
   nsIFrame* parent;
   gfx3DMatrix ctm;
   if (aFrame == aAncestor) {
     return ctm;
   }
   ctm = aFrame->GetTransformMatrix(aAncestor, &parent);
   while (parent && parent != aAncestor) {
     if (!parent->Preserves3DChildren()) {
       ctm.ProjectTo2D();
     }
     ctm = ctm * parent->GetTransformMatrix(aAncestor, &parent);
   }
   return ctm;
 }
 static nsIFrame*
 FindNearestCommonAncestorFrame(nsIFrame* aFrame1, nsIFrame* aFrame2)
 {
   nsAutoTArray<nsIFrame*,100> ancestors1;
   nsAutoTArray<nsIFrame*,100> ancestors2;
   nsIFrame* commonAncestor = nullptr;
   if (aFrame1->PresContext() == aFrame2->PresContext()) {
     commonAncestor = aFrame1->PresContext()->PresShell()->GetRootFrame();
   }
   for (nsIFrame* f = aFrame1; f != commonAncestor;
        f = nsLayoutUtils::GetCrossDocParentFrame(f)) {
     ancestors1.AppendElement(f);
   }
   for (nsIFrame* f = aFrame2; f != commonAncestor;
        f = nsLayoutUtils::GetCrossDocParentFrame(f)) {
     ancestors2.AppendElement(f);
   }
   uint32_t minLengths = std::min(ancestors1.Length(), ancestors2.Length());
   for (uint32_t i = 1; i <= minLengths; ++i) {
     if (ancestors1[ancestors1.Length() - i] == ancestors2[ancestors2.Length() - i]) {
       commonAncestor = ancestors1[ancestors1.Length() - i];
     } else {
       break;
     }
   }
   return commonAncestor;
 }
 nsLayoutUtils::TransformResult
 nsLayoutUtils::TransformPoints(nsIFrame* aFromFrame, nsIFrame* aToFrame,
                                uint32_t aPointCount, CSSPoint* aPoints)
 {
   nsIFrame* nearestCommonAncestor = FindNearestCommonAncestorFrame(aFromFrame, aToFrame);
   if (!nearestCommonAncestor) {
     return NO_COMMON_ANCESTOR;
   }
   gfx3DMatrix downToDest = GetTransformToAncestor(aToFrame, nearestCommonAncestor);
   if (downToDest.IsSingular()) {
     return NONINVERTIBLE_TRANSFORM;
   }
   downToDest.Invert();
   gfx3DMatrix upToAncestor = GetTransformToAncestor(aFromFrame, nearestCommonAncestor);
   CSSToLayoutDeviceScale devPixelsPerCSSPixelFromFrame(
     double(nsPresContext::AppUnitsPerCSSPixel())/
       aFromFrame->PresContext()->AppUnitsPerDevPixel());
   CSSToLayoutDeviceScale devPixelsPerCSSPixelToFrame(
     double(nsPresContext::AppUnitsPerCSSPixel())/
       aToFrame->PresContext()->AppUnitsPerDevPixel());
   for (uint32_t i = 0; i < aPointCount; ++i) {
     LayoutDevicePoint devPixels = aPoints[i] * devPixelsPerCSSPixelFromFrame;
     gfxPoint toDevPixels = downToDest.ProjectPoint(
         upToAncestor.ProjectPoint(gfxPoint(devPixels.x, devPixels.y)));
     // Divide here so that when the devPixelsPerCSSPixels are the same, we get the correct
     // answer instead of some inaccuracy multiplying a number by its reciprocal.
     aPoints[i] = LayoutDevicePoint(toDevPixels.x, toDevPixels.y) /
         devPixelsPerCSSPixelToFrame;
   }
   return TRANSFORM_SUCCEEDED;
 }
 bool
 nsLayoutUtils::GetLayerTransformForFrame(nsIFrame* aFrame,
                                          gfx3DMatrix* aTransform)
 {
   // FIXME/bug 796690: we can sometimes compute a transform in these
   // cases, it just increases complexity considerably.  Punt for now.
   if (aFrame->Preserves3DChildren() || aFrame->HasTransformGetter()) {
     return false;
   }
   nsIFrame* root = nsLayoutUtils::GetDisplayRootFrame(aFrame);
   if (root->HasAnyStateBits(NS_FRAME_UPDATE_LAYER_TREE)) {
     // Content may have been invalidated, so we can't reliably compute
     // the "layer transform" in general.
     return false;
   }
   // If the caller doesn't care about the value, early-return to skip
   // overhead below.
   if (!aTransform) {
     return true;
   }
   nsDisplayListBuilder builder(root, nsDisplayListBuilder::OTHER,
                                false/*don't build caret*/);
   nsDisplayList list;
   nsDisplayTransform* item =
     new (&builder) nsDisplayTransform(&builder, aFrame, &list);
   *aTransform =
     item->GetTransform();
   item->~nsDisplayTransform();
   return true;
 }
 static bool
 TransformGfxPointFromAncestor(nsIFrame *aFrame,
                               const gfxPoint &aPoint,
                               nsIFrame *aAncestor,
                               gfxPoint* aOut)
 {
   gfx3DMatrix ctm = nsLayoutUtils::GetTransformToAncestor(aFrame, aAncestor);
   float factor = aFrame->PresContext()->AppUnitsPerDevPixel();
   nsRect childBounds = aFrame->GetVisualOverflowRectRelativeToSelf();
   gfxRect childGfxBounds(NSAppUnitsToFloatPixels(childBounds.x, factor),
                          NSAppUnitsToFloatPixels(childBounds.y, factor),
                          NSAppUnitsToFloatPixels(childBounds.width, factor),
                          NSAppUnitsToFloatPixels(childBounds.height, factor));
   return ctm.UntransformPoint(aPoint, childGfxBounds, aOut);
 }
 static gfxRect
 TransformGfxRectToAncestor(nsIFrame *aFrame,
                            const gfxRect &aRect,
                            const nsIFrame *aAncestor,
                            bool* aPreservesAxisAlignedRectangles = nullptr)
 {
   gfx3DMatrix ctm = nsLayoutUtils::GetTransformToAncestor(aFrame, aAncestor);
   if (aPreservesAxisAlignedRectangles) {
     gfxMatrix matrix2d;
     *aPreservesAxisAlignedRectangles =
       ctm.Is2D(&matrix2d) && matrix2d.PreservesAxisAlignedRectangles();
   }
   return ctm.TransformBounds(aRect);
 }
 static SVGTextFrame*
 GetContainingSVGTextFrame(nsIFrame* aFrame)
 {
   if (!aFrame->IsSVGText()) {
     return nullptr;
   }
   return static_cast<SVGTextFrame*>
     (nsLayoutUtils::GetClosestFrameOfType(aFrame->GetParent(),
                                           nsGkAtoms::svgTextFrame));
 }
 nsPoint
 nsLayoutUtils::TransformAncestorPointToFrame(nsIFrame* aFrame,
                                              const nsPoint& aPoint,
                                              nsIFrame* aAncestor)
 {
     SVGTextFrame* text = GetContainingSVGTextFrame(aFrame);
     float factor = aFrame->PresContext()->AppUnitsPerDevPixel();
     gfxPoint result(NSAppUnitsToFloatPixels(aPoint.x, factor),
                     NSAppUnitsToFloatPixels(aPoint.y, factor));
     if (text) {
         if (!TransformGfxPointFromAncestor(text, result, aAncestor, &result)) {
             return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
         }
         result = text->TransformFramePointToTextChild(result, aFrame);
     } else {
         if (!TransformGfxPointFromAncestor(aFrame, result, nullptr, &result)) {
             return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
         }
     }
     return nsPoint(NSFloatPixelsToAppUnits(float(result.x), factor),
                    NSFloatPixelsToAppUnits(float(result.y), factor));
 }
 nsRect
 nsLayoutUtils::TransformFrameRectToAncestor(nsIFrame* aFrame,
                                             const nsRect& aRect,
                                             const nsIFrame* aAncestor,
                                             bool* aPreservesAxisAlignedRectangles /* = nullptr */)
 {
   SVGTextFrame* text = GetContainingSVGTextFrame(aFrame);
   float srcAppUnitsPerDevPixel = aFrame->PresContext()->AppUnitsPerDevPixel();
   gfxRect result;
   if (text) {
     result = text->TransformFrameRectFromTextChild(aRect, aFrame);
     result = TransformGfxRectToAncestor(text, result, aAncestor);
     // TransformFrameRectFromTextChild could involve any kind of transform, we
     // could drill down into it to get an answer out of it but we don't yet.
     if (aPreservesAxisAlignedRectangles)
       *aPreservesAxisAlignedRectangles = false;
   } else {
     result = gfxRect(NSAppUnitsToFloatPixels(aRect.x, srcAppUnitsPerDevPixel),
                      NSAppUnitsToFloatPixels(aRect.y, srcAppUnitsPerDevPixel),
                      NSAppUnitsToFloatPixels(aRect.width, srcAppUnitsPerDevPixel),
                      NSAppUnitsToFloatPixels(aRect.height, srcAppUnitsPerDevPixel));
     result = TransformGfxRectToAncestor(aFrame, result, aAncestor, aPreservesAxisAlignedRectangles);
   }
   float destAppUnitsPerDevPixel = aAncestor->PresContext()->AppUnitsPerDevPixel();
   return nsRect(NSFloatPixelsToAppUnits(float(result.x), destAppUnitsPerDevPixel),
                 NSFloatPixelsToAppUnits(float(result.y), destAppUnitsPerDevPixel),
                 NSFloatPixelsToAppUnits(float(result.width), destAppUnitsPerDevPixel),
                 NSFloatPixelsToAppUnits(float(result.height), destAppUnitsPerDevPixel));
 }
 static nsIntPoint GetWidgetOffset(nsIWidget* aWidget, nsIWidget*& aRootWidget) {
   nsIntPoint offset(0, 0);
   nsIWidget* parent = aWidget->GetParent();
   while (parent) {
     nsIntRect bounds;
     aWidget->GetBounds(bounds);
     offset += bounds.TopLeft();
     aWidget = parent;
     parent = aWidget->GetParent();
   }
   aRootWidget = aWidget;
   return offset;
 }
 nsPoint
 nsLayoutUtils::TranslateWidgetToView(nsPresContext* aPresContext,
                                      nsIWidget* aWidget, nsIntPoint aPt,
                                      nsView* aView)
 {
   nsPoint viewOffset;
   nsIWidget* viewWidget = aView->GetNearestWidget(&viewOffset);
   if (!viewWidget) {
     return nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
   }
   nsIWidget* fromRoot;
   nsIntPoint fromOffset = GetWidgetOffset(aWidget, fromRoot);
   nsIWidget* toRoot;
   nsIntPoint toOffset = GetWidgetOffset(viewWidget, toRoot);
   nsIntPoint widgetPoint;
   if (fromRoot == toRoot) {
     widgetPoint = aPt + fromOffset - toOffset;
   } else {
     nsIntPoint screenPoint = aWidget->WidgetToScreenOffset();
     widgetPoint = aPt + screenPoint - viewWidget->WidgetToScreenOffset();
   }
   nsPoint widgetAppUnits(aPresContext->DevPixelsToAppUnits(widgetPoint.x),
                          aPresContext->DevPixelsToAppUnits(widgetPoint.y));
   return widgetAppUnits - viewOffset;
 }
 // Combine aNewBreakType with aOrigBreakType, but limit the break types
 // to NS_STYLE_CLEAR_LEFT, RIGHT, BOTH.
 uint8_t
 nsLayoutUtils::CombineBreakType(uint8_t aOrigBreakType,
                                 uint8_t aNewBreakType)
 {
   uint8_t breakType = aOrigBreakType;
   switch(breakType) {
   case NS_STYLE_CLEAR_LEFT:
     if (NS_STYLE_CLEAR_RIGHT == aNewBreakType ||
         NS_STYLE_CLEAR_BOTH == aNewBreakType) {
       breakType = NS_STYLE_CLEAR_BOTH;
     }
     break;
   case NS_STYLE_CLEAR_RIGHT:
     if (NS_STYLE_CLEAR_LEFT == aNewBreakType ||
         NS_STYLE_CLEAR_BOTH == aNewBreakType) {
       breakType = NS_STYLE_CLEAR_BOTH;
     }
     break;
   case NS_STYLE_CLEAR_NONE:
     if (NS_STYLE_CLEAR_LEFT == aNewBreakType ||
         NS_STYLE_CLEAR_RIGHT == aNewBreakType ||
         NS_STYLE_CLEAR_BOTH == aNewBreakType) {
       breakType = aNewBreakType;
     }
   }
   return breakType;
 }
 #ifdef MOZ_DUMP_PAINTING
 #include <stdio.h>
 static bool gDumpEventList = false;
 int gPaintCount = 0;
 #endif
 nsresult
 nsLayoutUtils::GetRemoteContentIds(nsIFrame* aFrame,
                                    const nsRect& aTarget,
                                    nsTArray<ViewID> &aOutIDs,
                                    bool aIgnoreRootScrollFrame)
 {
   nsDisplayListBuilder builder(aFrame, nsDisplayListBuilder::EVENT_DELIVERY,
                                false);
   nsDisplayList list;
   if (aIgnoreRootScrollFrame) {
     nsIFrame* rootScrollFrame =
       aFrame->PresContext()->PresShell()->GetRootScrollFrame();
     if (rootScrollFrame) {
       builder.SetIgnoreScrollFrame(rootScrollFrame);
     }
   }
   builder.EnterPresShell(aFrame, aTarget);
   aFrame->BuildDisplayListForStackingContext(&builder, aTarget, &list);
   builder.LeavePresShell(aFrame, aTarget);
   nsAutoTArray<nsIFrame*,8> outFrames;
   nsDisplayItem::HitTestState hitTestState(&aOutIDs);
   list.HitTest(&builder, aTarget, &hitTestState, &outFrames);
   list.DeleteAll();
   return NS_OK;
 }
 nsIFrame*
 nsLayoutUtils::GetFrameForPoint(nsIFrame* aFrame, nsPoint aPt, uint32_t aFlags)
 {
   PROFILER_LABEL("nsLayoutUtils", "GetFrameForPoint");
   nsresult rv;
   nsAutoTArray<nsIFrame*,8> outFrames;
   rv = GetFramesForArea(aFrame, nsRect(aPt, nsSize(1, 1)), outFrames, aFlags);
   NS_ENSURE_SUCCESS(rv, nullptr);
   return outFrames.Length() ? outFrames.ElementAt(0) : nullptr;
 }
 nsresult
 nsLayoutUtils::GetFramesForArea(nsIFrame* aFrame, const nsRect& aRect,
                                 nsTArray<nsIFrame*> &aOutFrames,
                                 uint32_t aFlags)
 {
   PROFILER_LABEL("nsLayoutUtils","GetFramesForArea");
   nsDisplayListBuilder builder(aFrame, nsDisplayListBuilder::EVENT_DELIVERY,
                                false);
   nsDisplayList list;
   nsRect target(aRect);
   if (aFlags & IGNORE_PAINT_SUPPRESSION) {
     builder.IgnorePaintSuppression();
   }
   if (aFlags & IGNORE_ROOT_SCROLL_FRAME) {
     nsIFrame* rootScrollFrame =
       aFrame->PresContext()->PresShell()->GetRootScrollFrame();
     if (rootScrollFrame) {
       builder.SetIgnoreScrollFrame(rootScrollFrame);
     }
   }
   if (aFlags & IGNORE_CROSS_DOC) {
     builder.SetDescendIntoSubdocuments(false);
   }
   builder.EnterPresShell(aFrame, target);
   aFrame->BuildDisplayListForStackingContext(&builder, target, &list);
   builder.LeavePresShell(aFrame, target);
 #ifdef MOZ_DUMP_PAINTING
   if (gDumpEventList) {
     fprintf_stderr(stderr, "Event handling --- (%d,%d):\n", aRect.x, aRect.y);
     nsFrame::PrintDisplayList(&builder, list);
   }
 #endif
   nsDisplayItem::HitTestState hitTestState;
   list.HitTest(&builder, target, &hitTestState, &aOutFrames);
   list.DeleteAll();
   return NS_OK;
 }
 // This function is only used on B2G, and some compilers complain about
 // unused static functions, so we need to #ifdef it.
 #ifdef MOZ_WIDGET_GONK
 // aScrollFrame and aScrollFrameAsScrollable must be non-nullptr
 static FrameMetrics
 CalculateFrameMetricsForDisplayPort(nsIFrame* aScrollFrame,
                                     nsIScrollableFrame* aScrollFrameAsScrollable) {
   // Calculate the metrics necessary for calculating the displayport.
   // This code has a lot in common with the code in RecordFrameMetrics();
   // we may want to refactor this at some point.
   FrameMetrics metrics;
   nsPresContext* presContext = aScrollFrame->PresContext();
   nsIPresShell* presShell = presContext->PresShell();
   CSSToLayoutDeviceScale deviceScale(float(nsPresContext::AppUnitsPerCSSPixel())
                                      / presContext->AppUnitsPerDevPixel());
   ParentLayerToLayerScale resolution(presShell->GetResolution().width);
   LayoutDeviceToLayerScale cumulativeResolution(presShell->GetCumulativeResolution().width);
   metrics.mDevPixelsPerCSSPixel = deviceScale;
   metrics.mResolution = resolution;
   metrics.mCumulativeResolution = cumulativeResolution;
   metrics.SetZoom(deviceScale * cumulativeResolution * LayerToScreenScale(1));
   // Only the size of the composition bounds is relevant to the
   // displayport calculation, not its origin.
   nsSize compositionSize = nsLayoutUtils::CalculateCompositionSizeForFrame(aScrollFrame);
   metrics.mCompositionBounds
       = RoundedToInt(LayoutDeviceRect::FromAppUnits(nsRect(nsPoint(0, 0), compositionSize),
                                                     presContext->AppUnitsPerDevPixel())
                      * (cumulativeResolution / resolution));
   // This function is used for setting a display port for subframes, so
   // aScrollFrame will not be the root content document's root scroll frame.
   metrics.SetRootCompositionSize(
       nsLayoutUtils::CalculateRootCompositionSize(aScrollFrame, false, metrics));
   metrics.SetScrollOffset(CSSPoint::FromAppUnits(
       aScrollFrameAsScrollable->GetScrollPosition()));
   metrics.mScrollableRect = CSSRect::FromAppUnits(
       nsLayoutUtils::CalculateScrollableRectForFrame(aScrollFrameAsScrollable, nullptr));
   return metrics;
 }
 #endif
 bool
 nsLayoutUtils::GetOrMaybeCreateDisplayPort(nsDisplayListBuilder& aBuilder,
                                            nsIFrame* aScrollFrame,
                                            nsRect aDisplayPortBase,
                                            nsRect* aOutDisplayport) {
   nsIContent* content = aScrollFrame->GetContent();
   nsIScrollableFrame* scrollableFrame = do_QueryFrame(aScrollFrame);
   if (!content || !scrollableFrame) {
     return false;
   }
   // Set the base rect. Note that this will not influence 'haveDisplayPort',
   // which is based on either the whole rect or margins being set, but it
   // will affect what is returned in 'aOutDisplayPort' if margins are set.
   SetDisplayPortBase(content, aDisplayPortBase);
   bool haveDisplayPort = GetDisplayPort(content, aOutDisplayport);
 #ifdef MOZ_WIDGET_GONK
   // On B2G, we perform an optimization where we ensure that at least one
   // async-scrollable frame (i.e. one that WantsAsyncScroll()) has a displayport.
   // If that's not the case yet, and we are async-scrollable, we will get a
   // displayport.
   // Note: we only do this in processes where we do subframe scrolling to
   //       begin with (i.e., not in the parent process on B2G).
   if (WantSubAPZC() &&
       !aBuilder.HaveScrollableDisplayPort() &&
       scrollableFrame->WantAsyncScroll()) {
     // If we don't already have a displayport, calculate and set one.
     if (!haveDisplayPort) {
       FrameMetrics metrics = CalculateFrameMetricsForDisplayPort(aScrollFrame, scrollableFrame);
       LayerMargin displayportMargins = AsyncPanZoomController::CalculatePendingDisplayPort(
           metrics, ScreenPoint(0.0f, 0.0f), 0.0);
       nsIPresShell* presShell = aScrollFrame->PresContext()->GetPresShell();
       gfx::IntSize alignment = gfxPrefs::LayersTilesEnabled()
           ? gfx::IntSize(gfxPrefs::LayersTileWidth(), gfxPrefs::LayersTileHeight()) :
             gfx::IntSize(0, 0);
       nsLayoutUtils::SetDisplayPortMargins(
           content, presShell, displayportMargins, alignment.width,
           alignment.height, 0, nsLayoutUtils::RepaintMode::DoNotRepaint);
       haveDisplayPort = GetDisplayPort(content, aOutDisplayport);
       NS_ASSERTION(haveDisplayPort, "should have a displayport after having just set it");
     }
     // Record that the we now have a scrollable display port.
     aBuilder.SetHaveScrollableDisplayPort();
   }
 #endif
   return haveDisplayPort;
 }
 nsresult
 nsLayoutUtils::PaintFrame(nsRenderingContext* aRenderingContext, nsIFrame* aFrame,
                           const nsRegion& aDirtyRegion, nscolor aBackstop,
                           uint32_t aFlags)
 {
   PROFILER_LABEL("nsLayoutUtils","PaintFrame");
   if (aFlags & PAINT_WIDGET_LAYERS) {
     nsView* view = aFrame->GetView();
     if (!(view && view->GetWidget() && GetDisplayRootFrame(aFrame) == aFrame)) {
       aFlags &= ~PAINT_WIDGET_LAYERS;
       NS_ASSERTION(aRenderingContext, "need a rendering context");
     }
   }
   nsPresContext* presContext = aFrame->PresContext();
   nsIPresShell* presShell = presContext->PresShell();
   nsRootPresContext* rootPresContext = presContext->GetRootPresContext();
   if (!rootPresContext) {
     return NS_OK;
   }
   nsDisplayListBuilder builder(aFrame, nsDisplayListBuilder::PAINTING,
                            !(aFlags & PAINT_HIDE_CARET));
   nsIFrame* rootScrollFrame = presShell->GetRootScrollFrame();
   bool usingDisplayPort = false;
   nsRect displayport;
   if (rootScrollFrame && !aFrame->GetParent()) {
     nsRect displayportBase(
         nsPoint(0,0),
         nsLayoutUtils::CalculateCompositionSizeForFrame(rootScrollFrame));
     usingDisplayPort = nsLayoutUtils::GetOrMaybeCreateDisplayPort(
         builder, rootScrollFrame, displayportBase, &displayport);
   }
   nsRegion visibleRegion;
   if (aFlags & PAINT_WIDGET_LAYERS) {
     // This layer tree will be reused, so we'll need to calculate it
     // for the whole "visible" area of the window
     //
     // |ignoreViewportScrolling| and |usingDisplayPort| are persistent
     // document-rendering state.  We rely on PresShell to flush
     // retained layers as needed when that persistent state changes.
     if (!usingDisplayPort) {
       visibleRegion = aFrame->GetVisualOverflowRectRelativeToSelf();
     } else {
       visibleRegion = displayport;
     }
   } else {
     visibleRegion = aDirtyRegion;
   }
   // If we're going to display something different from what we'd normally
   // paint in a window then we will flush out any retained layer trees before
   // *and after* we draw.
   bool willFlushRetainedLayers = (aFlags & PAINT_HIDE_CARET) != 0;
   nsDisplayList list;
   if (aFlags & PAINT_IN_TRANSFORM) {
     builder.SetInTransform(true);
   }
   if (aFlags & PAINT_SYNC_DECODE_IMAGES) {
     builder.SetSyncDecodeImages(true);
   }
   if (aFlags & (PAINT_WIDGET_LAYERS | PAINT_TO_WINDOW)) {
     builder.SetPaintingToWindow(true);
   }
   if (aFlags & PAINT_IGNORE_SUPPRESSION) {
     builder.IgnorePaintSuppression();
   }
   // Windowed plugins aren't allowed in popups
   if ((aFlags & PAINT_WIDGET_LAYERS) &&
       !willFlushRetainedLayers &&
       !(aFlags & PAINT_DOCUMENT_RELATIVE) &&
       rootPresContext->NeedToComputePluginGeometryUpdates()) {
     builder.SetWillComputePluginGeometry(true);
   }
   nsRect canvasArea(nsPoint(0, 0), aFrame->GetSize());
   bool ignoreViewportScrolling =
     aFrame->GetParent() ? false : presShell->IgnoringViewportScrolling();
   if (ignoreViewportScrolling && rootScrollFrame) {
     nsIScrollableFrame* rootScrollableFrame =
       presShell->GetRootScrollFrameAsScrollable();
     if (aFlags & PAINT_DOCUMENT_RELATIVE) {
       // Make visibleRegion and aRenderingContext relative to the
       // scrolled frame instead of the root frame.
       nsPoint pos = rootScrollableFrame->GetScrollPosition();
       visibleRegion.MoveBy(-pos);
       if (aRenderingContext) {
         aRenderingContext->Translate(pos);
       }
     }
     builder.SetIgnoreScrollFrame(rootScrollFrame);
     nsCanvasFrame* canvasFrame =
       do_QueryFrame(rootScrollableFrame->GetScrolledFrame());
     if (canvasFrame) {
       // Use UnionRect here to ensure that areas where the scrollbars
       // were are still filled with the background color.
       canvasArea.UnionRect(canvasArea,
         canvasFrame->CanvasArea() + builder.ToReferenceFrame(canvasFrame));
     }
   }
   nsRect dirtyRect = visibleRegion.GetBounds();
   builder.EnterPresShell(aFrame, dirtyRect);
   {
     PROFILER_LABEL("nsLayoutUtils","PaintFrame::BuildDisplayList");
     aFrame->BuildDisplayListForStackingContext(&builder, dirtyRect, &list);
   }
   const bool paintAllContinuations = aFlags & PAINT_ALL_CONTINUATIONS;
   NS_ASSERTION(!paintAllContinuations || !aFrame->GetPrevContinuation(),
                "If painting all continuations, the frame must be "
                "first-continuation");
   nsIAtom* frameType = aFrame->GetType();
   if (paintAllContinuations) {
     nsIFrame* currentFrame = aFrame;
     while ((currentFrame = currentFrame->GetNextContinuation()) != nullptr) {
       PROFILER_LABEL("nsLayoutUtils","PaintFrame::ContinuationsBuildDisplayList");
       nsRect frameDirty = dirtyRect - builder.ToReferenceFrame(currentFrame);
       currentFrame->BuildDisplayListForStackingContext(&builder,
                                                        frameDirty, &list);
     }
   }
   // For the viewport frame in print preview/page layout we want to paint
   // the grey background behind the page, not the canvas color.
   if (frameType == nsGkAtoms::viewportFrame &&
       nsLayoutUtils::NeedsPrintPreviewBackground(presContext)) {
     nsRect bounds = nsRect(builder.ToReferenceFrame(aFrame),
                            aFrame->GetSize());
     presShell->AddPrintPreviewBackgroundItem(builder, list, aFrame, bounds);
   } else if (frameType != nsGkAtoms::pageFrame) {
     // For printing, this function is first called on an nsPageFrame, which
     // creates a display list with a PageContent item. The PageContent item's
     // paint function calls this function on the nsPageFrame's child which is
     // an nsPageContentFrame. We only want to add the canvas background color
     // item once, for the nsPageContentFrame.
     // Add the canvas background color to the bottom of the list. This
     // happens after we've built the list so that AddCanvasBackgroundColorItem
     // can monkey with the contents if necessary.
     canvasArea.IntersectRect(canvasArea, visibleRegion.GetBounds());
     presShell->AddCanvasBackgroundColorItem(
            builder, list, aFrame, canvasArea, aBackstop);
     // If the passed in backstop color makes us draw something different from
     // normal, we need to flush layers.
     if ((aFlags & PAINT_WIDGET_LAYERS) && !willFlushRetainedLayers) {
       nsView* view = aFrame->GetView();
       if (view) {
         nscolor backstop = presShell->ComputeBackstopColor(view);
         // The PresShell's canvas background color doesn't get updated until
         // EnterPresShell, so this check has to be done after that.
         nscolor canvasColor = presShell->GetCanvasBackground();
         if (NS_ComposeColors(aBackstop, canvasColor) !=
             NS_ComposeColors(backstop, canvasColor)) {
           willFlushRetainedLayers = true;
         }
       }
     }
   }
   builder.LeavePresShell(aFrame, dirtyRect);
   if (builder.GetHadToIgnorePaintSuppression()) {
     willFlushRetainedLayers = true;
   }
 #ifdef MOZ_DUMP_PAINTING
   FILE* savedDumpFile = gfxUtils::sDumpPaintFile;
   if (gfxUtils::sDumpPaintList || gfxUtils::sDumpPainting) {
     if (gfxUtils::sDumpPaintingToFile) {
       nsCString string("dump-");
       string.AppendInt(gPaintCount);
       string.Append(".html");
       gfxUtils::sDumpPaintFile = fopen(string.BeginReading(), "w");
     } else {
       gfxUtils::sDumpPaintFile = stderr;
     }
     if (gfxUtils::sDumpPaintingToFile) {
       fprintf_stderr(gfxUtils::sDumpPaintFile, "<html><head><script>var array = {}; function ViewImage(index) { window.location = array[index]; }</script></head><body>");
     }
     fprintf_stderr(gfxUtils::sDumpPaintFile, "Painting --- before optimization (dirty %d,%d,%d,%d):\n",
             dirtyRect.x, dirtyRect.y, dirtyRect.width, dirtyRect.height);
     nsFrame::PrintDisplayList(&builder, list, gfxUtils::sDumpPaintFile, gfxUtils::sDumpPaintingToFile);
     if (gfxUtils::sDumpPaintingToFile) {
       fprintf_stderr(gfxUtils::sDumpPaintFile, "<script>");
     }
   }
 #endif
   list.ComputeVisibilityForRoot(&builder, &visibleRegion,
                                 usingDisplayPort ? rootScrollFrame : nullptr);
   uint32_t flags = nsDisplayList::PAINT_DEFAULT;
   if (aFlags & PAINT_WIDGET_LAYERS) {
     flags |= nsDisplayList::PAINT_USE_WIDGET_LAYERS;
     if (willFlushRetainedLayers) {
       // The caller wanted to paint from retained layers, but set up
       // the paint in such a way that we can't use them.  We're going
       // to display something different from what we'd normally paint
       // in a window, so make sure we flush out any retained layer
       // trees before *and after* we draw.  Callers should be fixed to
       // not do this.
       NS_WARNING("Flushing retained layers!");
       flags |= nsDisplayList::PAINT_FLUSH_LAYERS;
     } else if (!(aFlags & PAINT_DOCUMENT_RELATIVE)) {
       nsIWidget *widget = aFrame->GetNearestWidget();
       if (widget) {
         builder.SetFinalTransparentRegion(visibleRegion);
         // If we're finished building display list items for painting of the outermost
         // pres shell, notify the widget about any toolbars we've encountered.
         widget->UpdateThemeGeometries(builder.GetThemeGeometries());
       }
     }
   }
   if (aFlags & PAINT_EXISTING_TRANSACTION) {
     flags |= nsDisplayList::PAINT_EXISTING_TRANSACTION;
   }
   if (aFlags & PAINT_NO_COMPOSITE) {
     flags |= nsDisplayList::PAINT_NO_COMPOSITE;
   }
   if (aFlags & PAINT_COMPRESSED) {
     flags |= nsDisplayList::PAINT_COMPRESSED;
   }
   list.PaintRoot(&builder, aRenderingContext, flags);
 #ifdef MOZ_DUMP_PAINTING
   if (gfxUtils::sDumpPaintList || gfxUtils::sDumpPainting) {
     if (gfxUtils::sDumpPaintingToFile) {
       fprintf_stderr(gfxUtils::sDumpPaintFile, "</script>");
     }
     fprintf_stderr(gfxUtils::sDumpPaintFile, "Painting --- after optimization:\n");
     nsFrame::PrintDisplayList(&builder, list, gfxUtils::sDumpPaintFile, gfxUtils::sDumpPaintingToFile);
     fprintf_stderr(gfxUtils::sDumpPaintFile, "Painting --- retained layer tree:\n");
     nsIWidget* widget = aFrame->GetNearestWidget();
     if (widget) {
       nsRefPtr<LayerManager> layerManager = widget->GetLayerManager();
       if (layerManager) {
         FrameLayerBuilder::DumpRetainedLayerTree(layerManager, gfxUtils::sDumpPaintFile,
                                                  gfxUtils::sDumpPaintingToFile);
       }
     }
     if (gfxUtils::sDumpPaintingToFile) {
       fprintf(gfxUtils::sDumpPaintFile, "</body></html>");
       fclose(gfxUtils::sDumpPaintFile);
     }
     gfxUtils::sDumpPaintFile = savedDumpFile;
     gPaintCount++;
   }
 #endif
   // Update the widget's opaque region information. This sets
   // glass boundaries on Windows. Also set up plugin clip regions and bounds.
   if ((aFlags & PAINT_WIDGET_LAYERS) &&
       !willFlushRetainedLayers &&
       !(aFlags & PAINT_DOCUMENT_RELATIVE)) {
     nsIWidget *widget = aFrame->GetNearestWidget();
     if (widget) {
       nsRegion excludedRegion = builder.GetExcludedGlassRegion();
       excludedRegion.Sub(excludedRegion, visibleRegion);
       nsIntRegion windowRegion(excludedRegion.ToNearestPixels(presContext->AppUnitsPerDevPixel()));
       widget->UpdateOpaqueRegion(windowRegion);
     }
   }
   if (builder.WillComputePluginGeometry()) {
     nsRefPtr<LayerManager> layerManager;
     nsIWidget* widget = aFrame->GetNearestWidget();
     if (widget) {
       layerManager = widget->GetLayerManager();
     }
     rootPresContext->ComputePluginGeometryUpdates(aFrame, &builder, &list);
     // We're not going to get a WillPaintWindow event here if we didn't do
     // widget invalidation, so just apply the plugin geometry update here instead.
     // We could instead have the compositor send back an equivalent to WillPaintWindow,
     // but it should be close enough to now not to matter.
     if (layerManager && !layerManager->NeedsWidgetInvalidation()) {
       rootPresContext->ApplyPluginGeometryUpdates();
     }
     // We told the compositor thread not to composite when it received the transaction because
     // we wanted to update plugins first. Schedule the composite now.
     if (layerManager) {
       layerManager->Composite();
     }
   }
   // Flush the list so we don't trigger the IsEmpty-on-destruction assertion
   list.DeleteAll();
   return NS_OK;
 }
 /**
  * Uses a binary search for find where the cursor falls in the line of text
  * It also keeps track of the part of the string that has already been measured
  * so it doesn't have to keep measuring the same text over and over
  *
  * @param "aBaseWidth" contains the width in twips of the portion
  * of the text that has already been measured, and aBaseInx contains
  * the index of the text that has already been measured.
  *
  * @param aTextWidth returns the (in twips) the length of the text that falls
  * before the cursor aIndex contains the index of the text where the cursor falls
  */
 bool
 nsLayoutUtils::BinarySearchForPosition(nsRenderingContext* aRendContext,
                         const char16_t* aText,
                         int32_t    aBaseWidth,
                         int32_t    aBaseInx,
                         int32_t    aStartInx,
                         int32_t    aEndInx,
                         int32_t    aCursorPos,
                         int32_t&   aIndex,
                         int32_t&   aTextWidth)
 {
   int32_t range = aEndInx - aStartInx;
   if ((range == 1) || (range == 2 && NS_IS_HIGH_SURROGATE(aText[aStartInx]))) {
     aIndex   = aStartInx + aBaseInx;
     aTextWidth = aRendContext->GetWidth(aText, aIndex);
     return true;
   }
   int32_t inx = aStartInx + (range / 2);
   // Make sure we don't leave a dangling low surrogate
   if (NS_IS_HIGH_SURROGATE(aText[inx-1]))
     inx++;
   int32_t textWidth = aRendContext->GetWidth(aText, inx);
   int32_t fullWidth = aBaseWidth + textWidth;
   if (fullWidth == aCursorPos) {
     aTextWidth = textWidth;
     aIndex = inx;
     return true;
   } else if (aCursorPos < fullWidth) {
     aTextWidth = aBaseWidth;
     if (BinarySearchForPosition(aRendContext, aText, aBaseWidth, aBaseInx, aStartInx, inx, aCursorPos, aIndex, aTextWidth)) {
       return true;
     }
   } else {
     aTextWidth = fullWidth;
     if (BinarySearchForPosition(aRendContext, aText, aBaseWidth, aBaseInx, inx, aEndInx, aCursorPos, aIndex, aTextWidth)) {
       return true;
     }
   }
   return false;
 }
 static void
 AddBoxesForFrame(nsIFrame* aFrame,
                  nsLayoutUtils::BoxCallback* aCallback)
 {
   nsIAtom* pseudoType = aFrame->StyleContext()->GetPseudo();
   if (pseudoType == nsCSSAnonBoxes::tableOuter) {
     AddBoxesForFrame(aFrame->GetFirstPrincipalChild(), aCallback);
     nsIFrame* kid = aFrame->GetFirstChild(nsIFrame::kCaptionList);
     if (kid) {
       AddBoxesForFrame(kid, aCallback);
     }
   } else if (pseudoType == nsCSSAnonBoxes::mozAnonymousBlock ||
              pseudoType == nsCSSAnonBoxes::mozAnonymousPositionedBlock ||
              pseudoType == nsCSSAnonBoxes::mozMathMLAnonymousBlock ||
              pseudoType == nsCSSAnonBoxes::mozXULAnonymousBlock) {
     for (nsIFrame* kid = aFrame->GetFirstPrincipalChild(); kid; kid = kid->GetNextSibling()) {
       AddBoxesForFrame(kid, aCallback);
     }
   } else {
     aCallback->AddBox(aFrame);
   }
 }
 void
 nsLayoutUtils::GetAllInFlowBoxes(nsIFrame* aFrame, BoxCallback* aCallback)
 {
   while (aFrame) {
     AddBoxesForFrame(aFrame, aCallback);
     aFrame = nsLayoutUtils::GetNextContinuationOrIBSplitSibling(aFrame);
   }
 }
 nsIFrame*
 nsLayoutUtils::GetFirstNonAnonymousFrame(nsIFrame* aFrame)
 {
   while (aFrame) {
     nsIAtom* pseudoType = aFrame->StyleContext()->GetPseudo();
     if (pseudoType == nsCSSAnonBoxes::tableOuter) {
       nsIFrame* f = GetFirstNonAnonymousFrame(aFrame->GetFirstPrincipalChild());
       if (f) {
         return f;
       }
       nsIFrame* kid = aFrame->GetFirstChild(nsIFrame::kCaptionList);
       if (kid) {
         f = GetFirstNonAnonymousFrame(kid);
         if (f) {
           return f;
         }
       }
     } else if (pseudoType == nsCSSAnonBoxes::mozAnonymousBlock ||
                pseudoType == nsCSSAnonBoxes::mozAnonymousPositionedBlock ||
                pseudoType == nsCSSAnonBoxes::mozMathMLAnonymousBlock ||
                pseudoType == nsCSSAnonBoxes::mozXULAnonymousBlock) {
       for (nsIFrame* kid = aFrame->GetFirstPrincipalChild(); kid; kid = kid->GetNextSibling()) {
         nsIFrame* f = GetFirstNonAnonymousFrame(kid);
         if (f) {
           return f;
         }
       }
     } else {
       return aFrame;
     }
     aFrame = nsLayoutUtils::GetNextContinuationOrIBSplitSibling(aFrame);
   }
   return nullptr;
 }
 struct BoxToRect : public nsLayoutUtils::BoxCallback {
   nsIFrame* mRelativeTo;
   nsLayoutUtils::RectCallback* mCallback;
   uint32_t mFlags;
   BoxToRect(nsIFrame* aRelativeTo, nsLayoutUtils::RectCallback* aCallback,
             uint32_t aFlags)
     : mRelativeTo(aRelativeTo), mCallback(aCallback), mFlags(aFlags) {}
   virtual void AddBox(nsIFrame* aFrame) MOZ_OVERRIDE {
     nsRect r;
     nsIFrame* outer = nsSVGUtils::GetOuterSVGFrameAndCoveredRegion(aFrame, &r);
     if (!outer) {
       outer = aFrame;
       switch (mFlags & nsLayoutUtils::RECTS_WHICH_BOX_MASK) {
         case nsLayoutUtils::RECTS_USE_CONTENT_BOX:
           r = aFrame->GetContentRectRelativeToSelf();
           break;
         case nsLayoutUtils::RECTS_USE_PADDING_BOX:
           r = aFrame->GetPaddingRectRelativeToSelf();
           break;
         case nsLayoutUtils::RECTS_USE_MARGIN_BOX:
           r = aFrame->GetMarginRectRelativeToSelf();
           break;
         default: // Use the border box
           r = aFrame->GetRectRelativeToSelf();
       }
     }
     if (mFlags & nsLayoutUtils::RECTS_ACCOUNT_FOR_TRANSFORMS) {
       r = nsLayoutUtils::TransformFrameRectToAncestor(outer, r, mRelativeTo);
     } else {
       r += outer->GetOffsetTo(mRelativeTo);
     }
     mCallback->AddRect(r);
   }
 };
 void
 nsLayoutUtils::GetAllInFlowRects(nsIFrame* aFrame, nsIFrame* aRelativeTo,
                                  RectCallback* aCallback, uint32_t aFlags)
 {
   BoxToRect converter(aRelativeTo, aCallback, aFlags);
   GetAllInFlowBoxes(aFrame, &converter);
 }
 nsLayoutUtils::RectAccumulator::RectAccumulator() : mSeenFirstRect(false) {}
 void nsLayoutUtils::RectAccumulator::AddRect(const nsRect& aRect) {
   mResultRect.UnionRect(mResultRect, aRect);
   if (!mSeenFirstRect) {
     mSeenFirstRect = true;
     mFirstRect = aRect;
   }
 }
 nsLayoutUtils::RectListBuilder::RectListBuilder(DOMRectList* aList)
   : mRectList(aList)
 {
 }
 void nsLayoutUtils::RectListBuilder::AddRect(const nsRect& aRect) {
   nsRefPtr<DOMRect> rect = new DOMRect(mRectList);
   rect->SetLayoutRect(aRect);
   mRectList->Append(rect);
 }
 nsIFrame* nsLayoutUtils::GetContainingBlockForClientRect(nsIFrame* aFrame)
 {
   return aFrame->PresContext()->PresShell()->GetRootFrame();
 }
 nsRect
 nsLayoutUtils::GetAllInFlowRectsUnion(nsIFrame* aFrame, nsIFrame* aRelativeTo,
                                       uint32_t aFlags) {
   RectAccumulator accumulator;
   GetAllInFlowRects(aFrame, aRelativeTo, &accumulator, aFlags);
   return accumulator.mResultRect.IsEmpty() ? accumulator.mFirstRect
           : accumulator.mResultRect;
 }
 nsRect
 nsLayoutUtils::GetTextShadowRectsUnion(const nsRect& aTextAndDecorationsRect,
                                        nsIFrame* aFrame,
                                        uint32_t aFlags)
 {
   const nsStyleText* textStyle = aFrame->StyleText();
   if (!textStyle->HasTextShadow())
     return aTextAndDecorationsRect;
   nsRect resultRect = aTextAndDecorationsRect;
   int32_t A2D = aFrame->PresContext()->AppUnitsPerDevPixel();
   for (uint32_t i = 0; i < textStyle->mTextShadow->Length(); ++i) {
     nsCSSShadowItem* shadow = textStyle->mTextShadow->ShadowAt(i);
     nsMargin blur = nsContextBoxBlur::GetBlurRadiusMargin(shadow->mRadius, A2D);
     if ((aFlags & EXCLUDE_BLUR_SHADOWS) && blur != nsMargin(0, 0, 0, 0))
       continue;
     nsRect tmpRect(aTextAndDecorationsRect);
     tmpRect.MoveBy(nsPoint(shadow->mXOffset, shadow->mYOffset));
     tmpRect.Inflate(blur);
     resultRect.UnionRect(resultRect, tmpRect);
   }
   return resultRect;
 }
 nsresult
 nsLayoutUtils::GetFontMetricsForFrame(const nsIFrame* aFrame,
                                       nsFontMetrics** aFontMetrics,
                                       float aInflation)
 {
   return nsLayoutUtils::GetFontMetricsForStyleContext(aFrame->StyleContext(),
                                                       aFontMetrics,
                                                       aInflation);
 }
 nsresult
 nsLayoutUtils::GetFontMetricsForStyleContext(nsStyleContext* aStyleContext,
                                              nsFontMetrics** aFontMetrics,
                                              float aInflation)
 {
   // pass the user font set object into the device context to pass along to CreateFontGroup
   nsPresContext* pc = aStyleContext->PresContext();
   gfxUserFontSet* fs = pc->GetUserFontSet();
   gfxTextPerfMetrics* tp = pc->GetTextPerfMetrics();
   nsFont font = aStyleContext->StyleFont()->mFont;
   // We need to not run font.size through floats when it's large since
   // doing so would be lossy.  Fortunately, in such cases, aInflation is
   // guaranteed to be 1.0f.
   if (aInflation != 1.0f) {
     font.size = NSToCoordRound(font.size * aInflation);
   }
   return pc->DeviceContext()->GetMetricsFor(
                   font, aStyleContext->StyleFont()->mLanguage,
                   fs, tp, *aFontMetrics);
 }
 nsIFrame*
 nsLayoutUtils::FindChildContainingDescendant(nsIFrame* aParent, nsIFrame* aDescendantFrame)
 {
   nsIFrame* result = aDescendantFrame;
   while (result) {
     nsIFrame* parent = result->GetParent();
     if (parent == aParent) {
       break;
     }
     // The frame is not an immediate child of aParent so walk up another level
     result = parent;
   }
   return result;
 }
 nsBlockFrame*
 nsLayoutUtils::GetAsBlock(nsIFrame* aFrame)
 {
   nsBlockFrame* block = do_QueryFrame(aFrame);
   return block;
 }
 nsBlockFrame*
 nsLayoutUtils::FindNearestBlockAncestor(nsIFrame* aFrame)
 {
   nsIFrame* nextAncestor;
   for (nextAncestor = aFrame->GetParent(); nextAncestor;
        nextAncestor = nextAncestor->GetParent()) {
     nsBlockFrame* block = GetAsBlock(nextAncestor);
     if (block)
       return block;
   }
   return nullptr;
 }
 nsIFrame*
 nsLayoutUtils::GetNonGeneratedAncestor(nsIFrame* aFrame)
 {
   if (!(aFrame->GetStateBits() & NS_FRAME_GENERATED_CONTENT))
     return aFrame;
   nsIFrame* f = aFrame;
   do {
     f = GetParentOrPlaceholderFor(f);
   } while (f->GetStateBits() & NS_FRAME_GENERATED_CONTENT);
   return f;
 }
 nsIFrame*
 nsLayoutUtils::GetParentOrPlaceholderFor(nsIFrame* aFrame)
 {
   if ((aFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW)
       && !aFrame->GetPrevInFlow()) {
     return aFrame->PresContext()->PresShell()->FrameManager()->
       GetPlaceholderFrameFor(aFrame);
   }
   return aFrame->GetParent();
 }
 nsIFrame*
 nsLayoutUtils::GetParentOrPlaceholderForCrossDoc(nsIFrame* aFrame)
 {
   nsIFrame* f = GetParentOrPlaceholderFor(aFrame);
   if (f)
     return f;
   return GetCrossDocParentFrame(aFrame);
 }
 nsIFrame*
 nsLayoutUtils::GetNextContinuationOrIBSplitSibling(nsIFrame *aFrame)
 {
   nsIFrame *result = aFrame->GetNextContinuation();
   if (result)
     return result;
   if ((aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT) != 0) {
     // We only store the ib-split sibling annotation with the first
     // frame in the continuation chain. Walk back to find that frame now.
     aFrame = aFrame->FirstContinuation();
     void* value = aFrame->Properties().Get(nsIFrame::IBSplitSibling());
     return static_cast<nsIFrame*>(value);
   }
   return nullptr;
 }
 nsIFrame*
 nsLayoutUtils::FirstContinuationOrIBSplitSibling(nsIFrame *aFrame)
 {
   nsIFrame *result = aFrame->FirstContinuation();
   if (result->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT) {
     while (true) {
       nsIFrame *f = static_cast<nsIFrame*>
         (result->Properties().Get(nsIFrame::IBSplitPrevSibling()));
       if (!f)
         break;
       result = f;
     }
   }
   return result;
 }
 bool
 nsLayoutUtils::IsFirstContinuationOrIBSplitSibling(nsIFrame *aFrame)
 {
   if (aFrame->GetPrevContinuation()) {
     return false;
   }
   if ((aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT) &&
       aFrame->Properties().Get(nsIFrame::IBSplitPrevSibling())) {
     return false;
   }
   return true;
 }
 bool
 nsLayoutUtils::IsViewportScrollbarFrame(nsIFrame* aFrame)
 {
   if (!aFrame)
     return false;
   nsIFrame* rootScrollFrame =
     aFrame->PresContext()->PresShell()->GetRootScrollFrame();
   if (!rootScrollFrame)
     return false;
   nsIScrollableFrame* rootScrollableFrame = do_QueryFrame(rootScrollFrame);
   NS_ASSERTION(rootScrollableFrame, "The root scorollable frame is null");
   if (!IsProperAncestorFrame(rootScrollFrame, aFrame))
     return false;
   nsIFrame* rootScrolledFrame = rootScrollableFrame->GetScrolledFrame();
   return !(rootScrolledFrame == aFrame ||
            IsProperAncestorFrame(rootScrolledFrame, aFrame));
 }
 static nscoord AddPercents(nsLayoutUtils::IntrinsicWidthType aType,
                            nscoord aCurrent, float aPercent)
 {
   nscoord result = aCurrent;
   if (aPercent > 0.0f && aType == nsLayoutUtils::PREF_WIDTH) {
     // XXX Should we also consider percentages for min widths, up to a
     // limit?
     if (aPercent >= 1.0f)
       result = nscoord_MAX;
     else
       result = NSToCoordRound(float(result) / (1.0f - aPercent));
   }
   return result;
 }
 // Use only for widths/heights (or their min/max), since it clamps
 // negative calc() results to 0.
 static bool GetAbsoluteCoord(const nsStyleCoord& aStyle, nscoord& aResult)
 {
   if (aStyle.IsCalcUnit()) {
     if (aStyle.CalcHasPercent()) {
       return false;
     }
     // If it has no percents, we can pass 0 for the percentage basis.
     aResult = nsRuleNode::ComputeComputedCalc(aStyle, 0);
     if (aResult < 0)
       aResult = 0;
     return true;
   }
   if (eStyleUnit_Coord != aStyle.GetUnit())
     return false;
   aResult = aStyle.GetCoordValue();
   NS_ASSERTION(aResult >= 0, "negative widths not allowed");
   return true;
 }
 // Only call on style coords for which GetAbsoluteCoord returned false.
 static bool
 GetPercentHeight(const nsStyleCoord& aStyle,
                  nsIFrame* aFrame,
                  nscoord& aResult)
 {
   if (eStyleUnit_Percent != aStyle.GetUnit() &&
       !aStyle.IsCalcUnit())
     return false;
   MOZ_ASSERT(!aStyle.IsCalcUnit() || aStyle.CalcHasPercent(),
              "GetAbsoluteCoord should have handled this");
   nsIFrame *f = aFrame->GetContainingBlock();
   if (!f) {
     NS_NOTREACHED("top of frame tree not a containing block");
     return false;
   }
   // During reflow, nsHTMLScrollFrame::ReflowScrolledFrame uses
   // SetComputedHeight on the reflow state for its child to propagate its
   // computed height to the scrolled content. So here we skip to the scroll
   // frame that contains this scrolled content in order to get the same
   // behavior as layout when computing percentage heights.
   if (f->StyleContext()->GetPseudo() == nsCSSAnonBoxes::scrolledContent) {
     f = f->GetParent();
   }
   const nsStylePosition *pos = f->StylePosition();
   nscoord h;
   if (!GetAbsoluteCoord(pos->mHeight, h) &&
       !GetPercentHeight(pos->mHeight, f, h)) {
     NS_ASSERTION(pos->mHeight.GetUnit() == eStyleUnit_Auto ||
                  pos->mHeight.HasPercent(),
                  "unknown height unit");
     nsIAtom* fType = f->GetType();
     if (fType != nsGkAtoms::viewportFrame && fType != nsGkAtoms::canvasFrame &&
         fType != nsGkAtoms::pageContentFrame) {
       // There's no basis for the percentage height, so it acts like auto.
       // Should we consider a max-height < min-height pair a basis for
       // percentage heights?  The spec is somewhat unclear, and not doing
       // so is simpler and avoids troubling discontinuities in behavior,
       // so I'll choose not to. -LDB
       return false;
     }
     NS_ASSERTION(pos->mHeight.GetUnit() == eStyleUnit_Auto,
                  "Unexpected height unit for viewport or canvas or page-content");
     // For the viewport, canvas, and page-content kids, the percentage
     // basis is just the parent height.
     h = f->GetSize().height;
     if (h == NS_UNCONSTRAINEDSIZE) {
       // We don't have a percentage basis after all
       return false;
     }
   }
   nscoord maxh;
   if (GetAbsoluteCoord(pos->mMaxHeight, maxh) ||
       GetPercentHeight(pos->mMaxHeight, f, maxh)) {
     if (maxh < h)
       h = maxh;
   } else {
     NS_ASSERTION(pos->mMaxHeight.GetUnit() == eStyleUnit_None ||
                  pos->mMaxHeight.HasPercent(),
                  "unknown max-height unit");
   }
   nscoord minh;
   if (GetAbsoluteCoord(pos->mMinHeight, minh) ||
       GetPercentHeight(pos->mMinHeight, f, minh)) {
     if (minh > h)
       h = minh;
   } else {
     NS_ASSERTION(pos->mMinHeight.HasPercent(),
                  "unknown min-height unit");
   }
   if (aStyle.IsCalcUnit()) {
     aResult = std::max(nsRuleNode::ComputeComputedCalc(aStyle, h), 0);
     return true;
   }
   aResult = NSToCoordRound(aStyle.GetPercentValue() * h);
   return true;
 }
 // Handles only -moz-max-content and -moz-min-content, and
 // -moz-fit-content for min-width and max-width, since the others
 // (-moz-fit-content for width, and -moz-available) have no effect on
 // intrinsic widths.
 enum eWidthProperty { PROP_WIDTH, PROP_MAX_WIDTH, PROP_MIN_WIDTH };
 static bool
 GetIntrinsicCoord(const nsStyleCoord& aStyle,
                   nsRenderingContext* aRenderingContext,
                   nsIFrame* aFrame,
                   eWidthProperty aProperty,
                   nscoord& aResult)
 {
   NS_PRECONDITION(aProperty == PROP_WIDTH || aProperty == PROP_MAX_WIDTH ||
                   aProperty == PROP_MIN_WIDTH, "unexpected property");
   if (aStyle.GetUnit() != eStyleUnit_Enumerated)
     return false;
   int32_t val = aStyle.GetIntValue();
   NS_ASSERTION(val == NS_STYLE_WIDTH_MAX_CONTENT ||
                val == NS_STYLE_WIDTH_MIN_CONTENT ||
                val == NS_STYLE_WIDTH_FIT_CONTENT ||
                val == NS_STYLE_WIDTH_AVAILABLE,
                "unexpected enumerated value for width property");
   if (val == NS_STYLE_WIDTH_AVAILABLE)
     return false;
   if (val == NS_STYLE_WIDTH_FIT_CONTENT) {
     if (aProperty == PROP_WIDTH)
       return false; // handle like 'width: auto'
     if (aProperty == PROP_MAX_WIDTH)
       // constrain large 'width' values down to -moz-max-content
       val = NS_STYLE_WIDTH_MAX_CONTENT;
     else
       // constrain small 'width' or 'max-width' values up to -moz-min-content
       val = NS_STYLE_WIDTH_MIN_CONTENT;
   }
   NS_ASSERTION(val == NS_STYLE_WIDTH_MAX_CONTENT ||
                val == NS_STYLE_WIDTH_MIN_CONTENT,
                "should have reduced everything remaining to one of these");
   // If aFrame is a container for font size inflation, then shrink
   // wrapping inside of it should not apply font size inflation.
   AutoMaybeDisableFontInflation an(aFrame);
   if (val == NS_STYLE_WIDTH_MAX_CONTENT)
     aResult = aFrame->GetPrefWidth(aRenderingContext);
   else
     aResult = aFrame->GetMinWidth(aRenderingContext);
   return true;
 }
 #undef  DEBUG_INTRINSIC_WIDTH
 #ifdef DEBUG_INTRINSIC_WIDTH
 static int32_t gNoiseIndent = 0;
 #endif
 /* static */ nscoord
 nsLayoutUtils::IntrinsicForContainer(nsRenderingContext *aRenderingContext,
                                      nsIFrame *aFrame,
                                      IntrinsicWidthType aType,
                                      uint32_t aFlags)
 {
   NS_PRECONDITION(aFrame, "null frame");
   NS_PRECONDITION(aType == MIN_WIDTH || aType == PREF_WIDTH, "bad type");
 #ifdef DEBUG_INTRINSIC_WIDTH
   nsFrame::IndentBy(stderr, gNoiseIndent);
   static_cast<nsFrame*>(aFrame)->ListTag(stderr);
   printf_stderr(" %s intrinsic width for container:\n",
          aType == MIN_WIDTH ? "min" : "pref");
 #endif
   // If aFrame is a container for font size inflation, then shrink
   // wrapping inside of it should not apply font size inflation.
   AutoMaybeDisableFontInflation an(aFrame);
   nsIFrame::IntrinsicWidthOffsetData offsets =
     aFrame->IntrinsicWidthOffsets(aRenderingContext);
   const nsStylePosition *stylePos = aFrame->StylePosition();
   uint8_t boxSizing = stylePos->mBoxSizing;
   const nsStyleCoord &styleWidth = stylePos->mWidth;
   const nsStyleCoord &styleMinWidth = stylePos->mMinWidth;
   const nsStyleCoord &styleMaxWidth = stylePos->mMaxWidth;
   // We build up two values starting with the content box, and then
   // adding padding, border and margin.  The result is normally
   // |result|.  Then, when we handle 'width', 'min-width', and
   // 'max-width', we use the results we've been building in |min| as a
   // minimum, overriding 'min-width'.  This ensures two things:
   //   * that we don't let a value of 'box-sizing' specifying a width
   //     smaller than the padding/border inside the box-sizing box give
   //     a content width less than zero
   //   * that we prevent tables from becoming smaller than their
   //     intrinsic minimum width
   nscoord result = 0, min = 0;
   nscoord maxw;
   bool haveFixedMaxWidth = GetAbsoluteCoord(styleMaxWidth, maxw);
   nscoord minw;
   bool haveFixedMinWidth = GetAbsoluteCoord(styleMinWidth, minw);
   // If we have a specified width (or a specified 'min-width' greater
   // than the specified 'max-width', which works out to the same thing),
   // don't even bother getting the frame's intrinsic width, because in
   // this case GetAbsoluteCoord(styleWidth, w) will always succeed, so
   // we'll never need the intrinsic dimensions.
   if (styleWidth.GetUnit() == eStyleUnit_Enumerated &&
       (styleWidth.GetIntValue() == NS_STYLE_WIDTH_MAX_CONTENT ||
        styleWidth.GetIntValue() == NS_STYLE_WIDTH_MIN_CONTENT)) {
     // -moz-fit-content and -moz-available enumerated widths compute intrinsic
     // widths just like auto.
     // For -moz-max-content and -moz-min-content, we handle them like
     // specified widths, but ignore box-sizing.
     boxSizing = NS_STYLE_BOX_SIZING_CONTENT;
   } else if (!styleWidth.ConvertsToLength() &&
              !(haveFixedMinWidth && haveFixedMaxWidth && maxw <= minw)) {
 #ifdef DEBUG_INTRINSIC_WIDTH
     ++gNoiseIndent;
 #endif
     if (aType == MIN_WIDTH)
       result = aFrame->GetMinWidth(aRenderingContext);
     else
       result = aFrame->GetPrefWidth(aRenderingContext);
 #ifdef DEBUG_INTRINSIC_WIDTH
     --gNoiseIndent;
     nsFrame::IndentBy(stderr, gNoiseIndent);
     static_cast<nsFrame*>(aFrame)->ListTag(stderr);
     printf_stderr(" %s intrinsic width from frame is %d.\n",
            aType == MIN_WIDTH ? "min" : "pref", result);
 #endif
     // Handle elements with an intrinsic ratio (or size) and a specified
     // height, min-height, or max-height.
     const nsStyleCoord &styleHeight = stylePos->mHeight;
     const nsStyleCoord &styleMinHeight = stylePos->mMinHeight;
     const nsStyleCoord &styleMaxHeight = stylePos->mMaxHeight;
     if (styleHeight.GetUnit() != eStyleUnit_Auto ||
         !(styleMinHeight.GetUnit() == eStyleUnit_Coord &&
           styleMinHeight.GetCoordValue() == 0) ||
         styleMaxHeight.GetUnit() != eStyleUnit_None) {
       nsSize ratio = aFrame->GetIntrinsicRatio();
       if (ratio.height != 0) {
         nscoord heightTakenByBoxSizing = 0;
         switch (boxSizing) {
         case NS_STYLE_BOX_SIZING_BORDER: {
           const nsStyleBorder* styleBorder = aFrame->StyleBorder();
           heightTakenByBoxSizing +=
             styleBorder->GetComputedBorder().TopBottom();
           // fall through
         }
         case NS_STYLE_BOX_SIZING_PADDING: {
           if (!(aFlags & IGNORE_PADDING)) {
             const nsStylePadding* stylePadding = aFrame->StylePadding();
             nscoord pad;
             if (GetAbsoluteCoord(stylePadding->mPadding.GetTop(), pad) ||
                 GetPercentHeight(stylePadding->mPadding.GetTop(), aFrame, pad)) {
               heightTakenByBoxSizing += pad;
             }
             if (GetAbsoluteCoord(stylePadding->mPadding.GetBottom(), pad) ||
                 GetPercentHeight(stylePadding->mPadding.GetBottom(), aFrame, pad)) {
               heightTakenByBoxSizing += pad;
             }
           }
           // fall through
         }
         case NS_STYLE_BOX_SIZING_CONTENT:
         default:
           break;
         }
         nscoord h;
         if (GetAbsoluteCoord(styleHeight, h) ||
             GetPercentHeight(styleHeight, aFrame, h)) {
           h = std::max(0, h - heightTakenByBoxSizing);
           result =
             NSToCoordRound(h * (float(ratio.width) / float(ratio.height)));
         }
         if (GetAbsoluteCoord(styleMaxHeight, h) ||
             GetPercentHeight(styleMaxHeight, aFrame, h)) {
           h = std::max(0, h - heightTakenByBoxSizing);
           nscoord maxWidth =
             NSToCoordRound(h * (float(ratio.width) / float(ratio.height)));
           if (maxWidth < result)
             result = maxWidth;
         }
         if (GetAbsoluteCoord(styleMinHeight, h) ||
             GetPercentHeight(styleMinHeight, aFrame, h)) {
           h = std::max(0, h - heightTakenByBoxSizing);
           nscoord minWidth =
             NSToCoordRound(h * (float(ratio.width) / float(ratio.height)));
           if (minWidth > result)
             result = minWidth;
         }
       }
     }
   }
   if (aFrame->GetType() == nsGkAtoms::tableFrame) {
     // Tables can't shrink smaller than their intrinsic minimum width,
     // no matter what.
     min = aFrame->GetMinWidth(aRenderingContext);
   }
   // We also need to track what has been added on outside of the box
   // (controlled by 'box-sizing') where 'width', 'min-width' and
   // 'max-width' are applied.  We have to account for these properties
   // after getting all the offsets (margin, border, padding) because
   // percentages do not operate linearly.
   // Doing this is ok because although percentages aren't handled
   // linearly, they are handled monotonically.
   nscoord coordOutsideWidth = 0;
   float pctOutsideWidth = 0;
   float pctTotal = 0.0f;
   if (!(aFlags & IGNORE_PADDING)) {
     coordOutsideWidth += offsets.hPadding;
     pctOutsideWidth += offsets.hPctPadding;
     if (boxSizing == NS_STYLE_BOX_SIZING_PADDING) {
       min += coordOutsideWidth;
       result = NSCoordSaturatingAdd(result, coordOutsideWidth);
       pctTotal += pctOutsideWidth;
       coordOutsideWidth = 0;
       pctOutsideWidth = 0.0f;
     }
   }
   coordOutsideWidth += offsets.hBorder;
   if (boxSizing == NS_STYLE_BOX_SIZING_BORDER) {
     min += coordOutsideWidth;
     result = NSCoordSaturatingAdd(result, coordOutsideWidth);
     pctTotal += pctOutsideWidth;
     coordOutsideWidth = 0;
     pctOutsideWidth = 0.0f;
   }
   coordOutsideWidth += offsets.hMargin;
   pctOutsideWidth += offsets.hPctMargin;
   min += coordOutsideWidth;
   result = NSCoordSaturatingAdd(result, coordOutsideWidth);
   pctTotal += pctOutsideWidth;
   nscoord w;
   if (GetAbsoluteCoord(styleWidth, w) ||
       GetIntrinsicCoord(styleWidth, aRenderingContext, aFrame,
                         PROP_WIDTH, w)) {
     result = AddPercents(aType, w + coordOutsideWidth, pctOutsideWidth);
   }
   else if (aType == MIN_WIDTH &&
            // The only cases of coord-percent-calc() units that
            // GetAbsoluteCoord didn't handle are percent and calc()s
            // containing percent.
            styleWidth.IsCoordPercentCalcUnit() &&
            aFrame->IsFrameOfType(nsIFrame::eReplaced)) {
     // A percentage width on replaced elements means they can shrink to 0.
     result = 0; // let |min| handle padding/border/margin
   }
   else {
     // NOTE: We could really do a lot better for percents and for some
     // cases of calc() containing percent (certainly including any where
     // the coefficient on the percent is positive and there are no max()
     // expressions).  However, doing better for percents wouldn't be
     // backwards compatible.
     result = AddPercents(aType, result, pctTotal);
   }
   if (haveFixedMaxWidth ||
       GetIntrinsicCoord(styleMaxWidth, aRenderingContext, aFrame,
                         PROP_MAX_WIDTH, maxw)) {
     maxw = AddPercents(aType, maxw + coordOutsideWidth, pctOutsideWidth);
     if (result > maxw)
       result = maxw;
   }
   if (haveFixedMinWidth ||
       GetIntrinsicCoord(styleMinWidth, aRenderingContext, aFrame,
                         PROP_MIN_WIDTH, minw)) {
     minw = AddPercents(aType, minw + coordOutsideWidth, pctOutsideWidth);
     if (result < minw)
       result = minw;
   }
   min = AddPercents(aType, min, pctTotal);
   if (result < min)
     result = min;
   const nsStyleDisplay *disp = aFrame->StyleDisplay();
   if (aFrame->IsThemed(disp)) {
     nsIntSize size(0, 0);
     bool canOverride = true;
     nsPresContext *presContext = aFrame->PresContext();
     presContext->GetTheme()->
       GetMinimumWidgetSize(aRenderingContext, aFrame, disp->mAppearance,
                            &size, &canOverride);
     nscoord themeWidth = presContext->DevPixelsToAppUnits(size.width);
     // GMWS() returns a border-box width
     themeWidth += offsets.hMargin;
     themeWidth = AddPercents(aType, themeWidth, offsets.hPctMargin);
     if (themeWidth > result || !canOverride)
       result = themeWidth;
   }
 #ifdef DEBUG_INTRINSIC_WIDTH
   nsFrame::IndentBy(stderr, gNoiseIndent);
   static_cast<nsFrame*>(aFrame)->ListTag(stderr);
   printf_stderr(" %s intrinsic width for container is %d twips.\n",
          aType == MIN_WIDTH ? "min" : "pref", result);
 #endif
   return result;
 }
 /* static */ nscoord
 nsLayoutUtils::ComputeCBDependentValue(nscoord aPercentBasis,
                                        const nsStyleCoord& aCoord)
 {
   NS_WARN_IF_FALSE(aPercentBasis != NS_UNCONSTRAINEDSIZE,
                    "have unconstrained width or height; this should only "
                    "result from very large sizes, not attempts at intrinsic "
                    "size calculation");
   if (aCoord.IsCoordPercentCalcUnit()) {
     return nsRuleNode::ComputeCoordPercentCalc(aCoord, aPercentBasis);
   }
   NS_ASSERTION(aCoord.GetUnit() == eStyleUnit_None ||
                aCoord.GetUnit() == eStyleUnit_Auto,
                "unexpected width value");
   return 0;
 }
 /* static */ nscoord
 nsLayoutUtils::ComputeWidthValue(
                  nsRenderingContext* aRenderingContext,
                  nsIFrame*            aFrame,
                  nscoord              aContainingBlockWidth,
                  nscoord              aContentEdgeToBoxSizing,
                  nscoord              aBoxSizingToMarginEdge,
                  const nsStyleCoord&  aCoord)
 {
   NS_PRECONDITION(aFrame, "non-null frame expected");
   NS_PRECONDITION(aRenderingContext, "non-null rendering context expected");
   NS_WARN_IF_FALSE(aContainingBlockWidth != NS_UNCONSTRAINEDSIZE,
                    "have unconstrained width; this should only result from "
                    "very large sizes, not attempts at intrinsic width "
                    "calculation");
   NS_PRECONDITION(aContainingBlockWidth >= 0,
                   "width less than zero");
   nscoord result;
   if (aCoord.IsCoordPercentCalcUnit()) {
     result = nsRuleNode::ComputeCoordPercentCalc(aCoord,
                                                  aContainingBlockWidth);
     // The result of a calc() expression might be less than 0; we
     // should clamp at runtime (below).  (Percentages and coords that
     // are less than 0 have already been dropped by the parser.)
     result -= aContentEdgeToBoxSizing;
   } else {
     MOZ_ASSERT(eStyleUnit_Enumerated == aCoord.GetUnit());
     // If aFrame is a container for font size inflation, then shrink
     // wrapping inside of it should not apply font size inflation.
     AutoMaybeDisableFontInflation an(aFrame);
     int32_t val = aCoord.GetIntValue();
     switch (val) {
       case NS_STYLE_WIDTH_MAX_CONTENT:
         result = aFrame->GetPrefWidth(aRenderingContext);
         NS_ASSERTION(result >= 0, "width less than zero");
         break;
       case NS_STYLE_WIDTH_MIN_CONTENT:
         result = aFrame->GetMinWidth(aRenderingContext);
         NS_ASSERTION(result >= 0, "width less than zero");
         break;
       case NS_STYLE_WIDTH_FIT_CONTENT:
         {
           nscoord pref = aFrame->GetPrefWidth(aRenderingContext),
                    min = aFrame->GetMinWidth(aRenderingContext),
                   fill = aContainingBlockWidth -
                          (aBoxSizingToMarginEdge + aContentEdgeToBoxSizing);
           result = std::max(min, std::min(pref, fill));
           NS_ASSERTION(result >= 0, "width less than zero");
         }
         break;
       case NS_STYLE_WIDTH_AVAILABLE:
         result = aContainingBlockWidth -
                  (aBoxSizingToMarginEdge + aContentEdgeToBoxSizing);
     }
   }
   return std::max(0, result);
 }
 /* static */ nscoord
 nsLayoutUtils::ComputeHeightDependentValue(
                  nscoord              aContainingBlockHeight,
                  const nsStyleCoord&  aCoord)
 {
   // XXXldb Some callers explicitly check aContainingBlockHeight
   // against NS_AUTOHEIGHT *and* unit against eStyleUnit_Percent or
   // calc()s containing percents before calling this function.
   // However, it would be much more likely to catch problems without
   // the unit conditions.
   // XXXldb Many callers pass a non-'auto' containing block height when
   // according to CSS2.1 they should be passing 'auto'.
   NS_PRECONDITION(NS_AUTOHEIGHT != aContainingBlockHeight ||
                   !aCoord.HasPercent(),
                   "unexpected containing block height");
   if (aCoord.IsCoordPercentCalcUnit()) {
     return nsRuleNode::ComputeCoordPercentCalc(aCoord, aContainingBlockHeight);
   }
   NS_ASSERTION(aCoord.GetUnit() == eStyleUnit_None ||
                aCoord.GetUnit() == eStyleUnit_Auto,
                "unexpected height value");
   return 0;
 }
 /* static */ void
 nsLayoutUtils::MarkDescendantsDirty(nsIFrame *aSubtreeRoot)
 {
   nsAutoTArray<nsIFrame*, 4> subtrees;
   subtrees.AppendElement(aSubtreeRoot);
   // dirty descendants, iterating over subtrees that may include
   // additional subtrees associated with placeholders
   do {
     nsIFrame *subtreeRoot = subtrees.ElementAt(subtrees.Length() - 1);
     subtrees.RemoveElementAt(subtrees.Length() - 1);
     // Mark all descendants dirty (using an nsTArray stack rather than
     // recursion).
     // Note that nsHTMLReflowState::InitResizeFlags has some similar
     // code; see comments there for how and why it differs.
     nsAutoTArray<nsIFrame*, 32> stack;
     stack.AppendElement(subtreeRoot);
     do {
       nsIFrame *f = stack.ElementAt(stack.Length() - 1);
       stack.RemoveElementAt(stack.Length() - 1);
       f->MarkIntrinsicWidthsDirty();
       if (f->GetType() == nsGkAtoms::placeholderFrame) {
         nsIFrame *oof = nsPlaceholderFrame::GetRealFrameForPlaceholder(f);
         if (!nsLayoutUtils::IsProperAncestorFrame(subtreeRoot, oof)) {
           // We have another distinct subtree we need to mark.
           subtrees.AppendElement(oof);
         }
       }
       nsIFrame::ChildListIterator lists(f);
       for (; !lists.IsDone(); lists.Next()) {
         nsFrameList::Enumerator childFrames(lists.CurrentList());
         for (; !childFrames.AtEnd(); childFrames.Next()) {
           nsIFrame* kid = childFrames.get();
           stack.AppendElement(kid);
         }
       }
     } while (stack.Length() != 0);
   } while (subtrees.Length() != 0);
 }
 #define MULDIV(a,b,c) (nscoord(int64_t(a) * int64_t(b) / int64_t(c)))
 /* static */ nsSize
 nsLayoutUtils::ComputeSizeWithIntrinsicDimensions(
                    nsRenderingContext* aRenderingContext, nsIFrame* aFrame,
                    const IntrinsicSize& aIntrinsicSize,
                    nsSize aIntrinsicRatio, nsSize aCBSize,
                    nsSize aMargin, nsSize aBorder, nsSize aPadding)
 {
   const nsStylePosition* stylePos = aFrame->StylePosition();
   // If we're a flex item, we'll compute our size a bit differently.
   const nsStyleCoord* widthStyleCoord = &(stylePos->mWidth);
   const nsStyleCoord* heightStyleCoord = &(stylePos->mHeight);
   bool isFlexItem = aFrame->IsFlexItem();
   bool isHorizontalFlexItem = false;
   if (isFlexItem) {
     // Flex items use their "flex-basis" property in place of their main-size
     // property (e.g. "width") for sizing purposes, *unless* they have
     // "flex-basis:auto", in which case they use their main-size property after
     // all.
     uint32_t flexDirection =
       aFrame->GetParent()->StylePosition()->mFlexDirection;
     isHorizontalFlexItem =
       flexDirection == NS_STYLE_FLEX_DIRECTION_ROW ||
       flexDirection == NS_STYLE_FLEX_DIRECTION_ROW_REVERSE;
     // NOTE: The logic here should match the similar chunk for determining
     // widthStyleCoord and heightStyleCoord in nsFrame::ComputeSize().
     const nsStyleCoord* flexBasis = &(stylePos->mFlexBasis);
     if (flexBasis->GetUnit() != eStyleUnit_Auto) {
       if (isHorizontalFlexItem) {
         widthStyleCoord = flexBasis;
       } else {
         // One caveat for vertical flex items: We don't support enumerated
         // values (e.g. "max-content") for height properties yet. So, if our
         // computed flex-basis is an enumerated value, we'll just behave as if
         // it were "auto", which means "use the main-size property after all"
         // (which is "height", in this case).
         // NOTE: Once we support intrinsic sizing keywords for "height",
         // we should remove this check.
         if (flexBasis->GetUnit() != eStyleUnit_Enumerated) {
           heightStyleCoord = flexBasis;
         }
       }
     }
   }
   // Handle intrinsic sizes and their interaction with
   // {min-,max-,}{width,height} according to the rules in
   // http://www.w3.org/TR/CSS21/visudet.html#min-max-widths
   // Note: throughout the following section of the function, I avoid
   // a * (b / c) because of its reduced accuracy relative to a * b / c
   // or (a * b) / c (which are equivalent).
   const bool isAutoWidth = widthStyleCoord->GetUnit() == eStyleUnit_Auto;
   const bool isAutoHeight = IsAutoHeight(*heightStyleCoord, aCBSize.height);
   nsSize boxSizingAdjust(0,0);
   switch (stylePos->mBoxSizing) {
     case NS_STYLE_BOX_SIZING_BORDER:
       boxSizingAdjust += aBorder;
       // fall through
     case NS_STYLE_BOX_SIZING_PADDING:
       boxSizingAdjust += aPadding;
   }
   nscoord boxSizingToMarginEdgeWidth =
     aMargin.width + aBorder.width + aPadding.width - boxSizingAdjust.width;
   nscoord width, minWidth, maxWidth, height, minHeight, maxHeight;
   if (!isAutoWidth) {
     width = nsLayoutUtils::ComputeWidthValue(aRenderingContext,
               aFrame, aCBSize.width, boxSizingAdjust.width,
               boxSizingToMarginEdgeWidth, *widthStyleCoord);
   }
   if (stylePos->mMaxWidth.GetUnit() != eStyleUnit_None &&
       !(isFlexItem && isHorizontalFlexItem)) {
     maxWidth = nsLayoutUtils::ComputeWidthValue(aRenderingContext,
                  aFrame, aCBSize.width, boxSizingAdjust.width,
                  boxSizingToMarginEdgeWidth, stylePos->mMaxWidth);
   } else {
     // NOTE: Flex items ignore their min & max sizing properties in their
     // flex container's main-axis.  (Those properties get applied later in
     // the flexbox algorithm.)
     maxWidth = nscoord_MAX;
   }
   if (!(isFlexItem && isHorizontalFlexItem)) {
     minWidth = nsLayoutUtils::ComputeWidthValue(aRenderingContext,
                  aFrame, aCBSize.width, boxSizingAdjust.width,
                  boxSizingToMarginEdgeWidth, stylePos->mMinWidth);
   } else {
     // NOTE: Flex items ignore their min & max sizing properties in their
     // flex container's main-axis.  (Those properties get applied later in
     // the flexbox algorithm.)
     minWidth = 0;
   }
   if (!isAutoHeight) {
     height = nsLayoutUtils::ComputeHeightValue(aCBSize.height,
                 boxSizingAdjust.height,
                 *heightStyleCoord);
   }
   if (!IsAutoHeight(stylePos->mMaxHeight, aCBSize.height) &&
       !(isFlexItem && !isHorizontalFlexItem)) {
     maxHeight = nsLayoutUtils::ComputeHeightValue(aCBSize.height,
                   boxSizingAdjust.height,
                   stylePos->mMaxHeight);
   } else {
     maxHeight = nscoord_MAX;
   }
   if (!IsAutoHeight(stylePos->mMinHeight, aCBSize.height) &&
       !(isFlexItem && !isHorizontalFlexItem)) {
     minHeight = nsLayoutUtils::ComputeHeightValue(aCBSize.height,
                   boxSizingAdjust.height,
                   stylePos->mMinHeight);
   } else {
     minHeight = 0;
   }
   // Resolve percentage intrinsic width/height as necessary:
   NS_ASSERTION(aCBSize.width != NS_UNCONSTRAINEDSIZE,
                "Our containing block must not have unconstrained width!");
   bool hasIntrinsicWidth, hasIntrinsicHeight;
   nscoord intrinsicWidth, intrinsicHeight;
   if (aIntrinsicSize.width.GetUnit() == eStyleUnit_Coord) {
     hasIntrinsicWidth = true;
     intrinsicWidth = aIntrinsicSize.width.GetCoordValue();
     if (intrinsicWidth < 0)
       intrinsicWidth = 0;
   } else {
     NS_ASSERTION(aIntrinsicSize.width.GetUnit() == eStyleUnit_None,
                  "unexpected unit");
     hasIntrinsicWidth = false;
     intrinsicWidth = 0;
   }
   if (aIntrinsicSize.height.GetUnit() == eStyleUnit_Coord) {
     hasIntrinsicHeight = true;
     intrinsicHeight = aIntrinsicSize.height.GetCoordValue();
     if (intrinsicHeight < 0)
       intrinsicHeight = 0;
   } else {
     NS_ASSERTION(aIntrinsicSize.height.GetUnit() == eStyleUnit_None,
                  "unexpected unit");
     hasIntrinsicHeight = false;
     intrinsicHeight = 0;
   }
   NS_ASSERTION(aIntrinsicRatio.width >= 0 && aIntrinsicRatio.height >= 0,
                "Intrinsic ratio has a negative component!");
   // Now calculate the used values for width and height:
   if (isAutoWidth) {
     if (isAutoHeight) {
       // 'auto' width, 'auto' height
       // Get tentative values - CSS 2.1 sections 10.3.2 and 10.6.2:
       nscoord tentWidth, tentHeight;
       if (hasIntrinsicWidth) {
         tentWidth = intrinsicWidth;
       } else if (hasIntrinsicHeight && aIntrinsicRatio.height > 0) {
         tentWidth = MULDIV(intrinsicHeight, aIntrinsicRatio.width, aIntrinsicRatio.height);
       } else if (aIntrinsicRatio.width > 0) {
         tentWidth = aCBSize.width - boxSizingToMarginEdgeWidth; // XXX scrollbar?
         if (tentWidth < 0) tentWidth = 0;
       } else {
         tentWidth = nsPresContext::CSSPixelsToAppUnits(300);
       }
       if (hasIntrinsicHeight) {
         tentHeight = intrinsicHeight;
       } else if (aIntrinsicRatio.width > 0) {
         tentHeight = MULDIV(tentWidth, aIntrinsicRatio.height, aIntrinsicRatio.width);
       } else {
         tentHeight = nsPresContext::CSSPixelsToAppUnits(150);
       }
       return ComputeAutoSizeWithIntrinsicDimensions(minWidth, minHeight,
                                                     maxWidth, maxHeight,
                                                     tentWidth, tentHeight);
     } else {
       // 'auto' width, non-'auto' height
       height = NS_CSS_MINMAX(height, minHeight, maxHeight);
       if (aIntrinsicRatio.height > 0) {
         width = MULDIV(height, aIntrinsicRatio.width, aIntrinsicRatio.height);
       } else if (hasIntrinsicWidth) {
         width = intrinsicWidth;
       } else {
         width = nsPresContext::CSSPixelsToAppUnits(300);
       }
       width = NS_CSS_MINMAX(width, minWidth, maxWidth);
     }
   } else {
     if (isAutoHeight) {
       // non-'auto' width, 'auto' height
       width = NS_CSS_MINMAX(width, minWidth, maxWidth);
       if (aIntrinsicRatio.width > 0) {
         height = MULDIV(width, aIntrinsicRatio.height, aIntrinsicRatio.width);
       } else if (hasIntrinsicHeight) {
         height = intrinsicHeight;
       } else {
         height = nsPresContext::CSSPixelsToAppUnits(150);
       }
       height = NS_CSS_MINMAX(height, minHeight, maxHeight);
     } else {
       // non-'auto' width, non-'auto' height
       width = NS_CSS_MINMAX(width, minWidth, maxWidth);
       height = NS_CSS_MINMAX(height, minHeight, maxHeight);
     }
   }
   return nsSize(width, height);
 }
 nsSize
 nsLayoutUtils::ComputeAutoSizeWithIntrinsicDimensions(nscoord minWidth, nscoord minHeight,
                                                       nscoord maxWidth, nscoord maxHeight,
                                                       nscoord tentWidth, nscoord tentHeight)
 {
   // Now apply min/max-width/height - CSS 2.1 sections 10.4 and 10.7:
   if (minWidth > maxWidth)
     maxWidth = minWidth;
   if (minHeight > maxHeight)
     maxHeight = minHeight;
   nscoord heightAtMaxWidth, heightAtMinWidth,
           widthAtMaxHeight, widthAtMinHeight;
   if (tentWidth > 0) {
     heightAtMaxWidth = MULDIV(maxWidth, tentHeight, tentWidth);
     if (heightAtMaxWidth < minHeight)
       heightAtMaxWidth = minHeight;
     heightAtMinWidth = MULDIV(minWidth, tentHeight, tentWidth);
     if (heightAtMinWidth > maxHeight)
       heightAtMinWidth = maxHeight;
   } else {
     heightAtMaxWidth = heightAtMinWidth = NS_CSS_MINMAX(tentHeight, minHeight, maxHeight);
   }
   if (tentHeight > 0) {
     widthAtMaxHeight = MULDIV(maxHeight, tentWidth, tentHeight);
     if (widthAtMaxHeight < minWidth)
       widthAtMaxHeight = minWidth;
     widthAtMinHeight = MULDIV(minHeight, tentWidth, tentHeight);
     if (widthAtMinHeight > maxWidth)
       widthAtMinHeight = maxWidth;
   } else {
     widthAtMaxHeight = widthAtMinHeight = NS_CSS_MINMAX(tentWidth, minWidth, maxWidth);
   }
   // The table at http://www.w3.org/TR/CSS21/visudet.html#min-max-widths :
   nscoord width, height;
   if (tentWidth > maxWidth) {
     if (tentHeight > maxHeight) {
       if (int64_t(maxWidth) * int64_t(tentHeight) <=
           int64_t(maxHeight) * int64_t(tentWidth)) {
         width = maxWidth;
         height = heightAtMaxWidth;
       } else {
         width = widthAtMaxHeight;
         height = maxHeight;
       }
     } else {
       // This also covers "(w > max-width) and (h < min-height)" since in
       // that case (max-width/w < 1), and with (h < min-height):
       //   max(max-width * h/w, min-height) == min-height
       width = maxWidth;
       height = heightAtMaxWidth;
     }
   } else if (tentWidth < minWidth) {
     if (tentHeight < minHeight) {
       if (int64_t(minWidth) * int64_t(tentHeight) <=
           int64_t(minHeight) * int64_t(tentWidth)) {
         width = widthAtMinHeight;
         height = minHeight;
       } else {
         width = minWidth;
         height = heightAtMinWidth;
       }
     } else {
       // This also covers "(w < min-width) and (h > max-height)" since in
       // that case (min-width/w > 1), and with (h > max-height):
       //   min(min-width * h/w, max-height) == max-height
       width = minWidth;
       height = heightAtMinWidth;
     }
   } else {
     if (tentHeight > maxHeight) {
       width = widthAtMaxHeight;
       height = maxHeight;
     } else if (tentHeight < minHeight) {
       width = widthAtMinHeight;
       height = minHeight;
     } else {
       width = tentWidth;
       height = tentHeight;
     }
   }
   return nsSize(width, height);
 }
 /* static */ nscoord
 nsLayoutUtils::MinWidthFromInline(nsIFrame* aFrame,
                                   nsRenderingContext* aRenderingContext)
 {
   NS_ASSERTION(!aFrame->IsContainerForFontSizeInflation(),
                "should not be container for font size inflation");
   nsIFrame::InlineMinWidthData data;
   DISPLAY_MIN_WIDTH(aFrame, data.prevLines);
   aFrame->AddInlineMinWidth(aRenderingContext, &data);
   data.ForceBreak(aRenderingContext);
   return data.prevLines;
 }
 /* static */ nscoord
 nsLayoutUtils::PrefWidthFromInline(nsIFrame* aFrame,
                                    nsRenderingContext* aRenderingContext)
 {
   NS_ASSERTION(!aFrame->IsContainerForFontSizeInflation(),
                "should not be container for font size inflation");
   nsIFrame::InlinePrefWidthData data;
   DISPLAY_PREF_WIDTH(aFrame, data.prevLines);
   aFrame->AddInlinePrefWidth(aRenderingContext, &data);
   data.ForceBreak(aRenderingContext);
   return data.prevLines;
 }
 static nscolor
 DarkenColor(nscolor aColor)
 {
   uint16_t  hue, sat, value;
   uint8_t alpha;
   // convert the RBG to HSV so we can get the lightness (which is the v)
   NS_RGB2HSV(aColor, hue, sat, value, alpha);
   // The goal here is to send white to black while letting colored
   // stuff stay colored... So we adopt the following approach.
   // Something with sat = 0 should end up with value = 0.  Something
   // with a high sat can end up with a high value and it's ok.... At
   // the same time, we don't want to make things lighter.  Do
   // something simple, since it seems to work.
   if (value > sat) {
     value = sat;
     // convert this color back into the RGB color space.
     NS_HSV2RGB(aColor, hue, sat, value, alpha);
   }
   return aColor;
 }
 // Check whether we should darken text/decoration colors. We need to do this if
 // background images and colors are being suppressed, because that means
 // light text will not be visible against the (presumed light-colored) background.
 static bool
 ShouldDarkenColors(nsPresContext* aPresContext)
 {
   return !aPresContext->GetBackgroundColorDraw() &&
          !aPresContext->GetBackgroundImageDraw();
 }
 nscolor
 nsLayoutUtils::GetColor(nsIFrame* aFrame, nsCSSProperty aProperty)
 {
   if (aProperty == eCSSProperty_color)
   {
     nscolor nativeColor = NS_RGB(0, 0, 0);
     if (GetNativeTextColor(aFrame, nativeColor))
       return nativeColor;
   }
   nscolor color = aFrame->GetVisitedDependentColor(aProperty);
   if (ShouldDarkenColors(aFrame->PresContext())) {
     color = DarkenColor(color);
   }
   return color;
 }
 bool
 nsLayoutUtils::GetNativeTextColor(nsIFrame* aFrame, nscolor& aColor)
 {
   nsPresContext *presContext = aFrame->PresContext();
   if (!presContext->IsChrome()) {
     // If native appearance was used to draw the background of the containing
     // frame, return a contrasting native foreground color instead of the
     // color from the element's style.  This avoids a problem where black
     // text was displayed on a black background when a Windows theme such as
     // "High Contrast Black" was used.  The background is drawn inside
     // nsNativeThemeWin::ClassicDrawWidgetBackground().
     //
     // Because both the background color and this foreground color are used
     // directly without exposing the colors via CSS computed styles, the
     // native colors are not leaked to content.
     nsIFrame* bgFrame =
                     nsCSSRendering::FindNonTransparentBackgroundFrame(aFrame);
     if (bgFrame) {
       const nsStyleDisplay* displayData = bgFrame->StyleDisplay();
       uint8_t widgetType = displayData->mAppearance;
       nsITheme *theme = presContext->GetTheme();
       if (theme && widgetType && theme->ThemeSupportsWidget(presContext,
                                                             bgFrame,
                                                             widgetType)) {
         bool isDisabled = false;
         nsIContent* frameContent = bgFrame->GetContent();
         if (frameContent && frameContent->IsElement()) {
           EventStates es = frameContent->AsElement()->State();
           isDisabled = es.HasState(NS_EVENT_STATE_DISABLED);
         }
         if (NS_SUCCEEDED(LookAndFeel::GetColorForNativeAppearance(widgetType,
                                                        isDisabled, &aColor))) {
             return true;
         }
       }
     }
   }
   return false;
 }
 gfxFloat
 nsLayoutUtils::GetSnappedBaselineY(nsIFrame* aFrame, gfxContext* aContext,
                                    nscoord aY, nscoord aAscent)
 {
   gfxFloat appUnitsPerDevUnit = aFrame->PresContext()->AppUnitsPerDevPixel();
   gfxFloat baseline = gfxFloat(aY) + aAscent;
   gfxRect putativeRect(0, baseline/appUnitsPerDevUnit, 1, 1);
   if (!aContext->UserToDevicePixelSnapped(putativeRect, true))
     return baseline;
   return aContext->DeviceToUser(putativeRect.TopLeft()).y * appUnitsPerDevUnit;
 }
 void
 nsLayoutUtils::DrawString(const nsIFrame*       aFrame,
                           nsRenderingContext*   aContext,
                           const char16_t*      aString,
                           int32_t               aLength,
                           nsPoint               aPoint,
                           nsStyleContext*       aStyleContext)
 {
   nsresult rv = NS_ERROR_FAILURE;
   nsPresContext* presContext = aFrame->PresContext();
   if (presContext->BidiEnabled()) {
     nsBidiLevel level =
       nsBidiPresUtils::BidiLevelFromStyle(aStyleContext ?
                                           aStyleContext : aFrame->StyleContext());
     rv = nsBidiPresUtils::RenderText(aString, aLength, level,
                                      presContext, *aContext, *aContext,
                                      aPoint.x, aPoint.y);
   }
   if (NS_FAILED(rv))
   {
     aContext->SetTextRunRTL(false);
     aContext->DrawString(aString, aLength, aPoint.x, aPoint.y);
   }
 }
 nscoord
 nsLayoutUtils::GetStringWidth(const nsIFrame*      aFrame,
                               nsRenderingContext* aContext,
                               const char16_t*     aString,
                               int32_t              aLength)
 {
   nsPresContext* presContext = aFrame->PresContext();
   if (presContext->BidiEnabled()) {
     nsBidiLevel level =
       nsBidiPresUtils::BidiLevelFromStyle(aFrame->StyleContext());
     return nsBidiPresUtils::MeasureTextWidth(aString, aLength,
                                              level, presContext, *aContext);
   }
   aContext->SetTextRunRTL(false);
   return aContext->GetWidth(aString, aLength);
 }
 /* static */ void
 nsLayoutUtils::PaintTextShadow(const nsIFrame* aFrame,
                                nsRenderingContext* aContext,
                                const nsRect& aTextRect,
                                const nsRect& aDirtyRect,
                                const nscolor& aForegroundColor,
                                TextShadowCallback aCallback,
                                void* aCallbackData)
 {
   const nsStyleText* textStyle = aFrame->StyleText();
   if (!textStyle->HasTextShadow())
     return;
   // Text shadow happens with the last value being painted at the back,
   // ie. it is painted first.
   gfxContext* aDestCtx = aContext->ThebesContext();
   for (uint32_t i = textStyle->mTextShadow->Length(); i > 0; --i) {
     nsCSSShadowItem* shadowDetails = textStyle->mTextShadow->ShadowAt(i - 1);
     nsPoint shadowOffset(shadowDetails->mXOffset,
                          shadowDetails->mYOffset);
     nscoord blurRadius = std::max(shadowDetails->mRadius, 0);
     nsRect shadowRect(aTextRect);
     shadowRect.MoveBy(shadowOffset);
     nsPresContext* presCtx = aFrame->PresContext();
     nsContextBoxBlur contextBoxBlur;
     gfxContext* shadowContext = contextBoxBlur.Init(shadowRect, 0, blurRadius,
                                                     presCtx->AppUnitsPerDevPixel(),
                                                     aDestCtx, aDirtyRect, nullptr);
     if (!shadowContext)
       continue;
     nscolor shadowColor;
     if (shadowDetails->mHasColor)
       shadowColor = shadowDetails->mColor;
     else
       shadowColor = aForegroundColor;
     // Conjure an nsRenderingContext from a gfxContext for drawing the text
     // to blur.
     nsRefPtr<nsRenderingContext> renderingContext = new nsRenderingContext();
     renderingContext->Init(presCtx->DeviceContext(), shadowContext);
     aDestCtx->Save();
     aDestCtx->NewPath();
     aDestCtx->SetColor(gfxRGBA(shadowColor));
     // The callback will draw whatever we want to blur as a shadow.
     aCallback(renderingContext, shadowOffset, shadowColor, aCallbackData);
     contextBoxBlur.DoPaint();
     aDestCtx->Restore();
   }
 }
 /* static */ nscoord
 nsLayoutUtils::GetCenteredFontBaseline(nsFontMetrics* aFontMetrics,
                                        nscoord         aLineHeight)
 {
   nscoord fontAscent = aFontMetrics->MaxAscent();
   nscoord fontHeight = aFontMetrics->MaxHeight();
   nscoord leading = aLineHeight - fontHeight;
   return fontAscent + leading/2;
 }
 /* static */ bool
 nsLayoutUtils::GetFirstLineBaseline(const nsIFrame* aFrame, nscoord* aResult)
 {
   LinePosition position;
   if (!GetFirstLinePosition(aFrame, &position))
     return false;
   *aResult = position.mBaseline;
   return true;
 }
 /* static */ bool
 nsLayoutUtils::GetFirstLinePosition(const nsIFrame* aFrame,
                                     LinePosition* aResult)
 {
   const nsBlockFrame* block = nsLayoutUtils::GetAsBlock(const_cast<nsIFrame*>(aFrame));
   if (!block) {
     // For the first-line baseline we also have to check for a table, and if
     // so, use the baseline of its first row.
     nsIAtom* fType = aFrame->GetType();
     if (fType == nsGkAtoms::tableOuterFrame) {
       aResult->mTop = 0;
       aResult->mBaseline = aFrame->GetBaseline();
       // This is what we want for the list bullet caller; not sure if
       // other future callers will want the same.
       aResult->mBottom = aFrame->GetSize().height;
       return true;
     }
     // For first-line baselines, we have to consider scroll frames.
     if (fType == nsGkAtoms::scrollFrame) {
       nsIScrollableFrame *sFrame = do_QueryFrame(const_cast<nsIFrame*>(aFrame));
       if (!sFrame) {
         NS_NOTREACHED("not scroll frame");
       }
       LinePosition kidPosition;
       if (GetFirstLinePosition(sFrame->GetScrolledFrame(), &kidPosition)) {
         // Consider only the border and padding that contributes to the
         // kid's position, not the scrolling, so we get the initial
         // position.
         *aResult = kidPosition + aFrame->GetUsedBorderAndPadding().top;
         return true;
       }
       return false;
     }
     if (fType == nsGkAtoms::fieldSetFrame) {
       LinePosition kidPosition;
       nsIFrame* kid = aFrame->GetFirstPrincipalChild();
       // kid might be a legend frame here, but that's ok.
       if (GetFirstLinePosition(kid, &kidPosition)) {
         *aResult = kidPosition + kid->GetNormalPosition().y;
         return true;
       }
       return false;
     }
     // No baseline.
     return false;
   }
   for (nsBlockFrame::const_line_iterator line = block->begin_lines(),
                                      line_end = block->end_lines();
        line != line_end; ++line) {
     if (line->IsBlock()) {
       nsIFrame *kid = line->mFirstChild;
       LinePosition kidPosition;
       if (GetFirstLinePosition(kid, &kidPosition)) {
         *aResult = kidPosition + kid->GetNormalPosition().y;
         return true;
       }
     } else {
       // XXX Is this the right test?  We have some bogus empty lines
       // floating around, but IsEmpty is perhaps too weak.
       if (line->BSize() != 0 || !line->IsEmpty()) {
         nscoord top = line->BStart();
         aResult->mTop = top;
         aResult->mBaseline = top + line->GetAscent();
         aResult->mBottom = top + line->BSize();
         return true;
       }
     }
   }
   return false;
 }
 /* static */ bool
 nsLayoutUtils::GetLastLineBaseline(const nsIFrame* aFrame, nscoord* aResult)
 {
   const nsBlockFrame* block = nsLayoutUtils::GetAsBlock(const_cast<nsIFrame*>(aFrame));
   if (!block)
     // No baseline.  (We intentionally don't descend into scroll frames.)
     return false;
   for (nsBlockFrame::const_reverse_line_iterator line = block->rbegin_lines(),
                                              line_end = block->rend_lines();
        line != line_end; ++line) {
     if (line->IsBlock()) {
       nsIFrame *kid = line->mFirstChild;
       nscoord kidBaseline;
       if (GetLastLineBaseline(kid, &kidBaseline)) {
         // Ignore relative positioning for baseline calculations
         *aResult = kidBaseline + kid->GetNormalPosition().y;
         return true;
       } else if (kid->GetType() == nsGkAtoms::scrollFrame) {
         // Use the bottom of the scroll frame.
         // XXX CSS2.1 really doesn't say what to do here.
         *aResult = kid->GetNormalPosition().y + kid->GetRect().height;
         return true;
       }
     } else {
       // XXX Is this the right test?  We have some bogus empty lines
       // floating around, but IsEmpty is perhaps too weak.
       if (line->BSize() != 0 || !line->IsEmpty()) {
         *aResult = line->BStart() + line->GetAscent();
         return true;
       }
     }
   }
   return false;
 }
 static nscoord
 CalculateBlockContentBottom(nsBlockFrame* aFrame)
 {
   NS_PRECONDITION(aFrame, "null ptr");
   nscoord contentBottom = 0;
   for (nsBlockFrame::line_iterator line = aFrame->begin_lines(),
                                    line_end = aFrame->end_lines();
        line != line_end; ++line) {
     if (line->IsBlock()) {
       nsIFrame* child = line->mFirstChild;
       nscoord offset = child->GetNormalPosition().y;
       contentBottom = std::max(contentBottom,
                         nsLayoutUtils::CalculateContentBottom(child) + offset);
     }
     else {
       contentBottom = std::max(contentBottom, line->BEnd());
     }
   }
   return contentBottom;
 }
 /* static */ nscoord
 nsLayoutUtils::CalculateContentBottom(nsIFrame* aFrame)
 {
   NS_PRECONDITION(aFrame, "null ptr");
   nscoord contentBottom = aFrame->GetRect().height;
   // We want scrollable overflow rather than visual because this
   // calculation is intended to affect layout.
   if (aFrame->GetScrollableOverflowRect().height > contentBottom) {
     nsIFrame::ChildListIDs skip(nsIFrame::kOverflowList |
                                 nsIFrame::kExcessOverflowContainersList |
                                 nsIFrame::kOverflowOutOfFlowList);
     nsBlockFrame* blockFrame = GetAsBlock(aFrame);
     if (blockFrame) {
       contentBottom =
         std::max(contentBottom, CalculateBlockContentBottom(blockFrame));
       skip |= nsIFrame::kPrincipalList;
     }
     nsIFrame::ChildListIterator lists(aFrame);
     for (; !lists.IsDone(); lists.Next()) {
       if (!skip.Contains(lists.CurrentID())) {
         nsFrameList::Enumerator childFrames(lists.CurrentList());
         for (; !childFrames.AtEnd(); childFrames.Next()) {
           nsIFrame* child = childFrames.get();
           nscoord offset = child->GetNormalPosition().y;
           contentBottom = std::max(contentBottom,
                                  CalculateContentBottom(child) + offset);
         }
       }
     }
   }
   return contentBottom;
 }
 /* static */ nsIFrame*
 nsLayoutUtils::GetClosestLayer(nsIFrame* aFrame)
 {
   nsIFrame* layer;
   for (layer = aFrame; layer; layer = layer->GetParent()) {
     if (layer->IsPositioned() ||
         (layer->GetParent() &&
           layer->GetParent()->GetType() == nsGkAtoms::scrollFrame))
       break;
   }
   if (layer)
     return layer;
   return aFrame->PresContext()->PresShell()->FrameManager()->GetRootFrame();
 }
 GraphicsFilter
 nsLayoutUtils::GetGraphicsFilterForFrame(nsIFrame* aForFrame)
 {
   GraphicsFilter defaultFilter = GraphicsFilter::FILTER_GOOD;
   nsStyleContext *sc;
   if (nsCSSRendering::IsCanvasFrame(aForFrame)) {
     nsCSSRendering::FindBackground(aForFrame, &sc);
   } else {
     sc = aForFrame->StyleContext();
   }
   switch (sc->StyleSVG()->mImageRendering) {
   case NS_STYLE_IMAGE_RENDERING_OPTIMIZESPEED:
     return GraphicsFilter::FILTER_FAST;
   case NS_STYLE_IMAGE_RENDERING_OPTIMIZEQUALITY:
     return GraphicsFilter::FILTER_BEST;
   case NS_STYLE_IMAGE_RENDERING_CRISPEDGES:
     return GraphicsFilter::FILTER_NEAREST;
   default:
     return defaultFilter;
   }
 }
 /**
  * Given an image being drawn into an appunit coordinate system, and
  * a point in that coordinate system, map the point back into image
  * pixel space.
  * @param aSize the size of the image, in pixels
  * @param aDest the rectangle that the image is being mapped into
  * @param aPt a point in the same coordinate system as the rectangle
  */
 static gfxPoint
 MapToFloatImagePixels(const gfxSize& aSize,
                       const gfxRect& aDest, const gfxPoint& aPt)
 {
   return gfxPoint(((aPt.x - aDest.X())*aSize.width)/aDest.Width(),
                   ((aPt.y - aDest.Y())*aSize.height)/aDest.Height());
 }
 /**
  * Given an image being drawn into an pixel-based coordinate system, and
  * a point in image space, map the point into the pixel-based coordinate
  * system.
  * @param aSize the size of the image, in pixels
  * @param aDest the rectangle that the image is being mapped into
  * @param aPt a point in image space
  */
 static gfxPoint
 MapToFloatUserPixels(const gfxSize& aSize,
                      const gfxRect& aDest, const gfxPoint& aPt)
 {
   return gfxPoint(aPt.x*aDest.Width()/aSize.width + aDest.X(),
                   aPt.y*aDest.Height()/aSize.height + aDest.Y());
 }
 /* static */ gfxRect
 nsLayoutUtils::RectToGfxRect(const nsRect& aRect, int32_t aAppUnitsPerDevPixel)
 {
   return gfxRect(gfxFloat(aRect.x) / aAppUnitsPerDevPixel,
                  gfxFloat(aRect.y) / aAppUnitsPerDevPixel,
                  gfxFloat(aRect.width) / aAppUnitsPerDevPixel,
                  gfxFloat(aRect.height) / aAppUnitsPerDevPixel);
 }
 struct SnappedImageDrawingParameters {
   // A transform from either device space or user space (depending on mResetCTM)
   // to image space
   gfxMatrix mUserSpaceToImageSpace;
   // A device-space, pixel-aligned rectangle to fill
   gfxRect mFillRect;
   // A pixel rectangle in tiled image space outside of which gfx should not
   // sample (using EXTEND_PAD as necessary)
   nsIntRect mSubimage;
   // Whether there's anything to draw at all
   bool mShouldDraw;
   // true iff the CTM of the rendering context needs to be reset to the
   // identity matrix before drawing
   bool mResetCTM;
   SnappedImageDrawingParameters()
    : mShouldDraw(false)
    , mResetCTM(false)
   {}
   SnappedImageDrawingParameters(const gfxMatrix& aUserSpaceToImageSpace,
                                 const gfxRect&   aFillRect,
                                 const nsIntRect& aSubimage,
                                 bool             aResetCTM)
    : mUserSpaceToImageSpace(aUserSpaceToImageSpace)
    , mFillRect(aFillRect)
    , mSubimage(aSubimage)
    , mShouldDraw(true)
    , mResetCTM(aResetCTM)
   {}
 };
 /**
  * Given a set of input parameters, compute certain output parameters
  * for drawing an image with the image snapping algorithm.
  * See https://wiki.mozilla.org/Gecko:Image_Snapping_and_Rendering
  *
  *  @see nsLayoutUtils::DrawImage() for the descriptions of input parameters
  */
 static SnappedImageDrawingParameters
 ComputeSnappedImageDrawingParameters(gfxContext*     aCtx,
                                      int32_t         aAppUnitsPerDevPixel,
                                      const nsRect    aDest,
                                      const nsRect    aFill,
                                      const nsPoint   aAnchor,
                                      const nsRect    aDirty,
                                      const nsIntSize aImageSize)
 {
   if (aDest.IsEmpty() || aFill.IsEmpty() || !aImageSize.width || !aImageSize.height)
     return SnappedImageDrawingParameters();
   gfxRect devPixelDest =
     nsLayoutUtils::RectToGfxRect(aDest, aAppUnitsPerDevPixel);
   gfxRect devPixelFill =
     nsLayoutUtils::RectToGfxRect(aFill, aAppUnitsPerDevPixel);
   gfxRect devPixelDirty =
     nsLayoutUtils::RectToGfxRect(aDirty, aAppUnitsPerDevPixel);
   gfxMatrix currentMatrix = aCtx->CurrentMatrix();
   gfxRect fill = devPixelFill;
   bool didSnap;
   // Snap even if we have a scale in the context. But don't snap if
   // we have something that's not translation+scale, or if the scale flips in
   // the X or Y direction, because snapped image drawing can't handle that yet.
   if (!currentMatrix.HasNonAxisAlignedTransform() &&
       currentMatrix.xx > 0.0 && currentMatrix.yy > 0.0 &&
       aCtx->UserToDevicePixelSnapped(fill, true)) {
     didSnap = true;
     if (fill.IsEmpty()) {
       return SnappedImageDrawingParameters();
     }
   } else {
     didSnap = false;
     fill = devPixelFill;
   }
   gfxSize imageSize(aImageSize.width, aImageSize.height);
   // Compute the set of pixels that would be sampled by an ideal rendering
   gfxPoint subimageTopLeft =
     MapToFloatImagePixels(imageSize, devPixelDest, devPixelFill.TopLeft());
   gfxPoint subimageBottomRight =
     MapToFloatImagePixels(imageSize, devPixelDest, devPixelFill.BottomRight());
   nsIntRect intSubimage;
   intSubimage.MoveTo(NSToIntFloor(subimageTopLeft.x),
                      NSToIntFloor(subimageTopLeft.y));
   intSubimage.SizeTo(NSToIntCeil(subimageBottomRight.x) - intSubimage.x,
                      NSToIntCeil(subimageBottomRight.y) - intSubimage.y);
   // Compute the anchor point and compute final fill rect.
   // This code assumes that pixel-based devices have one pixel per
   // device unit!
   gfxPoint anchorPoint(gfxFloat(aAnchor.x)/aAppUnitsPerDevPixel,
                        gfxFloat(aAnchor.y)/aAppUnitsPerDevPixel);
   gfxPoint imageSpaceAnchorPoint =
     MapToFloatImagePixels(imageSize, devPixelDest, anchorPoint);
   if (didSnap) {
     imageSpaceAnchorPoint.Round();
     anchorPoint = imageSpaceAnchorPoint;
     anchorPoint = MapToFloatUserPixels(imageSize, devPixelDest, anchorPoint);
     anchorPoint = currentMatrix.Transform(anchorPoint);
     anchorPoint.Round();
     // This form of Transform is safe to call since non-axis-aligned
     // transforms wouldn't be snapped.
     devPixelDirty = currentMatrix.Transform(devPixelDirty);
   }
   gfxFloat scaleX = imageSize.width*aAppUnitsPerDevPixel/aDest.width;
   gfxFloat scaleY = imageSize.height*aAppUnitsPerDevPixel/aDest.height;
   if (didSnap) {
     // We'll reset aCTX to the identity matrix before drawing, so we need to
     // adjust our scales to match.
     scaleX /= currentMatrix.xx;
     scaleY /= currentMatrix.yy;
   }
   gfxFloat translateX = imageSpaceAnchorPoint.x - anchorPoint.x*scaleX;
   gfxFloat translateY = imageSpaceAnchorPoint.y - anchorPoint.y*scaleY;
   gfxMatrix transform(scaleX, 0, 0, scaleY, translateX, translateY);
   gfxRect finalFillRect = fill;
   // If the user-space-to-image-space transform is not a straight
   // translation by integers, then filtering will occur, and
   // restricting the fill rect to the dirty rect would change the values
   // computed for edge pixels, which we can't allow.
   // Also, if didSnap is false then rounding out 'devPixelDirty' might not
   // produce pixel-aligned coordinates, which would also break the values
   // computed for edge pixels.
   if (didSnap && !transform.HasNonIntegerTranslation()) {
     devPixelDirty.RoundOut();
     finalFillRect = fill.Intersect(devPixelDirty);
   }
   if (finalFillRect.IsEmpty())
     return SnappedImageDrawingParameters();
   return SnappedImageDrawingParameters(transform, finalFillRect, intSubimage,
                                        didSnap);
 }
 static nsresult
 DrawImageInternal(nsRenderingContext*    aRenderingContext,
                   imgIContainer*         aImage,
                   GraphicsFilter         aGraphicsFilter,
                   const nsRect&          aDest,
                   const nsRect&          aFill,
                   const nsPoint&         aAnchor,
                   const nsRect&          aDirty,
                   const nsIntSize&       aImageSize,
                   const SVGImageContext* aSVGContext,
                   uint32_t               aImageFlags)
 {
   if (aDest.Contains(aFill)) {
     aImageFlags |= imgIContainer::FLAG_CLAMP;
   }
   int32_t appUnitsPerDevPixel = aRenderingContext->AppUnitsPerDevPixel();
   gfxContext* ctx = aRenderingContext->ThebesContext();
   SnappedImageDrawingParameters drawingParams =
     ComputeSnappedImageDrawingParameters(ctx, appUnitsPerDevPixel, aDest, aFill,
                                          aAnchor, aDirty, aImageSize);
   if (!drawingParams.mShouldDraw)
     return NS_OK;
   gfxContextMatrixAutoSaveRestore saveMatrix(ctx);
   if (drawingParams.mResetCTM) {
     ctx->IdentityMatrix();
   }
   aImage->Draw(ctx, aGraphicsFilter, drawingParams.mUserSpaceToImageSpace,
                drawingParams.mFillRect, drawingParams.mSubimage, aImageSize,
                aSVGContext, imgIContainer::FRAME_CURRENT, aImageFlags);
   return NS_OK;
 }
 /* static */ void
 nsLayoutUtils::DrawPixelSnapped(nsRenderingContext* aRenderingContext,
                                 gfxDrawable*         aDrawable,
                                 GraphicsFilter       aFilter,
                                 const nsRect&        aDest,
                                 const nsRect&        aFill,
                                 const nsPoint&       aAnchor,
                                 const nsRect&        aDirty)
 {
   int32_t appUnitsPerDevPixel = aRenderingContext->AppUnitsPerDevPixel();
   gfxContext* ctx = aRenderingContext->ThebesContext();
   gfxIntSize drawableSize = aDrawable->Size();
   nsIntSize imageSize(drawableSize.width, drawableSize.height);
   SnappedImageDrawingParameters drawingParams =
     ComputeSnappedImageDrawingParameters(ctx, appUnitsPerDevPixel, aDest, aFill,
                                          aAnchor, aDirty, imageSize);
   if (!drawingParams.mShouldDraw)
     return;
   gfxContextMatrixAutoSaveRestore saveMatrix(ctx);
   if (drawingParams.mResetCTM) {
     ctx->IdentityMatrix();
   }
   gfxRect sourceRect =
     drawingParams.mUserSpaceToImageSpace.Transform(drawingParams.mFillRect);
   gfxRect imageRect(0, 0, imageSize.width, imageSize.height);
   gfxRect subimage(drawingParams.mSubimage.x, drawingParams.mSubimage.y,
                    drawingParams.mSubimage.width, drawingParams.mSubimage.height);
   NS_ASSERTION(!sourceRect.Intersect(subimage).IsEmpty(),
                "We must be allowed to sample *some* source pixels!");
   gfxUtils::DrawPixelSnapped(ctx, aDrawable,
                              drawingParams.mUserSpaceToImageSpace, subimage,
                              sourceRect, imageRect, drawingParams.mFillRect,
                              gfxImageFormat::ARGB32, aFilter);
 }
 /* static */ nsresult
 nsLayoutUtils::DrawSingleUnscaledImage(nsRenderingContext* aRenderingContext,
                                        imgIContainer*       aImage,
                                        GraphicsFilter       aGraphicsFilter,
                                        const nsPoint&       aDest,
                                        const nsRect*        aDirty,
                                        uint32_t             aImageFlags,
                                        const nsRect*        aSourceArea)
 {
   nsIntSize imageSize;
   aImage->GetWidth(&imageSize.width);
   aImage->GetHeight(&imageSize.height);
   NS_ENSURE_TRUE(imageSize.width > 0 && imageSize.height > 0, NS_ERROR_FAILURE);
   nscoord appUnitsPerCSSPixel = nsDeviceContext::AppUnitsPerCSSPixel();
   nsSize size(imageSize.width*appUnitsPerCSSPixel,
               imageSize.height*appUnitsPerCSSPixel);
   nsRect source;
   if (aSourceArea) {
     source = *aSourceArea;
   } else {
     source.SizeTo(size);
   }
   nsRect dest(aDest - source.TopLeft(), size);
   nsRect fill(aDest, source.Size());
   // Ensure that only a single image tile is drawn. If aSourceArea extends
   // outside the image bounds, we want to honor the aSourceArea-to-aDest
   // translation but we don't want to actually tile the image.
   fill.IntersectRect(fill, dest);
   return DrawImageInternal(aRenderingContext, aImage, aGraphicsFilter,
                            dest, fill, aDest, aDirty ? *aDirty : dest,
                            imageSize, nullptr, aImageFlags);
 }
 /* static */ nsresult
 nsLayoutUtils::DrawSingleImage(nsRenderingContext*    aRenderingContext,
                                imgIContainer*         aImage,
                                GraphicsFilter         aGraphicsFilter,
                                const nsRect&          aDest,
                                const nsRect&          aDirty,
                                const SVGImageContext* aSVGContext,
                                uint32_t               aImageFlags,
                                const nsRect*          aSourceArea)
 {
   nsIntSize imageSize;
   if (aImage->GetType() == imgIContainer::TYPE_VECTOR) {
     // We choose a size for vector images that emulates a raster image which
     // is perfectly sized for the destination rect: each pixel in the image
     // maps exactly to a single pixel on-screen.
     nscoord appUnitsPerDevPx = aRenderingContext->AppUnitsPerDevPixel();
     imageSize.width = NSAppUnitsToIntPixels(aDest.width, appUnitsPerDevPx);
     imageSize.height = NSAppUnitsToIntPixels(aDest.height, appUnitsPerDevPx);
   } else {
     // Raster images have an intrinsic size, so we just use that.
     aImage->GetWidth(&imageSize.width);
     aImage->GetHeight(&imageSize.height);
   }
   NS_ENSURE_TRUE(imageSize.width > 0 && imageSize.height > 0, NS_ERROR_FAILURE);
   nsRect source;
   if (aSourceArea) {
     source = *aSourceArea;
   } else {
     nscoord appUnitsPerCSSPixel = nsDeviceContext::AppUnitsPerCSSPixel();
     source.SizeTo(imageSize.width*appUnitsPerCSSPixel,
                   imageSize.height*appUnitsPerCSSPixel);
   }
   nsRect dest = nsLayoutUtils::GetWholeImageDestination(imageSize, source,
                                                         aDest);
   // Ensure that only a single image tile is drawn. If aSourceArea extends
   // outside the image bounds, we want to honor the aSourceArea-to-aDest
   // transform but we don't want to actually tile the image.
   nsRect fill;
   fill.IntersectRect(aDest, dest);
   return DrawImageInternal(aRenderingContext, aImage, aGraphicsFilter, dest, fill,
                            fill.TopLeft(), aDirty, imageSize, aSVGContext, aImageFlags);
 }
 /* static */ void
 nsLayoutUtils::ComputeSizeForDrawing(imgIContainer *aImage,
                                      nsIntSize&     aImageSize, /*outparam*/
                                      nsSize&        aIntrinsicRatio, /*outparam*/
                                      bool&          aGotWidth,  /*outparam*/
                                      bool&          aGotHeight  /*outparam*/)
 {
   aGotWidth  = NS_SUCCEEDED(aImage->GetWidth(&aImageSize.width));
   aGotHeight = NS_SUCCEEDED(aImage->GetHeight(&aImageSize.height));
   bool gotRatio = NS_SUCCEEDED(aImage->GetIntrinsicRatio(&aIntrinsicRatio));
   if (!(aGotWidth && aGotHeight) && !gotRatio) {
     // We hit an error (say, because the image failed to load or couldn't be
     // decoded) and should return zero size.
     aGotWidth = aGotHeight = true;
     aImageSize = nsIntSize(0, 0);
     aIntrinsicRatio = nsSize(0, 0);
   }
 }
 /* static */ nsresult
 nsLayoutUtils::DrawBackgroundImage(nsRenderingContext* aRenderingContext,
                                    imgIContainer*      aImage,
                                    const nsIntSize&    aImageSize,
                                    GraphicsFilter      aGraphicsFilter,
                                    const nsRect&       aDest,
                                    const nsRect&       aFill,
                                    const nsPoint&      aAnchor,
                                    const nsRect&       aDirty,
                                    uint32_t            aImageFlags)
 {
   PROFILER_LABEL("layout", "nsLayoutUtils::DrawBackgroundImage");
   if (UseBackgroundNearestFiltering()) {
     aGraphicsFilter = GraphicsFilter::FILTER_NEAREST;
   }
   return DrawImageInternal(aRenderingContext, aImage, aGraphicsFilter,
                            aDest, aFill, aAnchor, aDirty,
                            aImageSize, nullptr, aImageFlags);
 }
 /* static */ nsresult
 nsLayoutUtils::DrawImage(nsRenderingContext* aRenderingContext,
                          imgIContainer*       aImage,
                          GraphicsFilter       aGraphicsFilter,
                          const nsRect&        aDest,
                          const nsRect&        aFill,
                          const nsPoint&       aAnchor,
                          const nsRect&        aDirty,
                          uint32_t             aImageFlags)
 {
   nsIntSize imageSize;
   nsSize imageRatio;
   bool gotHeight, gotWidth;
   ComputeSizeForDrawing(aImage, imageSize, imageRatio, gotWidth, gotHeight);
   // XXX Dimensionless images shouldn't fall back to filled-area size -- the
   //     caller should provide the image size, a la DrawBackgroundImage.
   if (gotWidth != gotHeight) {
     if (!gotWidth) {
       if (imageRatio.height != 0) {
         imageSize.width =
           NSCoordSaturatingNonnegativeMultiply(imageSize.height,
                                                float(imageRatio.width) /
                                                float(imageRatio.height));
         gotWidth = true;
       }
     } else {
       if (imageRatio.width != 0) {
         imageSize.height =
           NSCoordSaturatingNonnegativeMultiply(imageSize.width,
                                                float(imageRatio.height) /
                                                float(imageRatio.width));
         gotHeight = true;
       }
     }
   }
   if (!gotWidth) {
     imageSize.width = nsPresContext::AppUnitsToIntCSSPixels(aFill.width);
   }
   if (!gotHeight) {
     imageSize.height = nsPresContext::AppUnitsToIntCSSPixels(aFill.height);
   }
   return DrawImageInternal(aRenderingContext, aImage, aGraphicsFilter,
                            aDest, aFill, aAnchor, aDirty,
                            imageSize, nullptr, aImageFlags);
 }
 /* static */ nsRect
 nsLayoutUtils::GetWholeImageDestination(const nsIntSize& aWholeImageSize,
                                         const nsRect& aImageSourceArea,
                                         const nsRect& aDestArea)
 {
   double scaleX = double(aDestArea.width)/aImageSourceArea.width;
   double scaleY = double(aDestArea.height)/aImageSourceArea.height;
   nscoord destOffsetX = NSToCoordRound(aImageSourceArea.x*scaleX);
   nscoord destOffsetY = NSToCoordRound(aImageSourceArea.y*scaleY);
   nscoord appUnitsPerCSSPixel = nsDeviceContext::AppUnitsPerCSSPixel();
   nscoord wholeSizeX = NSToCoordRound(aWholeImageSize.width*appUnitsPerCSSPixel*scaleX);
   nscoord wholeSizeY = NSToCoordRound(aWholeImageSize.height*appUnitsPerCSSPixel*scaleY);
   return nsRect(aDestArea.TopLeft() - nsPoint(destOffsetX, destOffsetY),
                 nsSize(wholeSizeX, wholeSizeY));
 }
 /* static */ already_AddRefed<imgIContainer>
 nsLayoutUtils::OrientImage(imgIContainer* aContainer,
                            const nsStyleImageOrientation& aOrientation)
 {
   MOZ_ASSERT(aContainer, "Should have an image container");
   nsCOMPtr<imgIContainer> img(aContainer);
   if (aOrientation.IsFromImage()) {
     img = ImageOps::Orient(img, img->GetOrientation());
   } else if (!aOrientation.IsDefault()) {
     Angle angle = aOrientation.Angle();
     Flip flip  = aOrientation.IsFlipped() ? Flip::Horizontal
                                           : Flip::Unflipped;
     img = ImageOps::Orient(img, Orientation(angle, flip));
   }
   return img.forget();
 }
 static bool NonZeroStyleCoord(const nsStyleCoord& aCoord)
 {
   if (aCoord.IsCoordPercentCalcUnit()) {
     // Since negative results are clamped to 0, check > 0.
     return nsRuleNode::ComputeCoordPercentCalc(aCoord, nscoord_MAX) > 0 ||
            nsRuleNode::ComputeCoordPercentCalc(aCoord, 0) > 0;
   }
   return true;
 }
 /* static */ bool
 nsLayoutUtils::HasNonZeroCorner(const nsStyleCorners& aCorners)
 {
   NS_FOR_CSS_HALF_CORNERS(corner) {
     if (NonZeroStyleCoord(aCorners.Get(corner)))
       return true;
   }
   return false;
 }
 // aCorner is a "full corner" value, i.e. NS_CORNER_TOP_LEFT etc
 static bool IsCornerAdjacentToSide(uint8_t aCorner, css::Side aSide)
 {
   PR_STATIC_ASSERT((int)NS_SIDE_TOP == NS_CORNER_TOP_LEFT);
   PR_STATIC_ASSERT((int)NS_SIDE_RIGHT == NS_CORNER_TOP_RIGHT);
   PR_STATIC_ASSERT((int)NS_SIDE_BOTTOM == NS_CORNER_BOTTOM_RIGHT);
   PR_STATIC_ASSERT((int)NS_SIDE_LEFT == NS_CORNER_BOTTOM_LEFT);
   PR_STATIC_ASSERT((int)NS_SIDE_TOP == ((NS_CORNER_TOP_RIGHT - 1)&3));
   PR_STATIC_ASSERT((int)NS_SIDE_RIGHT == ((NS_CORNER_BOTTOM_RIGHT - 1)&3));
   PR_STATIC_ASSERT((int)NS_SIDE_BOTTOM == ((NS_CORNER_BOTTOM_LEFT - 1)&3));
   PR_STATIC_ASSERT((int)NS_SIDE_LEFT == ((NS_CORNER_TOP_LEFT - 1)&3));
   return aSide == aCorner || aSide == ((aCorner - 1)&3);
 }
 /* static */ bool
 nsLayoutUtils::HasNonZeroCornerOnSide(const nsStyleCorners& aCorners,
                                       css::Side aSide)
 {
   PR_STATIC_ASSERT(NS_CORNER_TOP_LEFT_X/2 == NS_CORNER_TOP_LEFT);
   PR_STATIC_ASSERT(NS_CORNER_TOP_LEFT_Y/2 == NS_CORNER_TOP_LEFT);
   PR_STATIC_ASSERT(NS_CORNER_TOP_RIGHT_X/2 == NS_CORNER_TOP_RIGHT);
   PR_STATIC_ASSERT(NS_CORNER_TOP_RIGHT_Y/2 == NS_CORNER_TOP_RIGHT);
   PR_STATIC_ASSERT(NS_CORNER_BOTTOM_RIGHT_X/2 == NS_CORNER_BOTTOM_RIGHT);
   PR_STATIC_ASSERT(NS_CORNER_BOTTOM_RIGHT_Y/2 == NS_CORNER_BOTTOM_RIGHT);
   PR_STATIC_ASSERT(NS_CORNER_BOTTOM_LEFT_X/2 == NS_CORNER_BOTTOM_LEFT);
   PR_STATIC_ASSERT(NS_CORNER_BOTTOM_LEFT_Y/2 == NS_CORNER_BOTTOM_LEFT);
   NS_FOR_CSS_HALF_CORNERS(corner) {
     // corner is a "half corner" value, so dividing by two gives us a
     // "full corner" value.
     if (NonZeroStyleCoord(aCorners.Get(corner)) &&
         IsCornerAdjacentToSide(corner/2, aSide))
       return true;
   }
   return false;
 }
 /* static */ nsTransparencyMode
 nsLayoutUtils::GetFrameTransparency(nsIFrame* aBackgroundFrame,
                                     nsIFrame* aCSSRootFrame) {
   if (aCSSRootFrame->StyleDisplay()->mOpacity < 1.0f)
     return eTransparencyTransparent;
   if (HasNonZeroCorner(aCSSRootFrame->StyleBorder()->mBorderRadius))
     return eTransparencyTransparent;
   if (aCSSRootFrame->StyleDisplay()->mAppearance == NS_THEME_WIN_GLASS)
     return eTransparencyGlass;
   if (aCSSRootFrame->StyleDisplay()->mAppearance == NS_THEME_WIN_BORDERLESS_GLASS)
     return eTransparencyBorderlessGlass;
   nsITheme::Transparency transparency;
   if (aCSSRootFrame->IsThemed(&transparency))
     return transparency == nsITheme::eTransparent
          ? eTransparencyTransparent
          : eTransparencyOpaque;
   // We need an uninitialized window to be treated as opaque because
   // doing otherwise breaks window display effects on some platforms,
   // specifically Vista. (bug 450322)
   if (aBackgroundFrame->GetType() == nsGkAtoms::viewportFrame &&
       !aBackgroundFrame->GetFirstPrincipalChild()) {
     return eTransparencyOpaque;
   }
   nsStyleContext* bgSC;
   if (!nsCSSRendering::FindBackground(aBackgroundFrame, &bgSC)) {
     return eTransparencyTransparent;
   }
   const nsStyleBackground* bg = bgSC->StyleBackground();
   if (NS_GET_A(bg->mBackgroundColor) < 255 ||
       // bottom layer's clip is used for the color
       bg->BottomLayer().mClip != NS_STYLE_BG_CLIP_BORDER)
     return eTransparencyTransparent;
   return eTransparencyOpaque;
 }
 static bool IsPopupFrame(nsIFrame* aFrame)
 {
   // aFrame is a popup it's the list control frame dropdown for a combobox.
   nsIAtom* frameType = aFrame->GetType();
   if (frameType == nsGkAtoms::listControlFrame) {
     nsListControlFrame* lcf = static_cast<nsListControlFrame*>(aFrame);
     return lcf->IsInDropDownMode();
   }
   // ... or if it's a XUL menupopup frame.
   return frameType == nsGkAtoms::menuPopupFrame;
 }
 /* static */ bool
 nsLayoutUtils::IsPopup(nsIFrame* aFrame)
 {
   // Optimization: the frame can't possibly be a popup if it has no view.
   if (!aFrame->HasView()) {
     NS_ASSERTION(!IsPopupFrame(aFrame), "popup frame must have a view");
     return false;
   }
   return IsPopupFrame(aFrame);
 }
 /* static */ nsIFrame*
 nsLayoutUtils::GetDisplayRootFrame(nsIFrame* aFrame)
 {
   // We could use GetRootPresContext() here if the
   // NS_FRAME_IN_POPUP frame bit is set.
   nsIFrame* f = aFrame;
   for (;;) {
     if (!f->HasAnyStateBits(NS_FRAME_IN_POPUP)) {
       f = f->PresContext()->FrameManager()->GetRootFrame();
     } else if (IsPopup(f)) {
       return f;
     }
     nsIFrame* parent = GetCrossDocParentFrame(f);
     if (!parent)
       return f;
     f = parent;
   }
 }
 /* static */ nsIFrame*
 nsLayoutUtils::GetReferenceFrame(nsIFrame* aFrame)
 {
   nsIFrame *f = aFrame;
   for (;;) {
     if (f->IsTransformed() || IsPopup(f)) {
       return f;
     }
     nsIFrame* parent = GetCrossDocParentFrame(f);
     if (!parent) {
       return f;
     }
     f = parent;
   }
 }
 /* static */ nsIFrame*
 nsLayoutUtils::GetTransformRootFrame(nsIFrame* aFrame)
 {
   nsIFrame *parent = nsLayoutUtils::GetCrossDocParentFrame(aFrame);
   while (parent && parent->Preserves3DChildren()) {
     parent = nsLayoutUtils::GetCrossDocParentFrame(parent);
   }
   return parent;
 }
 /* static */ uint32_t
 nsLayoutUtils::GetTextRunFlagsForStyle(nsStyleContext* aStyleContext,
                                        const nsStyleFont* aStyleFont,
                                        const nsStyleText* aStyleText,
                                        nscoord aLetterSpacing)
 {
   uint32_t result = 0;
   if (aLetterSpacing != 0) {
     result |= gfxTextRunFactory::TEXT_DISABLE_OPTIONAL_LIGATURES;
   }
   if (aStyleText->mControlCharacterVisibility == NS_STYLE_CONTROL_CHARACTER_VISIBILITY_HIDDEN) {
     result |= gfxTextRunFactory::TEXT_HIDE_CONTROL_CHARACTERS;
   }
   switch (aStyleContext->StyleSVG()->mTextRendering) {
   case NS_STYLE_TEXT_RENDERING_OPTIMIZESPEED:
     result |= gfxTextRunFactory::TEXT_OPTIMIZE_SPEED;
     break;
   case NS_STYLE_TEXT_RENDERING_AUTO:
     if (aStyleFont->mFont.size <
         aStyleContext->PresContext()->GetAutoQualityMinFontSize()) {
       result |= gfxTextRunFactory::TEXT_OPTIMIZE_SPEED;
     }
     break;
   default:
     break;
   }
   return result;
 }
 /* static */ void
 nsLayoutUtils::GetRectDifferenceStrips(const nsRect& aR1, const nsRect& aR2,
                                        nsRect* aHStrip, nsRect* aVStrip) {
   NS_ASSERTION(aR1.TopLeft() == aR2.TopLeft(),
                "expected rects at the same position");
   nsRect unionRect(aR1.x, aR1.y, std::max(aR1.width, aR2.width),
                    std::max(aR1.height, aR2.height));
   nscoord VStripStart = std::min(aR1.width, aR2.width);
   nscoord HStripStart = std::min(aR1.height, aR2.height);
   *aVStrip = unionRect;
   aVStrip->x += VStripStart;
   aVStrip->width -= VStripStart;
   *aHStrip = unionRect;
   aHStrip->y += HStripStart;
   aHStrip->height -= HStripStart;
 }
 nsDeviceContext*
 nsLayoutUtils::GetDeviceContextForScreenInfo(nsPIDOMWindow* aWindow)
 {
   if (!aWindow) {
     return nullptr;
   }
   nsCOMPtr<nsIDocShell> docShell = aWindow->GetDocShell();
   while (docShell) {
     // Now make sure our size is up to date.  That will mean that the device
     // context does the right thing on multi-monitor systems when we return it to
     // the caller.  It will also make sure that our prescontext has been created,
     // if we're supposed to have one.
     nsCOMPtr<nsPIDOMWindow> win = do_GetInterface(docShell);
     if (!win) {
       // No reason to go on
       return nullptr;
     }
     win->EnsureSizeUpToDate();
     nsRefPtr<nsPresContext> presContext;
     docShell->GetPresContext(getter_AddRefs(presContext));
     if (presContext) {
       nsDeviceContext* context = presContext->DeviceContext();
       if (context) {
         return context;
       }
     }
     nsCOMPtr<nsIDocShellTreeItem> parentItem;
     docShell->GetParent(getter_AddRefs(parentItem));
     docShell = do_QueryInterface(parentItem);
   }
   return nullptr;
 }
 /* static */ bool
 nsLayoutUtils::IsReallyFixedPos(nsIFrame* aFrame)
 {
   NS_PRECONDITION(aFrame->GetParent(),
                   "IsReallyFixedPos called on frame not in tree");
   NS_PRECONDITION(aFrame->StyleDisplay()->mPosition ==
                     NS_STYLE_POSITION_FIXED,
                   "IsReallyFixedPos called on non-'position:fixed' frame");
   nsIAtom *parentType = aFrame->GetParent()->GetType();
   return parentType == nsGkAtoms::viewportFrame ||
          parentType == nsGkAtoms::pageContentFrame;
 }
 nsLayoutUtils::SurfaceFromElementResult
 nsLayoutUtils::SurfaceFromElement(nsIImageLoadingContent* aElement,
                                   uint32_t aSurfaceFlags,
                                   DrawTarget* aTarget)
 {
   SurfaceFromElementResult result;
   nsresult rv;
   nsCOMPtr<imgIRequest> imgRequest;
   rv = aElement->GetRequest(nsIImageLoadingContent::CURRENT_REQUEST,
                             getter_AddRefs(imgRequest));
   if (NS_FAILED(rv) || !imgRequest)
     return result;
   uint32_t status;
   imgRequest->GetImageStatus(&status);
   if ((status & imgIRequest::STATUS_LOAD_COMPLETE) == 0) {
     // Spec says to use GetComplete, but that only works on
     // nsIDOMHTMLImageElement, and we support all sorts of other stuff
     // here.  Do this for now pending spec clarification.
     result.mIsStillLoading = (status & imgIRequest::STATUS_ERROR) == 0;
     return result;
   }
   nsCOMPtr<nsIPrincipal> principal;
   rv = imgRequest->GetImagePrincipal(getter_AddRefs(principal));
   if (NS_FAILED(rv))
     return result;
   nsCOMPtr<imgIContainer> imgContainer;
   rv = imgRequest->GetImage(getter_AddRefs(imgContainer));
   if (NS_FAILED(rv))
     return result;
   uint32_t noRasterize = aSurfaceFlags & SFE_NO_RASTERIZING_VECTORS;
   uint32_t whichFrame = (aSurfaceFlags & SFE_WANT_FIRST_FRAME)
                         ? (uint32_t) imgIContainer::FRAME_FIRST
                         : (uint32_t) imgIContainer::FRAME_CURRENT;
   uint32_t frameFlags = imgIContainer::FLAG_SYNC_DECODE;
   if (aSurfaceFlags & SFE_NO_COLORSPACE_CONVERSION)
     frameFlags |= imgIContainer::FLAG_DECODE_NO_COLORSPACE_CONVERSION;
   if (aSurfaceFlags & SFE_PREFER_NO_PREMULTIPLY_ALPHA) {
     frameFlags |= imgIContainer::FLAG_DECODE_NO_PREMULTIPLY_ALPHA;
     result.mIsPremultiplied = false;
   }
   int32_t imgWidth, imgHeight;
   rv = imgContainer->GetWidth(&imgWidth);
   nsresult rv2 = imgContainer->GetHeight(&imgHeight);
   if (NS_FAILED(rv) || NS_FAILED(rv2))
     return result;
   if (!noRasterize || imgContainer->GetType() == imgIContainer::TYPE_RASTER) {
     if (aSurfaceFlags & SFE_WANT_IMAGE_SURFACE) {
       frameFlags |= imgIContainer::FLAG_WANT_DATA_SURFACE;
     }
     result.mSourceSurface = imgContainer->GetFrame(whichFrame, frameFlags);
     if (!result.mSourceSurface) {
       return result;
     }
     // The surface we return is likely to be cached. We don't want to have to
     // convert to a surface that's compatible with aTarget each time it's used
     // (that would result in terrible performance), so we convert once here
     // upfront if aTarget is specified.
     if (aTarget) {
       RefPtr<SourceSurface> optSurface =
         aTarget->OptimizeSourceSurface(result.mSourceSurface);
       if (optSurface) {
         result.mSourceSurface = optSurface;
       }
     }
   } else {
     result.mDrawInfo.mImgContainer = imgContainer;
     result.mDrawInfo.mWhichFrame = whichFrame;
     result.mDrawInfo.mDrawingFlags = frameFlags;
   }
   int32_t corsmode;
   if (NS_SUCCEEDED(imgRequest->GetCORSMode(&corsmode))) {
     result.mCORSUsed = (corsmode != imgIRequest::CORS_NONE);
   }
   result.mSize = gfxIntSize(imgWidth, imgHeight);
   result.mPrincipal = principal.forget();
   // no images, including SVG images, can load content from another domain.
   result.mIsWriteOnly = false;
   result.mImageRequest = imgRequest.forget();
   return result;
 }
 nsLayoutUtils::SurfaceFromElementResult
 nsLayoutUtils::SurfaceFromElement(HTMLImageElement *aElement,
                                   uint32_t aSurfaceFlags,
                                   DrawTarget* aTarget)
 {
   return SurfaceFromElement(static_cast<nsIImageLoadingContent*>(aElement),
                             aSurfaceFlags, aTarget);
 }
 nsLayoutUtils::SurfaceFromElementResult
 nsLayoutUtils::SurfaceFromElement(HTMLCanvasElement* aElement,
                                   uint32_t aSurfaceFlags,
                                   DrawTarget* aTarget)
 {
   SurfaceFromElementResult result;
   bool* isPremultiplied = nullptr;
   if (aSurfaceFlags & SFE_PREFER_NO_PREMULTIPLY_ALPHA) {
     isPremultiplied = &result.mIsPremultiplied;
   }
   gfxIntSize size = aElement->GetSize();
   result.mSourceSurface = aElement->GetSurfaceSnapshot(isPremultiplied);
   if (!result.mSourceSurface) {
      // If the element doesn't have a context then we won't get a snapshot. The canvas spec wants us to not error and just
      // draw nothing, so return an empty surface.
      DrawTarget *ref = aTarget ? aTarget : gfxPlatform::GetPlatform()->ScreenReferenceDrawTarget();
      RefPtr<DrawTarget> dt = ref->CreateSimilarDrawTarget(IntSize(size.width, size.height),
                                                           SurfaceFormat::B8G8R8A8);
      if (dt) {
        result.mSourceSurface = dt->Snapshot();
      }
   } else if (aTarget) {
     RefPtr<SourceSurface> opt = aTarget->OptimizeSourceSurface(result.mSourceSurface);
     if (opt) {
       result.mSourceSurface = opt;
     }
   }
   // Ensure that any future changes to the canvas trigger proper invalidation,
   // in case this is being used by -moz-element()
   aElement->MarkContextClean();
   result.mSize = size;
   result.mPrincipal = aElement->NodePrincipal();
   result.mIsWriteOnly = aElement->IsWriteOnly();
   return result;
 }
 nsLayoutUtils::SurfaceFromElementResult
 nsLayoutUtils::SurfaceFromElement(HTMLVideoElement* aElement,
                                   uint32_t aSurfaceFlags,
                                   DrawTarget* aTarget)
 {
   SurfaceFromElementResult result;
   NS_WARN_IF_FALSE((aSurfaceFlags & SFE_PREFER_NO_PREMULTIPLY_ALPHA) == 0, "We can't support non-premultiplied alpha for video!");
   uint16_t readyState;
   if (NS_SUCCEEDED(aElement->GetReadyState(&readyState)) &&
       (readyState == nsIDOMHTMLMediaElement::HAVE_NOTHING ||
        readyState == nsIDOMHTMLMediaElement::HAVE_METADATA)) {
     result.mIsStillLoading = true;
     return result;
   }
   // If it doesn't have a principal, just bail
   nsCOMPtr<nsIPrincipal> principal = aElement->GetCurrentPrincipal();
   if (!principal)
     return result;
   ImageContainer *container = aElement->GetImageContainer();
   if (!container)
     return result;
   mozilla::gfx::IntSize size;
   result.mSourceSurface = container->GetCurrentAsSourceSurface(&size);
   if (!result.mSourceSurface)
     return result;
   if (aTarget) {
     RefPtr<SourceSurface> opt = aTarget->OptimizeSourceSurface(result.mSourceSurface);
     if (opt) {
       result.mSourceSurface = opt;
     }
   }
   result.mCORSUsed = aElement->GetCORSMode() != CORS_NONE;
   result.mSize = ThebesIntSize(size);
   result.mPrincipal = principal.forget();
   result.mIsWriteOnly = false;
   return result;
 }
 nsLayoutUtils::SurfaceFromElementResult
 nsLayoutUtils::SurfaceFromElement(dom::Element* aElement,
                                   uint32_t aSurfaceFlags,
                                   DrawTarget* aTarget)
 {
   // If it's a <canvas>, we may be able to just grab its internal surface
   if (HTMLCanvasElement* canvas =
         HTMLCanvasElement::FromContentOrNull(aElement)) {
     return SurfaceFromElement(canvas, aSurfaceFlags, aTarget);
   }
   // Maybe it's <video>?
   if (HTMLVideoElement* video =
         HTMLVideoElement::FromContentOrNull(aElement)) {
     return SurfaceFromElement(video, aSurfaceFlags, aTarget);
   }
   // Finally, check if it's a normal image
   nsCOMPtr<nsIImageLoadingContent> imageLoader = do_QueryInterface(aElement);
   if (!imageLoader) {
     return SurfaceFromElementResult();
   }
   return SurfaceFromElement(imageLoader, aSurfaceFlags, aTarget);
 }
 /* static */
 nsIContent*
 nsLayoutUtils::GetEditableRootContentByContentEditable(nsIDocument* aDocument)
 {
   // If the document is in designMode we should return nullptr.
   if (!aDocument || aDocument->HasFlag(NODE_IS_EDITABLE)) {
     return nullptr;
   }
   // contenteditable only works with HTML document.
   // Note: Use nsIDOMHTMLDocument rather than nsIHTMLDocument for getting the
   //       body node because nsIDOMHTMLDocument::GetBody() does something
   //       additional work for some cases and nsEditor uses them.
   nsCOMPtr<nsIDOMHTMLDocument> domHTMLDoc = do_QueryInterface(aDocument);
   if (!domHTMLDoc) {
     return nullptr;
   }
   Element* rootElement = aDocument->GetRootElement();
   if (rootElement && rootElement->IsEditable()) {
     return rootElement;
   }
   // If there are no editable root element, check its <body> element.
   // Note that the body element could be <frameset> element.
   nsCOMPtr<nsIDOMHTMLElement> body;
   nsresult rv = domHTMLDoc->GetBody(getter_AddRefs(body));
   nsCOMPtr<nsIContent> content = do_QueryInterface(body);
   if (NS_SUCCEEDED(rv) && content && content->IsEditable()) {
     return content;
   }
   return nullptr;
 }
 #ifdef DEBUG
 /* static */ void
 nsLayoutUtils::AssertNoDuplicateContinuations(nsIFrame* aContainer,
                                               const nsFrameList& aFrameList)
 {
   for (nsIFrame* f = aFrameList.FirstChild(); f ; f = f->GetNextSibling()) {
     // Check only later continuations of f; we deal with checking the
     // earlier continuations when we hit those earlier continuations in
     // the frame list.
     for (nsIFrame *c = f; (c = c->GetNextInFlow());) {
       NS_ASSERTION(c->GetParent() != aContainer ||
                    !aFrameList.ContainsFrame(c),
                    "Two continuations of the same frame in the same "
                    "frame list");
     }
   }
 }
 // Is one of aFrame's ancestors a letter frame?
 static bool
 IsInLetterFrame(nsIFrame *aFrame)
 {
   for (nsIFrame *f = aFrame->GetParent(); f; f = f->GetParent()) {
     if (f->GetType() == nsGkAtoms::letterFrame) {
       return true;
     }
   }
   return false;
 }
 /* static */ void
 nsLayoutUtils::AssertTreeOnlyEmptyNextInFlows(nsIFrame *aSubtreeRoot)
 {
   NS_ASSERTION(aSubtreeRoot->GetPrevInFlow(),
                "frame tree not empty, but caller reported complete status");
   // Also assert that text frames map no text.
   int32_t start, end;
   nsresult rv = aSubtreeRoot->GetOffsets(start, end);
   NS_ASSERTION(NS_SUCCEEDED(rv), "GetOffsets failed");
   // In some cases involving :first-letter, we'll partially unlink a
   // continuation in the middle of a continuation chain from its
   // previous and next continuations before destroying it, presumably so
   // that we don't also destroy the later continuations.  Once we've
   // done this, GetOffsets returns incorrect values.
   // For examples, see list of tests in
   // https://bugzilla.mozilla.org/show_bug.cgi?id=619021#c29
   NS_ASSERTION(start == end || IsInLetterFrame(aSubtreeRoot),
                "frame tree not empty, but caller reported complete status");
   nsIFrame::ChildListIterator lists(aSubtreeRoot);
   for (; !lists.IsDone(); lists.Next()) {
     nsFrameList::Enumerator childFrames(lists.CurrentList());
     for (; !childFrames.AtEnd(); childFrames.Next()) {
       nsLayoutUtils::AssertTreeOnlyEmptyNextInFlows(childFrames.get());
     }
   }
 }
 #endif
 static void
 GetFontFacesForFramesInner(nsIFrame* aFrame, nsFontFaceList* aFontFaceList)
 {
   NS_PRECONDITION(aFrame, "NULL frame pointer");
   if (aFrame->GetType() == nsGkAtoms::textFrame) {
     if (!aFrame->GetPrevContinuation()) {
       nsLayoutUtils::GetFontFacesForText(aFrame, 0, INT32_MAX, true,
                                          aFontFaceList);
     }
     return;
   }
   nsIFrame::ChildListID childLists[] = { nsIFrame::kPrincipalList,
                                          nsIFrame::kPopupList };
   for (size_t i = 0; i < ArrayLength(childLists); ++i) {
     nsFrameList children(aFrame->GetChildList(childLists[i]));
     for (nsFrameList::Enumerator e(children); !e.AtEnd(); e.Next()) {
       nsIFrame* child = e.get();
       child = nsPlaceholderFrame::GetRealFrameFor(child);
       GetFontFacesForFramesInner(child, aFontFaceList);
     }
   }
 }
 /* static */
 nsresult
 nsLayoutUtils::GetFontFacesForFrames(nsIFrame* aFrame,
                                      nsFontFaceList* aFontFaceList)
 {
   NS_PRECONDITION(aFrame, "NULL frame pointer");
   while (aFrame) {
     GetFontFacesForFramesInner(aFrame, aFontFaceList);
     aFrame = GetNextContinuationOrIBSplitSibling(aFrame);
   }
   return NS_OK;
 }
 /* static */
 nsresult
 nsLayoutUtils::GetFontFacesForText(nsIFrame* aFrame,
                                    int32_t aStartOffset, int32_t aEndOffset,
                                    bool aFollowContinuations,
                                    nsFontFaceList* aFontFaceList)
 {
   NS_PRECONDITION(aFrame, "NULL frame pointer");
   if (aFrame->GetType() != nsGkAtoms::textFrame) {
     return NS_OK;
   }
   nsTextFrame* curr = static_cast<nsTextFrame*>(aFrame);
   do {
     int32_t fstart = std::max(curr->GetContentOffset(), aStartOffset);
     int32_t fend = std::min(curr->GetContentEnd(), aEndOffset);
     if (fstart >= fend) {
       curr = static_cast<nsTextFrame*>(curr->GetNextContinuation());
       continue;
     }
     // curr is overlapping with the offset we want
     gfxSkipCharsIterator iter = curr->EnsureTextRun(nsTextFrame::eInflated);
     gfxTextRun* textRun = curr->GetTextRun(nsTextFrame::eInflated);
     NS_ENSURE_TRUE(textRun, NS_ERROR_OUT_OF_MEMORY);
     // include continuations in the range that share the same textrun
     nsTextFrame* next = nullptr;
     if (aFollowContinuations && fend < aEndOffset) {
       next = static_cast<nsTextFrame*>(curr->GetNextContinuation());
       while (next && next->GetTextRun(nsTextFrame::eInflated) == textRun) {
         fend = std::min(next->GetContentEnd(), aEndOffset);
         next = fend < aEndOffset ?
           static_cast<nsTextFrame*>(next->GetNextContinuation()) : nullptr;
       }
     }
     uint32_t skipStart = iter.ConvertOriginalToSkipped(fstart);
     uint32_t skipEnd = iter.ConvertOriginalToSkipped(fend);
     aFontFaceList->AddFontsFromTextRun(textRun, skipStart, skipEnd - skipStart);
     curr = next;
   } while (aFollowContinuations && curr);
   return NS_OK;
 }
 /* static */
 size_t
 nsLayoutUtils::SizeOfTextRunsForFrames(nsIFrame* aFrame,
                                        MallocSizeOf aMallocSizeOf,
                                        bool clear)
 {
   NS_PRECONDITION(aFrame, "NULL frame pointer");
   size_t total = 0;
   if (aFrame->GetType() == nsGkAtoms::textFrame) {
     nsTextFrame* textFrame = static_cast<nsTextFrame*>(aFrame);
     for (uint32_t i = 0; i < 2; ++i) {
       gfxTextRun *run = textFrame->GetTextRun(
         (i != 0) ? nsTextFrame::eInflated : nsTextFrame::eNotInflated);
       if (run) {
         if (clear) {
           run->ResetSizeOfAccountingFlags();
         } else {
           total += run->MaybeSizeOfIncludingThis(aMallocSizeOf);
         }
       }
     }
     return total;
   }
   nsAutoTArray<nsIFrame::ChildList,4> childListArray;
   aFrame->GetChildLists(&childListArray);
   for (nsIFrame::ChildListArrayIterator childLists(childListArray);
        !childLists.IsDone(); childLists.Next()) {
     for (nsFrameList::Enumerator e(childLists.CurrentList());
          !e.AtEnd(); e.Next()) {
       total += SizeOfTextRunsForFrames(e.get(), aMallocSizeOf, clear);
     }
   }
   return total;
 }
 /* static */
 void
 nsLayoutUtils::Initialize()
 {
   Preferences::AddUintVarCache(&sFontSizeInflationMaxRatio,
                                "font.size.inflation.maxRatio");
   Preferences::AddUintVarCache(&sFontSizeInflationEmPerLine,
                                "font.size.inflation.emPerLine");
   Preferences::AddUintVarCache(&sFontSizeInflationMinTwips,
                                "font.size.inflation.minTwips");
   Preferences::AddUintVarCache(&sFontSizeInflationLineThreshold,
                                "font.size.inflation.lineThreshold");
   Preferences::AddIntVarCache(&sFontSizeInflationMappingIntercept,
                               "font.size.inflation.mappingIntercept");
   Preferences::AddBoolVarCache(&sFontSizeInflationForceEnabled,
                                "font.size.inflation.forceEnabled");
   Preferences::AddBoolVarCache(&sFontSizeInflationDisabledInMasterProcess,
                                "font.size.inflation.disabledInMasterProcess");
   Preferences::AddBoolVarCache(&sInvalidationDebuggingIsEnabled,
                                "nglayout.debug.invalidation");
   Preferences::AddBoolVarCache(&sCSSVariablesEnabled,
                                "layout.css.variables.enabled");
   Preferences::AddBoolVarCache(&sInterruptibleReflowEnabled,
                                "layout.interruptible-reflow.enabled");
   Preferences::RegisterCallback(GridEnabledPrefChangeCallback,
                                 GRID_ENABLED_PREF_NAME);
   GridEnabledPrefChangeCallback(GRID_ENABLED_PREF_NAME, nullptr);
   Preferences::RegisterCallback(StickyEnabledPrefChangeCallback,
                                 STICKY_ENABLED_PREF_NAME);
   StickyEnabledPrefChangeCallback(STICKY_ENABLED_PREF_NAME, nullptr);
   Preferences::RegisterCallback(TextAlignTrueEnabledPrefChangeCallback,
                                 TEXT_ALIGN_TRUE_ENABLED_PREF_NAME);
   TextAlignTrueEnabledPrefChangeCallback(TEXT_ALIGN_TRUE_ENABLED_PREF_NAME,
                                          nullptr);
   nsComputedDOMStyle::RegisterPrefChangeCallbacks();
 }
 /* static */
 void
 nsLayoutUtils::Shutdown()
 {
   if (sContentMap) {
     delete sContentMap;
     sContentMap = nullptr;
   }
   Preferences::UnregisterCallback(GridEnabledPrefChangeCallback,
                                   GRID_ENABLED_PREF_NAME);
   Preferences::UnregisterCallback(StickyEnabledPrefChangeCallback,
                                   STICKY_ENABLED_PREF_NAME);
   nsComputedDOMStyle::UnregisterPrefChangeCallbacks();
 }
 /* static */
 void
 nsLayoutUtils::RegisterImageRequest(nsPresContext* aPresContext,
                                     imgIRequest* aRequest,
                                     bool* aRequestRegistered)
 {
   if (!aPresContext) {
     return;
   }
   if (aRequestRegistered && *aRequestRegistered) {
     // Our request is already registered with the refresh driver, so
     // no need to register it again.
     return;
   }
   if (aRequest) {
     if (!aPresContext->RefreshDriver()->AddImageRequest(aRequest)) {
       NS_WARNING("Unable to add image request");
       return;
     }
     if (aRequestRegistered) {
       *aRequestRegistered = true;
     }
   }
 }
 /* static */
 void
 nsLayoutUtils::RegisterImageRequestIfAnimated(nsPresContext* aPresContext,
                                               imgIRequest* aRequest,
                                               bool* aRequestRegistered)
 {
   if (!aPresContext) {
     return;
   }
   if (aRequestRegistered && *aRequestRegistered) {
     // Our request is already registered with the refresh driver, so
     // no need to register it again.
     return;
   }
   if (aRequest) {
     nsCOMPtr<imgIContainer> image;
     if (NS_SUCCEEDED(aRequest->GetImage(getter_AddRefs(image)))) {
       // Check to verify that the image is animated. If so, then add it to the
       // list of images tracked by the refresh driver.
       bool isAnimated = false;
       nsresult rv = image->GetAnimated(&isAnimated);
       if (NS_SUCCEEDED(rv) && isAnimated) {
         if (!aPresContext->RefreshDriver()->AddImageRequest(aRequest)) {
           NS_WARNING("Unable to add image request");
           return;
         }
         if (aRequestRegistered) {
           *aRequestRegistered = true;
         }
       }
     }
   }
 }
 /* static */
 void
 nsLayoutUtils::DeregisterImageRequest(nsPresContext* aPresContext,
                                       imgIRequest* aRequest,
                                       bool* aRequestRegistered)
 {
   if (!aPresContext) {
     return;
   }
   // Deregister our imgIRequest with the refresh driver to
   // complete tear-down, but only if it has been registered
   if (aRequestRegistered && !*aRequestRegistered) {
     return;
   }
   if (aRequest) {
     nsCOMPtr<imgIContainer> image;
     if (NS_SUCCEEDED(aRequest->GetImage(getter_AddRefs(image)))) {
       aPresContext->RefreshDriver()->RemoveImageRequest(aRequest);
       if (aRequestRegistered) {
         *aRequestRegistered = false;
       }
     }
   }
 }
 /* static */
 void
 nsLayoutUtils::PostRestyleEvent(Element* aElement,
                                 nsRestyleHint aRestyleHint,
                                 nsChangeHint aMinChangeHint)
 {
   nsIDocument* doc = aElement->GetCurrentDoc();
   if (doc) {
     nsCOMPtr<nsIPresShell> presShell = doc->GetShell();
     if (presShell) {
       presShell->GetPresContext()->RestyleManager()->PostRestyleEvent(
         aElement, aRestyleHint, aMinChangeHint);
     }
   }
 }
 nsSetAttrRunnable::nsSetAttrRunnable(nsIContent* aContent, nsIAtom* aAttrName,
                                      const nsAString& aValue)
   : mContent(aContent),
     mAttrName(aAttrName),
     mValue(aValue)
 {
   NS_ASSERTION(aContent && aAttrName, "Missing stuff, prepare to crash");
 }
 nsSetAttrRunnable::nsSetAttrRunnable(nsIContent* aContent, nsIAtom* aAttrName,
                                      int32_t aValue)
   : mContent(aContent),
     mAttrName(aAttrName)
 {
   NS_ASSERTION(aContent && aAttrName, "Missing stuff, prepare to crash");
   mValue.AppendInt(aValue);
 }
 NS_IMETHODIMP
 nsSetAttrRunnable::Run()
 {
   return mContent->SetAttr(kNameSpaceID_None, mAttrName, mValue, true);
 }
 nsUnsetAttrRunnable::nsUnsetAttrRunnable(nsIContent* aContent,
                                          nsIAtom* aAttrName)
   : mContent(aContent),
     mAttrName(aAttrName)
 {
   NS_ASSERTION(aContent && aAttrName, "Missing stuff, prepare to crash");
 }
 NS_IMETHODIMP
 nsUnsetAttrRunnable::Run()
 {
   return mContent->UnsetAttr(kNameSpaceID_None, mAttrName, true);
 }
 /**
  * Compute the minimum font size inside of a container with the given
  * width, such that **when the user zooms the container to fill the full
  * width of the device**, the fonts satisfy our minima.
  */
 static nscoord
 MinimumFontSizeFor(nsPresContext* aPresContext, nscoord aContainerWidth)
 {
   nsIPresShell* presShell = aPresContext->PresShell();
   uint32_t emPerLine = presShell->FontSizeInflationEmPerLine();
   uint32_t minTwips = presShell->FontSizeInflationMinTwips();
   if (emPerLine == 0 && minTwips == 0) {
     return 0;
   }
   // Clamp the container width to the device dimensions
   nscoord iFrameWidth = aPresContext->GetVisibleArea().width;
   nscoord effectiveContainerWidth = std::min(iFrameWidth, aContainerWidth);
   nscoord byLine = 0, byInch = 0;
   if (emPerLine != 0) {
     byLine = effectiveContainerWidth / emPerLine;
   }
   if (minTwips != 0) {
     // REVIEW: Is this giving us app units and sizes *not* counting
     // viewport scaling?
     float deviceWidthInches =
       aPresContext->ScreenWidthInchesForFontInflation();
     byInch = NSToCoordRound(effectiveContainerWidth /
                             (deviceWidthInches * 1440 /
                              minTwips ));
   }
   return std::max(byLine, byInch);
 }
 /* static */ float
 nsLayoutUtils::FontSizeInflationInner(const nsIFrame *aFrame,
                                       nscoord aMinFontSize)
 {
   // Note that line heights should be inflated by the same ratio as the
   // font size of the same text; thus we operate only on the font size
   // even when we're scaling a line height.
   nscoord styleFontSize = aFrame->StyleFont()->mFont.size;
   if (styleFontSize <= 0) {
     // Never scale zero font size.
     return 1.0;
   }
   if (aMinFontSize <= 0) {
     // No need to scale.
     return 1.0;
   }
   // If between this current frame and its font inflation container there is a
   // non-inline element with fixed width or height, then we should not inflate
   // fonts for this frame.
   for (const nsIFrame* f = aFrame;
        f && !f->IsContainerForFontSizeInflation();
        f = f->GetParent()) {
     nsIContent* content = f->GetContent();
     nsIAtom* fType = f->GetType();
     // Also, if there is more than one frame corresponding to a single
     // content node, we want the outermost one.
     if (!(f->GetParent() && f->GetParent()->GetContent() == content) &&
         // ignore width/height on inlines since they don't apply
         fType != nsGkAtoms::inlineFrame &&
         // ignore width on radios and checkboxes since we enlarge them and
         // they have width/height in ua.css
         fType != nsGkAtoms::formControlFrame) {
       nsStyleCoord stylePosWidth = f->StylePosition()->mWidth;
       nsStyleCoord stylePosHeight = f->StylePosition()->mHeight;
       if (stylePosWidth.GetUnit() != eStyleUnit_Auto ||
           stylePosHeight.GetUnit() != eStyleUnit_Auto) {
         return 1.0;
       }
     }
   }
   int32_t interceptParam = nsLayoutUtils::FontSizeInflationMappingIntercept();
   float maxRatio = (float)nsLayoutUtils::FontSizeInflationMaxRatio() / 100.0f;
   float ratio = float(styleFontSize) / float(aMinFontSize);
   float inflationRatio;
   // Given a minimum inflated font size m, a specified font size s, we want to
   // find the inflated font size i and then return the ratio of i to s (i/s).
   if (interceptParam >= 0) {
     // Since the mapping intercept parameter P is greater than zero, we use it
     // to determine the point where our mapping function intersects the i=s
     // line. This means that we have an equation of the form:
     //
     // i = m + s·(P/2)/(1 + P/2), if s <= (1 + P/2)·m
     // i = s, if s >= (1 + P/2)·m
     float intercept = 1 + float(interceptParam)/2.0f;
     if (ratio >= intercept) {
       // If we're already at 1+P/2 or more times the minimum, don't scale.
       return 1.0;
     }
     // The point (intercept, intercept) is where the part of the i vs. s graph
     // that's not slope 1 meets the i=s line.  (This part of the
     // graph is a line from (0, m), to that point). We calculate the
     // intersection point to be ((1+P/2)m, (1+P/2)m), where P is the
     // intercept parameter above. We then need to return i/s.
     inflationRatio = (1.0f + (ratio * (intercept - 1) / intercept)) / ratio;
   } else {
     // This is the case where P is negative. We essentially want to implement
     // the case for P=infinity here, so we make i = s + m, which means that
     // i/s = s/s + m/s = 1 + 1/ratio
     inflationRatio = 1 + 1.0f / ratio;
   }
   if (maxRatio > 1.0 && inflationRatio > maxRatio) {
     return maxRatio;
   } else {
     return inflationRatio;
   }
 }
 static bool
 ShouldInflateFontsForContainer(const nsIFrame *aFrame)
 {
   // We only want to inflate fonts for text that is in a place
   // with room to expand.  The question is what the best heuristic for
   // that is...
   // For now, we're going to use NS_FRAME_IN_CONSTRAINED_HEIGHT, which
   // indicates whether the frame is inside something with a constrained
   // height (propagating down the tree), but the propagation stops when
   // we hit overflow-y: scroll or auto.
   const nsStyleText* styleText = aFrame->StyleText();
   return styleText->mTextSizeAdjust != NS_STYLE_TEXT_SIZE_ADJUST_NONE &&
          !(aFrame->GetStateBits() & NS_FRAME_IN_CONSTRAINED_HEIGHT) &&
          // We also want to disable font inflation for containers that have
          // preformatted text.
          styleText->WhiteSpaceCanWrap(aFrame);
 }
 nscoord
 nsLayoutUtils::InflationMinFontSizeFor(const nsIFrame *aFrame)
 {
   nsPresContext *presContext = aFrame->PresContext();
   if (!FontSizeInflationEnabled(presContext) ||
       presContext->mInflationDisabledForShrinkWrap) {
     return 0;
   }
   for (const nsIFrame *f = aFrame; f; f = f->GetParent()) {
     if (f->IsContainerForFontSizeInflation()) {
       if (!ShouldInflateFontsForContainer(f)) {
         return 0;
       }
       nsFontInflationData *data =
         nsFontInflationData::FindFontInflationDataFor(aFrame);
       // FIXME: The need to null-check here is sort of a bug, and might
       // lead to incorrect results.
       if (!data || !data->InflationEnabled()) {
         return 0;
       }
       return MinimumFontSizeFor(aFrame->PresContext(),
                                 data->EffectiveWidth());
     }
   }
   NS_ABORT_IF_FALSE(false, "root should always be container");
   return 0;
 }
 float
 nsLayoutUtils::FontSizeInflationFor(const nsIFrame *aFrame)
 {
   if (aFrame->IsSVGText()) {
     const nsIFrame* container = aFrame;
     while (container->GetType() != nsGkAtoms::svgTextFrame) {
       container = container->GetParent();
     }
     NS_ASSERTION(container, "expected to find an ancestor SVGTextFrame");
     return
       static_cast<const SVGTextFrame*>(container)->GetFontSizeScaleFactor();
   }
   if (!FontSizeInflationEnabled(aFrame->PresContext())) {
     return 1.0f;
   }
   return FontSizeInflationInner(aFrame, InflationMinFontSizeFor(aFrame));
 }
 /* static */ bool
 nsLayoutUtils::FontSizeInflationEnabled(nsPresContext *aPresContext)
 {
   nsIPresShell* presShell = aPresContext->GetPresShell();
   if (!presShell) {
     return false;
   }
   return presShell->FontSizeInflationEnabled();
 }
 /* static */ nsRect
 nsLayoutUtils::GetBoxShadowRectForFrame(nsIFrame* aFrame,
                                         const nsSize& aFrameSize)
 {
   nsCSSShadowArray* boxShadows = aFrame->StyleBorder()->mBoxShadow;
   if (!boxShadows) {
     return nsRect();
   }
   nsRect shadows;
   int32_t A2D = aFrame->PresContext()->AppUnitsPerDevPixel();
   for (uint32_t i = 0; i < boxShadows->Length(); ++i) {
     nsRect tmpRect(nsPoint(0, 0), aFrameSize);
     nsCSSShadowItem* shadow = boxShadows->ShadowAt(i);
     // inset shadows are never painted outside the frame
     if (shadow->mInset)
       continue;
     tmpRect.MoveBy(nsPoint(shadow->mXOffset, shadow->mYOffset));
     tmpRect.Inflate(shadow->mSpread);
     tmpRect.Inflate(
       nsContextBoxBlur::GetBlurRadiusMargin(shadow->mRadius, A2D));
     shadows.UnionRect(shadows, tmpRect);
   }
   return shadows;
 }
 /* static */ void
 nsLayoutUtils::UpdateImageVisibilityForFrame(nsIFrame* aImageFrame)
 {
 #ifdef DEBUG
   nsIAtom* type = aImageFrame->GetType();
   MOZ_ASSERT(type == nsGkAtoms::imageFrame ||
              type == nsGkAtoms::imageControlFrame ||
              type == nsGkAtoms::svgImageFrame, "wrong type of frame");
 #endif
   nsCOMPtr<nsIImageLoadingContent> content = do_QueryInterface(aImageFrame->GetContent());
   if (!content) {
     return;
   }
   nsIPresShell* presShell = aImageFrame->PresContext()->PresShell();
   if (presShell->AssumeAllImagesVisible()) {
     presShell->EnsureImageInVisibleList(content);
     return;
   }
   bool visible = true;
   nsIFrame* f = aImageFrame->GetParent();
   nsRect rect = aImageFrame->GetContentRectRelativeToSelf();
   nsIFrame* rectFrame = aImageFrame;
   while (f) {
     nsIScrollableFrame* sf = do_QueryFrame(f);
     if (sf) {
       nsRect transformedRect =
         nsLayoutUtils::TransformFrameRectToAncestor(rectFrame, rect, f);
       if (!sf->IsRectNearlyVisible(transformedRect)) {
         visible = false;
         break;
       }
       // Move transformedRect to be contained in the scrollport as best we can
       // (it might not fit) to pretend that it was scrolled into view.
       nsRect scrollPort = sf->GetScrollPortRect();
       if (transformedRect.XMost() > scrollPort.XMost()) {
         transformedRect.x -= transformedRect.XMost() - scrollPort.XMost();
       }
       if (transformedRect.x < scrollPort.x) {
         transformedRect.x = scrollPort.x;
       }
       if (transformedRect.YMost() > scrollPort.YMost()) {
         transformedRect.y -= transformedRect.YMost() - scrollPort.YMost();
       }
       if (transformedRect.y < scrollPort.y) {
         transformedRect.y = scrollPort.y;
       }
       transformedRect.width = std::min(transformedRect.width, scrollPort.width);
       transformedRect.height = std::min(transformedRect.height, scrollPort.height);
       rect = transformedRect;
       rectFrame = f;
     }
     nsIFrame* parent = f->GetParent();
     if (!parent) {
       parent = nsLayoutUtils::GetCrossDocParentFrame(f);
       if (parent && parent->PresContext()->IsChrome()) {
         break;
       }
     }
     f = parent;
   }
   if (visible) {
     presShell->EnsureImageInVisibleList(content);
   } else {
     presShell->RemoveImageFromVisibleList(content);
   }
 }
 /* static */ nsSize
 nsLayoutUtils::CalculateCompositionSizeForFrame(nsIFrame* aFrame)
 {
   nsSize size(aFrame->GetSize());
   nsPresContext* presContext = aFrame->PresContext();
   nsIPresShell* presShell = presContext->PresShell();
   // See the comments in the code that calculates the root
   // composition bounds in RecordFrameMetrics.
   // TODO: Reuse that code here.
   bool isRootContentDocRootScrollFrame = presContext->IsRootContentDocument()
                                       && aFrame == presShell->GetRootScrollFrame();
   if (isRootContentDocRootScrollFrame) {
     if (nsIFrame* rootFrame = presShell->GetRootFrame()) {
       if (nsView* view = rootFrame->GetView()) {
         nsSize viewSize = view->GetBounds().Size();
         nsIWidget* widget =
 #ifdef MOZ_WIDGET_ANDROID
             rootFrame->GetNearestWidget();
 #else
             view->GetWidget();
 #endif
         if (widget) {
           nsIntRect widgetBounds;
           widget->GetBounds(widgetBounds);
           int32_t auPerDevPixel = presContext->AppUnitsPerDevPixel();
           size = nsSize(widgetBounds.width * auPerDevPixel,
                         widgetBounds.height * auPerDevPixel);
 #ifdef MOZ_WIDGET_ANDROID
           if (viewSize.height < size.height) {
             size.height = viewSize.height;
           }
 #endif
         } else {
           size = viewSize;
         }
       }
     }
   }
   // Adjust composition bounds for the size of scroll bars.
   nsIScrollableFrame* scrollableFrame = aFrame->GetScrollTargetFrame();
   if (scrollableFrame && !LookAndFeel::GetInt(LookAndFeel::eIntID_UseOverlayScrollbars)) {
     nsMargin margins = scrollableFrame->GetActualScrollbarSizes();
     size.width -= margins.LeftRight();
     size.height -= margins.TopBottom();
   }
   return size;
 }
 /* static */ CSSSize
 nsLayoutUtils::CalculateRootCompositionSize(nsIFrame* aFrame,
                                             bool aIsRootContentDocRootScrollFrame,
                                             const FrameMetrics& aMetrics)
 {
   if (aIsRootContentDocRootScrollFrame) {
     return ViewAs<LayerPixel>(ParentLayerSize(aMetrics.mCompositionBounds.Size()),
                               PixelCastJustification::ParentLayerToLayerForRootComposition)
            / aMetrics.LayersPixelsPerCSSPixel();
   }
   nsPresContext* presContext = aFrame->PresContext();
   LayerSize rootCompositionSize;
   nsPresContext* rootPresContext =
     presContext->GetToplevelContentDocumentPresContext();
   if (!rootPresContext) {
     rootPresContext = presContext->GetRootPresContext();
   }
   nsIPresShell* rootPresShell = nullptr;
   if (rootPresContext) {
     // See the comments in the code that calculates the root
     // composition bounds in RecordFrameMetrics.
     // TODO: Reuse that code here.
     nsIPresShell* rootPresShell = rootPresContext->PresShell();
     if (nsIFrame* rootFrame = rootPresShell->GetRootFrame()) {
       if (nsView* view = rootFrame->GetView()) {
         LayoutDeviceToParentLayerScale parentResolution(
           rootPresShell->GetCumulativeResolution().width
           / rootPresShell->GetResolution().width);
         int32_t rootAUPerDevPixel = rootPresContext->AppUnitsPerDevPixel();
         nsRect viewBounds = view->GetBounds();
         LayerSize viewSize = ViewAs<LayerPixel>(
           (LayoutDeviceRect::FromAppUnits(viewBounds, rootAUPerDevPixel)
            * parentResolution).Size(), PixelCastJustification::ParentLayerToLayerForRootComposition);
         nsIWidget* widget =
 #ifdef MOZ_WIDGET_ANDROID
             rootFrame->GetNearestWidget();
 #else
             view->GetWidget();
 #endif
         if (widget) {
           nsIntRect widgetBounds;
           widget->GetBounds(widgetBounds);
           rootCompositionSize = LayerSize(ViewAs<LayerPixel>(widgetBounds.Size()));
 #ifdef MOZ_WIDGET_ANDROID
           if (viewSize.height < rootCompositionSize.height) {
             rootCompositionSize.height = viewSize.height;
           }
 #endif
         } else {
           rootCompositionSize = viewSize;
         }
       }
     }
   } else {
     nsIWidget* widget = aFrame->GetNearestWidget();
     nsIntRect widgetBounds;
     widget->GetBounds(widgetBounds);
     rootCompositionSize = LayerSize(ViewAs<LayerPixel>(widgetBounds.Size()));
   }
   // Adjust composition size for the size of scroll bars.
   nsIFrame* rootRootScrollFrame = rootPresShell ? rootPresShell->GetRootScrollFrame() : nullptr;
   nsIScrollableFrame* rootScrollableFrame = nullptr;
   if (rootRootScrollFrame) {
     rootScrollableFrame = rootRootScrollFrame->GetScrollTargetFrame();
   }
   if (rootScrollableFrame && !LookAndFeel::GetInt(LookAndFeel::eIntID_UseOverlayScrollbars)) {
     CSSMargin margins = CSSMargin::FromAppUnits(rootScrollableFrame->GetActualScrollbarSizes());
     // Scrollbars are not subject to scaling, so CSS pixels = layer pixels for them.
     rootCompositionSize.width -= margins.LeftRight();
     rootCompositionSize.height -= margins.TopBottom();
   }
   return rootCompositionSize / aMetrics.LayersPixelsPerCSSPixel();
 }
 /* static */ nsRect
 nsLayoutUtils::CalculateScrollableRectForFrame(nsIScrollableFrame* aScrollableFrame, nsIFrame* aRootFrame)
 {
   nsRect contentBounds;
   if (aScrollableFrame) {
     contentBounds = aScrollableFrame->GetScrollRange();
     // We ifndef the below code for Fennec because it requires special behaviour
     // on the APZC side. Because Fennec has it's own PZC implementation which doesn't
     // provide the special behaviour, this code will cause it to break. We can remove
     // the ifndef once Fennec switches over to APZ or if we add the special handling
     // to Fennec
 #ifndef MOZ_WIDGET_ANDROID
     nsPoint scrollPosition = aScrollableFrame->GetScrollPosition();
     if (aScrollableFrame->GetScrollbarStyles().mVertical == NS_STYLE_OVERFLOW_HIDDEN) {
       contentBounds.y = scrollPosition.y;
       contentBounds.height = 0;
     }
     if (aScrollableFrame->GetScrollbarStyles().mHorizontal == NS_STYLE_OVERFLOW_HIDDEN) {
       contentBounds.x = scrollPosition.x;
       contentBounds.width = 0;
     }
 #endif
     contentBounds.width += aScrollableFrame->GetScrollPortRect().width;
     contentBounds.height += aScrollableFrame->GetScrollPortRect().height;
   } else {
     contentBounds = aRootFrame->GetRect();
   }
   return contentBounds;
 }
 /* static */ nsRect
 nsLayoutUtils::CalculateExpandedScrollableRect(nsIFrame* aFrame)
 {
   nsRect scrollableRect =
     CalculateScrollableRectForFrame(aFrame->GetScrollTargetFrame(),
                                     aFrame->PresContext()->PresShell()->GetRootFrame());
   nsSize compSize = CalculateCompositionSizeForFrame(aFrame);
   if (aFrame == aFrame->PresContext()->PresShell()->GetRootScrollFrame()) {
     // the composition size for the root scroll frame does not include the
     // local resolution, so we adjust.
     gfxSize res = aFrame->PresContext()->PresShell()->GetResolution();
     compSize.width = NSToCoordRound(compSize.width / ((float) res.width));
     compSize.height = NSToCoordRound(compSize.height / ((float) res.height));
   }
   if (scrollableRect.width < compSize.width) {
     scrollableRect.x = std::max(0,
                                 scrollableRect.x - (compSize.width - scrollableRect.width));
     scrollableRect.width = compSize.width;
   }
   if (scrollableRect.height < compSize.height) {
     scrollableRect.y = std::max(0,
                                 scrollableRect.y - (compSize.height - scrollableRect.height));
     scrollableRect.height = compSize.height;
   }
   return scrollableRect;
 }
 /* static */ bool
 nsLayoutUtils::WantSubAPZC()
 {
    // TODO Turn this on for inprocess OMTC on all platforms
    bool wantSubAPZC = gfxPrefs::APZSubframeEnabled();
 #ifdef MOZ_WIDGET_GONK
    if (XRE_GetProcessType() != GeckoProcessType_Content) {
      wantSubAPZC = false;
    }
 #endif
    return wantSubAPZC;
  }
 nsLayoutUtils::SurfaceFromElementResult::SurfaceFromElementResult()
   // Use safe default values here
   : mIsWriteOnly(true)
   , mIsStillLoading(false)
   , mCORSUsed(false)
   , mIsPremultiplied(true)
 {
 }
 bool
 nsLayoutUtils::IsNonWrapperBlock(nsIFrame* aFrame)
 {
   return GetAsBlock(aFrame) && !aFrame->IsBlockWrapper();
 }
 bool
 nsLayoutUtils::NeedsPrintPreviewBackground(nsPresContext* aPresContext)
 {
   return aPresContext->IsRootPaginatedDocument() &&
     (aPresContext->Type() == nsPresContext::eContext_PrintPreview ||
      aPresContext->Type() == nsPresContext::eContext_PageLayout);
 }
 AutoMaybeDisableFontInflation::AutoMaybeDisableFontInflation(nsIFrame *aFrame)
 {
   // FIXME: Now that inflation calculations are based on the flow
   // root's NCA's (nearest common ancestor of its inflatable
   // descendants) width, we could probably disable inflation in
   // fewer cases than we currently do.
   if (aFrame->IsContainerForFontSizeInflation()) {
     mPresContext = aFrame->PresContext();
     mOldValue = mPresContext->mInflationDisabledForShrinkWrap;
     mPresContext->mInflationDisabledForShrinkWrap = true;
   } else {
     // indicate we have nothing to restore
     mPresContext = nullptr;
   }
 }
 AutoMaybeDisableFontInflation::~AutoMaybeDisableFontInflation()
 {
   if (mPresContext) {
     mPresContext->mInflationDisabledForShrinkWrap = mOldValue;
   }
 }

The Tor Browser / annotate

layout/base/nsLayoutUtils.cpp@b8a032363ba2 (annotated)

layout/base/nsLayoutUtils.cpp