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

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

layout/base/nsCSSRendering.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:cindent:ts=2:et:sw=2:
 /* 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/. */
 /* utility functions for drawing borders and backgrounds */
 #include <ctime>
 #include "mozilla/DebugOnly.h"
 #include "mozilla/HashFunctions.h"
 #include "mozilla/MathAlgorithms.h"
 #include "nsStyleConsts.h"
 #include "nsPresContext.h"
 #include "nsIFrame.h"
 #include "nsPoint.h"
 #include "nsRect.h"
 #include "nsIPresShell.h"
 #include "nsFrameManager.h"
 #include "nsStyleContext.h"
 #include "nsGkAtoms.h"
 #include "nsCSSAnonBoxes.h"
 #include "nsIContent.h"
 #include "nsIDocumentInlines.h"
 #include "nsIScrollableFrame.h"
 #include "imgIRequest.h"
 #include "imgIContainer.h"
 #include "ImageOps.h"
 #include "nsCSSRendering.h"
 #include "nsCSSColorUtils.h"
 #include "nsITheme.h"
 #include "nsLayoutUtils.h"
 #include "nsBlockFrame.h"
 #include "gfxContext.h"
 #include "nsRenderingContext.h"
 #include "nsStyleStructInlines.h"
 #include "nsCSSFrameConstructor.h"
 #include "nsCSSProps.h"
 #include "nsContentUtils.h"
 #include "nsSVGEffects.h"
 #include "nsSVGIntegrationUtils.h"
 #include "gfxDrawable.h"
 #include "GeckoProfiler.h"
 #include "nsCSSRenderingBorders.h"
 #include "mozilla/css/ImageLoader.h"
 #include "ImageContainer.h"
 #include "mozilla/Telemetry.h"
 #include "gfxUtils.h"
 #include "gfxColor.h"
 #include "gfxGradientCache.h"
 #include "GraphicsFilter.h"
 #include <algorithm>
 using namespace mozilla;
 using namespace mozilla::css;
 using namespace mozilla::gfx;
 using mozilla::image::ImageOps;
 using mozilla::CSSSizeOrRatio;
 static int gFrameTreeLockCount = 0;
 // To avoid storing this data on nsInlineFrame (bloat) and to avoid
 // recalculating this for each frame in a continuation (perf), hold
 // a cache of various coordinate information that we need in order
 // to paint inline backgrounds.
 struct InlineBackgroundData
 {
   InlineBackgroundData()
       : mFrame(nullptr), mBlockFrame(nullptr)
   {
   }
   ~InlineBackgroundData()
   {
   }
   void Reset()
   {
     mBoundingBox.SetRect(0,0,0,0);
     mContinuationPoint = mLineContinuationPoint = mUnbrokenWidth = 0;
     mFrame = mBlockFrame = nullptr;
   }
   nsRect GetContinuousRect(nsIFrame* aFrame)
   {
     SetFrame(aFrame);
     nscoord x;
     if (mBidiEnabled) {
       x = mLineContinuationPoint;
       // Scan continuations on the same line as aFrame and accumulate the widths
       // of frames that are to the left (if this is an LTR block) or right
       // (if it's RTL) of the current one.
       bool isRtlBlock = (mBlockFrame->StyleVisibility()->mDirection ==
                            NS_STYLE_DIRECTION_RTL);
       nscoord curOffset = aFrame->GetOffsetTo(mBlockFrame).x;
       // No need to use our GetPrevContinuation/GetNextContinuation methods
       // here, since ib-split siblings are certainly not on the same line.
       nsIFrame* inlineFrame = aFrame->GetPrevContinuation();
       // If the continuation is fluid we know inlineFrame is not on the same line.
       // If it's not fluid, we need to test further to be sure.
       while (inlineFrame && !inlineFrame->GetNextInFlow() &&
              AreOnSameLine(aFrame, inlineFrame)) {
         nscoord frameXOffset = inlineFrame->GetOffsetTo(mBlockFrame).x;
         if(isRtlBlock == (frameXOffset >= curOffset)) {
           x += inlineFrame->GetSize().width;
         }
         inlineFrame = inlineFrame->GetPrevContinuation();
       }
       inlineFrame = aFrame->GetNextContinuation();
       while (inlineFrame && !inlineFrame->GetPrevInFlow() &&
              AreOnSameLine(aFrame, inlineFrame)) {
         nscoord frameXOffset = inlineFrame->GetOffsetTo(mBlockFrame).x;
         if(isRtlBlock == (frameXOffset >= curOffset)) {
           x += inlineFrame->GetSize().width;
         }
         inlineFrame = inlineFrame->GetNextContinuation();
       }
       if (isRtlBlock) {
         // aFrame itself is also to the right of its left edge, so add its width.
         x += aFrame->GetSize().width;
         // x is now the distance from the left edge of aFrame to the right edge
         // of the unbroken content. Change it to indicate the distance from the
         // left edge of the unbroken content to the left edge of aFrame.
         x = mUnbrokenWidth - x;
       }
     } else {
       x = mContinuationPoint;
     }
     // Assume background-origin: border and return a rect with offsets
     // relative to (0,0).  If we have a different background-origin,
     // then our rect should be deflated appropriately by our caller.
     return nsRect(-x, 0, mUnbrokenWidth, mFrame->GetSize().height);
   }
   nsRect GetBoundingRect(nsIFrame* aFrame)
   {
     SetFrame(aFrame);
     // Move the offsets relative to (0,0) which puts the bounding box into
     // our coordinate system rather than our parent's.  We do this by
     // moving it the back distance from us to the bounding box.
     // This also assumes background-origin: border, so our caller will
     // need to deflate us if needed.
     nsRect boundingBox(mBoundingBox);
     nsPoint point = mFrame->GetPosition();
     boundingBox.MoveBy(-point.x, -point.y);
     return boundingBox;
   }
 protected:
   nsIFrame*     mFrame;
   nsBlockFrame* mBlockFrame;
   nsRect        mBoundingBox;
   nscoord       mContinuationPoint;
   nscoord       mUnbrokenWidth;
   nscoord       mLineContinuationPoint;
   bool          mBidiEnabled;
   void SetFrame(nsIFrame* aFrame)
   {
     NS_PRECONDITION(aFrame, "Need a frame");
     NS_ASSERTION(gFrameTreeLockCount > 0,
                  "Can't call this when frame tree is not locked");
     if (aFrame == mFrame) {
       return;
     }
     nsIFrame *prevContinuation = GetPrevContinuation(aFrame);
     if (!prevContinuation || mFrame != prevContinuation) {
       // Ok, we've got the wrong frame.  We have to start from scratch.
       Reset();
       Init(aFrame);
       return;
     }
     // Get our last frame's size and add its width to our continuation
     // point before we cache the new frame.
     mContinuationPoint += mFrame->GetSize().width;
     // If this a new line, update mLineContinuationPoint.
     if (mBidiEnabled &&
         (aFrame->GetPrevInFlow() || !AreOnSameLine(mFrame, aFrame))) {
        mLineContinuationPoint = mContinuationPoint;
     }
     mFrame = aFrame;
   }
   nsIFrame* GetPrevContinuation(nsIFrame* aFrame)
   {
     nsIFrame* prevCont = aFrame->GetPrevContinuation();
     if (!prevCont &&
         (aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT)) {
       nsIFrame* block = static_cast<nsIFrame*>
         (aFrame->Properties().Get(nsIFrame::IBSplitPrevSibling()));
       if (block) {
         // The {ib} properties are only stored on first continuations
         NS_ASSERTION(!block->GetPrevContinuation(),
                      "Incorrect value for IBSplitPrevSibling");
         prevCont = static_cast<nsIFrame*>
           (block->Properties().Get(nsIFrame::IBSplitPrevSibling()));
         NS_ASSERTION(prevCont, "How did that happen?");
       }
     }
     return prevCont;
   }
   nsIFrame* GetNextContinuation(nsIFrame* aFrame)
   {
     nsIFrame* nextCont = aFrame->GetNextContinuation();
     if (!nextCont &&
         (aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT)) {
       // The {ib} properties are only stored on first continuations
       aFrame = aFrame->FirstContinuation();
       nsIFrame* block = static_cast<nsIFrame*>
         (aFrame->Properties().Get(nsIFrame::IBSplitSibling()));
       if (block) {
         nextCont = static_cast<nsIFrame*>
           (block->Properties().Get(nsIFrame::IBSplitSibling()));
         NS_ASSERTION(nextCont, "How did that happen?");
       }
     }
     return nextCont;
   }
   void Init(nsIFrame* aFrame)
   {
     mBidiEnabled = aFrame->PresContext()->BidiEnabled();
     if (mBidiEnabled) {
       // Find the containing block frame
       nsIFrame* frame = aFrame;
       do {
         frame = frame->GetParent();
         mBlockFrame = do_QueryFrame(frame);
       }
       while (frame && frame->IsFrameOfType(nsIFrame::eLineParticipant));
       NS_ASSERTION(mBlockFrame, "Cannot find containing block.");
     }
     // Start with the previous flow frame as our continuation point
     // is the total of the widths of the previous frames.
     nsIFrame* inlineFrame = GetPrevContinuation(aFrame);
     while (inlineFrame) {
       nsRect rect = inlineFrame->GetRect();
       mContinuationPoint += rect.width;
       if (mBidiEnabled && !AreOnSameLine(aFrame, inlineFrame)) {
         mLineContinuationPoint += rect.width;
       }
       mUnbrokenWidth += rect.width;
       mBoundingBox.UnionRect(mBoundingBox, rect);
       inlineFrame = GetPrevContinuation(inlineFrame);
     }
     // Next add this frame and subsequent frames to the bounding box and
     // unbroken width.
     inlineFrame = aFrame;
     while (inlineFrame) {
       nsRect rect = inlineFrame->GetRect();
       mUnbrokenWidth += rect.width;
       mBoundingBox.UnionRect(mBoundingBox, rect);
       inlineFrame = GetNextContinuation(inlineFrame);
     }
     mFrame = aFrame;
   }
   bool AreOnSameLine(nsIFrame* aFrame1, nsIFrame* aFrame2) {
     bool isValid1, isValid2;
     nsBlockInFlowLineIterator it1(mBlockFrame, aFrame1, &isValid1);
     nsBlockInFlowLineIterator it2(mBlockFrame, aFrame2, &isValid2);
     return isValid1 && isValid2 &&
       // Make sure aFrame1 and aFrame2 are in the same continuation of
       // mBlockFrame.
       it1.GetContainer() == it2.GetContainer() &&
       // And on the same line in it
       it1.GetLine() == it2.GetLine();
   }
 };
 // A resolved color stop --- with a specific position along the gradient line,
 // and a Thebes color
 struct ColorStop {
   ColorStop(double aPosition, gfxRGBA aColor) :
     mPosition(aPosition), mColor(aColor) {}
   double mPosition; // along the gradient line; 0=start, 1=end
   gfxRGBA mColor;
 };
 /* Local functions */
 static void DrawBorderImage(nsPresContext* aPresContext,
                             nsRenderingContext& aRenderingContext,
                             nsIFrame* aForFrame,
                             const nsRect& aBorderArea,
                             const nsStyleBorder& aStyleBorder,
                             const nsRect& aDirtyRect);
 static nscolor MakeBevelColor(mozilla::css::Side whichSide, uint8_t style,
                               nscolor aBackgroundColor,
                               nscolor aBorderColor);
 static InlineBackgroundData* gInlineBGData = nullptr;
 // Initialize any static variables used by nsCSSRendering.
 void nsCSSRendering::Init()
 {
   NS_ASSERTION(!gInlineBGData, "Init called twice");
   gInlineBGData = new InlineBackgroundData();
 }
 // Clean up any global variables used by nsCSSRendering.
 void nsCSSRendering::Shutdown()
 {
   delete gInlineBGData;
   gInlineBGData = nullptr;
 }
 /**
  * Make a bevel color
  */
 static nscolor
 MakeBevelColor(mozilla::css::Side whichSide, uint8_t style,
                nscolor aBackgroundColor, nscolor aBorderColor)
 {
   nscolor colors[2];
   nscolor theColor;
   // Given a background color and a border color
   // calculate the color used for the shading
   NS_GetSpecial3DColors(colors, aBackgroundColor, aBorderColor);
   if ((style == NS_STYLE_BORDER_STYLE_OUTSET) ||
       (style == NS_STYLE_BORDER_STYLE_RIDGE)) {
     // Flip colors for these two border styles
     switch (whichSide) {
     case NS_SIDE_BOTTOM: whichSide = NS_SIDE_TOP;    break;
     case NS_SIDE_RIGHT:  whichSide = NS_SIDE_LEFT;   break;
     case NS_SIDE_TOP:    whichSide = NS_SIDE_BOTTOM; break;
     case NS_SIDE_LEFT:   whichSide = NS_SIDE_RIGHT;  break;
     }
   }
   switch (whichSide) {
   case NS_SIDE_BOTTOM:
     theColor = colors[1];
     break;
   case NS_SIDE_RIGHT:
     theColor = colors[1];
     break;
   case NS_SIDE_TOP:
     theColor = colors[0];
     break;
   case NS_SIDE_LEFT:
   default:
     theColor = colors[0];
     break;
   }
   return theColor;
 }
 //----------------------------------------------------------------------
 // Thebes Border Rendering Code Start
 /*
  * Compute the float-pixel radii that should be used for drawing
  * this border/outline, given the various input bits.
  */
 /* static */ void
 nsCSSRendering::ComputePixelRadii(const nscoord *aAppUnitsRadii,
                                   nscoord aAppUnitsPerPixel,
                                   gfxCornerSizes *oBorderRadii)
 {
   gfxFloat radii[8];
   NS_FOR_CSS_HALF_CORNERS(corner)
     radii[corner] = gfxFloat(aAppUnitsRadii[corner]) / aAppUnitsPerPixel;
   (*oBorderRadii)[C_TL] = gfxSize(radii[NS_CORNER_TOP_LEFT_X],
                                   radii[NS_CORNER_TOP_LEFT_Y]);
   (*oBorderRadii)[C_TR] = gfxSize(radii[NS_CORNER_TOP_RIGHT_X],
                                   radii[NS_CORNER_TOP_RIGHT_Y]);
   (*oBorderRadii)[C_BR] = gfxSize(radii[NS_CORNER_BOTTOM_RIGHT_X],
                                   radii[NS_CORNER_BOTTOM_RIGHT_Y]);
   (*oBorderRadii)[C_BL] = gfxSize(radii[NS_CORNER_BOTTOM_LEFT_X],
                                   radii[NS_CORNER_BOTTOM_LEFT_Y]);
 }
 void
 nsCSSRendering::PaintBorder(nsPresContext* aPresContext,
                             nsRenderingContext& aRenderingContext,
                             nsIFrame* aForFrame,
                             const nsRect& aDirtyRect,
                             const nsRect& aBorderArea,
                             nsStyleContext* aStyleContext,
                             int aSkipSides)
 {
   PROFILER_LABEL("nsCSSRendering", "PaintBorder");
   nsStyleContext *styleIfVisited = aStyleContext->GetStyleIfVisited();
   const nsStyleBorder *styleBorder = aStyleContext->StyleBorder();
   // Don't check RelevantLinkVisited here, since we want to take the
   // same amount of time whether or not it's true.
   if (!styleIfVisited) {
     PaintBorderWithStyleBorder(aPresContext, aRenderingContext, aForFrame,
                                aDirtyRect, aBorderArea, *styleBorder,
                                aStyleContext, aSkipSides);
     return;
   }
   nsStyleBorder newStyleBorder(*styleBorder);
   // We could do something fancy to avoid the TrackImage/UntrackImage
   // work, but it doesn't seem worth it.  (We need to call TrackImage
   // since we're not going through nsRuleNode::ComputeBorderData.)
   newStyleBorder.TrackImage(aPresContext);
   NS_FOR_CSS_SIDES(side) {
     newStyleBorder.SetBorderColor(side,
       aStyleContext->GetVisitedDependentColor(
         nsCSSProps::SubpropertyEntryFor(eCSSProperty_border_color)[side]));
   }
   PaintBorderWithStyleBorder(aPresContext, aRenderingContext, aForFrame,
                              aDirtyRect, aBorderArea, newStyleBorder,
                              aStyleContext, aSkipSides);
   // We could do something fancy to avoid the TrackImage/UntrackImage
   // work, but it doesn't seem worth it.  (We need to call UntrackImage
   // since we're not going through nsStyleBorder::Destroy.)
   newStyleBorder.UntrackImage(aPresContext);
 }
 void
 nsCSSRendering::PaintBorderWithStyleBorder(nsPresContext* aPresContext,
                                            nsRenderingContext& aRenderingContext,
                                            nsIFrame* aForFrame,
                                            const nsRect& aDirtyRect,
                                            const nsRect& aBorderArea,
                                            const nsStyleBorder& aStyleBorder,
                                            nsStyleContext* aStyleContext,
                                            int aSkipSides)
 {
   nsMargin            border;
   nscoord             twipsRadii[8];
   nsCompatibility     compatMode = aPresContext->CompatibilityMode();
   SN("++ PaintBorder");
   // Check to see if we have an appearance defined.  If so, we let the theme
   // renderer draw the border.  DO not get the data from aForFrame, since the passed in style context
   // may be different!  Always use |aStyleContext|!
   const nsStyleDisplay* displayData = aStyleContext->StyleDisplay();
   if (displayData->mAppearance) {
     nsITheme *theme = aPresContext->GetTheme();
     if (theme && theme->ThemeSupportsWidget(aPresContext, aForFrame, displayData->mAppearance))
       return; // Let the theme handle it.
   }
   if (aStyleBorder.IsBorderImageLoaded()) {
     DrawBorderImage(aPresContext, aRenderingContext, aForFrame,
                     aBorderArea, aStyleBorder, aDirtyRect);
     return;
   }
   // Get our style context's color struct.
   const nsStyleColor* ourColor = aStyleContext->StyleColor();
   // in NavQuirks mode we want to use the parent's context as a starting point
   // for determining the background color
   nsIFrame* bgFrame = nsCSSRendering::FindNonTransparentBackgroundFrame
     (aForFrame, compatMode == eCompatibility_NavQuirks ? true : false);
   nsStyleContext* bgContext = bgFrame->StyleContext();
   nscolor bgColor =
     bgContext->GetVisitedDependentColor(eCSSProperty_background_color);
   border = aStyleBorder.GetComputedBorder();
   if ((0 == border.left) && (0 == border.right) &&
       (0 == border.top) && (0 == border.bottom)) {
     // Empty border area
     return;
   }
   nsSize frameSize = aForFrame->GetSize();
   if (&aStyleBorder == aForFrame->StyleBorder() &&
       frameSize == aBorderArea.Size()) {
     aForFrame->GetBorderRadii(twipsRadii);
   } else {
     nsIFrame::ComputeBorderRadii(aStyleBorder.mBorderRadius, frameSize,
                                  aBorderArea.Size(), aSkipSides, twipsRadii);
   }
   // Turn off rendering for all of the zero sized sides
   if (aSkipSides & SIDE_BIT_TOP) border.top = 0;
   if (aSkipSides & SIDE_BIT_RIGHT) border.right = 0;
   if (aSkipSides & SIDE_BIT_BOTTOM) border.bottom = 0;
   if (aSkipSides & SIDE_BIT_LEFT) border.left = 0;
   // get the inside and outside parts of the border
   nsRect outerRect(aBorderArea);
   SF(" outerRect: %d %d %d %d\n", outerRect.x, outerRect.y, outerRect.width, outerRect.height);
   // we can assume that we're already clipped to aDirtyRect -- I think? (!?)
   // Get our conversion values
   nscoord twipsPerPixel = aPresContext->DevPixelsToAppUnits(1);
   // convert outer and inner rects
   gfxRect oRect(nsLayoutUtils::RectToGfxRect(outerRect, twipsPerPixel));
   // convert the border widths
   gfxFloat borderWidths[4] = { gfxFloat(border.top / twipsPerPixel),
                                gfxFloat(border.right / twipsPerPixel),
                                gfxFloat(border.bottom / twipsPerPixel),
                                gfxFloat(border.left / twipsPerPixel) };
   // convert the radii
   gfxCornerSizes borderRadii;
   ComputePixelRadii(twipsRadii, twipsPerPixel, &borderRadii);
   uint8_t borderStyles[4];
   nscolor borderColors[4];
   nsBorderColors *compositeColors[4];
   // pull out styles, colors, composite colors
   NS_FOR_CSS_SIDES (i) {
     bool foreground;
     borderStyles[i] = aStyleBorder.GetBorderStyle(i);
     aStyleBorder.GetBorderColor(i, borderColors[i], foreground);
     aStyleBorder.GetCompositeColors(i, &compositeColors[i]);
     if (foreground)
       borderColors[i] = ourColor->mColor;
   }
   SF(" borderStyles: %d %d %d %d\n", borderStyles[0], borderStyles[1], borderStyles[2], borderStyles[3]);
   // start drawing
   gfxContext *ctx = aRenderingContext.ThebesContext();
   ctx->Save();
 #if 0
   // this will draw a transparent red backround underneath the oRect area
   ctx->Save();
   ctx->Rectangle(oRect);
   ctx->SetColor(gfxRGBA(1.0, 0.0, 0.0, 0.5));
   ctx->Fill();
   ctx->Restore();
 #endif
   //SF ("borderRadii: %f %f %f %f\n", borderRadii[0], borderRadii[1], borderRadii[2], borderRadii[3]);
   nsCSSBorderRenderer br(twipsPerPixel,
                          ctx,
                          oRect,
                          borderStyles,
                          borderWidths,
                          borderRadii,
                          borderColors,
                          compositeColors,
                          aSkipSides,
                          bgColor);
   br.DrawBorders();
   ctx->Restore();
   SN();
 }
 static nsRect
 GetOutlineInnerRect(nsIFrame* aFrame)
 {
   nsRect* savedOutlineInnerRect = static_cast<nsRect*>
     (aFrame->Properties().Get(nsIFrame::OutlineInnerRectProperty()));
   if (savedOutlineInnerRect)
     return *savedOutlineInnerRect;
   NS_NOTREACHED("we should have saved a frame property");
   return nsRect(nsPoint(0, 0), aFrame->GetSize());
 }
 void
 nsCSSRendering::PaintOutline(nsPresContext* aPresContext,
                              nsRenderingContext& aRenderingContext,
                              nsIFrame* aForFrame,
                              const nsRect& aDirtyRect,
                              const nsRect& aBorderArea,
                              nsStyleContext* aStyleContext)
 {
   nscoord             twipsRadii[8];
   // Get our style context's color struct.
   const nsStyleOutline* ourOutline = aStyleContext->StyleOutline();
   nscoord width;
   ourOutline->GetOutlineWidth(width);
   if (width == 0) {
     // Empty outline
     return;
   }
   nsIFrame* bgFrame = nsCSSRendering::FindNonTransparentBackgroundFrame
     (aForFrame, false);
   nsStyleContext* bgContext = bgFrame->StyleContext();
   nscolor bgColor =
     bgContext->GetVisitedDependentColor(eCSSProperty_background_color);
   nsRect innerRect;
   if (
 #ifdef MOZ_XUL
       aStyleContext->GetPseudoType() == nsCSSPseudoElements::ePseudo_XULTree
 #else
       false
 #endif
      ) {
     innerRect = aBorderArea;
   } else {
     innerRect = GetOutlineInnerRect(aForFrame) + aBorderArea.TopLeft();
   }
   nscoord offset = ourOutline->mOutlineOffset;
   innerRect.Inflate(offset, offset);
   // If the dirty rect is completely inside the border area (e.g., only the
   // content is being painted), then we can skip out now
   // XXX this isn't exactly true for rounded borders, where the inside curves may
   // encroach into the content area.  A safer calculation would be to
   // shorten insideRect by the radius one each side before performing this test.
   if (innerRect.Contains(aDirtyRect))
     return;
   nsRect outerRect = innerRect;
   outerRect.Inflate(width, width);
   // get the radius for our outline
   nsIFrame::ComputeBorderRadii(ourOutline->mOutlineRadius, aBorderArea.Size(),
                                outerRect.Size(), 0, twipsRadii);
   // Get our conversion values
   nscoord twipsPerPixel = aPresContext->DevPixelsToAppUnits(1);
   // get the outer rectangles
   gfxRect oRect(nsLayoutUtils::RectToGfxRect(outerRect, twipsPerPixel));
   // convert the radii
   nsMargin outlineMargin(width, width, width, width);
   gfxCornerSizes outlineRadii;
   ComputePixelRadii(twipsRadii, twipsPerPixel, &outlineRadii);
   uint8_t outlineStyle = ourOutline->GetOutlineStyle();
   uint8_t outlineStyles[4] = { outlineStyle,
                                outlineStyle,
                                outlineStyle,
                                outlineStyle };
   // This handles treating the initial color as 'currentColor'; if we
   // ever want 'invert' back we'll need to do a bit of work here too.
   nscolor outlineColor =
     aStyleContext->GetVisitedDependentColor(eCSSProperty_outline_color);
   nscolor outlineColors[4] = { outlineColor,
                                outlineColor,
                                outlineColor,
                                outlineColor };
   // convert the border widths
   gfxFloat outlineWidths[4] = { gfxFloat(width / twipsPerPixel),
                                 gfxFloat(width / twipsPerPixel),
                                 gfxFloat(width / twipsPerPixel),
                                 gfxFloat(width / twipsPerPixel) };
   // start drawing
   gfxContext *ctx = aRenderingContext.ThebesContext();
   ctx->Save();
   nsCSSBorderRenderer br(twipsPerPixel,
                          ctx,
                          oRect,
                          outlineStyles,
                          outlineWidths,
                          outlineRadii,
                          outlineColors,
                          nullptr, 0,
                          bgColor);
   br.DrawBorders();
   ctx->Restore();
   SN();
 }
 void
 nsCSSRendering::PaintFocus(nsPresContext* aPresContext,
                            nsRenderingContext& aRenderingContext,
                            const nsRect& aFocusRect,
                            nscolor aColor)
 {
   nscoord oneCSSPixel = nsPresContext::CSSPixelsToAppUnits(1);
   nscoord oneDevPixel = aPresContext->DevPixelsToAppUnits(1);
   gfxRect focusRect(nsLayoutUtils::RectToGfxRect(aFocusRect, oneDevPixel));
   gfxCornerSizes focusRadii;
   {
     nscoord twipsRadii[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
     ComputePixelRadii(twipsRadii, oneDevPixel, &focusRadii);
   }
   gfxFloat focusWidths[4] = { gfxFloat(oneCSSPixel / oneDevPixel),
                               gfxFloat(oneCSSPixel / oneDevPixel),
                               gfxFloat(oneCSSPixel / oneDevPixel),
                               gfxFloat(oneCSSPixel / oneDevPixel) };
   uint8_t focusStyles[4] = { NS_STYLE_BORDER_STYLE_DOTTED,
                              NS_STYLE_BORDER_STYLE_DOTTED,
                              NS_STYLE_BORDER_STYLE_DOTTED,
                              NS_STYLE_BORDER_STYLE_DOTTED };
   nscolor focusColors[4] = { aColor, aColor, aColor, aColor };
   gfxContext *ctx = aRenderingContext.ThebesContext();
   ctx->Save();
   // Because this renders a dotted border, the background color
   // should not be used.  Therefore, we provide a value that will
   // be blatantly wrong if it ever does get used.  (If this becomes
   // something that CSS can style, this function will then have access
   // to a style context and can use the same logic that PaintBorder
   // and PaintOutline do.)
   nsCSSBorderRenderer br(oneDevPixel,
                          ctx,
                          focusRect,
                          focusStyles,
                          focusWidths,
                          focusRadii,
                          focusColors,
                          nullptr, 0,
                          NS_RGB(255, 0, 0));
   br.DrawBorders();
   ctx->Restore();
   SN();
 }
 // Thebes Border Rendering Code End
 //----------------------------------------------------------------------
 //----------------------------------------------------------------------
 /**
  * Computes the placement of a background image.
  *
  * @param aOriginBounds is the box to which the tiling position should be
  * relative
  * This should correspond to 'background-origin' for the frame,
  * except when painting on the canvas, in which case the origin bounds
  * should be the bounds of the root element's frame.
  * @param aTopLeft the top-left corner where an image tile should be drawn
  * @param aAnchorPoint a point which should be pixel-aligned by
  * nsLayoutUtils::DrawImage. This is the same as aTopLeft, unless CSS
  * specifies a percentage (including 'right' or 'bottom'), in which case
  * it's that percentage within of aOriginBounds. So 'right' would set
  * aAnchorPoint.x to aOriginBounds.XMost().
  *
  * Points are returned relative to aOriginBounds.
  */
 static void
 ComputeBackgroundAnchorPoint(const nsStyleBackground::Layer& aLayer,
                              const nsSize& aOriginBounds,
                              const nsSize& aImageSize,
                              nsPoint* aTopLeft,
                              nsPoint* aAnchorPoint)
 {
   double percentX = aLayer.mPosition.mXPosition.mPercent;
   nscoord lengthX = aLayer.mPosition.mXPosition.mLength;
   aAnchorPoint->x = lengthX + NSToCoordRound(percentX*aOriginBounds.width);
   aTopLeft->x = lengthX +
     NSToCoordRound(percentX*(aOriginBounds.width - aImageSize.width));
   double percentY = aLayer.mPosition.mYPosition.mPercent;
   nscoord lengthY = aLayer.mPosition.mYPosition.mLength;
   aAnchorPoint->y = lengthY + NSToCoordRound(percentY*aOriginBounds.height);
   aTopLeft->y = lengthY +
     NSToCoordRound(percentY*(aOriginBounds.height - aImageSize.height));
 }
 nsIFrame*
 nsCSSRendering::FindNonTransparentBackgroundFrame(nsIFrame* aFrame,
                                                   bool aStartAtParent /*= false*/)
 {
   NS_ASSERTION(aFrame, "Cannot find NonTransparentBackgroundFrame in a null frame");
   nsIFrame* frame = nullptr;
   if (aStartAtParent) {
     frame = nsLayoutUtils::GetParentOrPlaceholderFor(aFrame);
   }
   if (!frame) {
     frame = aFrame;
   }
   while (frame) {
     // No need to call GetVisitedDependentColor because it always uses
     // this alpha component anyway.
     if (NS_GET_A(frame->StyleBackground()->mBackgroundColor) > 0)
       break;
     if (frame->IsThemed())
       break;
     nsIFrame* parent = nsLayoutUtils::GetParentOrPlaceholderFor(frame);
     if (!parent)
       break;
     frame = parent;
   }
   return frame;
 }
 // Returns true if aFrame is a canvas frame.
 // We need to treat the viewport as canvas because, even though
 // it does not actually paint a background, we need to get the right
 // background style so we correctly detect transparent documents.
 bool
 nsCSSRendering::IsCanvasFrame(nsIFrame* aFrame)
 {
   nsIAtom* frameType = aFrame->GetType();
   return frameType == nsGkAtoms::canvasFrame ||
          frameType == nsGkAtoms::rootFrame ||
          frameType == nsGkAtoms::pageContentFrame ||
          frameType == nsGkAtoms::viewportFrame;
 }
 nsIFrame*
 nsCSSRendering::FindBackgroundStyleFrame(nsIFrame* aForFrame)
 {
   const nsStyleBackground* result = aForFrame->StyleBackground();
   // Check if we need to do propagation from BODY rather than HTML.
   if (!result->IsTransparent()) {
     return aForFrame;
   }
   nsIContent* content = aForFrame->GetContent();
   // The root element content can't be null. We wouldn't know what
   // frame to create for aFrame.
   // Use |OwnerDoc| so it works during destruction.
   if (!content) {
     return aForFrame;
   }
   nsIDocument* document = content->OwnerDoc();
   dom::Element* bodyContent = document->GetBodyElement();
   // We need to null check the body node (bug 118829) since
   // there are cases, thanks to the fix for bug 5569, where we
   // will reflow a document with no body.  In particular, if a
   // SCRIPT element in the head blocks the parser and then has a
   // SCRIPT that does "document.location.href = 'foo'", then
   // nsParser::Terminate will call |DidBuildModel| methods
   // through to the content sink, which will call |StartLayout|
   // and thus |Initialize| on the pres shell.  See bug 119351
   // for the ugly details.
   if (!bodyContent) {
     return aForFrame;
   }
   nsIFrame *bodyFrame = bodyContent->GetPrimaryFrame();
   if (!bodyFrame) {
     return aForFrame;
   }
   return nsLayoutUtils::GetStyleFrame(bodyFrame);
 }
 /**
  * |FindBackground| finds the correct style data to use to paint the
  * background.  It is responsible for handling the following two
  * statements in section 14.2 of CSS2:
  *
  *   The background of the box generated by the root element covers the
  *   entire canvas.
  *
  *   For HTML documents, however, we recommend that authors specify the
  *   background for the BODY element rather than the HTML element. User
  *   agents should observe the following precedence rules to fill in the
  *   background: if the value of the 'background' property for the HTML
  *   element is different from 'transparent' then use it, else use the
  *   value of the 'background' property for the BODY element. If the
  *   resulting value is 'transparent', the rendering is undefined.
  *
  * Thus, in our implementation, it is responsible for ensuring that:
  *  + we paint the correct background on the |nsCanvasFrame|,
  *    |nsRootBoxFrame|, or |nsPageFrame|,
  *  + we don't paint the background on the root element, and
  *  + we don't paint the background on the BODY element in *some* cases,
  *    and for SGML-based HTML documents only.
  *
  * |FindBackground| returns true if a background should be painted, and
  * the resulting style context to use for the background information
  * will be filled in to |aBackground|.
  */
 nsStyleContext*
 nsCSSRendering::FindRootFrameBackground(nsIFrame* aForFrame)
 {
   return FindBackgroundStyleFrame(aForFrame)->StyleContext();
 }
 inline bool
 FindElementBackground(nsIFrame* aForFrame, nsIFrame* aRootElementFrame,
                       nsStyleContext** aBackgroundSC)
 {
   if (aForFrame == aRootElementFrame) {
     // We must have propagated our background to the viewport or canvas. Abort.
     return false;
   }
   *aBackgroundSC = aForFrame->StyleContext();
   // Return true unless the frame is for a BODY element whose background
   // was propagated to the viewport.
   nsIContent* content = aForFrame->GetContent();
   if (!content || content->Tag() != nsGkAtoms::body)
     return true; // not frame for a "body" element
   // It could be a non-HTML "body" element but that's OK, we'd fail the
   // bodyContent check below
   if (aForFrame->StyleContext()->GetPseudo())
     return true; // A pseudo-element frame.
   // We should only look at the <html> background if we're in an HTML document
   nsIDocument* document = content->OwnerDoc();
   dom::Element* bodyContent = document->GetBodyElement();
   if (bodyContent != content)
     return true; // this wasn't the background that was propagated
   // This can be called even when there's no root element yet, during frame
   // construction, via nsLayoutUtils::FrameHasTransparency and
   // nsContainerFrame::SyncFrameViewProperties.
   if (!aRootElementFrame)
     return true;
   const nsStyleBackground* htmlBG = aRootElementFrame->StyleBackground();
   return !htmlBG->IsTransparent();
 }
 bool
 nsCSSRendering::FindBackground(nsIFrame* aForFrame,
                                nsStyleContext** aBackgroundSC)
 {
   nsIFrame* rootElementFrame =
     aForFrame->PresContext()->PresShell()->FrameConstructor()->GetRootElementStyleFrame();
   if (IsCanvasFrame(aForFrame)) {
     *aBackgroundSC = FindCanvasBackground(aForFrame, rootElementFrame);
     return true;
   } else {
     return FindElementBackground(aForFrame, rootElementFrame, aBackgroundSC);
   }
 }
 void
 nsCSSRendering::BeginFrameTreesLocked()
 {
   ++gFrameTreeLockCount;
 }
 void
 nsCSSRendering::EndFrameTreesLocked()
 {
   NS_ASSERTION(gFrameTreeLockCount > 0, "Unbalanced EndFrameTreeLocked");
   --gFrameTreeLockCount;
   if (gFrameTreeLockCount == 0) {
     gInlineBGData->Reset();
   }
 }
 void
 nsCSSRendering::PaintBoxShadowOuter(nsPresContext* aPresContext,
                                     nsRenderingContext& aRenderingContext,
                                     nsIFrame* aForFrame,
                                     const nsRect& aFrameArea,
                                     const nsRect& aDirtyRect,
                                     float aOpacity)
 {
   const nsStyleBorder* styleBorder = aForFrame->StyleBorder();
   nsCSSShadowArray* shadows = styleBorder->mBoxShadow;
   if (!shadows)
     return;
   nscoord twipsPerPixel = aPresContext->DevPixelsToAppUnits(1);
   bool hasBorderRadius;
   bool nativeTheme; // mutually exclusive with hasBorderRadius
   gfxCornerSizes borderRadii;
   // Get any border radius, since box-shadow must also have rounded corners if the frame does
   const nsStyleDisplay* styleDisplay = aForFrame->StyleDisplay();
   nsITheme::Transparency transparency;
   if (aForFrame->IsThemed(styleDisplay, &transparency)) {
     // We don't respect border-radius for native-themed widgets
     hasBorderRadius = false;
     // For opaque (rectangular) theme widgets we can take the generic
     // border-box path with border-radius disabled.
     nativeTheme = transparency != nsITheme::eOpaque;
   } else {
     nativeTheme = false;
     nscoord twipsRadii[8];
     NS_ASSERTION(aFrameArea.Size() == aForFrame->VisualBorderRectRelativeToSelf().Size(),
                  "unexpected size");
     hasBorderRadius = aForFrame->GetBorderRadii(twipsRadii);
     if (hasBorderRadius) {
       ComputePixelRadii(twipsRadii, twipsPerPixel, &borderRadii);
     }
   }
   nsRect frameRect =
     nativeTheme ? aForFrame->GetVisualOverflowRectRelativeToSelf() + aFrameArea.TopLeft() : aFrameArea;
   gfxRect frameGfxRect(nsLayoutUtils::RectToGfxRect(frameRect, twipsPerPixel));
   frameGfxRect.Round();
   // We don't show anything that intersects with the frame we're blurring on. So tell the
   // blurrer not to do unnecessary work there.
   gfxRect skipGfxRect = frameGfxRect;
   bool useSkipGfxRect = true;
   if (nativeTheme) {
     // Optimize non-leaf native-themed frames by skipping computing pixels
     // in the padding-box. We assume the padding-box is going to be painted
     // opaquely for non-leaf frames.
     // XXX this may not be a safe assumption; we should make this go away
     // by optimizing box-shadow drawing more for the cases where we don't have a skip-rect.
     useSkipGfxRect = !aForFrame->IsLeaf();
     nsRect paddingRect =
       aForFrame->GetPaddingRect() - aForFrame->GetPosition() + aFrameArea.TopLeft();
     skipGfxRect = nsLayoutUtils::RectToGfxRect(paddingRect, twipsPerPixel);
   } else if (hasBorderRadius) {
     skipGfxRect.Deflate(gfxMargin(
         std::max(borderRadii[C_TL].height, borderRadii[C_TR].height), 0,
         std::max(borderRadii[C_BL].height, borderRadii[C_BR].height), 0));
   }
   for (uint32_t i = shadows->Length(); i > 0; --i) {
     nsCSSShadowItem* shadowItem = shadows->ShadowAt(i - 1);
     if (shadowItem->mInset)
       continue;
     nsRect shadowRect = frameRect;
     shadowRect.MoveBy(shadowItem->mXOffset, shadowItem->mYOffset);
     if (!nativeTheme) {
       shadowRect.Inflate(shadowItem->mSpread, shadowItem->mSpread);
     }
     // shadowRect won't include the blur, so make an extra rect here that includes the blur
     // for use in the even-odd rule below.
     nsRect shadowRectPlusBlur = shadowRect;
     nscoord blurRadius = shadowItem->mRadius;
     shadowRectPlusBlur.Inflate(
       nsContextBoxBlur::GetBlurRadiusMargin(blurRadius, twipsPerPixel));
     gfxRect shadowGfxRectPlusBlur =
       nsLayoutUtils::RectToGfxRect(shadowRectPlusBlur, twipsPerPixel);
     shadowGfxRectPlusBlur.RoundOut();
     // Set the shadow color; if not specified, use the foreground color
     nscolor shadowColor;
     if (shadowItem->mHasColor)
       shadowColor = shadowItem->mColor;
     else
       shadowColor = aForFrame->StyleColor()->mColor;
     gfxRGBA gfxShadowColor(shadowColor);
     gfxShadowColor.a *= aOpacity;
     gfxContext* renderContext = aRenderingContext.ThebesContext();
     if (nativeTheme) {
       nsContextBoxBlur blurringArea;
       // When getting the widget shape from the native theme, we're going
       // to draw the widget into the shadow surface to create a mask.
       // We need to ensure that there actually *is* a shadow surface
       // and that we're not going to draw directly into renderContext.
       gfxContext* shadowContext =
         blurringArea.Init(shadowRect, shadowItem->mSpread,
                           blurRadius, twipsPerPixel, renderContext, aDirtyRect,
                           useSkipGfxRect ? &skipGfxRect : nullptr,
                           nsContextBoxBlur::FORCE_MASK);
       if (!shadowContext)
         continue;
       // shadowContext is owned by either blurringArea or aRenderingContext.
       MOZ_ASSERT(shadowContext == blurringArea.GetContext());
       renderContext->Save();
       renderContext->SetColor(gfxShadowColor);
       // Draw the shape of the frame so it can be blurred. Recall how nsContextBoxBlur
       // doesn't make any temporary surfaces if blur is 0 and it just returns the original
       // surface? If we have no blur, we're painting this fill on the actual content surface
       // (renderContext == shadowContext) which is why we set up the color and clip
       // before doing this.
       // We don't clip the border-box from the shadow, nor any other box.
       // We assume that the native theme is going to paint over the shadow.
       // Draw the widget shape
       gfxContextMatrixAutoSaveRestore save(shadowContext);
       nsRefPtr<nsRenderingContext> wrapperCtx = new nsRenderingContext();
       wrapperCtx->Init(aPresContext->DeviceContext(), shadowContext);
       wrapperCtx->Translate(nsPoint(shadowItem->mXOffset,
                                     shadowItem->mYOffset));
       nsRect nativeRect;
       nativeRect.IntersectRect(frameRect, aDirtyRect);
       aPresContext->GetTheme()->DrawWidgetBackground(wrapperCtx, aForFrame,
           styleDisplay->mAppearance, aFrameArea, nativeRect);
       blurringArea.DoPaint();
       renderContext->Restore();
     } else {
       renderContext->Save();
       // Clip out the area of the actual frame so the shadow is not shown within
       // the frame
       renderContext->NewPath();
       renderContext->Rectangle(shadowGfxRectPlusBlur);
       if (hasBorderRadius) {
         renderContext->RoundedRectangle(frameGfxRect, borderRadii);
       } else {
         renderContext->Rectangle(frameGfxRect);
       }
       renderContext->SetFillRule(gfxContext::FILL_RULE_EVEN_ODD);
       renderContext->Clip();
       gfxCornerSizes clipRectRadii;
       if (hasBorderRadius) {
         gfxFloat spreadDistance = shadowItem->mSpread / twipsPerPixel;
         gfxFloat borderSizes[4];
         borderSizes[NS_SIDE_LEFT] = spreadDistance;
         borderSizes[NS_SIDE_TOP] = spreadDistance;
         borderSizes[NS_SIDE_RIGHT] = spreadDistance;
         borderSizes[NS_SIDE_BOTTOM] = spreadDistance;
         nsCSSBorderRenderer::ComputeOuterRadii(borderRadii, borderSizes,
             &clipRectRadii);
       }
       nsContextBoxBlur::BlurRectangle(renderContext,
                                       shadowRect,
                                       twipsPerPixel,
                                       hasBorderRadius ? &clipRectRadii : nullptr,
                                       blurRadius,
                                       gfxShadowColor,
                                       aDirtyRect,
                                       skipGfxRect);
       renderContext->Restore();
     }
   }
 }
 void
 nsCSSRendering::PaintBoxShadowInner(nsPresContext* aPresContext,
                                     nsRenderingContext& aRenderingContext,
                                     nsIFrame* aForFrame,
                                     const nsRect& aFrameArea,
                                     const nsRect& aDirtyRect)
 {
   const nsStyleBorder* styleBorder = aForFrame->StyleBorder();
   nsCSSShadowArray* shadows = styleBorder->mBoxShadow;
   if (!shadows)
     return;
   if (aForFrame->IsThemed() && aForFrame->GetContent() &&
       !nsContentUtils::IsChromeDoc(aForFrame->GetContent()->GetCurrentDoc())) {
     // There's no way of getting hold of a shape corresponding to a
     // "padding-box" for native-themed widgets, so just don't draw
     // inner box-shadows for them. But we allow chrome to paint inner
     // box shadows since chrome can be aware of the platform theme.
     return;
   }
   // Get any border radius, since box-shadow must also have rounded corners
   // if the frame does.
   nscoord twipsRadii[8];
   NS_ASSERTION(aForFrame->GetType() == nsGkAtoms::fieldSetFrame ||
                aFrameArea.Size() == aForFrame->GetSize(), "unexpected size");
   bool hasBorderRadius = aForFrame->GetBorderRadii(twipsRadii);
   nscoord twipsPerPixel = aPresContext->DevPixelsToAppUnits(1);
   nsRect paddingRect = aFrameArea;
   nsMargin border = aForFrame->GetUsedBorder();
   aForFrame->ApplySkipSides(border);
   paddingRect.Deflate(border);
   gfxCornerSizes innerRadii;
   if (hasBorderRadius) {
     gfxCornerSizes borderRadii;
     ComputePixelRadii(twipsRadii, twipsPerPixel, &borderRadii);
     gfxFloat borderSizes[4] = {
       gfxFloat(border.top / twipsPerPixel),
       gfxFloat(border.right / twipsPerPixel),
       gfxFloat(border.bottom / twipsPerPixel),
       gfxFloat(border.left / twipsPerPixel)
     };
     nsCSSBorderRenderer::ComputeInnerRadii(borderRadii, borderSizes,
                                            &innerRadii);
   }
   for (uint32_t i = shadows->Length(); i > 0; --i) {
     nsCSSShadowItem* shadowItem = shadows->ShadowAt(i - 1);
     if (!shadowItem->mInset)
       continue;
     /*
      * shadowRect: the frame's padding rect
      * shadowPaintRect: the area to paint on the temp surface, larger than shadowRect
      *                  so that blurs still happen properly near the edges
      * shadowClipRect: the area on the temporary surface within shadowPaintRect
      *                 that we will NOT paint in
      */
     nscoord blurRadius = shadowItem->mRadius;
     nsMargin blurMargin =
       nsContextBoxBlur::GetBlurRadiusMargin(blurRadius, twipsPerPixel);
     nsRect shadowPaintRect = paddingRect;
     shadowPaintRect.Inflate(blurMargin);
     nsRect shadowClipRect = paddingRect;
     shadowClipRect.MoveBy(shadowItem->mXOffset, shadowItem->mYOffset);
     shadowClipRect.Deflate(shadowItem->mSpread, shadowItem->mSpread);
     gfxCornerSizes clipRectRadii;
     if (hasBorderRadius) {
       // Calculate the radii the inner clipping rect will have
       gfxFloat spreadDistance = shadowItem->mSpread / twipsPerPixel;
       gfxFloat borderSizes[4] = {0, 0, 0, 0};
       // See PaintBoxShadowOuter and bug 514670
       if (innerRadii[C_TL].width > 0 || innerRadii[C_BL].width > 0) {
         borderSizes[NS_SIDE_LEFT] = spreadDistance;
       }
       if (innerRadii[C_TL].height > 0 || innerRadii[C_TR].height > 0) {
         borderSizes[NS_SIDE_TOP] = spreadDistance;
       }
       if (innerRadii[C_TR].width > 0 || innerRadii[C_BR].width > 0) {
         borderSizes[NS_SIDE_RIGHT] = spreadDistance;
       }
       if (innerRadii[C_BL].height > 0 || innerRadii[C_BR].height > 0) {
         borderSizes[NS_SIDE_BOTTOM] = spreadDistance;
       }
       nsCSSBorderRenderer::ComputeInnerRadii(innerRadii, borderSizes,
                                              &clipRectRadii);
     }
     // Set the "skip rect" to the area within the frame that we don't paint in,
     // including after blurring.
     nsRect skipRect = shadowClipRect;
     skipRect.Deflate(blurMargin);
     gfxRect skipGfxRect = nsLayoutUtils::RectToGfxRect(skipRect, twipsPerPixel);
     if (hasBorderRadius) {
       skipGfxRect.Deflate(gfxMargin(
           std::max(clipRectRadii[C_TL].height, clipRectRadii[C_TR].height), 0,
           std::max(clipRectRadii[C_BL].height, clipRectRadii[C_BR].height), 0));
     }
     // When there's a blur radius, gfxAlphaBoxBlur leaves the skiprect area
     // unchanged. And by construction the gfxSkipRect is not touched by the
     // rendered shadow (even after blurring), so those pixels must be completely
     // transparent in the shadow, so drawing them changes nothing.
     gfxContext* renderContext = aRenderingContext.ThebesContext();
     nsContextBoxBlur blurringArea;
     gfxContext* shadowContext =
       blurringArea.Init(shadowPaintRect, 0, blurRadius, twipsPerPixel,
                         renderContext, aDirtyRect, &skipGfxRect);
     if (!shadowContext)
       continue;
     // shadowContext is owned by either blurringArea or aRenderingContext.
     MOZ_ASSERT(shadowContext == renderContext ||
                shadowContext == blurringArea.GetContext());
     // Set the shadow color; if not specified, use the foreground color
     nscolor shadowColor;
     if (shadowItem->mHasColor)
       shadowColor = shadowItem->mColor;
     else
       shadowColor = aForFrame->StyleColor()->mColor;
     renderContext->Save();
     renderContext->SetColor(gfxRGBA(shadowColor));
     // Clip the context to the area of the frame's padding rect, so no part of the
     // shadow is painted outside. Also cut out anything beyond where the inset shadow
     // will be.
     gfxRect shadowGfxRect =
       nsLayoutUtils::RectToGfxRect(paddingRect, twipsPerPixel);
     shadowGfxRect.Round();
     renderContext->NewPath();
     if (hasBorderRadius)
       renderContext->RoundedRectangle(shadowGfxRect, innerRadii, false);
     else
       renderContext->Rectangle(shadowGfxRect);
     renderContext->Clip();
     // Fill the surface minus the area within the frame that we should
     // not paint in, and blur and apply it.
     gfxRect shadowPaintGfxRect =
       nsLayoutUtils::RectToGfxRect(shadowPaintRect, twipsPerPixel);
     shadowPaintGfxRect.RoundOut();
     gfxRect shadowClipGfxRect =
       nsLayoutUtils::RectToGfxRect(shadowClipRect, twipsPerPixel);
     shadowClipGfxRect.Round();
     shadowContext->NewPath();
     shadowContext->Rectangle(shadowPaintGfxRect);
     if (hasBorderRadius)
       shadowContext->RoundedRectangle(shadowClipGfxRect, clipRectRadii, false);
     else
       shadowContext->Rectangle(shadowClipGfxRect);
     shadowContext->SetFillRule(gfxContext::FILL_RULE_EVEN_ODD);
     shadowContext->Fill();
     blurringArea.DoPaint();
     renderContext->Restore();
   }
 }
 void
 nsCSSRendering::PaintBackground(nsPresContext* aPresContext,
                                 nsRenderingContext& aRenderingContext,
                                 nsIFrame* aForFrame,
                                 const nsRect& aDirtyRect,
                                 const nsRect& aBorderArea,
                                 uint32_t aFlags,
                                 nsRect* aBGClipRect,
                                 int32_t aLayer)
 {
   PROFILER_LABEL("nsCSSRendering", "PaintBackground");
   NS_PRECONDITION(aForFrame,
                   "Frame is expected to be provided to PaintBackground");
   nsStyleContext *sc;
   if (!FindBackground(aForFrame, &sc)) {
     // We don't want to bail out if moz-appearance is set on a root
     // node. If it has a parent content node, bail because it's not
     // a root, otherwise keep going in order to let the theme stuff
     // draw the background. The canvas really should be drawing the
     // bg, but there's no way to hook that up via css.
     if (!aForFrame->StyleDisplay()->mAppearance) {
       return;
     }
     nsIContent* content = aForFrame->GetContent();
     if (!content || content->GetParent()) {
       return;
     }
     sc = aForFrame->StyleContext();
   }
   PaintBackgroundWithSC(aPresContext, aRenderingContext, aForFrame,
                         aDirtyRect, aBorderArea, sc,
                         *aForFrame->StyleBorder(), aFlags,
                         aBGClipRect, aLayer);
 }
 void
 nsCSSRendering::PaintBackgroundColor(nsPresContext* aPresContext,
                                      nsRenderingContext& aRenderingContext,
                                      nsIFrame* aForFrame,
                                      const nsRect& aDirtyRect,
                                      const nsRect& aBorderArea,
                                      uint32_t aFlags)
 {
   PROFILER_LABEL("nsCSSRendering", "PaintBackgroundColor");
   NS_PRECONDITION(aForFrame,
                   "Frame is expected to be provided to PaintBackground");
   nsStyleContext *sc;
   if (!FindBackground(aForFrame, &sc)) {
     // We don't want to bail out if moz-appearance is set on a root
     // node. If it has a parent content node, bail because it's not
     // a root, other wise keep going in order to let the theme stuff
     // draw the background. The canvas really should be drawing the
     // bg, but there's no way to hook that up via css.
     if (!aForFrame->StyleDisplay()->mAppearance) {
       return;
     }
     nsIContent* content = aForFrame->GetContent();
     if (!content || content->GetParent()) {
       return;
     }
     sc = aForFrame->StyleContext();
   }
   PaintBackgroundColorWithSC(aPresContext, aRenderingContext, aForFrame,
                              aDirtyRect, aBorderArea, sc,
                              *aForFrame->StyleBorder(), aFlags);
 }
 static bool
 IsOpaqueBorderEdge(const nsStyleBorder& aBorder, mozilla::css::Side aSide)
 {
   if (aBorder.GetComputedBorder().Side(aSide) == 0)
     return true;
   switch (aBorder.GetBorderStyle(aSide)) {
   case NS_STYLE_BORDER_STYLE_SOLID:
   case NS_STYLE_BORDER_STYLE_GROOVE:
   case NS_STYLE_BORDER_STYLE_RIDGE:
   case NS_STYLE_BORDER_STYLE_INSET:
   case NS_STYLE_BORDER_STYLE_OUTSET:
     break;
   default:
     return false;
   }
   // If we're using a border image, assume it's not fully opaque,
   // because we may not even have the image loaded at this point, and
   // even if we did, checking whether the relevant tile is fully
   // opaque would be too much work.
   if (aBorder.mBorderImageSource.GetType() != eStyleImageType_Null)
     return false;
   nscolor color;
   bool isForeground;
   aBorder.GetBorderColor(aSide, color, isForeground);
   // We don't know the foreground color here, so if it's being used
   // we must assume it might be transparent.
   if (isForeground)
     return false;
   return NS_GET_A(color) == 255;
 }
 /**
  * Returns true if all border edges are either missing or opaque.
  */
 static bool
 IsOpaqueBorder(const nsStyleBorder& aBorder)
 {
   if (aBorder.mBorderColors)
     return false;
   NS_FOR_CSS_SIDES(i) {
     if (!IsOpaqueBorderEdge(aBorder, i))
       return false;
   }
   return true;
 }
 static inline void
 SetupDirtyRects(const nsRect& aBGClipArea, const nsRect& aCallerDirtyRect,
                 nscoord aAppUnitsPerPixel,
                 /* OUT: */
                 nsRect* aDirtyRect, gfxRect* aDirtyRectGfx)
 {
   aDirtyRect->IntersectRect(aBGClipArea, aCallerDirtyRect);
   // Compute the Thebes equivalent of the dirtyRect.
   *aDirtyRectGfx = nsLayoutUtils::RectToGfxRect(*aDirtyRect, aAppUnitsPerPixel);
   NS_WARN_IF_FALSE(aDirtyRect->IsEmpty() || !aDirtyRectGfx->IsEmpty(),
                    "converted dirty rect should not be empty");
   NS_ABORT_IF_FALSE(!aDirtyRect->IsEmpty() || aDirtyRectGfx->IsEmpty(),
                     "second should be empty if first is");
 }
 struct BackgroundClipState {
   nsRect mBGClipArea;  // Affected by mClippedRadii
   nsRect mAdditionalBGClipArea;  // Not affected by mClippedRadii
   nsRect mDirtyRect;
   gfxRect mDirtyRectGfx;
   gfxCornerSizes mClippedRadii;
   bool mRadiiAreOuter;
   bool mHasAdditionalBGClipArea;
   // Whether we are being asked to draw with a caller provided background
   // clipping area. If this is true we also disable rounded corners.
   bool mCustomClip;
 };
 static void
 GetBackgroundClip(gfxContext *aCtx, uint8_t aBackgroundClip,
                   uint8_t aBackgroundAttachment,
                   nsIFrame* aForFrame, const nsRect& aBorderArea,
                   const nsRect& aCallerDirtyRect, bool aHaveRoundedCorners,
                   const gfxCornerSizes& aBGRadii, nscoord aAppUnitsPerPixel,
                   /* out */ BackgroundClipState* aClipState)
 {
   aClipState->mBGClipArea = aBorderArea;
   aClipState->mHasAdditionalBGClipArea = false;
   aClipState->mCustomClip = false;
   aClipState->mRadiiAreOuter = true;
   aClipState->mClippedRadii = aBGRadii;
   if (aForFrame->GetType() == nsGkAtoms::scrollFrame &&
         NS_STYLE_BG_ATTACHMENT_LOCAL == aBackgroundAttachment) {
     // As of this writing, this is still in discussion in the CSS Working Group
     // http://lists.w3.org/Archives/Public/www-style/2013Jul/0250.html
     // The rectangle for 'background-clip' scrolls with the content,
     // but the background is also clipped at a non-scrolling 'padding-box'
     // like the content. (See below.)
     // Therefore, only 'content-box' makes a difference here.
     if (aBackgroundClip == NS_STYLE_BG_CLIP_CONTENT) {
       nsIScrollableFrame* scrollableFrame = do_QueryFrame(aForFrame);
       // Clip at a rectangle attached to the scrolled content.
       aClipState->mHasAdditionalBGClipArea = true;
       aClipState->mAdditionalBGClipArea = nsRect(
         aClipState->mBGClipArea.TopLeft()
           + scrollableFrame->GetScrolledFrame()->GetPosition()
           // For the dir=rtl case:
           + scrollableFrame->GetScrollRange().TopLeft(),
         scrollableFrame->GetScrolledRect().Size());
       nsMargin padding = aForFrame->GetUsedPadding();
       // padding-bottom is ignored on scrollable frames:
       // https://bugzilla.mozilla.org/show_bug.cgi?id=748518
       padding.bottom = 0;
       aForFrame->ApplySkipSides(padding);
       aClipState->mAdditionalBGClipArea.Deflate(padding);
     }
     // Also clip at a non-scrolling, rounded-corner 'padding-box',
     // same as the scrolled content because of the 'overflow' property.
     aBackgroundClip = NS_STYLE_BG_CLIP_PADDING;
   }
   if (aBackgroundClip != NS_STYLE_BG_CLIP_BORDER) {
     nsMargin border = aForFrame->GetUsedBorder();
     if (aBackgroundClip == NS_STYLE_BG_CLIP_MOZ_ALMOST_PADDING) {
       // Reduce |border| by 1px (device pixels) on all sides, if
       // possible, so that we don't get antialiasing seams between the
       // background and border.
       border.top = std::max(0, border.top - aAppUnitsPerPixel);
       border.right = std::max(0, border.right - aAppUnitsPerPixel);
       border.bottom = std::max(0, border.bottom - aAppUnitsPerPixel);
       border.left = std::max(0, border.left - aAppUnitsPerPixel);
     } else if (aBackgroundClip != NS_STYLE_BG_CLIP_PADDING) {
       NS_ASSERTION(aBackgroundClip == NS_STYLE_BG_CLIP_CONTENT,
                    "unexpected background-clip");
       border += aForFrame->GetUsedPadding();
     }
     aForFrame->ApplySkipSides(border);
     aClipState->mBGClipArea.Deflate(border);
     if (aHaveRoundedCorners) {
       gfxFloat borderSizes[4] = {
         gfxFloat(border.top / aAppUnitsPerPixel),
         gfxFloat(border.right / aAppUnitsPerPixel),
         gfxFloat(border.bottom / aAppUnitsPerPixel),
         gfxFloat(border.left / aAppUnitsPerPixel)
       };
       nsCSSBorderRenderer::ComputeInnerRadii(aBGRadii, borderSizes,
                                              &aClipState->mClippedRadii);
       aClipState->mRadiiAreOuter = false;
     }
   }
   if (!aHaveRoundedCorners && aClipState->mHasAdditionalBGClipArea) {
     // Do the intersection here to account for the fast path(?) below.
     aClipState->mBGClipArea =
       aClipState->mBGClipArea.Intersect(aClipState->mAdditionalBGClipArea);
     aClipState->mHasAdditionalBGClipArea = false;
   }
   SetupDirtyRects(aClipState->mBGClipArea, aCallerDirtyRect, aAppUnitsPerPixel,
                   &aClipState->mDirtyRect, &aClipState->mDirtyRectGfx);
 }
 static void
 SetupBackgroundClip(BackgroundClipState& aClipState, gfxContext *aCtx,
                     bool aHaveRoundedCorners, nscoord aAppUnitsPerPixel,
                     gfxContextAutoSaveRestore* aAutoSR)
 {
   if (aClipState.mDirtyRectGfx.IsEmpty()) {
     // Our caller won't draw anything under this condition, so no need
     // to set more up.
     return;
   }
   if (aClipState.mCustomClip) {
     // We don't support custom clips and rounded corners, arguably a bug, but
     // table painting seems to depend on it.
     return;
   }
   // If we have rounded corners, clip all subsequent drawing to the
   // rounded rectangle defined by bgArea and bgRadii (we don't know
   // whether the rounded corners intrude on the dirtyRect or not).
   // Do not do this if we have a caller-provided clip rect --
   // as above with bgArea, arguably a bug, but table painting seems
   // to depend on it.
   if (aHaveRoundedCorners || aClipState.mHasAdditionalBGClipArea) {
     aAutoSR->Reset(aCtx);
   }
   if (aClipState.mHasAdditionalBGClipArea) {
     gfxRect bgAreaGfx = nsLayoutUtils::RectToGfxRect(
       aClipState.mAdditionalBGClipArea, aAppUnitsPerPixel);
     bgAreaGfx.Round();
     bgAreaGfx.Condition();
     aCtx->NewPath();
     aCtx->Rectangle(bgAreaGfx, true);
     aCtx->Clip();
   }
   if (aHaveRoundedCorners) {
     gfxRect bgAreaGfx =
       nsLayoutUtils::RectToGfxRect(aClipState.mBGClipArea, aAppUnitsPerPixel);
     bgAreaGfx.Round();
     bgAreaGfx.Condition();
     if (bgAreaGfx.IsEmpty()) {
       // I think it's become possible to hit this since
       // http://hg.mozilla.org/mozilla-central/rev/50e934e4979b landed.
       NS_WARNING("converted background area should not be empty");
       // Make our caller not do anything.
       aClipState.mDirtyRectGfx.SizeTo(gfxSize(0.0, 0.0));
       return;
     }
     aCtx->NewPath();
     aCtx->RoundedRectangle(bgAreaGfx, aClipState.mClippedRadii, aClipState.mRadiiAreOuter);
     aCtx->Clip();
   }
 }
 static void
 DrawBackgroundColor(BackgroundClipState& aClipState, gfxContext *aCtx,
                     bool aHaveRoundedCorners, nscoord aAppUnitsPerPixel)
 {
   if (aClipState.mDirtyRectGfx.IsEmpty()) {
     // Our caller won't draw anything under this condition, so no need
     // to set more up.
     return;
   }
   // We don't support custom clips and rounded corners, arguably a bug, but
   // table painting seems to depend on it.
   if (!aHaveRoundedCorners || aClipState.mCustomClip) {
     aCtx->NewPath();
     aCtx->Rectangle(aClipState.mDirtyRectGfx, true);
     aCtx->Fill();
     return;
   }
   gfxRect bgAreaGfx =
     nsLayoutUtils::RectToGfxRect(aClipState.mBGClipArea, aAppUnitsPerPixel);
   bgAreaGfx.Round();
   bgAreaGfx.Condition();
   if (bgAreaGfx.IsEmpty()) {
     // I think it's become possible to hit this since
     // http://hg.mozilla.org/mozilla-central/rev/50e934e4979b landed.
     NS_WARNING("converted background area should not be empty");
     // Make our caller not do anything.
     aClipState.mDirtyRectGfx.SizeTo(gfxSize(0.0, 0.0));
     return;
   }
   aCtx->Save();
   gfxRect dirty = bgAreaGfx.Intersect(aClipState.mDirtyRectGfx);
   aCtx->NewPath();
   aCtx->Rectangle(dirty, true);
   aCtx->Clip();
   if (aClipState.mHasAdditionalBGClipArea) {
     gfxRect bgAdditionalAreaGfx = nsLayoutUtils::RectToGfxRect(
       aClipState.mAdditionalBGClipArea, aAppUnitsPerPixel);
     bgAdditionalAreaGfx.Round();
     bgAdditionalAreaGfx.Condition();
     aCtx->NewPath();
     aCtx->Rectangle(bgAdditionalAreaGfx, true);
     aCtx->Clip();
   }
   aCtx->NewPath();
   aCtx->RoundedRectangle(bgAreaGfx, aClipState.mClippedRadii,
                          aClipState.mRadiiAreOuter);
   aCtx->Fill();
   aCtx->Restore();
 }
 nscolor
 nsCSSRendering::DetermineBackgroundColor(nsPresContext* aPresContext,
                                          nsStyleContext* aStyleContext,
                                          nsIFrame* aFrame,
                                          bool& aDrawBackgroundImage,
                                          bool& aDrawBackgroundColor)
 {
   aDrawBackgroundImage = true;
   aDrawBackgroundColor = true;
   if (aFrame->HonorPrintBackgroundSettings()) {
     aDrawBackgroundImage = aPresContext->GetBackgroundImageDraw();
     aDrawBackgroundColor = aPresContext->GetBackgroundColorDraw();
   }
   const nsStyleBackground *bg = aStyleContext->StyleBackground();
   nscolor bgColor;
   if (aDrawBackgroundColor) {
     bgColor =
       aStyleContext->GetVisitedDependentColor(eCSSProperty_background_color);
     if (NS_GET_A(bgColor) == 0) {
       aDrawBackgroundColor = false;
     }
   } else {
     // If GetBackgroundColorDraw() is false, we are still expected to
     // draw color in the background of any frame that's not completely
     // transparent, but we are expected to use white instead of whatever
     // color was specified.
     bgColor = NS_RGB(255, 255, 255);
     if (aDrawBackgroundImage || !bg->IsTransparent()) {
       aDrawBackgroundColor = true;
     } else {
       bgColor = NS_RGBA(0,0,0,0);
     }
   }
   // We can skip painting the background color if a background image is opaque.
   if (aDrawBackgroundColor &&
       bg->BottomLayer().mRepeat.mXRepeat == NS_STYLE_BG_REPEAT_REPEAT &&
       bg->BottomLayer().mRepeat.mYRepeat == NS_STYLE_BG_REPEAT_REPEAT &&
       bg->BottomLayer().mImage.IsOpaque() &&
       bg->BottomLayer().mBlendMode == NS_STYLE_BLEND_NORMAL) {
     aDrawBackgroundColor = false;
   }
   return bgColor;
 }
 static gfxFloat
 ConvertGradientValueToPixels(const nsStyleCoord& aCoord,
                              gfxFloat aFillLength,
                              int32_t aAppUnitsPerPixel)
 {
   switch (aCoord.GetUnit()) {
     case eStyleUnit_Percent:
       return aCoord.GetPercentValue() * aFillLength;
     case eStyleUnit_Coord:
       return NSAppUnitsToFloatPixels(aCoord.GetCoordValue(), aAppUnitsPerPixel);
     case eStyleUnit_Calc: {
       const nsStyleCoord::Calc *calc = aCoord.GetCalcValue();
       return calc->mPercent * aFillLength +
              NSAppUnitsToFloatPixels(calc->mLength, aAppUnitsPerPixel);
     }
     default:
       NS_WARNING("Unexpected coord unit");
       return 0;
   }
 }
 // Given a box with size aBoxSize and origin (0,0), and an angle aAngle,
 // and a starting point for the gradient line aStart, find the endpoint of
 // the gradient line --- the intersection of the gradient line with a line
 // perpendicular to aAngle that passes through the farthest corner in the
 // direction aAngle.
 static gfxPoint
 ComputeGradientLineEndFromAngle(const gfxPoint& aStart,
                                 double aAngle,
                                 const gfxSize& aBoxSize)
 {
   double dx = cos(-aAngle);
   double dy = sin(-aAngle);
   gfxPoint farthestCorner(dx > 0 ? aBoxSize.width : 0,
                           dy > 0 ? aBoxSize.height : 0);
   gfxPoint delta = farthestCorner - aStart;
   double u = delta.x*dy - delta.y*dx;
   return farthestCorner + gfxPoint(-u*dy, u*dx);
 }
 // Compute the start and end points of the gradient line for a linear gradient.
 static void
 ComputeLinearGradientLine(nsPresContext* aPresContext,
                           nsStyleGradient* aGradient,
                           const gfxSize& aBoxSize,
                           gfxPoint* aLineStart,
                           gfxPoint* aLineEnd)
 {
   if (aGradient->mBgPosX.GetUnit() == eStyleUnit_None) {
     double angle;
     if (aGradient->mAngle.IsAngleValue()) {
       angle = aGradient->mAngle.GetAngleValueInRadians();
       if (!aGradient->mLegacySyntax) {
         angle = M_PI_2 - angle;
       }
     } else {
       angle = -M_PI_2; // defaults to vertical gradient starting from top
     }
     gfxPoint center(aBoxSize.width/2, aBoxSize.height/2);
     *aLineEnd = ComputeGradientLineEndFromAngle(center, angle, aBoxSize);
     *aLineStart = gfxPoint(aBoxSize.width, aBoxSize.height) - *aLineEnd;
   } else if (!aGradient->mLegacySyntax) {
     float xSign = aGradient->mBgPosX.GetPercentValue() * 2 - 1;
     float ySign = 1 - aGradient->mBgPosY.GetPercentValue() * 2;
     double angle = atan2(ySign * aBoxSize.width, xSign * aBoxSize.height);
     gfxPoint center(aBoxSize.width/2, aBoxSize.height/2);
     *aLineEnd = ComputeGradientLineEndFromAngle(center, angle, aBoxSize);
     *aLineStart = gfxPoint(aBoxSize.width, aBoxSize.height) - *aLineEnd;
   } else {
     int32_t appUnitsPerPixel = aPresContext->AppUnitsPerDevPixel();
     *aLineStart = gfxPoint(
       ConvertGradientValueToPixels(aGradient->mBgPosX, aBoxSize.width,
                                    appUnitsPerPixel),
       ConvertGradientValueToPixels(aGradient->mBgPosY, aBoxSize.height,
                                    appUnitsPerPixel));
     if (aGradient->mAngle.IsAngleValue()) {
       MOZ_ASSERT(aGradient->mLegacySyntax);
       double angle = aGradient->mAngle.GetAngleValueInRadians();
       *aLineEnd = ComputeGradientLineEndFromAngle(*aLineStart, angle, aBoxSize);
     } else {
       // No angle, the line end is just the reflection of the start point
       // through the center of the box
       *aLineEnd = gfxPoint(aBoxSize.width, aBoxSize.height) - *aLineStart;
     }
   }
 }
 // Compute the start and end points of the gradient line for a radial gradient.
 // Also returns the horizontal and vertical radii defining the circle or
 // ellipse to use.
 static void
 ComputeRadialGradientLine(nsPresContext* aPresContext,
                           nsStyleGradient* aGradient,
                           const gfxSize& aBoxSize,
                           gfxPoint* aLineStart,
                           gfxPoint* aLineEnd,
                           double* aRadiusX,
                           double* aRadiusY)
 {
   if (aGradient->mBgPosX.GetUnit() == eStyleUnit_None) {
     // Default line start point is the center of the box
     *aLineStart = gfxPoint(aBoxSize.width/2, aBoxSize.height/2);
   } else {
     int32_t appUnitsPerPixel = aPresContext->AppUnitsPerDevPixel();
     *aLineStart = gfxPoint(
       ConvertGradientValueToPixels(aGradient->mBgPosX, aBoxSize.width,
                                    appUnitsPerPixel),
       ConvertGradientValueToPixels(aGradient->mBgPosY, aBoxSize.height,
                                    appUnitsPerPixel));
   }
   // Compute gradient shape: the x and y radii of an ellipse.
   double radiusX, radiusY;
   double leftDistance = Abs(aLineStart->x);
   double rightDistance = Abs(aBoxSize.width - aLineStart->x);
   double topDistance = Abs(aLineStart->y);
   double bottomDistance = Abs(aBoxSize.height - aLineStart->y);
   switch (aGradient->mSize) {
   case NS_STYLE_GRADIENT_SIZE_CLOSEST_SIDE:
     radiusX = std::min(leftDistance, rightDistance);
     radiusY = std::min(topDistance, bottomDistance);
     if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_CIRCULAR) {
       radiusX = radiusY = std::min(radiusX, radiusY);
     }
     break;
   case NS_STYLE_GRADIENT_SIZE_CLOSEST_CORNER: {
     // Compute x and y distances to nearest corner
     double offsetX = std::min(leftDistance, rightDistance);
     double offsetY = std::min(topDistance, bottomDistance);
     if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_CIRCULAR) {
       radiusX = radiusY = NS_hypot(offsetX, offsetY);
     } else {
       // maintain aspect ratio
       radiusX = offsetX*M_SQRT2;
       radiusY = offsetY*M_SQRT2;
     }
     break;
   }
   case NS_STYLE_GRADIENT_SIZE_FARTHEST_SIDE:
     radiusX = std::max(leftDistance, rightDistance);
     radiusY = std::max(topDistance, bottomDistance);
     if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_CIRCULAR) {
       radiusX = radiusY = std::max(radiusX, radiusY);
     }
     break;
   case NS_STYLE_GRADIENT_SIZE_FARTHEST_CORNER: {
     // Compute x and y distances to nearest corner
     double offsetX = std::max(leftDistance, rightDistance);
     double offsetY = std::max(topDistance, bottomDistance);
     if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_CIRCULAR) {
       radiusX = radiusY = NS_hypot(offsetX, offsetY);
     } else {
       // maintain aspect ratio
       radiusX = offsetX*M_SQRT2;
       radiusY = offsetY*M_SQRT2;
     }
     break;
   }
   case NS_STYLE_GRADIENT_SIZE_EXPLICIT_SIZE: {
     int32_t appUnitsPerPixel = aPresContext->AppUnitsPerDevPixel();
     radiusX = ConvertGradientValueToPixels(aGradient->mRadiusX,
                                            aBoxSize.width, appUnitsPerPixel);
     radiusY = ConvertGradientValueToPixels(aGradient->mRadiusY,
                                            aBoxSize.height, appUnitsPerPixel);
     break;
   }
   default:
     radiusX = radiusY = 0;
     NS_ABORT_IF_FALSE(false, "unknown radial gradient sizing method");
   }
   *aRadiusX = radiusX;
   *aRadiusY = radiusY;
   double angle;
   if (aGradient->mAngle.IsAngleValue()) {
     angle = aGradient->mAngle.GetAngleValueInRadians();
   } else {
     // Default angle is 0deg
     angle = 0.0;
   }
   // The gradient line end point is where the gradient line intersects
   // the ellipse.
   *aLineEnd = *aLineStart + gfxPoint(radiusX*cos(-angle), radiusY*sin(-angle));
 }
 // Returns aFrac*aC2 + (1 - aFrac)*C1. The interpolation is done
 // in unpremultiplied space, which is what SVG gradients and cairo
 // gradients expect.
 static gfxRGBA
 InterpolateColor(const gfxRGBA& aC1, const gfxRGBA& aC2, double aFrac)
 {
   double other = 1 - aFrac;
   return gfxRGBA(aC2.r*aFrac + aC1.r*other,
                  aC2.g*aFrac + aC1.g*other,
                  aC2.b*aFrac + aC1.b*other,
                  aC2.a*aFrac + aC1.a*other);
 }
 static nscoord
 FindTileStart(nscoord aDirtyCoord, nscoord aTilePos, nscoord aTileDim)
 {
   NS_ASSERTION(aTileDim > 0, "Non-positive tile dimension");
   double multiples = floor(double(aDirtyCoord - aTilePos)/aTileDim);
   return NSToCoordRound(multiples*aTileDim + aTilePos);
 }
 void
 nsCSSRendering::PaintGradient(nsPresContext* aPresContext,
                               nsRenderingContext& aRenderingContext,
                               nsStyleGradient* aGradient,
                               const nsRect& aDirtyRect,
                               const nsRect& aDest,
                               const nsRect& aFillArea,
                               const CSSIntRect& aSrc,
                               const nsSize& aIntrinsicSize)
 {
   PROFILER_LABEL("nsCSSRendering", "PaintGradient");
   Telemetry::AutoTimer<Telemetry::GRADIENT_DURATION, Telemetry::Microsecond> gradientTimer;
   if (aDest.IsEmpty() || aFillArea.IsEmpty()) {
     return;
   }
   gfxContext *ctx = aRenderingContext.ThebesContext();
   nscoord appUnitsPerDevPixel = aPresContext->AppUnitsPerDevPixel();
   gfxSize srcSize = gfxSize(gfxFloat(aIntrinsicSize.width)/appUnitsPerDevPixel,
                             gfxFloat(aIntrinsicSize.height)/appUnitsPerDevPixel);
   bool cellContainsFill = aDest.Contains(aFillArea);
   // Compute "gradient line" start and end relative to the intrinsic size of
   // the gradient.
   gfxPoint lineStart, lineEnd;
   double radiusX = 0, radiusY = 0; // for radial gradients only
   if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_LINEAR) {
     ComputeLinearGradientLine(aPresContext, aGradient, srcSize,
                               &lineStart, &lineEnd);
   } else {
     ComputeRadialGradientLine(aPresContext, aGradient, srcSize,
                               &lineStart, &lineEnd, &radiusX, &radiusY);
   }
   gfxFloat lineLength = NS_hypot(lineEnd.x - lineStart.x,
                                   lineEnd.y - lineStart.y);
   NS_ABORT_IF_FALSE(aGradient->mStops.Length() >= 2,
                     "The parser should reject gradients with less than two stops");
   // Build color stop array and compute stop positions
   nsTArray<ColorStop> stops;
   // If there is a run of stops before stop i that did not have specified
   // positions, then this is the index of the first stop in that run, otherwise
   // it's -1.
   int32_t firstUnsetPosition = -1;
   for (uint32_t i = 0; i < aGradient->mStops.Length(); ++i) {
     const nsStyleGradientStop& stop = aGradient->mStops[i];
     double position;
     switch (stop.mLocation.GetUnit()) {
     case eStyleUnit_None:
       if (i == 0) {
         // First stop defaults to position 0.0
         position = 0.0;
       } else if (i == aGradient->mStops.Length() - 1) {
         // Last stop defaults to position 1.0
         position = 1.0;
       } else {
         // Other stops with no specified position get their position assigned
         // later by interpolation, see below.
         // Remeber where the run of stops with no specified position starts,
         // if it starts here.
         if (firstUnsetPosition < 0) {
           firstUnsetPosition = i;
         }
         stops.AppendElement(ColorStop(0, stop.mColor));
         continue;
       }
       break;
     case eStyleUnit_Percent:
       position = stop.mLocation.GetPercentValue();
       break;
     case eStyleUnit_Coord:
       position = lineLength < 1e-6 ? 0.0 :
           stop.mLocation.GetCoordValue() / appUnitsPerDevPixel / lineLength;
       break;
     case eStyleUnit_Calc:
       nsStyleCoord::Calc *calc;
       calc = stop.mLocation.GetCalcValue();
       position = calc->mPercent +
           ((lineLength < 1e-6) ? 0.0 :
           (NSAppUnitsToFloatPixels(calc->mLength, appUnitsPerDevPixel) / lineLength));
       break;
     default:
       NS_ABORT_IF_FALSE(false, "Unknown stop position type");
     }
     if (i > 0) {
       // Prevent decreasing stop positions by advancing this position
       // to the previous stop position, if necessary
       position = std::max(position, stops[i - 1].mPosition);
     }
     stops.AppendElement(ColorStop(position, stop.mColor));
     if (firstUnsetPosition > 0) {
       // Interpolate positions for all stops that didn't have a specified position
       double p = stops[firstUnsetPosition - 1].mPosition;
       double d = (stops[i].mPosition - p)/(i - firstUnsetPosition + 1);
       for (uint32_t j = firstUnsetPosition; j < i; ++j) {
         p += d;
         stops[j].mPosition = p;
       }
       firstUnsetPosition = -1;
     }
   }
   // Eliminate negative-position stops if the gradient is radial.
   double firstStop = stops[0].mPosition;
   if (aGradient->mShape != NS_STYLE_GRADIENT_SHAPE_LINEAR && firstStop < 0.0) {
     if (aGradient->mRepeating) {
       // Choose an instance of the repeated pattern that gives us all positive
       // stop-offsets.
       double lastStop = stops[stops.Length() - 1].mPosition;
       double stopDelta = lastStop - firstStop;
       // If all the stops are in approximately the same place then logic below
       // will kick in that makes us draw just the last stop color, so don't
       // try to do anything in that case. We certainly need to avoid
       // dividing by zero.
       if (stopDelta >= 1e-6) {
         double instanceCount = ceil(-firstStop/stopDelta);
         // Advance stops by instanceCount multiples of the period of the
         // repeating gradient.
         double offset = instanceCount*stopDelta;
         for (uint32_t i = 0; i < stops.Length(); i++) {
           stops[i].mPosition += offset;
         }
       }
     } else {
       // Move negative-position stops to position 0.0. We may also need
       // to set the color of the stop to the color the gradient should have
       // at the center of the ellipse.
       for (uint32_t i = 0; i < stops.Length(); i++) {
         double pos = stops[i].mPosition;
         if (pos < 0.0) {
           stops[i].mPosition = 0.0;
           // If this is the last stop, we don't need to adjust the color,
           // it will fill the entire area.
           if (i < stops.Length() - 1) {
             double nextPos = stops[i + 1].mPosition;
             // If nextPos is approximately equal to pos, then we don't
             // need to adjust the color of this stop because it's
             // not going to be displayed.
             // If nextPos is negative, we don't need to adjust the color of
             // this stop since it's not going to be displayed because
             // nextPos will also be moved to 0.0.
             if (nextPos >= 0.0 && nextPos - pos >= 1e-6) {
               // Compute how far the new position 0.0 is along the interval
               // between pos and nextPos.
               // XXX Color interpolation (in cairo, too) should use the
               // CSS 'color-interpolation' property!
               double frac = (0.0 - pos)/(nextPos - pos);
               stops[i].mColor =
                 InterpolateColor(stops[i].mColor, stops[i + 1].mColor, frac);
             }
           }
         }
       }
     }
     firstStop = stops[0].mPosition;
     NS_ABORT_IF_FALSE(firstStop >= 0.0, "Failed to fix stop offsets");
   }
   if (aGradient->mShape != NS_STYLE_GRADIENT_SHAPE_LINEAR && !aGradient->mRepeating) {
     // Direct2D can only handle a particular class of radial gradients because
     // of the way the it specifies gradients. Setting firstStop to 0, when we
     // can, will help us stay on the fast path. Currently we don't do this
     // for repeating gradients but we could by adjusting the stop collection
     // to start at 0
     firstStop = 0;
   }
   double lastStop = stops[stops.Length() - 1].mPosition;
   // Cairo gradients must have stop positions in the range [0, 1]. So,
   // stop positions will be normalized below by subtracting firstStop and then
   // multiplying by stopScale.
   double stopScale;
   double stopOrigin = firstStop;
   double stopEnd = lastStop;
   double stopDelta = lastStop - firstStop;
   bool zeroRadius = aGradient->mShape != NS_STYLE_GRADIENT_SHAPE_LINEAR &&
                       (radiusX < 1e-6 || radiusY < 1e-6);
   if (stopDelta < 1e-6 || lineLength < 1e-6 || zeroRadius) {
     // Stops are all at the same place. Map all stops to 0.0.
     // For repeating radial gradients, or for any radial gradients with
     // a zero radius, we need to fill with the last stop color, so just set
     // both radii to 0.
     if (aGradient->mRepeating || zeroRadius) {
       radiusX = radiusY = 0.0;
     }
     stopDelta = 0.0;
     lastStop = firstStop;
   }
   // Don't normalize non-repeating or degenerate gradients below 0..1
   // This keeps the gradient line as large as the box and doesn't
   // lets us avoiding having to get padding correct for stops
   // at 0 and 1
   if (!aGradient->mRepeating || stopDelta == 0.0) {
     stopOrigin = std::min(stopOrigin, 0.0);
     stopEnd = std::max(stopEnd, 1.0);
   }
   stopScale = 1.0/(stopEnd - stopOrigin);
   // Create the gradient pattern.
   nsRefPtr<gfxPattern> gradientPattern;
   bool forceRepeatToCoverTiles = false;
   gfxMatrix matrix;
   if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_LINEAR) {
     // Compute the actual gradient line ends we need to pass to cairo after
     // stops have been normalized.
     gfxPoint gradientStart = lineStart + (lineEnd - lineStart)*stopOrigin;
     gfxPoint gradientEnd = lineStart + (lineEnd - lineStart)*stopEnd;
     gfxPoint gradientStopStart = lineStart + (lineEnd - lineStart)*firstStop;
     gfxPoint gradientStopEnd = lineStart + (lineEnd - lineStart)*lastStop;
     if (stopDelta == 0.0) {
       // Stops are all at the same place. For repeating gradients, this will
       // just paint the last stop color. We don't need to do anything.
       // For non-repeating gradients, this should render as two colors, one
       // on each "side" of the gradient line segment, which is a point. All
       // our stops will be at 0.0; we just need to set the direction vector
       // correctly.
       gradientEnd = gradientStart + (lineEnd - lineStart);
       gradientStopEnd = gradientStopStart + (lineEnd - lineStart);
     }
     gradientPattern = new gfxPattern(gradientStart.x, gradientStart.y,
                                       gradientEnd.x, gradientEnd.y);
     // When the gradient line is parallel to the x axis from the left edge
     // to the right edge of a tile, then we can repeat by just repeating the
     // gradient.
     if (!cellContainsFill &&
         ((gradientStopStart.y == gradientStopEnd.y && gradientStopStart.x == 0 &&
           gradientStopEnd.x == srcSize.width) ||
           (gradientStopStart.x == gradientStopEnd.x && gradientStopStart.y == 0 &&
           gradientStopEnd.y == srcSize.height))) {
       forceRepeatToCoverTiles = true;
     }
   } else {
     NS_ASSERTION(firstStop >= 0.0,
                   "Negative stops not allowed for radial gradients");
     // To form an ellipse, we'll stretch a circle vertically, if necessary.
     // So our radii are based on radiusX.
     double innerRadius = radiusX*stopOrigin;
     double outerRadius = radiusX*stopEnd;
     if (stopDelta == 0.0) {
       // Stops are all at the same place.  See above (except we now have
       // the inside vs. outside of an ellipse).
       outerRadius = innerRadius + 1;
     }
     gradientPattern = new gfxPattern(lineStart.x, lineStart.y, innerRadius,
                                      lineStart.x, lineStart.y, outerRadius);
     if (radiusX != radiusY) {
       // Stretch the circles into ellipses vertically by setting a transform
       // in the pattern.
       // Recall that this is the transform from user space to pattern space.
       // So to stretch the ellipse by factor of P vertically, we scale
       // user coordinates by 1/P.
       matrix.Translate(lineStart);
       matrix.Scale(1.0, radiusX/radiusY);
       matrix.Translate(-lineStart);
     }
   }
   // Use a pattern transform to take account of source and dest rects
   matrix.Translate(gfxPoint(aPresContext->CSSPixelsToDevPixels(aSrc.x),
                             aPresContext->CSSPixelsToDevPixels(aSrc.y)));
   matrix.Scale(gfxFloat(aPresContext->CSSPixelsToAppUnits(aSrc.width))/aDest.width,
                gfxFloat(aPresContext->CSSPixelsToAppUnits(aSrc.height))/aDest.height);
   gradientPattern->SetMatrix(matrix);
   if (gradientPattern->CairoStatus())
     return;
   if (stopDelta == 0.0) {
     // Non-repeating gradient with all stops in same place -> just add
     // first stop and last stop, both at position 0.
     // Repeating gradient with all stops in the same place, or radial
     // gradient with radius of 0 -> just paint the last stop color.
     // We use firstStop offset to keep |stops| with same units (will later normalize to 0).
     gfxRGBA firstColor(stops[0].mColor);
     gfxRGBA lastColor(stops.LastElement().mColor);
     stops.Clear();
     if (!aGradient->mRepeating && !zeroRadius) {
       stops.AppendElement(ColorStop(firstStop, firstColor));
     }
     stops.AppendElement(ColorStop(firstStop, lastColor));
   }
   bool isRepeat = aGradient->mRepeating || forceRepeatToCoverTiles;
   // Now set normalized color stops in pattern.
   if (!ctx->IsCairo()) {
     // Offscreen gradient surface cache (not a tile):
     // On some backends (e.g. D2D), the GradientStops object holds an offscreen surface
     // which is a lookup table used to evaluate the gradient. This surface can use
     // much memory (ram and/or GPU ram) and can be expensive to create. So we cache it.
     // The cache key correlates 1:1 with the arguments for CreateGradientStops (also the implied backend type)
     // Note that GradientStop is a simple struct with a stop value (while GradientStops has the surface).
     nsTArray<gfx::GradientStop> rawStops(stops.Length());
     rawStops.SetLength(stops.Length());
     for(uint32_t i = 0; i < stops.Length(); i++) {
       rawStops[i].color = gfx::Color(stops[i].mColor.r, stops[i].mColor.g, stops[i].mColor.b, stops[i].mColor.a);
       rawStops[i].offset = stopScale * (stops[i].mPosition - stopOrigin);
     }
     mozilla::RefPtr<mozilla::gfx::GradientStops> gs =
       gfxGradientCache::GetOrCreateGradientStops(ctx->GetDrawTarget(),
                                                  rawStops,
                                                  isRepeat ? gfx::ExtendMode::REPEAT : gfx::ExtendMode::CLAMP);
     gradientPattern->SetColorStops(gs);
   } else {
     for (uint32_t i = 0; i < stops.Length(); i++) {
       double pos = stopScale*(stops[i].mPosition - stopOrigin);
       gradientPattern->AddColorStop(pos, stops[i].mColor);
     }
     // Set repeat mode. Default cairo extend mode is PAD.
     if (isRepeat) {
       gradientPattern->SetExtend(gfxPattern::EXTEND_REPEAT);
     }
   }
   // Paint gradient tiles. This isn't terribly efficient, but doing it this
   // way is simple and sure to get pixel-snapping right. We could speed things
   // up by drawing tiles into temporary surfaces and copying those to the
   // destination, but after pixel-snapping tiles may not all be the same size.
   nsRect dirty;
   if (!dirty.IntersectRect(aDirtyRect, aFillArea))
     return;
   gfxRect areaToFill =
     nsLayoutUtils::RectToGfxRect(aFillArea, appUnitsPerDevPixel);
   gfxMatrix ctm = ctx->CurrentMatrix();
   bool isCTMPreservingAxisAlignedRectangles = ctm.PreservesAxisAlignedRectangles();
   // xStart/yStart are the top-left corner of the top-left tile.
   nscoord xStart = FindTileStart(dirty.x, aDest.x, aDest.width);
   nscoord yStart = FindTileStart(dirty.y, aDest.y, aDest.height);
   nscoord xEnd = forceRepeatToCoverTiles ? xStart + aDest.width : dirty.XMost();
   nscoord yEnd = forceRepeatToCoverTiles ? yStart + aDest.height : dirty.YMost();
   // x and y are the top-left corner of the tile to draw
   for (nscoord y = yStart; y < yEnd; y += aDest.height) {
     for (nscoord x = xStart; x < xEnd; x += aDest.width) {
       // The coordinates of the tile
       gfxRect tileRect = nsLayoutUtils::RectToGfxRect(
                       nsRect(x, y, aDest.width, aDest.height),
                       appUnitsPerDevPixel);
       // The actual area to fill with this tile is the intersection of this
       // tile with the overall area we're supposed to be filling
       gfxRect fillRect =
         forceRepeatToCoverTiles ? areaToFill : tileRect.Intersect(areaToFill);
       // Try snapping the fill rect. Snap its top-left and bottom-right
       // independently to preserve the orientation.
       gfxPoint snappedFillRectTopLeft = fillRect.TopLeft();
       gfxPoint snappedFillRectTopRight = fillRect.TopRight();
       gfxPoint snappedFillRectBottomRight = fillRect.BottomRight();
       // Snap three points instead of just two to ensure we choose the
       // correct orientation if there's a reflection.
       if (isCTMPreservingAxisAlignedRectangles &&
           ctx->UserToDevicePixelSnapped(snappedFillRectTopLeft, true) &&
           ctx->UserToDevicePixelSnapped(snappedFillRectBottomRight, true) &&
           ctx->UserToDevicePixelSnapped(snappedFillRectTopRight, true)) {
         if (snappedFillRectTopLeft.x == snappedFillRectBottomRight.x ||
             snappedFillRectTopLeft.y == snappedFillRectBottomRight.y) {
           // Nothing to draw; avoid scaling by zero and other weirdness that
           // could put the context in an error state.
           continue;
         }
         // Set the context's transform to the transform that maps fillRect to
         // snappedFillRect. The part of the gradient that was going to
         // exactly fill fillRect will fill snappedFillRect instead.
         gfxMatrix transform = gfxUtils::TransformRectToRect(fillRect,
             snappedFillRectTopLeft, snappedFillRectTopRight,
             snappedFillRectBottomRight);
         ctx->SetMatrix(transform);
       }
       ctx->NewPath();
       ctx->Rectangle(fillRect);
       ctx->Translate(tileRect.TopLeft());
       ctx->SetPattern(gradientPattern);
       ctx->Fill();
       ctx->SetMatrix(ctm);
     }
   }
 }
 void
 nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
                                       nsRenderingContext& aRenderingContext,
                                       nsIFrame* aForFrame,
                                       const nsRect& aDirtyRect,
                                       const nsRect& aBorderArea,
                                       nsStyleContext* aBackgroundSC,
                                       const nsStyleBorder& aBorder,
                                       uint32_t aFlags,
                                       nsRect* aBGClipRect,
                                       int32_t aLayer)
 {
   NS_PRECONDITION(aForFrame,
                   "Frame is expected to be provided to PaintBackground");
   // Check to see if we have an appearance defined.  If so, we let the theme
   // renderer draw the background and bail out.
   // XXXzw this ignores aBGClipRect.
   const nsStyleDisplay* displayData = aForFrame->StyleDisplay();
   if (displayData->mAppearance) {
     nsITheme *theme = aPresContext->GetTheme();
     if (theme && theme->ThemeSupportsWidget(aPresContext, aForFrame,
                                             displayData->mAppearance)) {
       nsRect drawing(aBorderArea);
       theme->GetWidgetOverflow(aPresContext->DeviceContext(),
                                aForFrame, displayData->mAppearance, &drawing);
       drawing.IntersectRect(drawing, aDirtyRect);
       theme->DrawWidgetBackground(&aRenderingContext, aForFrame,
                                   displayData->mAppearance, aBorderArea,
                                   drawing);
       return;
     }
   }
   // For canvas frames (in the CSS sense) we draw the background color using
   // a solid color item that gets added in nsLayoutUtils::PaintFrame,
   // or nsSubDocumentFrame::BuildDisplayList (bug 488242). (The solid
   // color may be moved into nsDisplayCanvasBackground by
   // nsPresShell::AddCanvasBackgroundColorItem, and painted by
   // nsDisplayCanvasBackground directly.) Either way we don't need to
   // paint the background color here.
   bool isCanvasFrame = IsCanvasFrame(aForFrame);
   // Determine whether we are drawing background images and/or
   // background colors.
   bool drawBackgroundImage;
   bool drawBackgroundColor;
   nscolor bgColor = DetermineBackgroundColor(aPresContext,
                                              aBackgroundSC,
                                              aForFrame,
                                              drawBackgroundImage,
                                              drawBackgroundColor);
   // If we're drawing a specific layer, we don't want to draw the
   // background color.
   const nsStyleBackground *bg = aBackgroundSC->StyleBackground();
   if (drawBackgroundColor && aLayer >= 0) {
     drawBackgroundColor = false;
   }
   // At this point, drawBackgroundImage and drawBackgroundColor are
   // true if and only if we are actually supposed to paint an image or
   // color into aDirtyRect, respectively.
   if (!drawBackgroundImage && !drawBackgroundColor)
     return;
   // Compute the outermost boundary of the area that might be painted.
   gfxContext *ctx = aRenderingContext.ThebesContext();
   nscoord appUnitsPerPixel = aPresContext->AppUnitsPerDevPixel();
   // Same coordinate space as aBorderArea & aBGClipRect
   gfxCornerSizes bgRadii;
   bool haveRoundedCorners;
   {
     nscoord radii[8];
     nsSize frameSize = aForFrame->GetSize();
     if (&aBorder == aForFrame->StyleBorder() &&
         frameSize == aBorderArea.Size()) {
       haveRoundedCorners = aForFrame->GetBorderRadii(radii);
     } else {
       haveRoundedCorners = nsIFrame::ComputeBorderRadii(aBorder.mBorderRadius,
                                    frameSize, aBorderArea.Size(),
                                    aForFrame->GetSkipSides(), radii);
     }
     if (haveRoundedCorners)
       ComputePixelRadii(radii, appUnitsPerPixel, &bgRadii);
   }
   // The 'bgClipArea' (used only by the image tiling logic, far below)
   // is the caller-provided aBGClipRect if any, or else the area
   // determined by the value of 'background-clip' in
   // SetupCurrentBackgroundClip.  (Arguably it should be the
   // intersection, but that breaks the table painter -- in particular,
   // taking the intersection breaks reftests/bugs/403249-1[ab].)
   BackgroundClipState clipState;
   uint8_t currentBackgroundClip;
   bool isSolidBorder;
   if (aBGClipRect) {
     clipState.mBGClipArea = *aBGClipRect;
     clipState.mCustomClip = true;
     SetupDirtyRects(clipState.mBGClipArea, aDirtyRect, appUnitsPerPixel,
                     &clipState.mDirtyRect, &clipState.mDirtyRectGfx);
   } else {
     // The background is rendered over the 'background-clip' area,
     // which is normally equal to the border area but may be reduced
     // to the padding area by CSS.  Also, if the border is solid, we
     // don't need to draw outside the padding area.  In either case,
     // if the borders are rounded, make sure we use the same inner
     // radii as the border code will.
     // The background-color is drawn based on the bottom
     // background-clip.
     currentBackgroundClip = bg->BottomLayer().mClip;
     isSolidBorder =
       (aFlags & PAINTBG_WILL_PAINT_BORDER) && IsOpaqueBorder(aBorder);
     if (isSolidBorder && currentBackgroundClip == NS_STYLE_BG_CLIP_BORDER) {
       // If we have rounded corners, we need to inflate the background
       // drawing area a bit to avoid seams between the border and
       // background.
       currentBackgroundClip = haveRoundedCorners ?
         NS_STYLE_BG_CLIP_MOZ_ALMOST_PADDING : NS_STYLE_BG_CLIP_PADDING;
     }
     GetBackgroundClip(ctx, currentBackgroundClip, bg->BottomLayer().mAttachment,
                       aForFrame, aBorderArea,
                       aDirtyRect, haveRoundedCorners, bgRadii, appUnitsPerPixel,
                       &clipState);
   }
   // If we might be using a background color, go ahead and set it now.
   if (drawBackgroundColor && !isCanvasFrame)
     ctx->SetColor(gfxRGBA(bgColor));
   gfxContextAutoSaveRestore autoSR;
   // If there is no background image, draw a color.  (If there is
   // neither a background image nor a color, we wouldn't have gotten
   // this far.)
   if (!drawBackgroundImage) {
     if (!isCanvasFrame) {
       DrawBackgroundColor(clipState, ctx, haveRoundedCorners, appUnitsPerPixel);
     }
     return;
   }
   if (bg->mImageCount < 1) {
     // Return if there are no background layers, all work from this point
     // onwards happens iteratively on these.
     return;
   }
   // Validate the layer range before we start iterating.
   int32_t startLayer = aLayer;
   int32_t nLayers = 1;
   if (startLayer < 0) {
     startLayer = (int32_t)bg->mImageCount - 1;
     nLayers = bg->mImageCount;
   }
   // Ensure we get invalidated for loads of the image.  We need to do
   // this here because this might be the only code that knows about the
   // association of the style data with the frame.
   if (aBackgroundSC != aForFrame->StyleContext()) {
     NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT_WITH_RANGE(i, bg, startLayer, nLayers) {
       aForFrame->AssociateImage(bg->mLayers[i].mImage, aPresContext);
     }
   }
   // The background color is rendered over the entire dirty area,
   // even if the image isn't.
   if (drawBackgroundColor && !isCanvasFrame) {
     DrawBackgroundColor(clipState, ctx, haveRoundedCorners, appUnitsPerPixel);
   }
   if (drawBackgroundImage) {
     bool clipSet = false;
     NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT_WITH_RANGE(i, bg, bg->mImageCount - 1,
                                                               nLayers + (bg->mImageCount -
                                                                          startLayer - 1)) {
       const nsStyleBackground::Layer &layer = bg->mLayers[i];
       if (!aBGClipRect) {
         uint8_t newBackgroundClip = layer.mClip;
         if (isSolidBorder && newBackgroundClip == NS_STYLE_BG_CLIP_BORDER) {
           newBackgroundClip = haveRoundedCorners ?
             NS_STYLE_BG_CLIP_MOZ_ALMOST_PADDING : NS_STYLE_BG_CLIP_PADDING;
         }
         if (currentBackgroundClip != newBackgroundClip || !clipSet) {
           currentBackgroundClip = newBackgroundClip;
           // If clipSet is false that means this is the bottom layer and we
           // already called GetBackgroundClip above and it stored its results
           // in clipState.
           if (clipSet) {
             GetBackgroundClip(ctx, currentBackgroundClip, layer.mAttachment, aForFrame,
                               aBorderArea, aDirtyRect, haveRoundedCorners,
                               bgRadii, appUnitsPerPixel, &clipState);
           }
           SetupBackgroundClip(clipState, ctx, haveRoundedCorners,
                               appUnitsPerPixel, &autoSR);
           clipSet = true;
         }
       }
       if ((aLayer < 0 || i == (uint32_t)startLayer) &&
           !clipState.mDirtyRectGfx.IsEmpty()) {
         nsBackgroundLayerState state = PrepareBackgroundLayer(aPresContext, aForFrame,
             aFlags, aBorderArea, clipState.mBGClipArea, *bg, layer);
         if (!state.mFillArea.IsEmpty()) {
           if (state.mCompositingOp != gfxContext::OPERATOR_OVER) {
             NS_ASSERTION(ctx->CurrentOperator() == gfxContext::OPERATOR_OVER,
                          "It is assumed the initial operator is OPERATOR_OVER, when it is restored later");
             ctx->SetOperator(state.mCompositingOp);
           }
           state.mImageRenderer.DrawBackground(aPresContext, aRenderingContext,
                                               state.mDestArea, state.mFillArea,
                                               state.mAnchor + aBorderArea.TopLeft(),
                                               clipState.mDirtyRect);
           if (state.mCompositingOp != gfxContext::OPERATOR_OVER) {
             ctx->SetOperator(gfxContext::OPERATOR_OVER);
           }
         }
       }
     }
   }
 }
 void
 nsCSSRendering::PaintBackgroundColorWithSC(nsPresContext* aPresContext,
                                            nsRenderingContext& aRenderingContext,
                                            nsIFrame* aForFrame,
                                            const nsRect& aDirtyRect,
                                            const nsRect& aBorderArea,
                                            nsStyleContext* aBackgroundSC,
                                            const nsStyleBorder& aBorder,
                                            uint32_t aFlags)
 {
   NS_PRECONDITION(aForFrame,
                   "Frame is expected to be provided to PaintBackground");
   // Check to see if we have an appearance defined.  If so, we let the theme
   // renderer draw the background and bail out.
   const nsStyleDisplay* displayData = aForFrame->StyleDisplay();
   if (displayData->mAppearance) {
     nsITheme *theme = aPresContext->GetTheme();
     if (theme && theme->ThemeSupportsWidget(aPresContext, aForFrame,
                                             displayData->mAppearance)) {
       NS_ERROR("Shouldn't be trying to paint a background color if we are themed!");
       return;
     }
   }
   NS_ASSERTION(!IsCanvasFrame(aForFrame), "Should not be trying to paint a background color for canvas frames!");
   // Determine whether we are drawing background images and/or
   // background colors.
   bool drawBackgroundImage;
   bool drawBackgroundColor;
   nscolor bgColor = DetermineBackgroundColor(aPresContext,
                                              aBackgroundSC,
                                              aForFrame,
                                              drawBackgroundImage,
                                              drawBackgroundColor);
   NS_ASSERTION(drawBackgroundImage || drawBackgroundColor,
                "Should not be trying to paint a background if we don't have one");
   if (!drawBackgroundColor) {
     return;
   }
   // Compute the outermost boundary of the area that might be painted.
   gfxContext *ctx = aRenderingContext.ThebesContext();
   nscoord appUnitsPerPixel = aPresContext->AppUnitsPerDevPixel();
   // Same coordinate space as aBorderArea
   gfxCornerSizes bgRadii;
   bool haveRoundedCorners;
   {
     nscoord radii[8];
     nsSize frameSize = aForFrame->GetSize();
     if (&aBorder == aForFrame->StyleBorder() &&
         frameSize == aBorderArea.Size()) {
       haveRoundedCorners = aForFrame->GetBorderRadii(radii);
     } else {
       haveRoundedCorners = nsIFrame::ComputeBorderRadii(aBorder.mBorderRadius,
                                    frameSize, aBorderArea.Size(),
                                    aForFrame->GetSkipSides(), radii);
     }
     if (haveRoundedCorners)
       ComputePixelRadii(radii, appUnitsPerPixel, &bgRadii);
   }
   // The background is rendered over the 'background-clip' area,
   // which is normally equal to the border area but may be reduced
   // to the padding area by CSS.  Also, if the border is solid, we
   // don't need to draw outside the padding area.  In either case,
   // if the borders are rounded, make sure we use the same inner
   // radii as the border code will.
   // The background-color is drawn based on the bottom
   // background-clip.
   const nsStyleBackground *bg = aBackgroundSC->StyleBackground();
   uint8_t currentBackgroundClip = bg->BottomLayer().mClip;
   bool isSolidBorder =
     (aFlags & PAINTBG_WILL_PAINT_BORDER) && IsOpaqueBorder(aBorder);
   if (isSolidBorder && currentBackgroundClip == NS_STYLE_BG_CLIP_BORDER) {
     // If we have rounded corners, we need to inflate the background
     // drawing area a bit to avoid seams between the border and
     // background.
     currentBackgroundClip = haveRoundedCorners ?
       NS_STYLE_BG_CLIP_MOZ_ALMOST_PADDING : NS_STYLE_BG_CLIP_PADDING;
   }
   BackgroundClipState clipState;
   GetBackgroundClip(ctx, currentBackgroundClip, bg->BottomLayer().mAttachment,
                     aForFrame, aBorderArea,
                     aDirtyRect, haveRoundedCorners, bgRadii, appUnitsPerPixel,
                     &clipState);
   ctx->SetColor(gfxRGBA(bgColor));
   gfxContextAutoSaveRestore autoSR;
   DrawBackgroundColor(clipState, ctx, haveRoundedCorners, appUnitsPerPixel);
 }
 static inline bool
 IsTransformed(nsIFrame* aForFrame, nsIFrame* aTopFrame)
 {
   for (nsIFrame* f = aForFrame; f != aTopFrame; f = f->GetParent()) {
     if (f->IsTransformed()) {
       return true;
     }
   }
   return false;
 }
 nsRect
 nsCSSRendering::ComputeBackgroundPositioningArea(nsPresContext* aPresContext,
                                                  nsIFrame* aForFrame,
                                                  const nsRect& aBorderArea,
                                                  const nsStyleBackground& aBackground,
                                                  const nsStyleBackground::Layer& aLayer,
                                                  nsIFrame** aAttachedToFrame)
 {
   // Compute background origin area relative to aBorderArea now as we may need
   // it to compute the effective image size for a CSS gradient.
   nsRect bgPositioningArea(0, 0, 0, 0);
   nsIAtom* frameType = aForFrame->GetType();
   nsIFrame* geometryFrame = aForFrame;
   if (frameType == nsGkAtoms::inlineFrame) {
     // XXXjwalden Strictly speaking this is not quite faithful to how
     // background-break is supposed to interact with background-origin values,
     // but it's a non-trivial amount of work to make it fully conformant, and
     // until the specification is more finalized (and assuming background-break
     // even makes the cut) it doesn't make sense to hammer out exact behavior.
     switch (aBackground.mBackgroundInlinePolicy) {
     case NS_STYLE_BG_INLINE_POLICY_EACH_BOX:
       bgPositioningArea = nsRect(nsPoint(0,0), aBorderArea.Size());
       break;
     case NS_STYLE_BG_INLINE_POLICY_BOUNDING_BOX:
       bgPositioningArea = gInlineBGData->GetBoundingRect(aForFrame);
       break;
     default:
       NS_ERROR("Unknown background-inline-policy value!  "
                "Please, teach me what to do.");
     case NS_STYLE_BG_INLINE_POLICY_CONTINUOUS:
       bgPositioningArea = gInlineBGData->GetContinuousRect(aForFrame);
       break;
     }
   } else if (frameType == nsGkAtoms::canvasFrame) {
     geometryFrame = aForFrame->GetFirstPrincipalChild();
     // geometryFrame might be null if this canvas is a page created
     // as an overflow container (e.g. the in-flow content has already
     // finished and this page only displays the continuations of
     // absolutely positioned content).
     if (geometryFrame) {
       bgPositioningArea = geometryFrame->GetRect();
     }
   } else if (frameType == nsGkAtoms::scrollFrame &&
              NS_STYLE_BG_ATTACHMENT_LOCAL == aLayer.mAttachment) {
     nsIScrollableFrame* scrollableFrame = do_QueryFrame(aForFrame);
     bgPositioningArea = nsRect(
       scrollableFrame->GetScrolledFrame()->GetPosition()
         // For the dir=rtl case:
         + scrollableFrame->GetScrollRange().TopLeft(),
       scrollableFrame->GetScrolledRect().Size());
     // The ScrolledRect’s size does not include the borders or scrollbars,
     // reverse the handling of background-origin
     // compared to the common case below.
     if (aLayer.mOrigin == NS_STYLE_BG_ORIGIN_BORDER) {
       nsMargin border = geometryFrame->GetUsedBorder();
       geometryFrame->ApplySkipSides(border);
       bgPositioningArea.Inflate(border);
       bgPositioningArea.Inflate(scrollableFrame->GetActualScrollbarSizes());
     } else if (aLayer.mOrigin != NS_STYLE_BG_ORIGIN_PADDING) {
       nsMargin padding = geometryFrame->GetUsedPadding();
       geometryFrame->ApplySkipSides(padding);
       bgPositioningArea.Deflate(padding);
       NS_ASSERTION(aLayer.mOrigin == NS_STYLE_BG_ORIGIN_CONTENT,
                    "unknown background-origin value");
     }
     *aAttachedToFrame = aForFrame;
     return bgPositioningArea;
   } else {
     bgPositioningArea = nsRect(nsPoint(0,0), aBorderArea.Size());
   }
   // Background images are tiled over the 'background-clip' area
   // but the origin of the tiling is based on the 'background-origin' area
   if (aLayer.mOrigin != NS_STYLE_BG_ORIGIN_BORDER && geometryFrame) {
     nsMargin border = geometryFrame->GetUsedBorder();
     if (aLayer.mOrigin != NS_STYLE_BG_ORIGIN_PADDING) {
       border += geometryFrame->GetUsedPadding();
       NS_ASSERTION(aLayer.mOrigin == NS_STYLE_BG_ORIGIN_CONTENT,
                    "unknown background-origin value");
     }
     geometryFrame->ApplySkipSides(border);
     bgPositioningArea.Deflate(border);
   }
   nsIFrame* attachedToFrame = aForFrame;
   if (NS_STYLE_BG_ATTACHMENT_FIXED == aLayer.mAttachment) {
     // If it's a fixed background attachment, then the image is placed
     // relative to the viewport, which is the area of the root frame
     // in a screen context or the page content frame in a print context.
     attachedToFrame = aPresContext->PresShell()->FrameManager()->GetRootFrame();
     NS_ASSERTION(attachedToFrame, "no root frame");
     nsIFrame* pageContentFrame = nullptr;
     if (aPresContext->IsPaginated()) {
       pageContentFrame =
         nsLayoutUtils::GetClosestFrameOfType(aForFrame, nsGkAtoms::pageContentFrame);
       if (pageContentFrame) {
         attachedToFrame = pageContentFrame;
       }
       // else this is an embedded shell and its root frame is what we want
     }
     // Set the background positioning area to the viewport's area
     // (relative to aForFrame)
     bgPositioningArea =
       nsRect(-aForFrame->GetOffsetTo(attachedToFrame), attachedToFrame->GetSize());
     if (!pageContentFrame) {
       // Subtract the size of scrollbars.
       nsIScrollableFrame* scrollableFrame =
         aPresContext->PresShell()->GetRootScrollFrameAsScrollable();
       if (scrollableFrame) {
         nsMargin scrollbars = scrollableFrame->GetActualScrollbarSizes();
         bgPositioningArea.Deflate(scrollbars);
       }
     }
   }
   *aAttachedToFrame = attachedToFrame;
   return bgPositioningArea;
 }
 // Apply the CSS image sizing algorithm as it applies to background images.
 // See http://www.w3.org/TR/css3-background/#the-background-size .
 // aIntrinsicSize is the size that the background image 'would like to be'.
 // It can be found by calling nsImageRenderer::ComputeIntrinsicSize.
 static nsSize
 ComputeDrawnSizeForBackground(const CSSSizeOrRatio& aIntrinsicSize,
                               const nsSize& aBgPositioningArea,
                               const nsStyleBackground::Size& aLayerSize)
 {
   // Size is dictated by cover or contain rules.
   if (aLayerSize.mWidthType == nsStyleBackground::Size::eContain ||
       aLayerSize.mWidthType == nsStyleBackground::Size::eCover) {
     nsImageRenderer::FitType fitType =
       aLayerSize.mWidthType == nsStyleBackground::Size::eCover
         ? nsImageRenderer::COVER
         : nsImageRenderer::CONTAIN;
     return nsImageRenderer::ComputeConstrainedSize(aBgPositioningArea,
                                                    aIntrinsicSize.mRatio,
                                                    fitType);
   }
   // No cover/contain constraint, use default algorithm.
   CSSSizeOrRatio specifiedSize;
   if (aLayerSize.mWidthType == nsStyleBackground::Size::eLengthPercentage) {
     specifiedSize.SetWidth(
       aLayerSize.ResolveWidthLengthPercentage(aBgPositioningArea));
   }
   if (aLayerSize.mHeightType == nsStyleBackground::Size::eLengthPercentage) {
     specifiedSize.SetHeight(
       aLayerSize.ResolveHeightLengthPercentage(aBgPositioningArea));
   }
   return nsImageRenderer::ComputeConcreteSize(specifiedSize,
                                               aIntrinsicSize,
                                               aBgPositioningArea);
 }
 nsBackgroundLayerState
 nsCSSRendering::PrepareBackgroundLayer(nsPresContext* aPresContext,
                                        nsIFrame* aForFrame,
                                        uint32_t aFlags,
                                        const nsRect& aBorderArea,
                                        const nsRect& aBGClipRect,
                                        const nsStyleBackground& aBackground,
                                        const nsStyleBackground::Layer& aLayer)
 {
   /*
    * The background properties we need to keep in mind when drawing background
    * layers are:
    *
    *   background-image
    *   background-repeat
    *   background-attachment
    *   background-position
    *   background-clip
    *   background-origin
    *   background-size
    *   background-break (-moz-background-inline-policy)
    *   background-blend-mode
    *
    * (background-color applies to the entire element and not to individual
    * layers, so it is irrelevant to this method.)
    *
    * These properties have the following dependencies upon each other when
    * determining rendering:
    *
    *   background-image
    *     no dependencies
    *   background-repeat
    *     no dependencies
    *   background-attachment
    *     no dependencies
    *   background-position
    *     depends upon background-size (for the image's scaled size) and
    *     background-break (for the background positioning area)
    *   background-clip
    *     no dependencies
    *   background-origin
    *     depends upon background-attachment (only in the case where that value
    *     is 'fixed')
    *   background-size
    *     depends upon background-break (for the background positioning area for
    *     resolving percentages), background-image (for the image's intrinsic
    *     size), background-repeat (if that value is 'round'), and
    *     background-origin (for the background painting area, when
    *     background-repeat is 'round')
    *   background-break
    *     depends upon background-origin (specifying how the boxes making up the
    *     background positioning area are determined)
    *
    * As a result of only-if dependencies we don't strictly do a topological
    * sort of the above properties when processing, but it's pretty close to one:
    *
    *   background-clip (by caller)
    *   background-image
    *   background-break, background-origin
    *   background-attachment (postfix for background-{origin,break} if 'fixed')
    *   background-size
    *   background-position
    *   background-repeat
    */
   uint32_t irFlags = 0;
   if (aFlags & nsCSSRendering::PAINTBG_SYNC_DECODE_IMAGES) {
     irFlags |= nsImageRenderer::FLAG_SYNC_DECODE_IMAGES;
   }
   if (aFlags & nsCSSRendering::PAINTBG_TO_WINDOW) {
     irFlags |= nsImageRenderer::FLAG_PAINTING_TO_WINDOW;
   }
   nsBackgroundLayerState state(aForFrame, &aLayer.mImage, irFlags);
   if (!state.mImageRenderer.PrepareImage()) {
     // There's no image or it's not ready to be painted.
     return state;
   }
   // The frame to which the background is attached
   nsIFrame* attachedToFrame = aForFrame;
   // Compute background origin area relative to aBorderArea now as we may need
   // it to compute the effective image size for a CSS gradient.
   nsRect bgPositioningArea =
     ComputeBackgroundPositioningArea(aPresContext, aForFrame, aBorderArea,
                                      aBackground, aLayer, &attachedToFrame);
   // For background-attachment:fixed backgrounds, we'll limit the area
   // where the background can be drawn to the viewport.
   nsRect bgClipRect = aBGClipRect;
   // Compute the anchor point.
   //
   // relative to aBorderArea.TopLeft() (which is where the top-left
   // of aForFrame's border-box will be rendered)
   nsPoint imageTopLeft;
   if (NS_STYLE_BG_ATTACHMENT_FIXED == aLayer.mAttachment) {
     if ((aFlags & nsCSSRendering::PAINTBG_TO_WINDOW) &&
         !IsTransformed(aForFrame, attachedToFrame)) {
       // Clip background-attachment:fixed backgrounds to the viewport, if we're
       // painting to the screen and not transformed. This avoids triggering
       // tiling in common cases, without affecting output since drawing is
       // always clipped to the viewport when we draw to the screen. (But it's
       // not a pure optimization since it can affect the values of pixels at the
       // edge of the viewport --- whether they're sampled from a putative "next
       // tile" or not.)
       bgClipRect.IntersectRect(bgClipRect, bgPositioningArea + aBorderArea.TopLeft());
     }
   }
   // Scale the image as specified for background-size and as required for
   // proper background positioning when background-position is defined with
   // percentages.
   CSSSizeOrRatio intrinsicSize = state.mImageRenderer.ComputeIntrinsicSize();
   nsSize bgPositionSize = bgPositioningArea.Size();
   nsSize imageSize = ComputeDrawnSizeForBackground(intrinsicSize,
                                                    bgPositionSize,
                                                    aLayer.mSize);
   if (imageSize.width <= 0 || imageSize.height <= 0)
     return state;
   state.mImageRenderer.SetPreferredSize(intrinsicSize,
                                         imageSize);
   // Compute the position of the background now that the background's size is
   // determined.
   ComputeBackgroundAnchorPoint(aLayer, bgPositionSize, imageSize,
                                &imageTopLeft, &state.mAnchor);
   imageTopLeft += bgPositioningArea.TopLeft();
   state.mAnchor += bgPositioningArea.TopLeft();
   state.mDestArea = nsRect(imageTopLeft + aBorderArea.TopLeft(), imageSize);
   state.mFillArea = state.mDestArea;
   int repeatX = aLayer.mRepeat.mXRepeat;
   int repeatY = aLayer.mRepeat.mYRepeat;
   if (repeatX == NS_STYLE_BG_REPEAT_REPEAT) {
     state.mFillArea.x = bgClipRect.x;
     state.mFillArea.width = bgClipRect.width;
   }
   if (repeatY == NS_STYLE_BG_REPEAT_REPEAT) {
     state.mFillArea.y = bgClipRect.y;
     state.mFillArea.height = bgClipRect.height;
   }
   state.mFillArea.IntersectRect(state.mFillArea, bgClipRect);
   state.mCompositingOp = GetGFXBlendMode(aLayer.mBlendMode);
   return state;
 }
 nsRect
 nsCSSRendering::GetBackgroundLayerRect(nsPresContext* aPresContext,
                                        nsIFrame* aForFrame,
                                        const nsRect& aBorderArea,
                                        const nsRect& aClipRect,
                                        const nsStyleBackground& aBackground,
                                        const nsStyleBackground::Layer& aLayer,
                                        uint32_t aFlags)
 {
   nsBackgroundLayerState state =
       PrepareBackgroundLayer(aPresContext, aForFrame, aFlags, aBorderArea,
                              aClipRect, aBackground, aLayer);
   return state.mFillArea;
 }
 /* static */ bool
 nsCSSRendering::IsBackgroundImageDecodedForStyleContextAndLayer(
   const nsStyleBackground *aBackground, uint32_t aLayer)
 {
   const nsStyleImage* image = &aBackground->mLayers[aLayer].mImage;
   if (image->GetType() == eStyleImageType_Image) {
     nsCOMPtr<imgIContainer> img;
     if (NS_SUCCEEDED(image->GetImageData()->GetImage(getter_AddRefs(img)))) {
       if (!img->IsDecoded()) {
         return false;
       }
     }
   }
   return true;
 }
 /* static */ bool
 nsCSSRendering::AreAllBackgroundImagesDecodedForFrame(nsIFrame* aFrame)
 {
   const nsStyleBackground *bg = aFrame->StyleContext()->StyleBackground();
   NS_FOR_VISIBLE_BACKGROUND_LAYERS_BACK_TO_FRONT(i, bg) {
     if (!IsBackgroundImageDecodedForStyleContextAndLayer(bg, i)) {
       return false;
     }
   }
   return true;
 }
 static void
 DrawBorderImage(nsPresContext*       aPresContext,
                 nsRenderingContext&  aRenderingContext,
                 nsIFrame*            aForFrame,
                 const nsRect&        aBorderArea,
                 const nsStyleBorder& aStyleBorder,
                 const nsRect&        aDirtyRect)
 {
   NS_PRECONDITION(aStyleBorder.IsBorderImageLoaded(),
                   "drawing border image that isn't successfully loaded");
   if (aDirtyRect.IsEmpty())
     return;
   nsImageRenderer renderer(aForFrame, &aStyleBorder.mBorderImageSource, 0);
   // Ensure we get invalidated for loads and animations of the image.
   // We need to do this here because this might be the only code that
   // knows about the association of the style data with the frame.
   // XXX We shouldn't really... since if anybody is passing in a
   // different style, they'll potentially have the wrong size for the
   // border too.
   aForFrame->AssociateImage(aStyleBorder.mBorderImageSource, aPresContext);
   if (!renderer.PrepareImage()) {
     return;
   }
   // Determine the border image area, which by default corresponds to the
   // border box but can be modified by 'border-image-outset'.
   nsRect borderImgArea(aBorderArea);
   borderImgArea.Inflate(aStyleBorder.GetImageOutset());
   // Calculate the image size used to compute slice points.
   CSSSizeOrRatio intrinsicSize = renderer.ComputeIntrinsicSize();
   nsSize imageSize = nsImageRenderer::ComputeConcreteSize(CSSSizeOrRatio(),
                                                           intrinsicSize,
                                                           borderImgArea.Size());
   renderer.SetPreferredSize(intrinsicSize, imageSize);
   // Compute the used values of 'border-image-slice' and 'border-image-width';
   // we do them together because the latter can depend on the former.
   nsMargin slice;
   nsMargin border;
   NS_FOR_CSS_SIDES(s) {
     nsStyleCoord coord = aStyleBorder.mBorderImageSlice.Get(s);
     int32_t imgDimension = NS_SIDE_IS_VERTICAL(s)
                            ? imageSize.width : imageSize.height;
     nscoord borderDimension = NS_SIDE_IS_VERTICAL(s)
                            ? borderImgArea.width : borderImgArea.height;
     double value;
     switch (coord.GetUnit()) {
       case eStyleUnit_Percent:
         value = coord.GetPercentValue() * imgDimension;
         break;
       case eStyleUnit_Factor:
         value = nsPresContext::CSSPixelsToAppUnits(
           NS_lround(coord.GetFactorValue()));
         break;
       default:
         NS_NOTREACHED("unexpected CSS unit for image slice");
         value = 0;
         break;
     }
     if (value < 0)
       value = 0;
     if (value > imgDimension)
       value = imgDimension;
     slice.Side(s) = value;
     nsMargin borderWidths(aStyleBorder.GetComputedBorder());
     coord = aStyleBorder.mBorderImageWidth.Get(s);
     switch (coord.GetUnit()) {
       case eStyleUnit_Coord: // absolute dimension
         value = coord.GetCoordValue();
         break;
       case eStyleUnit_Percent:
         value = coord.GetPercentValue() * borderDimension;
         break;
       case eStyleUnit_Factor:
         value = coord.GetFactorValue() * borderWidths.Side(s);
         break;
       case eStyleUnit_Auto:  // same as the slice value, in CSS pixels
         value = slice.Side(s);
         break;
       default:
         NS_NOTREACHED("unexpected CSS unit for border image area division");
         value = 0;
         break;
     }
     // NSToCoordRoundWithClamp rounds towards infinity, but that's OK
     // because we expect value to be non-negative.
     MOZ_ASSERT(value >= 0);
     border.Side(s) = NSToCoordRoundWithClamp(value);
     MOZ_ASSERT(border.Side(s) >= 0);
   }
   // "If two opposite border-image-width offsets are large enough that they
   // overlap, their used values are proportionately reduced until they no
   // longer overlap."
   uint32_t combinedBorderWidth = uint32_t(border.left) +
                                  uint32_t(border.right);
   double scaleX = combinedBorderWidth > uint32_t(borderImgArea.width)
                   ? borderImgArea.width / double(combinedBorderWidth)
                   : 1.0;
   uint32_t combinedBorderHeight = uint32_t(border.top) +
                                   uint32_t(border.bottom);
   double scaleY = combinedBorderHeight > uint32_t(borderImgArea.height)
                   ? borderImgArea.height / double(combinedBorderHeight)
                   : 1.0;
   double scale = std::min(scaleX, scaleY);
   if (scale < 1.0) {
     border.left *= scale;
     border.right *= scale;
     border.top *= scale;
     border.bottom *= scale;
     NS_ASSERTION(border.left + border.right <= borderImgArea.width &&
                  border.top + border.bottom <= borderImgArea.height,
                  "rounding error in width reduction???");
   }
   // These helper tables recharacterize the 'slice' and 'width' margins
   // in a more convenient form: they are the x/y/width/height coords
   // required for various bands of the border, and they have been transformed
   // to be relative to the innerRect (for 'slice') or the page (for 'border').
   enum {
     LEFT, MIDDLE, RIGHT,
     TOP = LEFT, BOTTOM = RIGHT
   };
   const nscoord borderX[3] = {
     borderImgArea.x + 0,
     borderImgArea.x + border.left,
     borderImgArea.x + borderImgArea.width - border.right,
   };
   const nscoord borderY[3] = {
     borderImgArea.y + 0,
     borderImgArea.y + border.top,
     borderImgArea.y + borderImgArea.height - border.bottom,
   };
   const nscoord borderWidth[3] = {
     border.left,
     borderImgArea.width - border.left - border.right,
     border.right,
   };
   const nscoord borderHeight[3] = {
     border.top,
     borderImgArea.height - border.top - border.bottom,
     border.bottom,
   };
   const int32_t sliceX[3] = {
 ,
     slice.left,
     imageSize.width - slice.right,
   };
   const int32_t sliceY[3] = {
 ,
     slice.top,
     imageSize.height - slice.bottom,
   };
   const int32_t sliceWidth[3] = {
     slice.left,
     std::max(imageSize.width - slice.left - slice.right, 0),
     slice.right,
   };
   const int32_t sliceHeight[3] = {
     slice.top,
     std::max(imageSize.height - slice.top - slice.bottom, 0),
     slice.bottom,
   };
   for (int i = LEFT; i <= RIGHT; i++) {
     for (int j = TOP; j <= BOTTOM; j++) {
       uint8_t fillStyleH, fillStyleV;
       nsSize unitSize;
       if (i == MIDDLE && j == MIDDLE) {
         // Discard the middle portion unless set to fill.
         if (NS_STYLE_BORDER_IMAGE_SLICE_NOFILL ==
             aStyleBorder.mBorderImageFill) {
           continue;
         }
         NS_ASSERTION(NS_STYLE_BORDER_IMAGE_SLICE_FILL ==
                      aStyleBorder.mBorderImageFill,
                      "Unexpected border image fill");
         // css-background:
         //     The middle image's width is scaled by the same factor as the
         //     top image unless that factor is zero or infinity, in which
         //     case the scaling factor of the bottom is substituted, and
         //     failing that, the width is not scaled. The height of the
         //     middle image is scaled by the same factor as the left image
         //     unless that factor is zero or infinity, in which case the
         //     scaling factor of the right image is substituted, and failing
         //     that, the height is not scaled.
         gfxFloat hFactor, vFactor;
         if (0 < border.left && 0 < slice.left)
           vFactor = gfxFloat(border.left)/slice.left;
         else if (0 < border.right && 0 < slice.right)
           vFactor = gfxFloat(border.right)/slice.right;
         else
           vFactor = 1;
         if (0 < border.top && 0 < slice.top)
           hFactor = gfxFloat(border.top)/slice.top;
         else if (0 < border.bottom && 0 < slice.bottom)
           hFactor = gfxFloat(border.bottom)/slice.bottom;
         else
           hFactor = 1;
         unitSize.width = sliceWidth[i]*hFactor;
         unitSize.height = sliceHeight[j]*vFactor;
         fillStyleH = aStyleBorder.mBorderImageRepeatH;
         fillStyleV = aStyleBorder.mBorderImageRepeatV;
       } else if (i == MIDDLE) { // top, bottom
         // Sides are always stretched to the thickness of their border,
         // and stretched proportionately on the other axis.
         gfxFloat factor;
         if (0 < borderHeight[j] && 0 < sliceHeight[j])
           factor = gfxFloat(borderHeight[j])/sliceHeight[j];
         else
           factor = 1;
         unitSize.width = sliceWidth[i]*factor;
         unitSize.height = borderHeight[j];
         fillStyleH = aStyleBorder.mBorderImageRepeatH;
         fillStyleV = NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH;
       } else if (j == MIDDLE) { // left, right
         gfxFloat factor;
         if (0 < borderWidth[i] && 0 < sliceWidth[i])
           factor = gfxFloat(borderWidth[i])/sliceWidth[i];
         else
           factor = 1;
         unitSize.width = borderWidth[i];
         unitSize.height = sliceHeight[j]*factor;
         fillStyleH = NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH;
         fillStyleV = aStyleBorder.mBorderImageRepeatV;
       } else {
         // Corners are always stretched to fit the corner.
         unitSize.width = borderWidth[i];
         unitSize.height = borderHeight[j];
         fillStyleH = NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH;
         fillStyleV = NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH;
       }
       nsRect destArea(borderX[i], borderY[j], borderWidth[i], borderHeight[j]);
       nsRect subArea(sliceX[i], sliceY[j], sliceWidth[i], sliceHeight[j]);
       nsIntRect intSubArea = subArea.ToOutsidePixels(nsPresContext::AppUnitsPerCSSPixel());
       renderer.DrawBorderImageComponent(aPresContext,
                                         aRenderingContext, aDirtyRect,
                                         destArea, CSSIntRect(intSubArea.x,
                                                              intSubArea.y,
                                                              intSubArea.width,
                                                              intSubArea.height),
                                         fillStyleH, fillStyleV,
                                         unitSize, j * (RIGHT + 1) + i);
     }
   }
 }
 // Begin table border-collapsing section
 // These functions were written to not disrupt the normal ones and yet satisfy some additional requirements
 // At some point, all functions should be unified to include the additional functionality that these provide
 static nscoord
 RoundIntToPixel(nscoord aValue,
                 nscoord aTwipsPerPixel,
                 bool    aRoundDown = false)
 {
   if (aTwipsPerPixel <= 0)
     // We must be rendering to a device that has a resolution greater than Twips!
     // In that case, aValue is as accurate as it's going to get.
     return aValue;
   nscoord halfPixel = NSToCoordRound(aTwipsPerPixel / 2.0f);
   nscoord extra = aValue % aTwipsPerPixel;
   nscoord finalValue = (!aRoundDown && (extra >= halfPixel)) ? aValue + (aTwipsPerPixel - extra) : aValue - extra;
   return finalValue;
 }
 static nscoord
 RoundFloatToPixel(float   aValue,
                   nscoord aTwipsPerPixel,
                   bool    aRoundDown = false)
 {
   return RoundIntToPixel(NSToCoordRound(aValue), aTwipsPerPixel, aRoundDown);
 }
 static void
 SetPoly(const nsRect& aRect,
         nsPoint*      poly)
 {
   poly[0].x = aRect.x;
   poly[0].y = aRect.y;
   poly[1].x = aRect.x + aRect.width;
   poly[1].y = aRect.y;
   poly[2].x = aRect.x + aRect.width;
   poly[2].y = aRect.y + aRect.height;
   poly[3].x = aRect.x;
   poly[3].y = aRect.y + aRect.height;
   poly[4].x = aRect.x;
   poly[4].y = aRect.y;
 }
 static void
 DrawSolidBorderSegment(nsRenderingContext& aContext,
                        nsRect               aRect,
                        nscoord              aTwipsPerPixel,
                        uint8_t              aStartBevelSide = 0,
                        nscoord              aStartBevelOffset = 0,
                        uint8_t              aEndBevelSide = 0,
                        nscoord              aEndBevelOffset = 0)
 {
   if ((aRect.width == aTwipsPerPixel) || (aRect.height == aTwipsPerPixel) ||
       ((0 == aStartBevelOffset) && (0 == aEndBevelOffset))) {
     // simple line or rectangle
     if ((NS_SIDE_TOP == aStartBevelSide) || (NS_SIDE_BOTTOM == aStartBevelSide)) {
       if (1 == aRect.height)
         aContext.DrawLine(aRect.TopLeft(), aRect.BottomLeft());
       else
         aContext.FillRect(aRect);
     }
     else {
       if (1 == aRect.width)
         aContext.DrawLine(aRect.TopLeft(), aRect.TopRight());
       else
         aContext.FillRect(aRect);
     }
   }
   else {
     // polygon with beveling
     nsPoint poly[5];
     SetPoly(aRect, poly);
     switch(aStartBevelSide) {
     case NS_SIDE_TOP:
       poly[0].x += aStartBevelOffset;
       poly[4].x = poly[0].x;
       break;
     case NS_SIDE_BOTTOM:
       poly[3].x += aStartBevelOffset;
       break;
     case NS_SIDE_RIGHT:
       poly[1].y += aStartBevelOffset;
       break;
     case NS_SIDE_LEFT:
       poly[0].y += aStartBevelOffset;
       poly[4].y = poly[0].y;
     }
     switch(aEndBevelSide) {
     case NS_SIDE_TOP:
       poly[1].x -= aEndBevelOffset;
       break;
     case NS_SIDE_BOTTOM:
       poly[2].x -= aEndBevelOffset;
       break;
     case NS_SIDE_RIGHT:
       poly[2].y -= aEndBevelOffset;
       break;
     case NS_SIDE_LEFT:
       poly[3].y -= aEndBevelOffset;
     }
     aContext.FillPolygon(poly, 5);
   }
 }
 static void
 GetDashInfo(nscoord  aBorderLength,
             nscoord  aDashLength,
             nscoord  aTwipsPerPixel,
             int32_t& aNumDashSpaces,
             nscoord& aStartDashLength,
             nscoord& aEndDashLength)
 {
   aNumDashSpaces = 0;
   if (aStartDashLength + aDashLength + aEndDashLength >= aBorderLength) {
     aStartDashLength = aBorderLength;
     aEndDashLength = 0;
   }
   else {
     aNumDashSpaces = (aBorderLength - aDashLength)/ (2 * aDashLength); // round down
     nscoord extra = aBorderLength - aStartDashLength - aEndDashLength - (((2 * aNumDashSpaces) - 1) * aDashLength);
     if (extra > 0) {
       nscoord half = RoundIntToPixel(extra / 2, aTwipsPerPixel);
       aStartDashLength += half;
       aEndDashLength += (extra - half);
     }
   }
 }
 void
 nsCSSRendering::DrawTableBorderSegment(nsRenderingContext&     aContext,
                                        uint8_t                  aBorderStyle,
                                        nscolor                  aBorderColor,
                                        const nsStyleBackground* aBGColor,
                                        const nsRect&            aBorder,
                                        int32_t                  aAppUnitsPerCSSPixel,
                                        uint8_t                  aStartBevelSide,
                                        nscoord                  aStartBevelOffset,
                                        uint8_t                  aEndBevelSide,
                                        nscoord                  aEndBevelOffset)
 {
   aContext.SetColor (aBorderColor);
   bool horizontal = ((NS_SIDE_TOP == aStartBevelSide) || (NS_SIDE_BOTTOM == aStartBevelSide));
   nscoord twipsPerPixel = NSIntPixelsToAppUnits(1, aAppUnitsPerCSSPixel);
   uint8_t ridgeGroove = NS_STYLE_BORDER_STYLE_RIDGE;
   if ((twipsPerPixel >= aBorder.width) || (twipsPerPixel >= aBorder.height) ||
       (NS_STYLE_BORDER_STYLE_DASHED == aBorderStyle) || (NS_STYLE_BORDER_STYLE_DOTTED == aBorderStyle)) {
     // no beveling for 1 pixel border, dash or dot
     aStartBevelOffset = 0;
     aEndBevelOffset = 0;
   }
   gfxContext *ctx = aContext.ThebesContext();
   gfxContext::AntialiasMode oldMode = ctx->CurrentAntialiasMode();
   ctx->SetAntialiasMode(gfxContext::MODE_ALIASED);
   switch (aBorderStyle) {
   case NS_STYLE_BORDER_STYLE_NONE:
   case NS_STYLE_BORDER_STYLE_HIDDEN:
     //NS_ASSERTION(false, "style of none or hidden");
     break;
   case NS_STYLE_BORDER_STYLE_DOTTED:
   case NS_STYLE_BORDER_STYLE_DASHED:
     {
       nscoord dashLength = (NS_STYLE_BORDER_STYLE_DASHED == aBorderStyle) ? DASH_LENGTH : DOT_LENGTH;
       // make the dash length proportional to the border thickness
       dashLength *= (horizontal) ? aBorder.height : aBorder.width;
       // make the min dash length for the ends 1/2 the dash length
       nscoord minDashLength = (NS_STYLE_BORDER_STYLE_DASHED == aBorderStyle)
                               ? RoundFloatToPixel(((float)dashLength) / 2.0f, twipsPerPixel) : dashLength;
       minDashLength = std::max(minDashLength, twipsPerPixel);
       nscoord numDashSpaces = 0;
       nscoord startDashLength = minDashLength;
       nscoord endDashLength   = minDashLength;
       if (horizontal) {
         GetDashInfo(aBorder.width, dashLength, twipsPerPixel, numDashSpaces, startDashLength, endDashLength);
         nsRect rect(aBorder.x, aBorder.y, startDashLength, aBorder.height);
         DrawSolidBorderSegment(aContext, rect, twipsPerPixel);
         for (int32_t spaceX = 0; spaceX < numDashSpaces; spaceX++) {
           rect.x += rect.width + dashLength;
           rect.width = (spaceX == (numDashSpaces - 1)) ? endDashLength : dashLength;
           DrawSolidBorderSegment(aContext, rect, twipsPerPixel);
         }
       }
       else {
         GetDashInfo(aBorder.height, dashLength, twipsPerPixel, numDashSpaces, startDashLength, endDashLength);
         nsRect rect(aBorder.x, aBorder.y, aBorder.width, startDashLength);
         DrawSolidBorderSegment(aContext, rect, twipsPerPixel);
         for (int32_t spaceY = 0; spaceY < numDashSpaces; spaceY++) {
           rect.y += rect.height + dashLength;
           rect.height = (spaceY == (numDashSpaces - 1)) ? endDashLength : dashLength;
           DrawSolidBorderSegment(aContext, rect, twipsPerPixel);
         }
       }
     }
     break;
   case NS_STYLE_BORDER_STYLE_GROOVE:
     ridgeGroove = NS_STYLE_BORDER_STYLE_GROOVE; // and fall through to ridge
   case NS_STYLE_BORDER_STYLE_RIDGE:
     if ((horizontal && (twipsPerPixel >= aBorder.height)) ||
         (!horizontal && (twipsPerPixel >= aBorder.width))) {
       // a one pixel border
       DrawSolidBorderSegment(aContext, aBorder, twipsPerPixel, aStartBevelSide, aStartBevelOffset,
                              aEndBevelSide, aEndBevelOffset);
     }
     else {
       nscoord startBevel = (aStartBevelOffset > 0)
                             ? RoundFloatToPixel(0.5f * (float)aStartBevelOffset, twipsPerPixel, true) : 0;
       nscoord endBevel =   (aEndBevelOffset > 0)
                             ? RoundFloatToPixel(0.5f * (float)aEndBevelOffset, twipsPerPixel, true) : 0;
       mozilla::css::Side ridgeGrooveSide = (horizontal) ? NS_SIDE_TOP : NS_SIDE_LEFT;
       // FIXME: In theory, this should use the visited-dependent
       // background color, but I don't care.
       aContext.SetColor (
         MakeBevelColor(ridgeGrooveSide, ridgeGroove, aBGColor->mBackgroundColor, aBorderColor));
       nsRect rect(aBorder);
       nscoord half;
       if (horizontal) { // top, bottom
         half = RoundFloatToPixel(0.5f * (float)aBorder.height, twipsPerPixel);
         rect.height = half;
         if (NS_SIDE_TOP == aStartBevelSide) {
           rect.x += startBevel;
           rect.width -= startBevel;
         }
         if (NS_SIDE_TOP == aEndBevelSide) {
           rect.width -= endBevel;
         }
         DrawSolidBorderSegment(aContext, rect, twipsPerPixel, aStartBevelSide,
                                startBevel, aEndBevelSide, endBevel);
       }
       else { // left, right
         half = RoundFloatToPixel(0.5f * (float)aBorder.width, twipsPerPixel);
         rect.width = half;
         if (NS_SIDE_LEFT == aStartBevelSide) {
           rect.y += startBevel;
           rect.height -= startBevel;
         }
         if (NS_SIDE_LEFT == aEndBevelSide) {
           rect.height -= endBevel;
         }
         DrawSolidBorderSegment(aContext, rect, twipsPerPixel, aStartBevelSide,
                                startBevel, aEndBevelSide, endBevel);
       }
       rect = aBorder;
       ridgeGrooveSide = (NS_SIDE_TOP == ridgeGrooveSide) ? NS_SIDE_BOTTOM : NS_SIDE_RIGHT;
       // FIXME: In theory, this should use the visited-dependent
       // background color, but I don't care.
       aContext.SetColor (
         MakeBevelColor(ridgeGrooveSide, ridgeGroove, aBGColor->mBackgroundColor, aBorderColor));
       if (horizontal) {
         rect.y = rect.y + half;
         rect.height = aBorder.height - half;
         if (NS_SIDE_BOTTOM == aStartBevelSide) {
           rect.x += startBevel;
           rect.width -= startBevel;
         }
         if (NS_SIDE_BOTTOM == aEndBevelSide) {
           rect.width -= endBevel;
         }
         DrawSolidBorderSegment(aContext, rect, twipsPerPixel, aStartBevelSide,
                                startBevel, aEndBevelSide, endBevel);
       }
       else {
         rect.x = rect.x + half;
         rect.width = aBorder.width - half;
         if (NS_SIDE_RIGHT == aStartBevelSide) {
           rect.y += aStartBevelOffset - startBevel;
           rect.height -= startBevel;
         }
         if (NS_SIDE_RIGHT == aEndBevelSide) {
           rect.height -= endBevel;
         }
         DrawSolidBorderSegment(aContext, rect, twipsPerPixel, aStartBevelSide,
                                startBevel, aEndBevelSide, endBevel);
       }
     }
     break;
   case NS_STYLE_BORDER_STYLE_DOUBLE:
     // We can only do "double" borders if the thickness of the border
     // is more than 2px.  Otherwise, we fall through to painting a
     // solid border.
     if ((aBorder.width > 2*twipsPerPixel || horizontal) &&
         (aBorder.height > 2*twipsPerPixel || !horizontal)) {
       nscoord startBevel = (aStartBevelOffset > 0)
                             ? RoundFloatToPixel(0.333333f * (float)aStartBevelOffset, twipsPerPixel) : 0;
       nscoord endBevel =   (aEndBevelOffset > 0)
                             ? RoundFloatToPixel(0.333333f * (float)aEndBevelOffset, twipsPerPixel) : 0;
       if (horizontal) { // top, bottom
         nscoord thirdHeight = RoundFloatToPixel(0.333333f * (float)aBorder.height, twipsPerPixel);
         // draw the top line or rect
         nsRect topRect(aBorder.x, aBorder.y, aBorder.width, thirdHeight);
         if (NS_SIDE_TOP == aStartBevelSide) {
           topRect.x += aStartBevelOffset - startBevel;
           topRect.width -= aStartBevelOffset - startBevel;
         }
         if (NS_SIDE_TOP == aEndBevelSide) {
           topRect.width -= aEndBevelOffset - endBevel;
         }
         DrawSolidBorderSegment(aContext, topRect, twipsPerPixel, aStartBevelSide,
                                startBevel, aEndBevelSide, endBevel);
         // draw the botom line or rect
         nscoord heightOffset = aBorder.height - thirdHeight;
         nsRect bottomRect(aBorder.x, aBorder.y + heightOffset, aBorder.width, aBorder.height - heightOffset);
         if (NS_SIDE_BOTTOM == aStartBevelSide) {
           bottomRect.x += aStartBevelOffset - startBevel;
           bottomRect.width -= aStartBevelOffset - startBevel;
         }
         if (NS_SIDE_BOTTOM == aEndBevelSide) {
           bottomRect.width -= aEndBevelOffset - endBevel;
         }
         DrawSolidBorderSegment(aContext, bottomRect, twipsPerPixel, aStartBevelSide,
                                startBevel, aEndBevelSide, endBevel);
       }
       else { // left, right
         nscoord thirdWidth = RoundFloatToPixel(0.333333f * (float)aBorder.width, twipsPerPixel);
         nsRect leftRect(aBorder.x, aBorder.y, thirdWidth, aBorder.height);
         if (NS_SIDE_LEFT == aStartBevelSide) {
           leftRect.y += aStartBevelOffset - startBevel;
           leftRect.height -= aStartBevelOffset - startBevel;
         }
         if (NS_SIDE_LEFT == aEndBevelSide) {
           leftRect.height -= aEndBevelOffset - endBevel;
         }
         DrawSolidBorderSegment(aContext, leftRect, twipsPerPixel, aStartBevelSide,
                                startBevel, aEndBevelSide, endBevel);
         nscoord widthOffset = aBorder.width - thirdWidth;
         nsRect rightRect(aBorder.x + widthOffset, aBorder.y, aBorder.width - widthOffset, aBorder.height);
         if (NS_SIDE_RIGHT == aStartBevelSide) {
           rightRect.y += aStartBevelOffset - startBevel;
           rightRect.height -= aStartBevelOffset - startBevel;
         }
         if (NS_SIDE_RIGHT == aEndBevelSide) {
           rightRect.height -= aEndBevelOffset - endBevel;
         }
         DrawSolidBorderSegment(aContext, rightRect, twipsPerPixel, aStartBevelSide,
                                startBevel, aEndBevelSide, endBevel);
       }
       break;
     }
     // else fall through to solid
   case NS_STYLE_BORDER_STYLE_SOLID:
     DrawSolidBorderSegment(aContext, aBorder, twipsPerPixel, aStartBevelSide,
                            aStartBevelOffset, aEndBevelSide, aEndBevelOffset);
     break;
   case NS_STYLE_BORDER_STYLE_OUTSET:
   case NS_STYLE_BORDER_STYLE_INSET:
     NS_ASSERTION(false, "inset, outset should have been converted to groove, ridge");
     break;
   case NS_STYLE_BORDER_STYLE_AUTO:
     NS_ASSERTION(false, "Unexpected 'auto' table border");
     break;
   }
   ctx->SetAntialiasMode(oldMode);
 }
 // End table border-collapsing section
 gfxRect
 nsCSSRendering::ExpandPaintingRectForDecorationLine(nsIFrame* aFrame,
                                                     const uint8_t aStyle,
                                                     const gfxRect& aClippedRect,
                                                     const gfxFloat aXInFrame,
                                                     const gfxFloat aCycleLength)
 {
   switch (aStyle) {
     case NS_STYLE_TEXT_DECORATION_STYLE_DOTTED:
     case NS_STYLE_TEXT_DECORATION_STYLE_DASHED:
     case NS_STYLE_TEXT_DECORATION_STYLE_WAVY:
       break;
     default:
       NS_ERROR("Invalid style was specified");
       return aClippedRect;
   }
   nsBlockFrame* block = nullptr;
   // Note that when we paint the decoration lines in relative positioned
   // box, we should paint them like all of the boxes are positioned as static.
   nscoord frameXInBlockAppUnits = 0;
   for (nsIFrame* f = aFrame; f; f = f->GetParent()) {
     block = do_QueryFrame(f);
     if (block) {
       break;
     }
     frameXInBlockAppUnits += f->GetNormalPosition().x;
   }
   NS_ENSURE_TRUE(block, aClippedRect);
   nsPresContext *pc = aFrame->PresContext();
   gfxFloat frameXInBlock = pc->AppUnitsToGfxUnits(frameXInBlockAppUnits);
   int32_t rectXInBlock = int32_t(NS_round(frameXInBlock + aXInFrame));
   int32_t extraLeft =
     rectXInBlock - (rectXInBlock / int32_t(aCycleLength) * aCycleLength);
   gfxRect rect(aClippedRect);
   rect.x -= extraLeft;
   rect.width += extraLeft;
   return rect;
 }
 void
 nsCSSRendering::PaintDecorationLine(nsIFrame* aFrame,
                                     gfxContext* aGfxContext,
                                     const gfxRect& aDirtyRect,
                                     const nscolor aColor,
                                     const gfxPoint& aPt,
                                     const gfxFloat aXInFrame,
                                     const gfxSize& aLineSize,
                                     const gfxFloat aAscent,
                                     const gfxFloat aOffset,
                                     const uint8_t aDecoration,
                                     const uint8_t aStyle,
                                     const gfxFloat aDescentLimit)
 {
   NS_ASSERTION(aStyle != NS_STYLE_TEXT_DECORATION_STYLE_NONE, "aStyle is none");
   gfxRect rect =
     GetTextDecorationRectInternal(aPt, aLineSize, aAscent, aOffset,
                                   aDecoration, aStyle, aDescentLimit);
   if (rect.IsEmpty() || !rect.Intersects(aDirtyRect)) {
     return;
   }
   if (aDecoration != NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE &&
       aDecoration != NS_STYLE_TEXT_DECORATION_LINE_OVERLINE &&
       aDecoration != NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH) {
     NS_ERROR("Invalid decoration value!");
     return;
   }
   gfxFloat lineHeight = std::max(NS_round(aLineSize.height), 1.0);
   bool contextIsSaved = false;
   gfxFloat oldLineWidth;
   nsRefPtr<gfxPattern> oldPattern;
   switch (aStyle) {
     case NS_STYLE_TEXT_DECORATION_STYLE_SOLID:
     case NS_STYLE_TEXT_DECORATION_STYLE_DOUBLE:
       oldLineWidth = aGfxContext->CurrentLineWidth();
       oldPattern = aGfxContext->GetPattern();
       break;
     case NS_STYLE_TEXT_DECORATION_STYLE_DASHED: {
       aGfxContext->Save();
       contextIsSaved = true;
       aGfxContext->Clip(rect);
       gfxFloat dashWidth = lineHeight * DOT_LENGTH * DASH_LENGTH;
       gfxFloat dash[2] = { dashWidth, dashWidth };
       aGfxContext->SetLineCap(gfxContext::LINE_CAP_BUTT);
       aGfxContext->SetDash(dash, 2, 0.0);
       rect = ExpandPaintingRectForDecorationLine(aFrame, aStyle, rect,
                                                  aXInFrame, dashWidth * 2);
       // We should continue to draw the last dash even if it is not in the rect.
       rect.width += dashWidth;
       break;
     }
     case NS_STYLE_TEXT_DECORATION_STYLE_DOTTED: {
       aGfxContext->Save();
       contextIsSaved = true;
       aGfxContext->Clip(rect);
       gfxFloat dashWidth = lineHeight * DOT_LENGTH;
       gfxFloat dash[2];
       if (lineHeight > 2.0) {
         dash[0] = 0.0;
         dash[1] = dashWidth * 2.0;
         aGfxContext->SetLineCap(gfxContext::LINE_CAP_ROUND);
       } else {
         dash[0] = dashWidth;
         dash[1] = dashWidth;
       }
       aGfxContext->SetDash(dash, 2, 0.0);
       rect = ExpandPaintingRectForDecorationLine(aFrame, aStyle, rect,
                                                  aXInFrame, dashWidth * 2);
       // We should continue to draw the last dot even if it is not in the rect.
       rect.width += dashWidth;
       break;
     }
     case NS_STYLE_TEXT_DECORATION_STYLE_WAVY:
       aGfxContext->Save();
       contextIsSaved = true;
       aGfxContext->Clip(rect);
       if (lineHeight > 2.0) {
         aGfxContext->SetAntialiasMode(gfxContext::MODE_COVERAGE);
       } else {
         // Don't use anti-aliasing here.  Because looks like lighter color wavy
         // line at this case.  And probably, users don't think the
         // non-anti-aliased wavy line is not pretty.
         aGfxContext->SetAntialiasMode(gfxContext::MODE_ALIASED);
       }
       break;
     default:
       NS_ERROR("Invalid style value!");
       return;
   }
   // The y position should be set to the middle of the line.
   rect.y += lineHeight / 2;
   aGfxContext->SetColor(gfxRGBA(aColor));
   aGfxContext->SetLineWidth(lineHeight);
   switch (aStyle) {
     case NS_STYLE_TEXT_DECORATION_STYLE_SOLID:
       aGfxContext->NewPath();
       aGfxContext->MoveTo(rect.TopLeft());
       aGfxContext->LineTo(rect.TopRight());
       aGfxContext->Stroke();
       break;
     case NS_STYLE_TEXT_DECORATION_STYLE_DOUBLE:
       /**
        *  We are drawing double line as:
        *
        * +-------------------------------------------+
        * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| ^
        * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| | lineHeight
        * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| v
        * |                                           |
        * |                                           |
        * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| ^
        * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| | lineHeight
        * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| v
        * +-------------------------------------------+
        */
       aGfxContext->NewPath();
       aGfxContext->MoveTo(rect.TopLeft());
       aGfxContext->LineTo(rect.TopRight());
       rect.height -= lineHeight;
       aGfxContext->MoveTo(rect.BottomLeft());
       aGfxContext->LineTo(rect.BottomRight());
       aGfxContext->Stroke();
       break;
     case NS_STYLE_TEXT_DECORATION_STYLE_DOTTED:
     case NS_STYLE_TEXT_DECORATION_STYLE_DASHED:
       aGfxContext->NewPath();
       aGfxContext->MoveTo(rect.TopLeft());
       aGfxContext->LineTo(rect.TopRight());
       aGfxContext->Stroke();
       break;
     case NS_STYLE_TEXT_DECORATION_STYLE_WAVY: {
       /**
        *  We are drawing wavy line as:
        *
        *  P: Path, X: Painted pixel
        *
        *     +---------------------------------------+
        *   XX|X            XXXXXX            XXXXXX  |
        *   PP|PX          XPPPPPPX          XPPPPPPX |    ^
        *   XX|XPX        XPXXXXXXPX        XPXXXXXXPX|    |
        *     | XPX      XPX      XPX      XPX      XP|X   |adv
        *     |  XPXXXXXXPX        XPXXXXXXPX        X|PX  |
        *     |   XPPPPPPX          XPPPPPPX          |XPX v
        *     |    XXXXXX            XXXXXX           | XX
        *     +---------------------------------------+
        *      <---><--->                                ^
        *      adv  flatLengthAtVertex                   rightMost
        *
        *  1. Always starts from top-left of the drawing area, however, we need
        *     to draw  the line from outside of the rect.  Because the start
        *     point of the line is not good style if we draw from inside it.
        *  2. First, draw horizontal line from outside the rect to top-left of
        *     the rect;
        *  3. Goes down to bottom of the area at 45 degrees.
        *  4. Slides to right horizontaly, see |flatLengthAtVertex|.
        *  5. Goes up to top of the area at 45 degrees.
        *  6. Slides to right horizontaly.
        *  7. Repeat from 2 until reached to right-most edge of the area.
        */
       gfxFloat adv = rect.Height() - lineHeight;
       gfxFloat flatLengthAtVertex = std::max((lineHeight - 1.0) * 2.0, 1.0);
       // Align the start of wavy lines to the nearest ancestor block.
       gfxFloat cycleLength = 2 * (adv + flatLengthAtVertex);
       rect = ExpandPaintingRectForDecorationLine(aFrame, aStyle, rect,
                                                  aXInFrame, cycleLength);
       // figure out if we can trim whole cycles from the left and right edges
       // of the line, to try and avoid creating an unnecessarily long and
       // complex path
       int32_t skipCycles = floor((aDirtyRect.x - rect.x) / cycleLength);
       if (skipCycles > 0) {
         rect.x += skipCycles * cycleLength;
         rect.width -= skipCycles * cycleLength;
       }
       rect.x += lineHeight / 2.0;
       gfxPoint pt(rect.TopLeft());
       gfxFloat rightMost = pt.x + rect.Width() + lineHeight;
       skipCycles = floor((rightMost - aDirtyRect.XMost()) / cycleLength);
       if (skipCycles > 0) {
         rightMost -= skipCycles * cycleLength;
       }
       aGfxContext->NewPath();
       pt.x -= lineHeight;
       aGfxContext->MoveTo(pt); // 1
       pt.x = rect.X();
       aGfxContext->LineTo(pt); // 2
       bool goDown = true;
       uint32_t iter = 0;
       while (pt.x < rightMost) {
         if (++iter > 1000) {
           // stroke the current path and start again, to avoid pathological
           // behavior in cairo with huge numbers of path segments
           aGfxContext->Stroke();
           aGfxContext->NewPath();
           aGfxContext->MoveTo(pt);
           iter = 0;
         }
         pt.x += adv;
         pt.y += goDown ? adv : -adv;
         aGfxContext->LineTo(pt); // 3 and 5
         pt.x += flatLengthAtVertex;
         aGfxContext->LineTo(pt); // 4 and 6
         goDown = !goDown;
       }
       aGfxContext->Stroke();
       break;
     }
     default:
       NS_ERROR("Invalid style value!");
       break;
   }
   if (contextIsSaved) {
     aGfxContext->Restore();
   } else {
     aGfxContext->SetPattern(oldPattern);
     aGfxContext->SetLineWidth(oldLineWidth);
   }
 }
 void
 nsCSSRendering::DecorationLineToPath(nsIFrame* aFrame,
                                      gfxContext* aGfxContext,
                                      const gfxRect& aDirtyRect,
                                      const nscolor aColor,
                                      const gfxPoint& aPt,
                                      const gfxFloat aXInFrame,
                                      const gfxSize& aLineSize,
                                      const gfxFloat aAscent,
                                      const gfxFloat aOffset,
                                      const uint8_t aDecoration,
                                      const uint8_t aStyle,
                                      const gfxFloat aDescentLimit)
 {
   NS_ASSERTION(aStyle != NS_STYLE_TEXT_DECORATION_STYLE_NONE, "aStyle is none");
   aGfxContext->NewPath();
   gfxRect rect =
     GetTextDecorationRectInternal(aPt, aLineSize, aAscent, aOffset,
                                   aDecoration, aStyle, aDescentLimit);
   if (rect.IsEmpty() || !rect.Intersects(aDirtyRect)) {
     return;
   }
   if (aDecoration != NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE &&
       aDecoration != NS_STYLE_TEXT_DECORATION_LINE_OVERLINE &&
       aDecoration != NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH) {
     NS_ERROR("Invalid decoration value!");
     return;
   }
   if (aStyle != NS_STYLE_TEXT_DECORATION_STYLE_SOLID) {
     // For the moment, we support only solid text decorations.
     return;
   }
   gfxFloat lineHeight = std::max(NS_round(aLineSize.height), 1.0);
   // The y position should be set to the middle of the line.
   rect.y += lineHeight / 2;
   aGfxContext->Rectangle
     (gfxRect(gfxPoint(rect.TopLeft() - gfxPoint(0.0, lineHeight / 2)),
              gfxSize(rect.Width(), lineHeight)));
 }
 nsRect
 nsCSSRendering::GetTextDecorationRect(nsPresContext* aPresContext,
                                       const gfxSize& aLineSize,
                                       const gfxFloat aAscent,
                                       const gfxFloat aOffset,
                                       const uint8_t aDecoration,
                                       const uint8_t aStyle,
                                       const gfxFloat aDescentLimit)
 {
   NS_ASSERTION(aPresContext, "aPresContext is null");
   NS_ASSERTION(aStyle != NS_STYLE_TEXT_DECORATION_STYLE_NONE, "aStyle is none");
   gfxRect rect =
     GetTextDecorationRectInternal(gfxPoint(0, 0), aLineSize, aAscent, aOffset,
                                   aDecoration, aStyle, aDescentLimit);
   // The rect values are already rounded to nearest device pixels.
   nsRect r;
   r.x = aPresContext->GfxUnitsToAppUnits(rect.X());
   r.y = aPresContext->GfxUnitsToAppUnits(rect.Y());
   r.width = aPresContext->GfxUnitsToAppUnits(rect.Width());
   r.height = aPresContext->GfxUnitsToAppUnits(rect.Height());
   return r;
 }
 gfxRect
 nsCSSRendering::GetTextDecorationRectInternal(const gfxPoint& aPt,
                                               const gfxSize& aLineSize,
                                               const gfxFloat aAscent,
                                               const gfxFloat aOffset,
                                               const uint8_t aDecoration,
                                               const uint8_t aStyle,
                                               const gfxFloat aDescentLimit)
 {
   NS_ASSERTION(aStyle <= NS_STYLE_TEXT_DECORATION_STYLE_WAVY,
                "Invalid aStyle value");
   if (aStyle == NS_STYLE_TEXT_DECORATION_STYLE_NONE)
     return gfxRect(0, 0, 0, 0);
   bool canLiftUnderline = aDescentLimit >= 0.0;
   const gfxFloat left  = floor(aPt.x + 0.5),
                  right = floor(aPt.x + aLineSize.width + 0.5);
   gfxRect r(left, 0, right - left, 0);
   gfxFloat lineHeight = NS_round(aLineSize.height);
   lineHeight = std::max(lineHeight, 1.0);
   gfxFloat ascent = NS_round(aAscent);
   gfxFloat descentLimit = floor(aDescentLimit);
   gfxFloat suggestedMaxRectHeight = std::max(std::min(ascent, descentLimit), 1.0);
   r.height = lineHeight;
   if (aStyle == NS_STYLE_TEXT_DECORATION_STYLE_DOUBLE) {
     /**
      *  We will draw double line as:
      *
      * +-------------------------------------------+
      * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| ^
      * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| | lineHeight
      * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| v
      * |                                           | ^
      * |                                           | | gap
      * |                                           | v
      * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| ^
      * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| | lineHeight
      * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| v
      * +-------------------------------------------+
      */
     gfxFloat gap = NS_round(lineHeight / 2.0);
     gap = std::max(gap, 1.0);
     r.height = lineHeight * 2.0 + gap;
     if (canLiftUnderline) {
       if (r.Height() > suggestedMaxRectHeight) {
         // Don't shrink the line height, because the thickness has some meaning.
         // We can just shrink the gap at this time.
         r.height = std::max(suggestedMaxRectHeight, lineHeight * 2.0 + 1.0);
       }
     }
   } else if (aStyle == NS_STYLE_TEXT_DECORATION_STYLE_WAVY) {
     /**
      *  We will draw wavy line as:
      *
      * +-------------------------------------------+
      * |XXXXX            XXXXXX            XXXXXX  | ^
      * |XXXXXX          XXXXXXXX          XXXXXXXX | | lineHeight
      * |XXXXXXX        XXXXXXXXXX        XXXXXXXXXX| v
      * |     XXX      XXX      XXX      XXX      XX|
      * |      XXXXXXXXXX        XXXXXXXXXX        X|
      * |       XXXXXXXX          XXXXXXXX          |
      * |        XXXXXX            XXXXXX           |
      * +-------------------------------------------+
      */
     r.height = lineHeight > 2.0 ? lineHeight * 4.0 : lineHeight * 3.0;
     if (canLiftUnderline) {
       if (r.Height() > suggestedMaxRectHeight) {
         // Don't shrink the line height even if there is not enough space,
         // because the thickness has some meaning.  E.g., the 1px wavy line and
         // 2px wavy line can be used for different meaning in IME selections
         // at same time.
         r.height = std::max(suggestedMaxRectHeight, lineHeight * 2.0);
       }
     }
   }
   gfxFloat baseline = floor(aPt.y + aAscent + 0.5);
   gfxFloat offset = 0.0;
   switch (aDecoration) {
     case NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE:
       offset = aOffset;
       if (canLiftUnderline) {
         if (descentLimit < -offset + r.Height()) {
           // If we can ignore the offset and the decoration line is overflowing,
           // we should align the bottom edge of the decoration line rect if it's
           // possible.  Otherwise, we should lift up the top edge of the rect as
           // far as possible.
           gfxFloat offsetBottomAligned = -descentLimit + r.Height();
           gfxFloat offsetTopAligned = 0.0;
           offset = std::min(offsetBottomAligned, offsetTopAligned);
         }
       }
       break;
     case NS_STYLE_TEXT_DECORATION_LINE_OVERLINE:
       offset = aOffset - lineHeight + r.Height();
       break;
     case NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH: {
       gfxFloat extra = floor(r.Height() / 2.0 + 0.5);
       extra = std::max(extra, lineHeight);
       offset = aOffset - lineHeight + extra;
       break;
     }
     default:
       NS_ERROR("Invalid decoration value!");
   }
   r.y = baseline - floor(offset + 0.5);
   return r;
 }
 // ------------------
 // ImageRenderer
 // ------------------
 nsImageRenderer::nsImageRenderer(nsIFrame* aForFrame,
                                  const nsStyleImage* aImage,
                                  uint32_t aFlags)
   : mForFrame(aForFrame)
   , mImage(aImage)
   , mType(aImage->GetType())
   , mImageContainer(nullptr)
   , mGradientData(nullptr)
   , mPaintServerFrame(nullptr)
   , mIsReady(false)
   , mSize(0, 0)
   , mFlags(aFlags)
 {
 }
 nsImageRenderer::~nsImageRenderer()
 {
 }
 bool
 nsImageRenderer::PrepareImage()
 {
   if (mImage->IsEmpty())
     return false;
   if (!mImage->IsComplete()) {
     // Make sure the image is actually decoding
     mImage->StartDecoding();
     // check again to see if we finished
     if (!mImage->IsComplete()) {
       // We can not prepare the image for rendering if it is not fully loaded.
       //
       // Special case: If we requested a sync decode and we have an image, push
       // on through because the Draw() will do a sync decode then
       nsCOMPtr<imgIContainer> img;
       if (!((mFlags & FLAG_SYNC_DECODE_IMAGES) &&
             (mType == eStyleImageType_Image) &&
             (NS_SUCCEEDED(mImage->GetImageData()->GetImage(getter_AddRefs(img))))))
         return false;
     }
   }
   switch (mType) {
     case eStyleImageType_Image:
     {
       nsCOMPtr<imgIContainer> srcImage;
       DebugOnly<nsresult> rv =
         mImage->GetImageData()->GetImage(getter_AddRefs(srcImage));
       NS_ABORT_IF_FALSE(NS_SUCCEEDED(rv) && srcImage,
                         "If GetImage() is failing, mImage->IsComplete() "
                         "should have returned false");
       if (!mImage->GetCropRect()) {
         mImageContainer.swap(srcImage);
       } else {
         nsIntRect actualCropRect;
         bool isEntireImage;
         bool success =
           mImage->ComputeActualCropRect(actualCropRect, &isEntireImage);
         NS_ASSERTION(success, "ComputeActualCropRect() should not fail here");
         if (!success || actualCropRect.IsEmpty()) {
           // The cropped image has zero size
           return false;
         }
         if (isEntireImage) {
           // The cropped image is identical to the source image
           mImageContainer.swap(srcImage);
         } else {
           nsCOMPtr<imgIContainer> subImage = ImageOps::Clip(srcImage, actualCropRect);
           mImageContainer.swap(subImage);
         }
       }
       mIsReady = true;
       break;
     }
     case eStyleImageType_Gradient:
       mGradientData = mImage->GetGradientData();
       mIsReady = true;
       break;
     case eStyleImageType_Element:
     {
       nsAutoString elementId =
         NS_LITERAL_STRING("#") + nsDependentString(mImage->GetElementId());
       nsCOMPtr<nsIURI> targetURI;
       nsCOMPtr<nsIURI> base = mForFrame->GetContent()->GetBaseURI();
       nsContentUtils::NewURIWithDocumentCharset(getter_AddRefs(targetURI), elementId,
                                                 mForFrame->GetContent()->GetCurrentDoc(), base);
       nsSVGPaintingProperty* property = nsSVGEffects::GetPaintingPropertyForURI(
           targetURI, mForFrame->FirstContinuation(),
           nsSVGEffects::BackgroundImageProperty());
       if (!property)
         return false;
       mPaintServerFrame = property->GetReferencedFrame();
       // If the referenced element doesn't have a frame we might still be able
       // to paint it if it's an <img>, <canvas>, or <video> element.
       if (!mPaintServerFrame) {
         mImageElementSurface =
           nsLayoutUtils::SurfaceFromElement(property->GetReferencedElement());
         if (!mImageElementSurface.mSourceSurface)
           return false;
       }
       mIsReady = true;
       break;
     }
     case eStyleImageType_Null:
     default:
       break;
   }
   return mIsReady;
 }
 nsSize
 CSSSizeOrRatio::ComputeConcreteSize() const
 {
   NS_ASSERTION(CanComputeConcreteSize(), "Cannot compute");
   if (mHasWidth && mHasHeight) {
     return nsSize(mWidth, mHeight);
   }
   if (mHasWidth) {
     nscoord height = NSCoordSaturatingNonnegativeMultiply(
       mWidth,
       double(mRatio.height) / mRatio.width);
     return nsSize(mWidth, height);
   }
   MOZ_ASSERT(mHasHeight);
   nscoord width = NSCoordSaturatingNonnegativeMultiply(
     mHeight,
     double(mRatio.width) / mRatio.height);
   return nsSize(width, mHeight);
 }
 CSSSizeOrRatio
 nsImageRenderer::ComputeIntrinsicSize()
 {
   NS_ASSERTION(mIsReady, "Ensure PrepareImage() has returned true "
                          "before calling me");
   CSSSizeOrRatio result;
   switch (mType) {
     case eStyleImageType_Image:
     {
       bool haveWidth, haveHeight;
       nsIntSize imageIntSize;
       nsLayoutUtils::ComputeSizeForDrawing(mImageContainer, imageIntSize,
                                            result.mRatio, haveWidth, haveHeight);
       if (haveWidth) {
         result.SetWidth(nsPresContext::CSSPixelsToAppUnits(imageIntSize.width));
       }
       if (haveHeight) {
         result.SetHeight(nsPresContext::CSSPixelsToAppUnits(imageIntSize.height));
       }
       break;
     }
     case eStyleImageType_Element:
     {
       // XXX element() should have the width/height of the referenced element,
       //     and that element's ratio, if it matches.  If it doesn't match, it
       //     should have no width/height or ratio.  See element() in CSS images:
       //     <http://dev.w3.org/csswg/css-images-4/#element-notation>.
       //     Make sure to change nsStyleBackground::Size::DependsOnFrameSize
       //     when fixing this!
       if (mPaintServerFrame) {
         // SVG images have no intrinsic size
         if (!mPaintServerFrame->IsFrameOfType(nsIFrame::eSVG)) {
           // The intrinsic image size for a generic nsIFrame paint server is
           // the union of the border-box rects of all of its continuations,
           // rounded to device pixels.
           int32_t appUnitsPerDevPixel =
             mForFrame->PresContext()->AppUnitsPerDevPixel();
           result.SetSize(
             nsSVGIntegrationUtils::GetContinuationUnionSize(mPaintServerFrame).
               ToNearestPixels(appUnitsPerDevPixel).
               ToAppUnits(appUnitsPerDevPixel));
         }
       } else {
         NS_ASSERTION(mImageElementSurface.mSourceSurface, "Surface should be ready.");
         gfxIntSize surfaceSize = mImageElementSurface.mSize;
         result.SetSize(
           nsSize(nsPresContext::CSSPixelsToAppUnits(surfaceSize.width),
                  nsPresContext::CSSPixelsToAppUnits(surfaceSize.height)));
       }
       break;
     }
     case eStyleImageType_Gradient:
       // Per <http://dev.w3.org/csswg/css3-images/#gradients>, gradients have no
       // intrinsic dimensions.
     case eStyleImageType_Null:
     default:
       break;
   }
   return result;
 }
 /* static */ nsSize
 nsImageRenderer::ComputeConcreteSize(const CSSSizeOrRatio& aSpecifiedSize,
                                      const CSSSizeOrRatio& aIntrinsicSize,
                                      const nsSize& aDefaultSize)
 {
   // The specified size is fully specified, just use that
   if (aSpecifiedSize.IsConcrete()) {
     return aSpecifiedSize.ComputeConcreteSize();
   }
   MOZ_ASSERT(!aSpecifiedSize.mHasWidth || !aSpecifiedSize.mHasHeight);
   if (!aSpecifiedSize.mHasWidth && !aSpecifiedSize.mHasHeight) {
     // no specified size, try using the intrinsic size
     if (aIntrinsicSize.CanComputeConcreteSize()) {
       return aIntrinsicSize.ComputeConcreteSize();
     }
     if (aIntrinsicSize.mHasWidth) {
       return nsSize(aIntrinsicSize.mWidth, aDefaultSize.height);
     }
     if (aIntrinsicSize.mHasHeight) {
       return nsSize(aDefaultSize.width, aIntrinsicSize.mHeight);
     }
     // couldn't use the intrinsic size either, revert to using the default size
     return ComputeConstrainedSize(aDefaultSize,
                                   aIntrinsicSize.mRatio,
                                   CONTAIN);
   }
   MOZ_ASSERT(aSpecifiedSize.mHasWidth || aSpecifiedSize.mHasHeight);
   // The specified height is partial, try to compute the missing part.
   if (aSpecifiedSize.mHasWidth) {
     nscoord height;
     if (aIntrinsicSize.HasRatio()) {
       height = NSCoordSaturatingNonnegativeMultiply(
         aSpecifiedSize.mWidth,
         double(aIntrinsicSize.mRatio.height) / aIntrinsicSize.mRatio.width);
     } else if (aIntrinsicSize.mHasHeight) {
       height = aIntrinsicSize.mHeight;
     } else {
       height = aDefaultSize.height;
     }
     return nsSize(aSpecifiedSize.mWidth, height);
   }
   MOZ_ASSERT(aSpecifiedSize.mHasHeight);
   nscoord width;
   if (aIntrinsicSize.HasRatio()) {
     width = NSCoordSaturatingNonnegativeMultiply(
       aSpecifiedSize.mHeight,
       double(aIntrinsicSize.mRatio.width) / aIntrinsicSize.mRatio.height);
   } else if (aIntrinsicSize.mHasWidth) {
     width = aIntrinsicSize.mWidth;
   } else {
     width = aDefaultSize.width;
   }
   return nsSize(width, aSpecifiedSize.mHeight);
 }
 /* static */ nsSize
 nsImageRenderer::ComputeConstrainedSize(const nsSize& aConstrainingSize,
                                         const nsSize& aIntrinsicRatio,
                                         FitType aFitType)
 {
   if (aIntrinsicRatio.width <= 0 && aIntrinsicRatio.height <= 0) {
     return aConstrainingSize;
   }
   float scaleX = double(aConstrainingSize.width) / aIntrinsicRatio.width;
   float scaleY = double(aConstrainingSize.height) / aIntrinsicRatio.height;
   nsSize size;
   if ((aFitType == CONTAIN) == (scaleX < scaleY)) {
     size.width = aConstrainingSize.width;
     size.height = NSCoordSaturatingNonnegativeMultiply(
                     aIntrinsicRatio.height, scaleX);
   } else {
     size.width = NSCoordSaturatingNonnegativeMultiply(
                    aIntrinsicRatio.width, scaleY);
     size.height = aConstrainingSize.height;
   }
   return size;
 }
 /**
  * mSize is the image's "preferred" size for this particular rendering, while
  * the drawn (aka concrete) size is the actual rendered size after accounting
  * for background-size etc..  The preferred size is most often the image's
  * intrinsic dimensions.  But for images with incomplete intrinsic dimensions,
  * the preferred size varies, depending on the specified and default sizes, see
  * nsImageRenderer::Compute*Size.
  *
  * This distinction is necessary because the components of a vector image are
  * specified with respect to its preferred size for a rendering situation, not
  * to its actual rendered size.  For example, consider a 4px wide background
  * vector image with no height which contains a left-aligned
  * 2px wide black rectangle with height 100%.  If the background-size width is
  * auto (or 4px), the vector image will render 4px wide, and the black rectangle
  * will be 2px wide.  If the background-size width is 8px, the vector image will
  * render 8px wide, and the black rectangle will be 4px wide -- *not* 2px wide.
  * In both cases mSize.width will be 4px; but in the first case the returned
  * width will be 4px, while in the second case the returned width will be 8px.
  */
 void
 nsImageRenderer::SetPreferredSize(const CSSSizeOrRatio& aIntrinsicSize,
                                   const nsSize& aDefaultSize)
 {
   mSize.width = aIntrinsicSize.mHasWidth
                   ? aIntrinsicSize.mWidth
                   : aDefaultSize.width;
   mSize.height = aIntrinsicSize.mHasHeight
                   ? aIntrinsicSize.mHeight
                   : aDefaultSize.height;
 }
 // Convert from nsImageRenderer flags to the flags we want to use for drawing in
 // the imgIContainer namespace.
 static uint32_t
 ConvertImageRendererToDrawFlags(uint32_t aImageRendererFlags)
 {
   uint32_t drawFlags = imgIContainer::FLAG_NONE;
   if (aImageRendererFlags & nsImageRenderer::FLAG_SYNC_DECODE_IMAGES) {
     drawFlags |= imgIContainer::FLAG_SYNC_DECODE;
   }
   if (aImageRendererFlags & nsImageRenderer::FLAG_PAINTING_TO_WINDOW) {
     drawFlags |= imgIContainer::FLAG_HIGH_QUALITY_SCALING;
   }
   return drawFlags;
 }
 void
 nsImageRenderer::Draw(nsPresContext*       aPresContext,
                       nsRenderingContext&  aRenderingContext,
                       const nsRect&        aDirtyRect,
                       const nsRect&        aFill,
                       const nsRect&        aDest,
                       const CSSIntRect&    aSrc)
 {
   if (!mIsReady) {
     NS_NOTREACHED("Ensure PrepareImage() has returned true before calling me");
     return;
   }
   if (aDest.IsEmpty() || aFill.IsEmpty() ||
       mSize.width <= 0 || mSize.height <= 0) {
     return;
   }
   GraphicsFilter graphicsFilter =
     nsLayoutUtils::GetGraphicsFilterForFrame(mForFrame);
   switch (mType) {
     case eStyleImageType_Image:
     {
       nsLayoutUtils::DrawSingleImage(&aRenderingContext, mImageContainer,
                                      graphicsFilter, aFill, aDirtyRect,
                                      nullptr,
                                      ConvertImageRendererToDrawFlags(mFlags));
       return;
     }
     case eStyleImageType_Gradient:
     {
       nsCSSRendering::PaintGradient(aPresContext, aRenderingContext,
                                     mGradientData, aDirtyRect,
                                     aDest, aFill, aSrc, mSize);
       return;
     }
     case eStyleImageType_Element:
     {
       nsRefPtr<gfxDrawable> drawable = DrawableForElement(aDest,
                                                           aRenderingContext);
       if (!drawable) {
         NS_WARNING("Could not create drawable for element");
         return;
       }
       nsLayoutUtils::DrawPixelSnapped(&aRenderingContext, drawable, graphicsFilter,
                                       aDest, aFill, aDest.TopLeft(), aDirtyRect);
       return;
     }
     case eStyleImageType_Null:
     default:
       return;
   }
 }
 already_AddRefed<gfxDrawable>
 nsImageRenderer::DrawableForElement(const nsRect& aImageRect,
                                     nsRenderingContext&  aRenderingContext)
 {
   NS_ASSERTION(mType == eStyleImageType_Element,
                "DrawableForElement only makes sense if backed by an element");
   if (mPaintServerFrame) {
     int32_t appUnitsPerDevPixel = mForFrame->PresContext()->AppUnitsPerDevPixel();
     nsRect destRect = aImageRect - aImageRect.TopLeft();
     nsIntSize roundedOut = destRect.ToOutsidePixels(appUnitsPerDevPixel).Size();
     gfxIntSize imageSize(roundedOut.width, roundedOut.height);
     nsRefPtr<gfxDrawable> drawable =
       nsSVGIntegrationUtils::DrawableFromPaintServer(
         mPaintServerFrame, mForFrame, mSize, imageSize,
         aRenderingContext.ThebesContext()->CurrentMatrix(),
         mFlags & FLAG_SYNC_DECODE_IMAGES
           ? nsSVGIntegrationUtils::FLAG_SYNC_DECODE_IMAGES
           : 0);
     return drawable.forget();
   }
   NS_ASSERTION(mImageElementSurface.mSourceSurface, "Surface should be ready.");
   nsRefPtr<gfxDrawable> drawable = new gfxSurfaceDrawable(
                                 mImageElementSurface.mSourceSurface,
                                 mImageElementSurface.mSize);
   return drawable.forget();
 }
 void
 nsImageRenderer::DrawBackground(nsPresContext*       aPresContext,
                                 nsRenderingContext&  aRenderingContext,
                                 const nsRect&        aDest,
                                 const nsRect&        aFill,
                                 const nsPoint&       aAnchor,
                                 const nsRect&        aDirty)
 {
   if (!mIsReady) {
     NS_NOTREACHED("Ensure PrepareImage() has returned true before calling me");
     return;
   }
   if (aDest.IsEmpty() || aFill.IsEmpty() ||
       mSize.width <= 0 || mSize.height <= 0) {
     return;
   }
   if (mType == eStyleImageType_Image) {
     GraphicsFilter graphicsFilter =
       nsLayoutUtils::GetGraphicsFilterForFrame(mForFrame);
     nsLayoutUtils::DrawBackgroundImage(&aRenderingContext, mImageContainer,
                 nsIntSize(nsPresContext::AppUnitsToIntCSSPixels(mSize.width),
                           nsPresContext::AppUnitsToIntCSSPixels(mSize.height)),
                 graphicsFilter,
                 aDest, aFill, aAnchor, aDirty,
                 ConvertImageRendererToDrawFlags(mFlags));
     return;
   }
   Draw(aPresContext, aRenderingContext,
        aDirty, aFill, aDest,
        CSSIntRect(0, 0,
                   nsPresContext::AppUnitsToIntCSSPixels(mSize.width),
                   nsPresContext::AppUnitsToIntCSSPixels(mSize.height)));
 }
 /**
  * Compute the size and position of the master copy of the image. I.e., a single
  * tile used to fill the dest rect.
  * aFill The destination rect to be filled
  * aHFill and aVFill are the repeat patterns for the component -
  * NS_STYLE_BORDER_IMAGE_REPEAT_* - i.e., how a tiling unit is used to fill aFill
  * aUnitSize The size of the source rect in dest coords.
  */
 static nsRect
 ComputeTile(const nsRect&        aFill,
             uint8_t              aHFill,
             uint8_t              aVFill,
             const nsSize&        aUnitSize)
 {
   nsRect tile;
   switch (aHFill) {
   case NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH:
     tile.x = aFill.x;
     tile.width = aFill.width;
     break;
   case NS_STYLE_BORDER_IMAGE_REPEAT_REPEAT:
     tile.x = aFill.x + aFill.width/2 - aUnitSize.width/2;
     tile.width = aUnitSize.width;
     break;
   case NS_STYLE_BORDER_IMAGE_REPEAT_ROUND:
     tile.x = aFill.x;
     tile.width = aFill.width / ceil(gfxFloat(aFill.width)/aUnitSize.width);
     break;
   default:
     NS_NOTREACHED("unrecognized border-image fill style");
   }
   switch (aVFill) {
   case NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH:
     tile.y = aFill.y;
     tile.height = aFill.height;
     break;
   case NS_STYLE_BORDER_IMAGE_REPEAT_REPEAT:
     tile.y = aFill.y + aFill.height/2 - aUnitSize.height/2;
     tile.height = aUnitSize.height;
     break;
   case NS_STYLE_BORDER_IMAGE_REPEAT_ROUND:
     tile.y = aFill.y;
     tile.height = aFill.height/ceil(gfxFloat(aFill.height)/aUnitSize.height);
     break;
   default:
     NS_NOTREACHED("unrecognized border-image fill style");
   }
   return tile;
 }
 /**
  * Returns true if the given set of arguments will require the tiles which fill
  * the dest rect to be scaled from the source tile. See comment on ComputeTile
  * for argument descriptions.
  */
 static bool
 RequiresScaling(const nsRect&        aFill,
                 uint8_t              aHFill,
                 uint8_t              aVFill,
                 const nsSize&        aUnitSize)
 {
   // If we have no tiling in either direction, we can skip the intermediate
   // scaling step.
   return (aHFill != NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH ||
           aVFill != NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH) &&
          (aUnitSize.width != aFill.width ||
           aUnitSize.height != aFill.height);
 }
 void
 nsImageRenderer::DrawBorderImageComponent(nsPresContext*       aPresContext,
                                           nsRenderingContext&  aRenderingContext,
                                           const nsRect&        aDirtyRect,
                                           const nsRect&        aFill,
                                           const CSSIntRect&    aSrc,
                                           uint8_t              aHFill,
                                           uint8_t              aVFill,
                                           const nsSize&        aUnitSize,
                                           uint8_t              aIndex)
 {
   if (!mIsReady) {
     NS_NOTREACHED("Ensure PrepareImage() has returned true before calling me");
     return;
   }
   if (aFill.IsEmpty() || aSrc.IsEmpty()) {
     return;
   }
   if (mType == eStyleImageType_Image) {
     nsCOMPtr<imgIContainer> subImage;
     if ((subImage = mImage->GetSubImage(aIndex)) == nullptr) {
       subImage = ImageOps::Clip(mImageContainer, nsIntRect(aSrc.x,
                                                            aSrc.y,
                                                            aSrc.width,
                                                            aSrc.height));
       mImage->SetSubImage(aIndex, subImage);
     }
     GraphicsFilter graphicsFilter =
       nsLayoutUtils::GetGraphicsFilterForFrame(mForFrame);
     if (!RequiresScaling(aFill, aHFill, aVFill, aUnitSize)) {
       nsLayoutUtils::DrawSingleImage(&aRenderingContext,
                                      subImage,
                                      graphicsFilter,
                                      aFill, aDirtyRect,
                                      nullptr,
                                      imgIContainer::FLAG_NONE);
       return;
     }
     nsRect tile = ComputeTile(aFill, aHFill, aVFill, aUnitSize);
     nsLayoutUtils::DrawImage(&aRenderingContext,
                              subImage,
                              graphicsFilter,
                              tile, aFill, tile.TopLeft(), aDirtyRect,
                              imgIContainer::FLAG_NONE);
     return;
   }
   nsRect destTile = RequiresScaling(aFill, aHFill, aVFill, aUnitSize)
                   ? ComputeTile(aFill, aHFill, aVFill, aUnitSize)
                   : aFill;
   if (mType == eStyleImageType_Element) {
     // This path is horribly slow - we read and copy the source nine times(!)
     // It could be easily optimised by only reading the source once and caching
     // it. It could be further optimised by caching the sub-images between draws
     // but that would be a bit harder because you would have to know when to
     // invalidate the cache. A special case optimisation would be when
     // border-image-slice is proportional to the border widths, in which case
     // the subimages do not need to be independently scaled, then we don't need
     // subimages at all.
     // In any case, such optimisations are probably not worth doing because it
     // seems unlikely anyone would use -moz-element as the source for a border
     // image.
     // draw the source image slice into an intermediate surface
     nsPresContext* presContext = mForFrame->PresContext();
     gfxRect srcRect = gfxRect(presContext->CSSPixelsToDevPixels(aSrc.x),
                               presContext->CSSPixelsToDevPixels(aSrc.y),
                               presContext->CSSPixelsToDevPixels(aSrc.width),
                               presContext->CSSPixelsToDevPixels(aSrc.height));
     RefPtr<DrawTarget> srcSlice = gfxPlatform::GetPlatform()->
       CreateOffscreenContentDrawTarget(IntSize(srcRect.width, srcRect.height),
                              SurfaceFormat::B8G8R8A8);
     nsRefPtr<gfxContext> ctx = new gfxContext(srcSlice);
     // grab the entire source
     nsRefPtr<gfxDrawable> drawable = DrawableForElement(nsRect(nsPoint(), mSize),
                                                         aRenderingContext);
     if (!drawable) {
       NS_WARNING("Could not create drawable for element");
       return;
     }
     // draw the source into our intermediate surface
     GraphicsFilter graphicsFilter =
       nsLayoutUtils::GetGraphicsFilterForFrame(mForFrame);
     gfxMatrix transform;
     transform.Translate(gfxPoint(srcRect.x, srcRect.y));
     bool success = drawable->Draw(ctx,
                                   gfxRect(0, 0, srcRect.width, srcRect.height),
                                   false,
                                   graphicsFilter,
                                   transform);
     if (!success) {
       NS_WARNING("Could not copy element image");
       return;
     }
     // Ensure that drawing the image gets flushed to the target.
     ctx = nullptr;
     // draw the slice
     nsRefPtr<gfxSurfaceDrawable> srcSliceDrawable =
       new gfxSurfaceDrawable(srcSlice,
                              gfxIntSize(srcRect.width, srcRect.height));
     nsPoint anchor(nsPresContext::CSSPixelsToAppUnits(aSrc.x),
                    nsPresContext::CSSPixelsToAppUnits(aSrc.y));
     nsLayoutUtils::DrawPixelSnapped(&aRenderingContext, srcSliceDrawable,
                                     graphicsFilter, destTile, aFill,
                                     anchor, aDirtyRect);
     return;
   }
   Draw(aPresContext, aRenderingContext, aDirtyRect, aFill, destTile, aSrc);
 }
 bool
 nsImageRenderer::IsRasterImage()
 {
   if (mType != eStyleImageType_Image || !mImageContainer)
     return false;
   return mImageContainer->GetType() == imgIContainer::TYPE_RASTER;
 }
 bool
 nsImageRenderer::IsAnimatedImage()
 {
   if (mType != eStyleImageType_Image || !mImageContainer)
     return false;
   bool animated = false;
   if (NS_SUCCEEDED(mImageContainer->GetAnimated(&animated)) && animated)
     return true;
   return false;
 }
 already_AddRefed<mozilla::layers::ImageContainer>
 nsImageRenderer::GetContainer(LayerManager* aManager)
 {
   if (mType != eStyleImageType_Image || !mImageContainer)
     return nullptr;
   nsRefPtr<ImageContainer> container;
   nsresult rv = mImageContainer->GetImageContainer(aManager, getter_AddRefs(container));
   NS_ENSURE_SUCCESS(rv, nullptr);
   return container.forget();
 }
 #define MAX_BLUR_RADIUS 300
 #define MAX_SPREAD_RADIUS 50
 static inline gfxPoint ComputeBlurStdDev(nscoord aBlurRadius,
                                          int32_t aAppUnitsPerDevPixel,
                                          gfxFloat aScaleX,
                                          gfxFloat aScaleY)
 {
   // http://dev.w3.org/csswg/css3-background/#box-shadow says that the
   // standard deviation of the blur should be half the given blur value.
   gfxFloat blurStdDev = gfxFloat(aBlurRadius) / gfxFloat(aAppUnitsPerDevPixel);
   return gfxPoint(std::min((blurStdDev * aScaleX),
                            gfxFloat(MAX_BLUR_RADIUS)) / 2.0,
                   std::min((blurStdDev * aScaleY),
                            gfxFloat(MAX_BLUR_RADIUS)) / 2.0);
 }
 static inline gfxIntSize
 ComputeBlurRadius(nscoord aBlurRadius,
                   int32_t aAppUnitsPerDevPixel,
                   gfxFloat aScaleX = 1.0,
                   gfxFloat aScaleY = 1.0)
 {
   gfxPoint scaledBlurStdDev = ComputeBlurStdDev(aBlurRadius, aAppUnitsPerDevPixel,
                                                 aScaleX, aScaleY);
   return
     gfxAlphaBoxBlur::CalculateBlurRadius(scaledBlurStdDev);
 }
 // -----
 // nsContextBoxBlur
 // -----
 gfxContext*
 nsContextBoxBlur::Init(const nsRect& aRect, nscoord aSpreadRadius,
                        nscoord aBlurRadius,
                        int32_t aAppUnitsPerDevPixel,
                        gfxContext* aDestinationCtx,
                        const nsRect& aDirtyRect,
                        const gfxRect* aSkipRect,
                        uint32_t aFlags)
 {
   if (aRect.IsEmpty()) {
     mContext = nullptr;
     return nullptr;
   }
   gfxFloat scaleX = 1;
   gfxFloat scaleY = 1;
   // Do blurs in device space when possible.
   // Chrome/Skia always does the blurs in device space
   // and will sometimes get incorrect results (e.g. rotated blurs)
   gfxMatrix transform = aDestinationCtx->CurrentMatrix();
   // XXX: we could probably handle negative scales but for now it's easier just to fallback
   if (transform.HasNonAxisAlignedTransform() || transform.xx <= 0.0 || transform.yy <= 0.0) {
     transform = gfxMatrix();
   } else {
     scaleX = transform.xx;
     scaleY = transform.yy;
   }
   // compute a large or smaller blur radius
   gfxIntSize blurRadius = ComputeBlurRadius(aBlurRadius, aAppUnitsPerDevPixel, scaleX, scaleY);
   gfxIntSize spreadRadius = gfxIntSize(std::min(int32_t(aSpreadRadius * scaleX / aAppUnitsPerDevPixel),
                                               int32_t(MAX_SPREAD_RADIUS)),
                                        std::min(int32_t(aSpreadRadius * scaleY / aAppUnitsPerDevPixel),
                                               int32_t(MAX_SPREAD_RADIUS)));
   mDestinationCtx = aDestinationCtx;
   // If not blurring, draw directly onto the destination device
   if (blurRadius.width <= 0 && blurRadius.height <= 0 &&
       spreadRadius.width <= 0 && spreadRadius.height <= 0 &&
       !(aFlags & FORCE_MASK)) {
     mContext = aDestinationCtx;
     return mContext;
   }
   // Convert from app units to device pixels
   gfxRect rect = nsLayoutUtils::RectToGfxRect(aRect, aAppUnitsPerDevPixel);
   gfxRect dirtyRect =
     nsLayoutUtils::RectToGfxRect(aDirtyRect, aAppUnitsPerDevPixel);
   dirtyRect.RoundOut();
   rect = transform.TransformBounds(rect);
   mPreTransformed = !transform.IsIdentity();
   // Create the temporary surface for blurring
   dirtyRect = transform.TransformBounds(dirtyRect);
   if (aSkipRect) {
     gfxRect skipRect = transform.TransformBounds(*aSkipRect);
     mContext = blur.Init(rect, spreadRadius,
                          blurRadius, &dirtyRect, &skipRect);
   } else {
     mContext = blur.Init(rect, spreadRadius,
                          blurRadius, &dirtyRect, nullptr);
   }
   if (mContext) {
     // we don't need to blur if skipRect is equal to rect
     // and mContext will be nullptr
     mContext->Multiply(transform);
   }
   return mContext;
 }
 void
 nsContextBoxBlur::DoPaint()
 {
   if (mContext == mDestinationCtx)
     return;
   gfxContextMatrixAutoSaveRestore saveMatrix(mDestinationCtx);
   if (mPreTransformed) {
     mDestinationCtx->IdentityMatrix();
   }
   blur.Paint(mDestinationCtx);
 }
 gfxContext*
 nsContextBoxBlur::GetContext()
 {
   return mContext;
 }
 /* static */ nsMargin
 nsContextBoxBlur::GetBlurRadiusMargin(nscoord aBlurRadius,
                                       int32_t aAppUnitsPerDevPixel)
 {
   gfxIntSize blurRadius = ComputeBlurRadius(aBlurRadius, aAppUnitsPerDevPixel);
   nsMargin result;
   result.top    = blurRadius.height * aAppUnitsPerDevPixel;
   result.right  = blurRadius.width  * aAppUnitsPerDevPixel;
   result.bottom = blurRadius.height * aAppUnitsPerDevPixel;
   result.left   = blurRadius.width  * aAppUnitsPerDevPixel;
   return result;
 }
 /* static */ void
 nsContextBoxBlur::BlurRectangle(gfxContext* aDestinationCtx,
                                 const nsRect& aRect,
                                 int32_t aAppUnitsPerDevPixel,
                                 gfxCornerSizes* aCornerRadii,
                                 nscoord aBlurRadius,
                                 const gfxRGBA& aShadowColor,
                                 const nsRect& aDirtyRect,
                                 const gfxRect& aSkipRect)
 {
   if (aRect.IsEmpty()) {
     return;
   }
   gfxRect shadowGfxRect =
     nsLayoutUtils::RectToGfxRect(aRect, aAppUnitsPerDevPixel);
   if (aBlurRadius <= 0) {
     aDestinationCtx->SetColor(aShadowColor);
     aDestinationCtx->NewPath();
     if (aCornerRadii) {
       aDestinationCtx->RoundedRectangle(shadowGfxRect, *aCornerRadii);
     } else {
       aDestinationCtx->Rectangle(shadowGfxRect);
     }
     aDestinationCtx->Fill();
     return;
   }
   gfxFloat scaleX = 1;
   gfxFloat scaleY = 1;
   // Do blurs in device space when possible.
   // Chrome/Skia always does the blurs in device space
   // and will sometimes get incorrect results (e.g. rotated blurs)
   gfxMatrix transform = aDestinationCtx->CurrentMatrix();
   // XXX: we could probably handle negative scales but for now it's easier just to fallback
   if (!transform.HasNonAxisAlignedTransform() && transform.xx > 0.0 && transform.yy > 0.0) {
     scaleX = transform.xx;
     scaleY = transform.yy;
     aDestinationCtx->IdentityMatrix();
   } else {
     transform = gfxMatrix();
   }
   gfxPoint blurStdDev = ComputeBlurStdDev(aBlurRadius, aAppUnitsPerDevPixel, scaleX, scaleY);
   gfxRect dirtyRect =
     nsLayoutUtils::RectToGfxRect(aDirtyRect, aAppUnitsPerDevPixel);
   dirtyRect.RoundOut();
   shadowGfxRect = transform.TransformBounds(shadowGfxRect);
   dirtyRect = transform.TransformBounds(dirtyRect);
   gfxRect skipRect = transform.TransformBounds(aSkipRect);
   if (aCornerRadii) {
     aCornerRadii->Scale(scaleX, scaleY);
   }
   gfxAlphaBoxBlur::BlurRectangle(aDestinationCtx,
                                  shadowGfxRect,
                                  aCornerRadii,
                                  blurStdDev,
                                  aShadowColor,
                                  dirtyRect,
                                  skipRect);
 }

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

layout/base/nsCSSRendering.cpp