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

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

layout/base/nsLayoutUtils.h

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 -*- */
 /* 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/. */
 #ifndef nsLayoutUtils_h__
 #define nsLayoutUtils_h__
 #include "mozilla/MemoryReporting.h"
 #include "nsChangeHint.h"
 #include "nsAutoPtr.h"
 #include "nsFrameList.h"
 #include "mozilla/layout/FrameChildList.h"
 #include "nsThreadUtils.h"
 #include "nsIPrincipal.h"
 #include "GraphicsFilter.h"
 #include "nsCSSPseudoElements.h"
 #include "FrameMetrics.h"
 #include "gfx3DMatrix.h"
 #include "nsIWidget.h"
 #include "nsCSSProperty.h"
 #include "nsStyleCoord.h"
 #include "nsStyleConsts.h"
 #include "nsGkAtoms.h"
 #include "nsRuleNode.h"
 #include "imgIContainer.h"
 #include "mozilla/gfx/2D.h"
 #include "Units.h"
 #include <limits>
 #include <algorithm>
 class nsIFormControlFrame;
 class nsPresContext;
 class nsIContent;
 class nsIAtom;
 class nsIScrollableFrame;
 class nsIDOMEvent;
 class nsRegion;
 class nsDisplayListBuilder;
 class nsDisplayItem;
 class nsFontMetrics;
 class nsFontFaceList;
 class nsIImageLoadingContent;
 class nsStyleContext;
 class nsBlockFrame;
 class gfxASurface;
 class gfxDrawable;
 class nsView;
 class nsIFrame;
 class nsStyleCoord;
 class nsStyleCorners;
 class gfxContext;
 class nsPIDOMWindow;
 class imgIRequest;
 class nsIDocument;
 class gfxPoint;
 struct nsStyleFont;
 struct nsStyleImageOrientation;
 struct nsOverflowAreas;
 namespace mozilla {
 class SVGImageContext;
 struct IntrinsicSize;
 struct ContainerLayerParameters;
 namespace dom {
 class DOMRectList;
 class Element;
 class HTMLImageElement;
 class HTMLCanvasElement;
 class HTMLVideoElement;
 } // namespace dom
 namespace layers {
 class Layer;
 }
 }
 namespace mozilla {
 struct DisplayPortPropertyData {
   DisplayPortPropertyData(const nsRect& aRect, uint32_t aPriority)
     : mRect(aRect)
     , mPriority(aPriority)
   {}
   nsRect mRect;
   uint32_t mPriority;
 };
 struct DisplayPortMarginsPropertyData {
   DisplayPortMarginsPropertyData(const LayerMargin& aMargins,
                                  uint32_t aAlignmentX, uint32_t aAlignmentY,
                                  uint32_t aPriority)
     : mMargins(aMargins)
     , mAlignmentX(aAlignmentX)
     , mAlignmentY(aAlignmentY)
     , mPriority(aPriority)
   {}
   LayerMargin mMargins;
   uint32_t mAlignmentX;
   uint32_t mAlignmentY;
   uint32_t mPriority;
 };
 template <class AnimationsOrTransitions>
 extern AnimationsOrTransitions* HasAnimationOrTransition(nsIContent* aContent,
                                                          nsIAtom* aAnimationProperty,
                                                          nsCSSProperty aProperty);
 } // namespace mozilla
 /**
  * nsLayoutUtils is a namespace class used for various helper
  * functions that are useful in multiple places in layout.  The goal
  * is not to define multiple copies of the same static helper.
  */
 class nsLayoutUtils
 {
   typedef ::GraphicsFilter GraphicsFilter;
   typedef mozilla::dom::DOMRectList DOMRectList;
   typedef mozilla::layers::Layer Layer;
   typedef mozilla::ContainerLayerParameters ContainerLayerParameters;
   typedef mozilla::gfx::SourceSurface SourceSurface;
   typedef mozilla::gfx::DrawTarget DrawTarget;
   typedef mozilla::gfx::Rect Rect;
 public:
   typedef mozilla::layers::FrameMetrics FrameMetrics;
   typedef FrameMetrics::ViewID ViewID;
   typedef mozilla::CSSPoint CSSPoint;
   typedef mozilla::CSSSize CSSSize;
   typedef mozilla::LayerMargin LayerMargin;
   /**
    * Finds previously assigned ViewID for the given content element, if any.
    * Returns whether a ViewID was previously assigned.
    */
   static bool FindIDFor(const nsIContent* aContent, ViewID* aOutViewId);
   /**
    * Finds previously assigned or generates a unique ViewID for the given
    * content element.
    */
   static ViewID FindOrCreateIDFor(nsIContent* aContent);
   /**
    * Find content for given ID.
    */
   static nsIContent* FindContentFor(ViewID aId);
   /**
    * Find the scrollable frame for a given ID.
    */
   static nsIScrollableFrame* FindScrollableFrameFor(ViewID aId);
   /**
    * Get display port for the given element.
    */
   static bool GetDisplayPort(nsIContent* aContent, nsRect *aResult = nullptr);
   MOZ_BEGIN_NESTED_ENUM_CLASS(RepaintMode, uint8_t)
     Repaint,
     DoNotRepaint
   MOZ_END_NESTED_ENUM_CLASS(RepaintMode)
   /**
    * Set the display port margins for a content element to be used with a
    * display port base (see SetDisplayPortBase()).
    * See also nsIDOMWindowUtils.setDisplayPortMargins.
    * @param aContent the content element for which to set the margins
    * @param aPresShell the pres shell for the document containing the element
    * @param aMargins the margins to set
    * @param aAlignmentX, alignmentY the amount of pixels to which to align the
    *                                displayport built by combining the base
    *                                rect with the margins, in either direction
    * @param aPriority a priority value to determine which margins take effect
    *                  when multiple callers specify margins
    * @param aRepaintMode whether to schedule a paint after setting the margins
    */
   static void SetDisplayPortMargins(nsIContent* aContent,
                                     nsIPresShell* aPresShell,
                                     const LayerMargin& aMargins,
                                     uint32_t aAlignmentX,
                                     uint32_t aAlignmentY,
                                     uint32_t aPriority = 0,
                                     RepaintMode aRepaintMode = RepaintMode::Repaint);
   /**
    * Set the display port base rect for given element to be used with display
    * port margins.
    * SetDisplayPortBaseIfNotSet is like SetDisplayPortBase except it only sets
    * the display port base to aBase if no display port base is currently set.
    */
   static void SetDisplayPortBase(nsIContent* aContent, const nsRect& aBase);
   static void SetDisplayPortBaseIfNotSet(nsIContent* aContent, const nsRect& aBase);
   /**
    * Get the critical display port for the given element.
    */
   static bool GetCriticalDisplayPort(nsIContent* aContent, nsRect* aResult = nullptr);
   /**
    * Use heuristics to figure out the child list that
    * aChildFrame is currently in.
    */
   static mozilla::layout::FrameChildListID GetChildListNameFor(nsIFrame* aChildFrame);
   /**
    * GetBeforeFrame returns the outermost :before frame of the given frame, if
    * one exists.  This is typically O(1).  The frame passed in must be
    * the first-in-flow.
    *
    * @param aFrame the frame whose :before is wanted
    * @return the :before frame or nullptr if there isn't one
    */
   static nsIFrame* GetBeforeFrame(nsIFrame* aFrame);
   /**
    * GetAfterFrame returns the outermost :after frame of the given frame, if one
    * exists.  This will walk the in-flow chain to the last-in-flow if
    * needed.  This function is typically O(N) in the number of child
    * frames, following in-flows, etc.
    *
    * @param aFrame the frame whose :after is wanted
    * @return the :after frame or nullptr if there isn't one
    */
   static nsIFrame* GetAfterFrame(nsIFrame* aFrame);
   /**
    * Given a frame, search up the frame tree until we find an
    * ancestor that (or the frame itself) is of type aFrameType, if any.
    *
    * @param aFrame the frame to start at
    * @param aFrameType the frame type to look for
    * @return a frame of the given type or nullptr if no
    *         such ancestor exists
    */
   static nsIFrame* GetClosestFrameOfType(nsIFrame* aFrame, nsIAtom* aFrameType);
   /**
    * Given a frame, search up the frame tree until we find an
    * ancestor that (or the frame itself) is a "Page" frame, if any.
    *
    * @param aFrame the frame to start at
    * @return a frame of type nsGkAtoms::pageFrame or nullptr if no
    *         such ancestor exists
    */
   static nsIFrame* GetPageFrame(nsIFrame* aFrame)
   {
     return GetClosestFrameOfType(aFrame, nsGkAtoms::pageFrame);
   }
   /**
    * Given a frame which is the primary frame for an element,
    * return the frame that has the non-psuedoelement style context for
    * the content.
    * This is aPrimaryFrame itself except for tableOuter frames.
    */
   static nsIFrame* GetStyleFrame(nsIFrame* aPrimaryFrame);
   /**
    * Given a content node,
    * return the frame that has the non-psuedoelement style context for
    * the content.  May return null.
    * This is aContent->GetPrimaryFrame() except for tableOuter frames.
    */
   static nsIFrame* GetStyleFrame(const nsIContent* aContent);
   /**
    * IsGeneratedContentFor returns true if aFrame is the outermost
    * frame for generated content of type aPseudoElement for aContent.
    * aFrame *might not* have the aPseudoElement pseudo-style! For example
    * it might be a table outer frame and the inner table frame might
    * have the pseudo-style.
    *
    * @param aContent the content node we're looking at.  If this is
    *        null, then we just assume that aFrame has the right content
    *        pointer.
    * @param aFrame the frame we're looking at
    * @param aPseudoElement the pseudo type we're interested in
    * @return whether aFrame is the generated aPseudoElement frame for aContent
    */
   static bool IsGeneratedContentFor(nsIContent* aContent, nsIFrame* aFrame,
                                       nsIAtom* aPseudoElement);
 #ifdef DEBUG
   // TODO: remove, see bug 598468.
   static bool gPreventAssertInCompareTreePosition;
 #endif // DEBUG
   /**
    * CompareTreePosition determines whether aContent1 comes before or
    * after aContent2 in a preorder traversal of the content tree.
    *
    * @param aCommonAncestor either null, or a common ancestor of
    *                        aContent1 and aContent2.  Actually this is
    *                        only a hint; if it's not an ancestor of
    *                        aContent1 or aContent2, this function will
    *                        still work, but it will be slower than
    *                        normal.
    * @return < 0 if aContent1 is before aContent2
    *         > 0 if aContent1 is after aContent2,
    *         0 otherwise (meaning they're the same, or they're in
    *           different documents)
    */
   static int32_t CompareTreePosition(nsIContent* aContent1,
                                      nsIContent* aContent2,
                                      const nsIContent* aCommonAncestor = nullptr)
   {
     return DoCompareTreePosition(aContent1, aContent2, -1, 1, aCommonAncestor);
   }
   /*
    * More generic version of |CompareTreePosition|.  |aIf1Ancestor|
    * gives the value to return when 1 is an ancestor of 2, and likewise
    * for |aIf2Ancestor|.  Passing (-1, 1) gives preorder traversal
    * order, and (1, -1) gives postorder traversal order.
    */
   static int32_t DoCompareTreePosition(nsIContent* aContent1,
                                        nsIContent* aContent2,
                                        int32_t aIf1Ancestor,
                                        int32_t aIf2Ancestor,
                                        const nsIContent* aCommonAncestor = nullptr);
   /**
    * CompareTreePosition determines whether aFrame1 comes before or
    * after aFrame2 in a preorder traversal of the frame tree, where out
    * of flow frames are treated as children of their placeholders. This is
    * basically the same ordering as DoCompareTreePosition(nsIContent*) except
    * that it handles anonymous content properly and there are subtleties with
    * continuations.
    *
    * @param aCommonAncestor either null, or a common ancestor of
    *                        aContent1 and aContent2.  Actually this is
    *                        only a hint; if it's not an ancestor of
    *                        aContent1 or aContent2, this function will
    *                        still work, but it will be slower than
    *                        normal.
    * @return < 0 if aContent1 is before aContent2
    *         > 0 if aContent1 is after aContent2,
    *         0 otherwise (meaning they're the same, or they're in
    *           different frame trees)
    */
   static int32_t CompareTreePosition(nsIFrame* aFrame1,
                                      nsIFrame* aFrame2,
                                      nsIFrame* aCommonAncestor = nullptr)
   {
     return DoCompareTreePosition(aFrame1, aFrame2, -1, 1, aCommonAncestor);
   }
   static int32_t CompareTreePosition(nsIFrame* aFrame1,
                                      nsIFrame* aFrame2,
                                      nsTArray<nsIFrame*>& aFrame2Ancestors,
                                      nsIFrame* aCommonAncestor = nullptr)
   {
     return DoCompareTreePosition(aFrame1, aFrame2, aFrame2Ancestors,
                                  -1, 1, aCommonAncestor);
   }
   /*
    * More generic version of |CompareTreePosition|.  |aIf1Ancestor|
    * gives the value to return when 1 is an ancestor of 2, and likewise
    * for |aIf2Ancestor|.  Passing (-1, 1) gives preorder traversal
    * order, and (1, -1) gives postorder traversal order.
    */
   static int32_t DoCompareTreePosition(nsIFrame* aFrame1,
                                        nsIFrame* aFrame2,
                                        int32_t aIf1Ancestor,
                                        int32_t aIf2Ancestor,
                                        nsIFrame* aCommonAncestor = nullptr);
   static nsIFrame* FillAncestors(nsIFrame* aFrame,
                                  nsIFrame* aStopAtAncestor,
                                  nsTArray<nsIFrame*>* aAncestors);
   static int32_t DoCompareTreePosition(nsIFrame* aFrame1,
                                        nsIFrame* aFrame2,
                                        nsTArray<nsIFrame*>& aFrame2Ancestors,
                                        int32_t aIf1Ancestor,
                                        int32_t aIf2Ancestor,
                                        nsIFrame* aCommonAncestor);
   /**
    * LastContinuationWithChild gets the last continuation in aFrame's chain
    * that has a child, or the first continuation if the frame has no children.
    */
   static nsIFrame* LastContinuationWithChild(nsIFrame* aFrame);
   /**
    * GetLastSibling simply finds the last sibling of aFrame, or returns nullptr if
    * aFrame is null.
    */
   static nsIFrame* GetLastSibling(nsIFrame* aFrame);
   /**
    * FindSiblingViewFor locates the child of aParentView that aFrame's
    * view should be inserted 'above' (i.e., before in sibling view
    * order).  This is the first child view of aParentView whose
    * corresponding content is before aFrame's content (view siblings
    * are in reverse content order).
    */
   static nsView* FindSiblingViewFor(nsView* aParentView, nsIFrame* aFrame);
   /**
    * Get the parent of aFrame. If aFrame is the root frame for a document,
    * and the document has a parent document in the same view hierarchy, then
    * we try to return the subdocumentframe in the parent document.
    * @param aExtraOffset [in/out] if non-null, then as we cross documents
    * an extra offset may be required and it will be added to aCrossDocOffset.
    * Be careful dealing with this extra offset as it is in app units of the
    * parent document, which may have a different app units per dev pixel ratio
    * than the child document.
    */
   static nsIFrame* GetCrossDocParentFrame(const nsIFrame* aFrame,
                                           nsPoint* aCrossDocOffset = nullptr);
   /**
    * IsProperAncestorFrame checks whether aAncestorFrame is an ancestor
    * of aFrame and not equal to aFrame.
    * @param aCommonAncestor nullptr, or a common ancestor of aFrame and
    * aAncestorFrame. If non-null, this can bound the search and speed up
    * the function
    */
   static bool IsProperAncestorFrame(nsIFrame* aAncestorFrame, nsIFrame* aFrame,
                                       nsIFrame* aCommonAncestor = nullptr);
   /**
    * Like IsProperAncestorFrame, but looks across document boundaries.
    *
    * Just like IsAncestorFrameCrossDoc, except that it returns false when
    * aFrame == aAncestorFrame.
    */
   static bool IsProperAncestorFrameCrossDoc(nsIFrame* aAncestorFrame, nsIFrame* aFrame,
                                               nsIFrame* aCommonAncestor = nullptr);
   /**
    * IsAncestorFrameCrossDoc checks whether aAncestorFrame is an ancestor
    * of aFrame or equal to aFrame, looking across document boundaries.
    * @param aCommonAncestor nullptr, or a common ancestor of aFrame and
    * aAncestorFrame. If non-null, this can bound the search and speed up
    * the function.
    *
    * Just like IsProperAncestorFrameCrossDoc, except that it returns true when
    * aFrame == aAncestorFrame.
    */
   static bool IsAncestorFrameCrossDoc(const nsIFrame* aAncestorFrame, const nsIFrame* aFrame,
                                         const nsIFrame* aCommonAncestor = nullptr);
   /**
    * Sets the fixed-pos metadata properties on aLayer.
    * aAnchorRect is the basic anchor rectangle. If aFixedPosFrame is not a viewport
    * frame, then we pick a corner of aAnchorRect to as the anchor point for the
    * fixed-pos layer (i.e. the point to remain stable during zooming), based
    * on which of the fixed-pos frame's CSS absolute positioning offset
    * properties (top, left, right, bottom) are auto. aAnchorRect is in the
    * coordinate space of aLayer's container layer (i.e. relative to the reference
    * frame of the display item which is building aLayer's container layer).
    */
   static void SetFixedPositionLayerData(Layer* aLayer, const nsIFrame* aViewportFrame,
                                         const nsRect& aAnchorRect,
                                         const nsIFrame* aFixedPosFrame,
                                         nsPresContext* aPresContext,
                                         const ContainerLayerParameters& aContainerParameters);
   /**
    * Return true if aPresContext's viewport has a displayport.
    * Fills in aDisplayPort with the displayport rectangle if non-null.
    */
   static bool ViewportHasDisplayPort(nsPresContext* aPresContext,
                                      nsRect* aDisplayPort = nullptr);
   /**
    * Return true if aFrame is a fixed-pos frame and is a child of a viewport
    * which has a displayport. These frames get special treatment from the compositor.
    * aDisplayPort, if non-null, is set to the display port rectangle (relative to
    * the viewport).
    */
   static bool IsFixedPosFrameInDisplayPort(const nsIFrame* aFrame,
                                            nsRect* aDisplayPort = nullptr);
   /**
    * Finds the nearest ancestor frame to aItem that is considered to have (or
    * will have) "animated geometry". For example the scrolled frames of
    * scrollframes which are actively being scrolled fall into this category.
    * Frames with certain CSS properties that are being animated (e.g.
    * 'left'/'top' etc) are also placed in this category.
    * Frames with different active geometry roots are in different ThebesLayers,
    * so that we can animate the geometry root by changing its transform (either
    * on the main thread or in the compositor).
    * The animated geometry root is required to be a descendant (or equal to)
    * aItem's ReferenceFrame(), which means that we will fall back to
    * returning aItem->ReferenceFrame() when we can't find another animated
    * geometry root.
    */
   static nsIFrame* GetAnimatedGeometryRootFor(nsDisplayItem* aItem,
                                               nsDisplayListBuilder* aBuilder);
   /**
     * GetScrollableFrameFor returns the scrollable frame for a scrolled frame
     */
   static nsIScrollableFrame* GetScrollableFrameFor(const nsIFrame *aScrolledFrame);
   /**
    * GetNearestScrollableFrameForDirection locates the first ancestor of
    * aFrame (or aFrame itself) that is scrollable with overflow:scroll or
    * overflow:auto in the given direction and where either the scrollbar for
    * that direction is visible or the frame can be scrolled by some
    * positive amount in that direction.
    * The search extends across document boundaries.
    *
    * @param  aFrame the frame to start with
    * @param  aDirection Whether it's for horizontal or vertical scrolling.
    * @return the nearest scrollable frame or nullptr if not found
    */
   enum Direction { eHorizontal, eVertical };
   static nsIScrollableFrame* GetNearestScrollableFrameForDirection(nsIFrame* aFrame,
                                                                    Direction aDirection);
   enum {
     SCROLLABLE_SAME_DOC = 0x01,
     SCROLLABLE_INCLUDE_HIDDEN = 0x02
   };
   /**
    * GetNearestScrollableFrame locates the first ancestor of aFrame
    * (or aFrame itself) that is scrollable with overflow:scroll or
    * overflow:auto in some direction.
    *
    * @param  aFrame the frame to start with
    * @param  aFlags if SCROLLABLE_SAME_DOC is set, do not search across
    * document boundaries. If SCROLLABLE_INCLUDE_HIDDEN is set, include
    * frames scrollable with overflow:hidden.
    * @return the nearest scrollable frame or nullptr if not found
    */
   static nsIScrollableFrame* GetNearestScrollableFrame(nsIFrame* aFrame,
                                                        uint32_t aFlags = 0);
   /**
    * GetScrolledRect returns the range of allowable scroll offsets
    * for aScrolledFrame, assuming the scrollable overflow area is
    * aScrolledFrameOverflowArea and the scrollport size is aScrollPortSize.
    * aDirection is either NS_STYLE_DIRECTION_LTR or NS_STYLE_DIRECTION_RTL.
    */
   static nsRect GetScrolledRect(nsIFrame* aScrolledFrame,
                                 const nsRect& aScrolledFrameOverflowArea,
                                 const nsSize& aScrollPortSize,
                                 uint8_t aDirection);
   /**
    * HasPseudoStyle returns true if aContent (whose primary style
    * context is aStyleContext) has the aPseudoElement pseudo-style
    * attached to it; returns false otherwise.
    *
    * @param aContent the content node we're looking at
    * @param aStyleContext aContent's style context
    * @param aPseudoElement the id of the pseudo style we care about
    * @param aPresContext the presentation context
    * @return whether aContent has aPseudoElement style attached to it
    */
   static bool HasPseudoStyle(nsIContent* aContent,
                                nsStyleContext* aStyleContext,
                                nsCSSPseudoElements::Type aPseudoElement,
                                nsPresContext* aPresContext);
   /**
    * If this frame is a placeholder for a float, then return the float,
    * otherwise return nullptr.  aPlaceholder must be a placeholder frame.
    */
   static nsIFrame* GetFloatFromPlaceholder(nsIFrame* aPlaceholder);
   // Combine aNewBreakType with aOrigBreakType, but limit the break types
   // to NS_STYLE_CLEAR_LEFT, RIGHT, LEFT_AND_RIGHT.
   static uint8_t CombineBreakType(uint8_t aOrigBreakType, uint8_t aNewBreakType);
   /**
    * Get the coordinates of a given DOM mouse event, relative to a given
    * frame. Works only for DOM events generated by WidgetGUIEvents.
    * @param aDOMEvent the event
    * @param aFrame the frame to make coordinates relative to
    * @return the point, or (NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE) if
    * for some reason the coordinates for the mouse are not known (e.g.,
    * the event is not a GUI event).
    */
   static nsPoint GetDOMEventCoordinatesRelativeTo(nsIDOMEvent* aDOMEvent,
                                                   nsIFrame* aFrame);
   /**
    * Get the coordinates of a given native mouse event, relative to a given
    * frame.
    * @param aEvent the event
    * @param aFrame the frame to make coordinates relative to
    * @return the point, or (NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE) if
    * for some reason the coordinates for the mouse are not known (e.g.,
    * the event is not a GUI event).
    */
   static nsPoint GetEventCoordinatesRelativeTo(
                    const mozilla::WidgetEvent* aEvent,
                    nsIFrame* aFrame);
   /**
    * Get the coordinates of a given point relative to an event and a
    * given frame.
    * @param aEvent the event
    * @param aPoint the point to get the coordinates relative to
    * @param aFrame the frame to make coordinates relative to
    * @return the point, or (NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE) if
    * for some reason the coordinates for the mouse are not known (e.g.,
    * the event is not a GUI event).
    */
   static nsPoint GetEventCoordinatesRelativeTo(
                    const mozilla::WidgetEvent* aEvent,
                    const nsIntPoint aPoint,
                    nsIFrame* aFrame);
   /**
    * Get the coordinates of a given point relative to a widget and a
    * given frame.
    * @param aWidget the event src widget
    * @param aPoint the point to get the coordinates relative to
    * @param aFrame the frame to make coordinates relative to
    * @return the point, or (NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE) if
    * for some reason the coordinates for the mouse are not known (e.g.,
    * the event is not a GUI event).
    */
   static nsPoint GetEventCoordinatesRelativeTo(nsIWidget* aWidget,
                                                const nsIntPoint aPoint,
                                                nsIFrame* aFrame);
   /**
    * Get the popup frame of a given native mouse event.
    * @param aPresContext only check popups within aPresContext or a descendant
    * @param aEvent  the event.
    * @return        Null, if there is no popup frame at the point, otherwise,
    *                returns top-most popup frame at the point.
    */
   static nsIFrame* GetPopupFrameForEventCoordinates(
                      nsPresContext* aPresContext,
                      const mozilla::WidgetEvent* aEvent);
   /**
    * Translate from widget coordinates to the view's coordinates
    * @param aPresContext the PresContext for the view
    * @param aWidget the widget
    * @param aPt the point relative to the widget
    * @param aView  view to which returned coordinates are relative
    * @return the point in the view's coordinates
    */
   static nsPoint TranslateWidgetToView(nsPresContext* aPresContext,
                                        nsIWidget* aWidget, nsIntPoint aPt,
                                        nsView* aView);
   /**
    * Given a matrix and a point, let T be the transformation matrix translating points
    * in the coordinate space with origin aOrigin to the coordinate space used by the
    * matrix.  If M is the stored matrix, this function returns (T-1)MT, the matrix
    * that's equivalent to aMatrix but in the coordinate space that treats aOrigin
    * as the origin.
    *
    * @param aOrigin The origin to translate to.
    * @param aMatrix The matrix to change the basis of.
    * @return A matrix equivalent to aMatrix, but operating in the coordinate system with
    *         origin aOrigin.
    */
   static gfx3DMatrix ChangeMatrixBasis(const gfxPoint3D &aOrigin, const gfx3DMatrix &aMatrix);
   /**
    * Find IDs corresponding to a scrollable content element in the child process.
    * In correspondence with the shadow layer tree, you can use this to perform a
    * hit test that corresponds to a specific shadow layer that you can then perform
    * transformations on to do parent-side scrolling.
    *
    * @param aFrame The root frame of a stack context
    * @param aTarget The rect to hit test relative to the frame origin
    * @param aOutIDs All found IDs are added here
    * @param aIgnoreRootScrollFrame a boolean to control if the display list
    *        builder should ignore the root scroll frame
    */
   static nsresult GetRemoteContentIds(nsIFrame* aFrame,
                                      const nsRect& aTarget,
                                      nsTArray<ViewID> &aOutIDs,
                                      bool aIgnoreRootScrollFrame);
   enum FrameForPointFlags {
     /**
      * When set, paint suppression is ignored, so we'll return non-root page
      * elements even if paint suppression is stopping them from painting.
      */
     IGNORE_PAINT_SUPPRESSION = 0x01,
     /**
      * When set, clipping due to the root scroll frame (and any other viewport-
      * related clipping) is ignored.
      */
     IGNORE_ROOT_SCROLL_FRAME = 0x02,
     /**
      * When set, return only content in the same document as aFrame.
      */
     IGNORE_CROSS_DOC = 0x04
   };
   /**
    * Given aFrame, the root frame of a stacking context, find its descendant
    * frame under the point aPt that receives a mouse event at that location,
    * or nullptr if there is no such frame.
    * @param aPt the point, relative to the frame origin
    * @param aFlags some combination of FrameForPointFlags
    */
   static nsIFrame* GetFrameForPoint(nsIFrame* aFrame, nsPoint aPt,
                                     uint32_t aFlags = 0);
   /**
    * Given aFrame, the root frame of a stacking context, find all descendant
    * frames under the area of a rectangle that receives a mouse event,
    * or nullptr if there is no such frame.
    * @param aRect the rect, relative to the frame origin
    * @param aOutFrames an array to add all the frames found
    * @param aFlags some combination of FrameForPointFlags
    */
   static nsresult GetFramesForArea(nsIFrame* aFrame, const nsRect& aRect,
                                    nsTArray<nsIFrame*> &aOutFrames,
                                    uint32_t aFlags = 0);
   /**
    * Transform aRect relative to aFrame up to the coordinate system of
    * aAncestor. Computes the bounding-box of the true quadrilateral.
    * Pass non-null aPreservesAxisAlignedRectangles and it will be set to true if
    * we only need to use a 2d transform that PreservesAxisAlignedRectangles().
    */
   static nsRect TransformFrameRectToAncestor(nsIFrame* aFrame,
                                              const nsRect& aRect,
                                              const nsIFrame* aAncestor,
                                              bool* aPreservesAxisAlignedRectangles = nullptr);
   /**
    * Gets the transform for aFrame relative to aAncestor. Pass null for aAncestor
    * to go up to the root frame.
    */
   static gfx3DMatrix GetTransformToAncestor(nsIFrame *aFrame, const nsIFrame *aAncestor);
   /**
    * Transforms a list of CSSPoints from aFromFrame to aToFrame, taking into
    * account all relevant transformations on the frames up to (but excluding)
    * their nearest common ancestor.
    * If we encounter a transform that we need to invert but which is
    * non-invertible, we return NONINVERTIBLE_TRANSFORM. If the frames have
    * no common ancestor, we return NO_COMMON_ANCESTOR.
    * If this returns TRANSFORM_SUCCEEDED, the points in aPoints are transformed
    * in-place, otherwise they are untouched.
    */
   enum TransformResult {
     TRANSFORM_SUCCEEDED,
     NO_COMMON_ANCESTOR,
     NONINVERTIBLE_TRANSFORM
   };
   static TransformResult TransformPoints(nsIFrame* aFromFrame, nsIFrame* aToFrame,
                                          uint32_t aPointCount, CSSPoint* aPoints);
   /**
    * Return true if a "layer transform" could be computed for aFrame,
    * and optionally return the computed transform.  The returned
    * transform is what would be set on the layer currently if a layers
    * transaction were opened at the time this helper is called.
    */
   static bool GetLayerTransformForFrame(nsIFrame* aFrame,
                                         gfx3DMatrix* aTransform);
   /**
    * Given a point in the global coordinate space, returns that point expressed
    * in the coordinate system of aFrame.  This effectively inverts all transforms
    * between this point and the root frame.
    *
    * @param aFrame The frame that acts as the coordinate space container.
    * @param aPoint The point, in the global space, to get in the frame-local space.
    * @return aPoint, expressed in aFrame's canonical coordinate space.
    */
   static nsPoint TransformRootPointToFrame(nsIFrame* aFrame,
                                            const nsPoint &aPoint)
   {
     return TransformAncestorPointToFrame(aFrame, aPoint, nullptr);
   }
   /**
    * Transform aPoint relative to aAncestor down to the coordinate system of
    * aFrame.
    */
   static nsPoint TransformAncestorPointToFrame(nsIFrame* aFrame,
                                                const nsPoint& aPoint,
                                                nsIFrame* aAncestor);
   /**
    * Helper function that, given a rectangle and a matrix, returns the smallest
    * rectangle containing the image of the source rectangle.
    *
    * @param aBounds The rectangle to transform.
    * @param aMatrix The matrix to transform it with.
    * @param aFactor The number of app units per graphics unit.
    * @return The smallest rect that contains the image of aBounds.
    */
   static nsRect MatrixTransformRect(const nsRect &aBounds,
                                     const gfx3DMatrix &aMatrix, float aFactor);
   /**
    * Helper function that, given a rectangle and a matrix, returns the smallest
    * rectangle containing the image of the source rectangle rounded out to the nearest
    * pixel value.
    *
    * @param aBounds The rectangle to transform.
    * @param aMatrix The matrix to transform it with.
    * @param aFactor The number of app units per graphics unit.
    * @return The smallest rect that contains the image of aBounds.
    */
   static nsRect MatrixTransformRectOut(const nsRect &aBounds,
                                     const gfx3DMatrix &aMatrix, float aFactor);
   /**
    * Helper function that, given a point and a matrix, returns the image
    * of that point under the matrix transform.
    *
    * @param aPoint The point to transform.
    * @param aMatrix The matrix to transform it with.
    * @param aFactor The number of app units per graphics unit.
    * @return The image of the point under the transform.
    */
   static nsPoint MatrixTransformPoint(const nsPoint &aPoint,
                                       const gfx3DMatrix &aMatrix, float aFactor);
   /**
    * Given a graphics rectangle in graphics space, return a rectangle in
    * app space that contains the graphics rectangle, rounding out as necessary.
    *
    * @param aRect The graphics rect to round outward.
    * @param aFactor The number of app units per graphics unit.
    * @return The smallest rectangle in app space that contains aRect.
    */
   static nsRect RoundGfxRectToAppRect(const Rect &aRect, float aFactor);
   /**
    * Given a graphics rectangle in graphics space, return a rectangle in
    * app space that contains the graphics rectangle, rounding out as necessary.
    *
    * @param aRect The graphics rect to round outward.
    * @param aFactor The number of app units per graphics unit.
    * @return The smallest rectangle in app space that contains aRect.
    */
   static nsRect RoundGfxRectToAppRect(const gfxRect &aRect, float aFactor);
   /**
    * Returns a subrectangle of aContainedRect that is entirely inside the rounded
    * rect. Complex cases are handled conservatively by returning a smaller
    * rect than necessary.
    */
   static nsRegion RoundedRectIntersectRect(const nsRect& aRoundedRect,
                                            const nscoord aRadii[8],
                                            const nsRect& aContainedRect);
   /**
    * Return whether any part of aTestRect is inside of the rounded
    * rectangle formed by aBounds and aRadii (which are indexed by the
    * NS_CORNER_* constants in nsStyleConsts.h). This is precise.
    */
   static bool RoundedRectIntersectsRect(const nsRect& aRoundedRect,
                                         const nscoord aRadii[8],
                                         const nsRect& aTestRect);
   enum {
     PAINT_IN_TRANSFORM = 0x01,
     PAINT_SYNC_DECODE_IMAGES = 0x02,
     PAINT_WIDGET_LAYERS = 0x04,
     PAINT_IGNORE_SUPPRESSION = 0x08,
     PAINT_DOCUMENT_RELATIVE = 0x10,
     PAINT_HIDE_CARET = 0x20,
     PAINT_ALL_CONTINUATIONS = 0x40,
     PAINT_TO_WINDOW = 0x80,
     PAINT_EXISTING_TRANSACTION = 0x100,
     PAINT_NO_COMPOSITE = 0x200,
     PAINT_COMPRESSED = 0x400
   };
   /**
    * Given aFrame, the root frame of a stacking context, paint it and its
    * descendants to aRenderingContext.
    * @param aRenderingContext a rendering context translated so that (0,0)
    * is the origin of aFrame; for best results, (0,0) should transform
    * to pixel-aligned coordinates. This can be null, in which case
    * aFrame must be a "display root" (root frame for a root document,
    * or the root of a popup) with an associated widget and we draw using
    * the layer manager for the frame's widget.
    * @param aDirtyRegion the region that must be painted, in the coordinates
    * of aFrame
    * @param aBackstop paint the dirty area with this color before drawing
    * the actual content; pass NS_RGBA(0,0,0,0) to draw no background
    * @param aFlags if PAINT_IN_TRANSFORM is set, then we assume
    * this is inside a transform or SVG foreignObject. If
    * PAINT_SYNC_DECODE_IMAGES is set, we force synchronous decode on all
    * images. If PAINT_WIDGET_LAYERS is set, aFrame must be a display root,
    * and we will use the frame's widget's layer manager to paint
    * even if aRenderingContext is non-null. This is useful if you want
    * to force rendering to use the widget's layer manager for testing
    * or speed. PAINT_WIDGET_LAYERS must be set if aRenderingContext is null.
    * If PAINT_DOCUMENT_RELATIVE is used, the visible region is interpreted
    * as being relative to the document.  (Normally it's relative to the CSS
    * viewport.) PAINT_TO_WINDOW sets painting to window to true on the display
    * list builder even if we can't tell that we are painting to the window.
    * If PAINT_EXISTING_TRANSACTION is set, then BeginTransaction() has already
    * been called on aFrame's widget's layer manager and should not be
    * called again.
    * If PAINT_COMPRESSED is set, the FrameLayerBuilder should be set to compressed mode
    * to avoid short cut optimizations.
    *
    * So there are three possible behaviours:
    * 1) PAINT_WIDGET_LAYERS is set and aRenderingContext is null; we paint
    * by calling BeginTransaction on the widget's layer manager
    * 2) PAINT_WIDGET_LAYERS is set and aRenderingContext is non-null; we
    * paint by calling BeginTransactionWithTarget on the widget's layer
    * maanger
    * 3) PAINT_WIDGET_LAYERS is not set and aRenderingContext is non-null;
    * we paint by construct a BasicLayerManager and calling
    * BeginTransactionWithTarget on it. This is desirable if we're doing
    * something like drawWindow in a mode where what gets rendered doesn't
    * necessarily correspond to what's visible in the window; we don't
    * want to mess up the widget's layer tree.
    */
   static nsresult PaintFrame(nsRenderingContext* aRenderingContext, nsIFrame* aFrame,
                              const nsRegion& aDirtyRegion, nscolor aBackstop,
                              uint32_t aFlags = 0);
   /**
    * Uses a binary search for find where the cursor falls in the line of text
    * It also keeps track of the part of the string that has already been measured
    * so it doesn't have to keep measuring the same text over and over
    *
    * @param "aBaseWidth" contains the width in twips of the portion
    * of the text that has already been measured, and aBaseInx contains
    * the index of the text that has already been measured.
    *
    * @param aTextWidth returns the (in twips) the length of the text that falls
    * before the cursor aIndex contains the index of the text where the cursor falls
    */
   static bool
   BinarySearchForPosition(nsRenderingContext* acx,
                           const char16_t* aText,
                           int32_t    aBaseWidth,
                           int32_t    aBaseInx,
                           int32_t    aStartInx,
                           int32_t    aEndInx,
                           int32_t    aCursorPos,
                           int32_t&   aIndex,
                           int32_t&   aTextWidth);
   class BoxCallback {
   public:
     virtual void AddBox(nsIFrame* aFrame) = 0;
   };
   /**
    * Collect all CSS boxes associated with aFrame and its
    * continuations, "drilling down" through outer table frames and
    * some anonymous blocks since they're not real CSS boxes.
    * If aFrame is null, no boxes are returned.
    * SVG frames return a single box, themselves.
    */
   static void GetAllInFlowBoxes(nsIFrame* aFrame, BoxCallback* aCallback);
   /**
    * Find the first frame descendant of aFrame (including aFrame) which is
    * not an anonymous frame that getBoxQuads/getClientRects should ignore.
    */
   static nsIFrame* GetFirstNonAnonymousFrame(nsIFrame* aFrame);
   class RectCallback {
   public:
     virtual void AddRect(const nsRect& aRect) = 0;
   };
   struct RectAccumulator : public RectCallback {
     nsRect mResultRect;
     nsRect mFirstRect;
     bool mSeenFirstRect;
     RectAccumulator();
     virtual void AddRect(const nsRect& aRect);
   };
   struct RectListBuilder : public RectCallback {
     DOMRectList* mRectList;
     RectListBuilder(DOMRectList* aList);
     virtual void AddRect(const nsRect& aRect);
   };
   static nsIFrame* GetContainingBlockForClientRect(nsIFrame* aFrame);
   enum {
     RECTS_ACCOUNT_FOR_TRANSFORMS = 0x01,
     // Two bits for specifying which box type to use.
     // With neither bit set (default), use the border box.
     RECTS_USE_CONTENT_BOX = 0x02,
     RECTS_USE_PADDING_BOX = 0x04,
     RECTS_USE_MARGIN_BOX = 0x06, // both bits set
     RECTS_WHICH_BOX_MASK = 0x06 // bitmask for these two bits
   };
   /**
    * Collect all CSS boxes (content, padding, border, or margin) associated
    * with aFrame and its continuations, "drilling down" through outer table
    * frames and some anonymous blocks since they're not real CSS boxes.
    * The boxes are positioned relative to aRelativeTo (taking scrolling
    * into account) and passed to the callback in frame-tree order.
    * If aFrame is null, no boxes are returned.
    * For SVG frames, returns one rectangle, the bounding box.
    * If aFlags includes RECTS_ACCOUNT_FOR_TRANSFORMS, then when converting
    * the boxes into aRelativeTo coordinates, transforms (including CSS
    * and SVG transforms) are taken into account.
    * If aFlags includes one of RECTS_USE_CONTENT_BOX, RECTS_USE_PADDING_BOX,
    * or RECTS_USE_MARGIN_BOX, the corresponding type of box is used.
    * Otherwise (by default), the border box is used.
    */
   static void GetAllInFlowRects(nsIFrame* aFrame, nsIFrame* aRelativeTo,
                                 RectCallback* aCallback, uint32_t aFlags = 0);
   /**
    * Computes the union of all rects returned by GetAllInFlowRects. If
    * the union is empty, returns the first rect.
    * If aFlags includes RECTS_ACCOUNT_FOR_TRANSFORMS, then when converting
    * the boxes into aRelativeTo coordinates, transforms (including CSS
    * and SVG transforms) are taken into account.
    * If aFlags includes one of RECTS_USE_CONTENT_BOX, RECTS_USE_PADDING_BOX,
    * or RECTS_USE_MARGIN_BOX, the corresponding type of box is used.
    * Otherwise (by default), the border box is used.
    */
   static nsRect GetAllInFlowRectsUnion(nsIFrame* aFrame, nsIFrame* aRelativeTo,
                                        uint32_t aFlags = 0);
   enum {
     EXCLUDE_BLUR_SHADOWS = 0x01
   };
   /**
    * Takes a text-shadow array from the style properties of a given nsIFrame and
    * computes the union of those shadows along with the given initial rect.
    * If there are no shadows, the initial rect is returned.
    */
   static nsRect GetTextShadowRectsUnion(const nsRect& aTextAndDecorationsRect,
                                         nsIFrame* aFrame,
                                         uint32_t aFlags = 0);
   /**
    * Get the font metrics corresponding to the frame's style data.
    * @param aFrame the frame
    * @param aFontMetrics the font metrics result
    * @param aSizeInflation number to multiply font size by
    * @return success or failure code
    */
   static nsresult GetFontMetricsForFrame(const nsIFrame* aFrame,
                                          nsFontMetrics** aFontMetrics,
                                          float aSizeInflation = 1.0f);
   /**
    * Get the font metrics corresponding to the given style data.
    * @param aStyleContext the style data
    * @param aFontMetrics the font metrics result
    * @param aSizeInflation number to multiply font size by
    * @return success or failure code
    */
   static nsresult GetFontMetricsForStyleContext(nsStyleContext* aStyleContext,
                                                 nsFontMetrics** aFontMetrics,
                                                 float aSizeInflation = 1.0f);
   /**
    * Find the immediate child of aParent whose frame subtree contains
    * aDescendantFrame. Returns null if aDescendantFrame is not a descendant
    * of aParent.
    */
   static nsIFrame* FindChildContainingDescendant(nsIFrame* aParent, nsIFrame* aDescendantFrame);
   /**
    * Find the nearest ancestor that's a block
    */
   static nsBlockFrame* FindNearestBlockAncestor(nsIFrame* aFrame);
   /**
    * Find the nearest ancestor that's not for generated content. Will return
    * aFrame if aFrame is not for generated content.
    */
   static nsIFrame* GetNonGeneratedAncestor(nsIFrame* aFrame);
   /**
    * Cast aFrame to an nsBlockFrame* or return null if it's not
    * an nsBlockFrame.
    */
   static nsBlockFrame* GetAsBlock(nsIFrame* aFrame);
   /*
    * Whether the frame is an nsBlockFrame which is not a wrapper block.
    */
   static bool IsNonWrapperBlock(nsIFrame* aFrame);
   /**
    * If aFrame is an out of flow frame, return its placeholder, otherwise
    * return its parent.
    */
   static nsIFrame* GetParentOrPlaceholderFor(nsIFrame* aFrame);
   /**
    * If aFrame is an out of flow frame, return its placeholder, otherwise
    * return its (possibly cross-doc) parent.
    */
   static nsIFrame* GetParentOrPlaceholderForCrossDoc(nsIFrame* aFrame);
   /**
    * Get a frame's next-in-flow, or, if it doesn't have one, its
    * block-in-inline-split sibling.
    */
   static nsIFrame*
   GetNextContinuationOrIBSplitSibling(nsIFrame *aFrame);
   /**
    * Get the first frame in the continuation-plus-ib-split-sibling chain
    * containing aFrame.
    */
   static nsIFrame*
   FirstContinuationOrIBSplitSibling(nsIFrame *aFrame);
   /**
    * Is FirstContinuationOrIBSplitSibling(aFrame) going to return
    * aFrame?
    */
   static bool
   IsFirstContinuationOrIBSplitSibling(nsIFrame *aFrame);
   /**
    * Check whether aFrame is a part of the scrollbar or scrollcorner of
    * the root content.
    * @param aFrame the checking frame
    * @return if TRUE, the frame is a part of the scrollbar or scrollcorner of
    *         the root content.
    */
   static bool IsViewportScrollbarFrame(nsIFrame* aFrame);
   /**
    * Get the contribution of aFrame to its containing block's intrinsic
    * width.  This considers the child's intrinsic width, its 'width',
    * 'min-width', and 'max-width' properties, and its padding, border,
    * and margin.
    */
   enum IntrinsicWidthType { MIN_WIDTH, PREF_WIDTH };
   enum {
     IGNORE_PADDING = 0x01
   };
   static nscoord IntrinsicForContainer(nsRenderingContext* aRenderingContext,
                                        nsIFrame* aFrame,
                                        IntrinsicWidthType aType,
                                        uint32_t aFlags = 0);
   /*
    * Convert nsStyleCoord to nscoord when percentages depend on the
    * containing block size.
    * @param aPercentBasis The width or height of the containing block
    * (whichever the client wants to use for resolving percentages).
    */
   static nscoord ComputeCBDependentValue(nscoord aPercentBasis,
                                          const nsStyleCoord& aCoord);
   /*
    * Convert nsStyleCoord to nscoord when percentages depend on the
    * containing block width, and enumerated values are for width,
    * min-width, or max-width.  Returns the content-box width value based
    * on aContentEdgeToBoxSizing and aBoxSizingToMarginEdge (which are
    * also used for the enumerated values for width.  This function does
    * not handle 'auto'.  It ensures that the result is nonnegative.
    *
    * @param aRenderingContext Rendering context for font measurement/metrics.
    * @param aFrame Frame whose (min-/max-/)width is being computed
    * @param aContainingBlockWidth Width of aFrame's containing block.
    * @param aContentEdgeToBoxSizing The sum of any left/right padding and
    *          border that goes inside the rect chosen by box-sizing.
    * @param aBoxSizingToMarginEdge The sum of any left/right padding, border,
    *          and margin that goes outside the rect chosen by box-sizing.
    * @param aCoord The width value to compute.
    */
   static nscoord ComputeWidthValue(
                    nsRenderingContext* aRenderingContext,
                    nsIFrame*            aFrame,
                    nscoord              aContainingBlockWidth,
                    nscoord              aContentEdgeToBoxSizing,
                    nscoord              aBoxSizingToMarginEdge,
                    const nsStyleCoord&  aCoord);
   /*
    * Convert nsStyleCoord to nscoord when percentages depend on the
    * containing block height.
    */
   static nscoord ComputeHeightDependentValue(
                    nscoord              aContainingBlockHeight,
                    const nsStyleCoord&  aCoord);
   /*
    * Likewise, but for 'height', 'min-height', or 'max-height'.
    */
   static nscoord ComputeHeightValue(nscoord aContainingBlockHeight,
                                     nscoord aContentEdgeToBoxSizingBoxEdge,
                                     const nsStyleCoord& aCoord)
   {
     MOZ_ASSERT(aContainingBlockHeight != nscoord_MAX || !aCoord.HasPercent(),
                "caller must deal with %% of unconstrained height");
     MOZ_ASSERT(aCoord.IsCoordPercentCalcUnit());
     nscoord result =
       nsRuleNode::ComputeCoordPercentCalc(aCoord, aContainingBlockHeight);
     // Clamp calc(), and the subtraction for box-sizing.
     return std::max(0, result - aContentEdgeToBoxSizingBoxEdge);
   }
   static bool IsAutoHeight(const nsStyleCoord &aCoord, nscoord aCBHeight)
   {
     nsStyleUnit unit = aCoord.GetUnit();
     return unit == eStyleUnit_Auto ||  // only for 'height'
            unit == eStyleUnit_None ||  // only for 'max-height'
            (aCBHeight == nscoord_MAX && aCoord.HasPercent());
   }
   static bool IsPaddingZero(const nsStyleCoord &aCoord)
   {
     return (aCoord.GetUnit() == eStyleUnit_Coord &&
             aCoord.GetCoordValue() == 0) ||
            (aCoord.GetUnit() == eStyleUnit_Percent &&
             aCoord.GetPercentValue() == 0.0f) ||
            (aCoord.IsCalcUnit() &&
             // clamp negative calc() to 0
             nsRuleNode::ComputeCoordPercentCalc(aCoord, nscoord_MAX) <= 0 &&
             nsRuleNode::ComputeCoordPercentCalc(aCoord, 0) <= 0);
   }
   static bool IsMarginZero(const nsStyleCoord &aCoord)
   {
     return (aCoord.GetUnit() == eStyleUnit_Coord &&
             aCoord.GetCoordValue() == 0) ||
            (aCoord.GetUnit() == eStyleUnit_Percent &&
             aCoord.GetPercentValue() == 0.0f) ||
            (aCoord.IsCalcUnit() &&
             nsRuleNode::ComputeCoordPercentCalc(aCoord, nscoord_MAX) == 0 &&
             nsRuleNode::ComputeCoordPercentCalc(aCoord, 0) == 0);
   }
   static void MarkDescendantsDirty(nsIFrame *aSubtreeRoot);
   /*
    * Calculate the used values for 'width' and 'height' for a replaced element.
    *
    *   http://www.w3.org/TR/CSS21/visudet.html#min-max-widths
    */
   static nsSize ComputeSizeWithIntrinsicDimensions(
                     nsRenderingContext* aRenderingContext, nsIFrame* aFrame,
                     const mozilla::IntrinsicSize& aIntrinsicSize,
                     nsSize aIntrinsicRatio, nsSize aCBSize,
                     nsSize aMargin, nsSize aBorder, nsSize aPadding);
   /*
    * Calculate the used values for 'width' and 'height' when width
    * and height are 'auto'. The tentWidth and tentHeight arguments should be
    * the result of applying the rules for computing intrinsic sizes and ratios.
    * as specified by CSS 2.1 sections 10.3.2 and 10.6.2
    */
   static nsSize ComputeAutoSizeWithIntrinsicDimensions(nscoord minWidth, nscoord minHeight,
                                                        nscoord maxWidth, nscoord maxHeight,
                                                        nscoord tentWidth, nscoord tentHeight);
   // Implement nsIFrame::GetPrefWidth in terms of nsIFrame::AddInlinePrefWidth
   static nscoord PrefWidthFromInline(nsIFrame* aFrame,
                                      nsRenderingContext* aRenderingContext);
   // Implement nsIFrame::GetMinWidth in terms of nsIFrame::AddInlineMinWidth
   static nscoord MinWidthFromInline(nsIFrame* aFrame,
                                     nsRenderingContext* aRenderingContext);
   // Get a suitable foreground color for painting aProperty for aFrame.
   static nscolor GetColor(nsIFrame* aFrame, nsCSSProperty aProperty);
   // Get the native text color if appropriate.  If false is returned, callers
   // should fallback to the CSS color.
   static bool GetNativeTextColor(nsIFrame* aFrame, nscolor& aColor);
   // Get a baseline y position in app units that is snapped to device pixels.
   static gfxFloat GetSnappedBaselineY(nsIFrame* aFrame, gfxContext* aContext,
                                       nscoord aY, nscoord aAscent);
   static void DrawString(const nsIFrame*       aFrame,
                          nsRenderingContext*   aContext,
                          const char16_t*      aString,
                          int32_t               aLength,
                          nsPoint               aPoint,
                          nsStyleContext*       aStyleContext = nullptr);
   static nscoord GetStringWidth(const nsIFrame*      aFrame,
                                 nsRenderingContext* aContext,
                                 const char16_t*     aString,
                                 int32_t              aLength);
   /**
    * Helper function for drawing text-shadow. The callback's job
    * is to draw whatever needs to be blurred onto the given context.
    */
   typedef void (* TextShadowCallback)(nsRenderingContext* aCtx,
                                       nsPoint aShadowOffset,
                                       const nscolor& aShadowColor,
                                       void* aData);
   static void PaintTextShadow(const nsIFrame*     aFrame,
                               nsRenderingContext* aContext,
                               const nsRect&       aTextRect,
                               const nsRect&       aDirtyRect,
                               const nscolor&      aForegroundColor,
                               TextShadowCallback  aCallback,
                               void*               aCallbackData);
   /**
    * Gets the baseline to vertically center text from a font within a
    * line of specified height.
    *
    * Returns the baseline position relative to the top of the line.
    */
   static nscoord GetCenteredFontBaseline(nsFontMetrics* aFontMetrics,
                                          nscoord         aLineHeight);
   /**
    * Derive a baseline of |aFrame| (measured from its top border edge)
    * from its first in-flow line box (not descending into anything with
    * 'overflow' not 'visible', potentially including aFrame itself).
    *
    * Returns true if a baseline was found (and fills in aResult).
    * Otherwise returns false.
    */
   static bool GetFirstLineBaseline(const nsIFrame* aFrame, nscoord* aResult);
   /**
    * Just like GetFirstLineBaseline, except also returns the top and
    * bottom of the line with the baseline.
    *
    * Returns true if a line was found (and fills in aResult).
    * Otherwise returns false.
    */
   struct LinePosition {
     nscoord mTop, mBaseline, mBottom;
     LinePosition operator+(nscoord aOffset) const {
       LinePosition result;
       result.mTop = mTop + aOffset;
       result.mBaseline = mBaseline + aOffset;
       result.mBottom = mBottom + aOffset;
       return result;
     }
   };
   static bool GetFirstLinePosition(const nsIFrame* aFrame,
                                    LinePosition* aResult);
   /**
    * Derive a baseline of |aFrame| (measured from its top border edge)
    * from its last in-flow line box (not descending into anything with
    * 'overflow' not 'visible', potentially including aFrame itself).
    *
    * Returns true if a baseline was found (and fills in aResult).
    * Otherwise returns false.
    */
   static bool GetLastLineBaseline(const nsIFrame* aFrame, nscoord* aResult);
   /**
    * Returns a y coordinate relative to this frame's origin that represents
    * the logical bottom of the frame or its visible content, whichever is lower.
    * Relative positioning is ignored and margins and glyph bounds are not
    * considered.
    * This value will be >= mRect.height() and <= overflowRect.YMost() unless
    * relative positioning is applied.
    */
   static nscoord CalculateContentBottom(nsIFrame* aFrame);
   /**
    * Gets the closest frame (the frame passed in or one of its parents) that
    * qualifies as a "layer"; used in DOM0 methods that depends upon that
    * definition. This is the nearest frame that is either positioned or scrolled
    * (the child of a scroll frame).
    */
   static nsIFrame* GetClosestLayer(nsIFrame* aFrame);
   /**
    * Gets the graphics filter for the frame
    */
   static GraphicsFilter GetGraphicsFilterForFrame(nsIFrame* aFrame);
   /* N.B. The only difference between variants of the Draw*Image
    * functions below is the type of the aImage argument.
    */
   /**
    * Draw a background image.  The image's dimensions are as specified in aDest;
    * the image itself is not consulted to determine a size.
    * See https://wiki.mozilla.org/Gecko:Image_Snapping_and_Rendering
    *   @param aRenderingContext Where to draw the image, set up with an
    *                            appropriate scale and transform for drawing in
    *                            app units.
    *   @param aImage            The image.
    *   @param aImageSize        The unscaled size of the image being drawn.
    *                            (This might be the image's size if no scaling
    *                            occurs, or it might be the image's size if
    *                            the image is a vector image being rendered at
    *                            that size.)
    *   @param aDest             The position and scaled area where one copy of
    *                            the image should be drawn.
    *   @param aFill             The area to be filled with copies of the
    *                            image.
    *   @param aAnchor           A point in aFill which we will ensure is
    *                            pixel-aligned in the output.
    *   @param aDirty            Pixels outside this area may be skipped.
    *   @param aImageFlags       Image flags of the imgIContainer::FLAG_* variety
    */
   static nsresult DrawBackgroundImage(nsRenderingContext* aRenderingContext,
                                       imgIContainer*      aImage,
                                       const nsIntSize&    aImageSize,
                                       GraphicsFilter      aGraphicsFilter,
                                       const nsRect&       aDest,
                                       const nsRect&       aFill,
                                       const nsPoint&      aAnchor,
                                       const nsRect&       aDirty,
                                       uint32_t            aImageFlags);
   /**
    * Draw an image.
    * See https://wiki.mozilla.org/Gecko:Image_Snapping_and_Rendering
    *   @param aRenderingContext Where to draw the image, set up with an
    *                            appropriate scale and transform for drawing in
    *                            app units.
    *   @param aImage            The image.
    *   @param aDest             Where one copy of the image should mapped to.
    *   @param aFill             The area to be filled with copies of the
    *                            image.
    *   @param aAnchor           A point in aFill which we will ensure is
    *                            pixel-aligned in the output.
    *   @param aDirty            Pixels outside this area may be skipped.
    *   @param aImageFlags       Image flags of the imgIContainer::FLAG_* variety
    */
   static nsresult DrawImage(nsRenderingContext* aRenderingContext,
                             imgIContainer*       aImage,
                             GraphicsFilter       aGraphicsFilter,
                             const nsRect&        aDest,
                             const nsRect&        aFill,
                             const nsPoint&       aAnchor,
                             const nsRect&        aDirty,
                             uint32_t             aImageFlags);
   /**
    * Convert an nsRect to a gfxRect.
    */
   static gfxRect RectToGfxRect(const nsRect& aRect,
                                int32_t aAppUnitsPerDevPixel);
   /**
    * Draw a drawable using the pixel snapping algorithm.
    * See https://wiki.mozilla.org/Gecko:Image_Snapping_and_Rendering
    *   @param aRenderingContext Where to draw the image, set up with an
    *                            appropriate scale and transform for drawing in
    *                            app units.
    *   @param aDrawable         The drawable we want to draw.
    *   @param aFilter           The graphics filter we should draw with.
    *   @param aDest             Where one copy of the image should mapped to.
    *   @param aFill             The area to be filled with copies of the
    *                            image.
    *   @param aAnchor           A point in aFill which we will ensure is
    *                            pixel-aligned in the output.
    *   @param aDirty            Pixels outside this area may be skipped.
    */
   static void DrawPixelSnapped(nsRenderingContext* aRenderingContext,
                                gfxDrawable*         aDrawable,
                                GraphicsFilter       aFilter,
                                const nsRect&        aDest,
                                const nsRect&        aFill,
                                const nsPoint&       aAnchor,
                                const nsRect&        aDirty);
   /**
    * Draw a whole image without scaling or tiling.
    *
    *   @param aRenderingContext Where to draw the image, set up with an
    *                            appropriate scale and transform for drawing in
    *                            app units.
    *   @param aImage            The image.
    *   @param aDest             The top-left where the image should be drawn
    *   @param aDirty            If non-null, then pixels outside this area may
    *                            be skipped.
    *   @param aImageFlags       Image flags of the imgIContainer::FLAG_* variety
    *   @param aSourceArea       If non-null, this area is extracted from
    *                            the image and drawn at aDest. It's
    *                            in appunits. For best results it should
    *                            be aligned with image pixels.
    */
   static nsresult DrawSingleUnscaledImage(nsRenderingContext* aRenderingContext,
                                           imgIContainer*       aImage,
                                           GraphicsFilter       aGraphicsFilter,
                                           const nsPoint&       aDest,
                                           const nsRect*        aDirty,
                                           uint32_t             aImageFlags,
                                           const nsRect*        aSourceArea = nullptr);
   /**
    * Draw a whole image without tiling.
    *
    *   @param aRenderingContext Where to draw the image, set up with an
    *                            appropriate scale and transform for drawing in
    *                            app units.
    *   @param aImage            The image.
    *   @param aDest             The area that the image should fill
    *   @param aDirty            Pixels outside this area may be skipped.
    *   @param aSVGContext       If non-null, SVG-related rendering context
    *                            such as overridden attributes on the image
    *                            document's root <svg> node. Ignored for
    *                            raster images.
    *   @param aImageFlags       Image flags of the imgIContainer::FLAG_*
    *                            variety.
    *   @param aSourceArea       If non-null, this area is extracted from
    *                            the image and drawn in aDest. It's
    *                            in appunits. For best results it should
    *                            be aligned with image pixels.
    */
   static nsresult DrawSingleImage(nsRenderingContext*    aRenderingContext,
                                   imgIContainer*         aImage,
                                   GraphicsFilter         aGraphicsFilter,
                                   const nsRect&          aDest,
                                   const nsRect&          aDirty,
                                   const mozilla::SVGImageContext* aSVGContext,
                                   uint32_t               aImageFlags,
                                   const nsRect*          aSourceArea = nullptr);
   /**
    * Given an imgIContainer, this method attempts to obtain an intrinsic
    * px-valued height & width for it.  If the imgIContainer has a non-pixel
    * value for either height or width, this method tries to generate a pixel
    * value for that dimension using the intrinsic ratio (if available).  The
    * intrinsic ratio will be assigned to aIntrinsicRatio; if there's no
    * intrinsic ratio then (0, 0) will be assigned.
    *
    * This method will always set aGotWidth and aGotHeight to indicate whether
    * we were able to successfully obtain (or compute) a value for each
    * dimension.
    *
    * NOTE: This method is similar to ComputeSizeWithIntrinsicDimensions.  The
    * difference is that this one is simpler and is suited to places where we
    * have less information about the frame tree.
    */
   static void ComputeSizeForDrawing(imgIContainer* aImage,
                                     nsIntSize&     aImageSize,
                                     nsSize&        aIntrinsicRatio,
                                     bool&          aGotWidth,
                                     bool&          aGotHeight);
   /**
    * Given a source area of an image (in appunits) and a destination area
    * that we want to map that source area too, computes the area that
    * would be covered by the whole image. This is useful for passing to
    * the aDest parameter of DrawImage, when we want to draw a subimage
    * of an overall image.
    */
   static nsRect GetWholeImageDestination(const nsIntSize& aWholeImageSize,
                                          const nsRect& aImageSourceArea,
                                          const nsRect& aDestArea);
   /**
    * Given an image container and an orientation, returns an image container
    * that contains the same image, reoriented appropriately. May return the
    * original image container if no changes are needed.
    *
    * @param aContainer   The image container to apply the orientation to.
    * @param aOrientation The desired orientation.
    */
   static already_AddRefed<imgIContainer>
   OrientImage(imgIContainer* aContainer,
               const nsStyleImageOrientation& aOrientation);
   /**
    * Determine if any corner radius is of nonzero size
    *   @param aCorners the |nsStyleCorners| object to check
    *   @return true unless all the coordinates are 0%, 0 or null.
    *
    * A corner radius with one dimension zero and one nonzero is
    * treated as a nonzero-radius corner, even though it will end up
    * being rendered like a zero-radius corner.  This is because such
    * corners are not expected to appear outside of test cases, and it's
    * simpler to implement the test this way.
    */
   static bool HasNonZeroCorner(const nsStyleCorners& aCorners);
   /**
    * Determine if there is any corner radius on corners adjacent to the
    * given side.
    */
   static bool HasNonZeroCornerOnSide(const nsStyleCorners& aCorners,
                                        mozilla::css::Side aSide);
   /**
    * Determine if a widget is likely to require transparency or translucency.
    *   @param aBackgroundFrame The frame that the background is set on. For
    *                           <window>s, this will be the canvas frame.
    *   @param aCSSRootFrame    The frame that holds CSS properties affecting
    *                           the widget's transparency. For menupopups,
    *                           aBackgroundFrame and aCSSRootFrame will be the
    *                           same.
    *   @return a value suitable for passing to SetWindowTranslucency
    */
   static nsTransparencyMode GetFrameTransparency(nsIFrame* aBackgroundFrame,
                                                  nsIFrame* aCSSRootFrame);
   /**
    * A frame is a popup if it has its own floating window. Menus, panels
    * and combobox dropdowns are popups.
    */
   static bool IsPopup(nsIFrame* aFrame);
   /**
    * Find the nearest "display root". This is the nearest enclosing
    * popup frame or the root prescontext's root frame.
    */
   static nsIFrame* GetDisplayRootFrame(nsIFrame* aFrame);
   /**
    * Get the reference frame that would be used when constructing a
    * display item for this frame.  (Note, however, that
    * nsDisplayTransform use the reference frame appropriate for their
    * GetTransformRootFrame(), rather than using their own frame as a
    * reference frame.)
    *
    * This duplicates some of the logic of GetDisplayRootFrame above and
    * of nsDisplayListBuilder::FindReferenceFrameFor.
    *
    * If you have an nsDisplayListBuilder, you should get the reference
    * frame from it instead of calling this.
    */
   static nsIFrame* GetReferenceFrame(nsIFrame* aFrame);
   /**
    * Get the parent of this frame, except if that parent is part of a
    * preserve-3d hierarchy, get the parent of the root of the
    * preserve-3d hierarchy.
    *
    * (This is used as the starting point for reference frame computation
    * for nsDisplayTransform display items.)
    */
   static nsIFrame* GetTransformRootFrame(nsIFrame* aFrame);
   /**
    * Get textrun construction flags determined by a given style; in particular
    * some combination of:
    * -- TEXT_DISABLE_OPTIONAL_LIGATURES if letter-spacing is in use
    * -- TEXT_OPTIMIZE_SPEED if the text-rendering CSS property and font size
    * and prefs indicate we should be optimizing for speed over quality
    */
   static uint32_t GetTextRunFlagsForStyle(nsStyleContext* aStyleContext,
                                           const nsStyleFont* aStyleFont,
                                           const nsStyleText* aStyleText,
                                           nscoord aLetterSpacing);
   /**
    * Takes two rectangles whose origins must be the same, and computes
    * the difference between their union and their intersection as two
    * rectangles. (This difference is a superset of the difference
    * between the two rectangles.)
    */
   static void GetRectDifferenceStrips(const nsRect& aR1, const nsRect& aR2,
                                       nsRect* aHStrip, nsRect* aVStrip);
   /**
    * Get a device context that can be used to get up-to-date device
    * dimensions for the given window. For some reason, this is more
    * complicated than it ought to be in multi-monitor situations.
    */
   static nsDeviceContext*
   GetDeviceContextForScreenInfo(nsPIDOMWindow* aWindow);
   /**
    * Some frames with 'position: fixed' (nsStylePosition::mDisplay ==
    * NS_STYLE_POSITION_FIXED) are not really fixed positioned, since
    * they're inside an element with -moz-transform.  This function says
    * whether such an element is a real fixed-pos element.
    */
   static bool IsReallyFixedPos(nsIFrame* aFrame);
   /**
    * Obtain a gfxASurface from the given DOM element, if possible.
    * This obtains the most natural surface from the element; that
    * is, the one that can be obtained with the fewest conversions.
    *
    * The flags below can modify the behaviour of this function.  The
    * result is returned as a SurfaceFromElementResult struct, also
    * defined below.
    *
    * Currently, this will do:
    *  - HTML Canvas elements: will return the underlying canvas surface
    *  - HTML Video elements: will return the current video frame
    *  - Image elements: will return the image
    *
    * The above results are modified by the below flags (copying,
    * forcing image surface, etc.).
    */
   enum {
     /* When creating a new surface, create an image surface */
     SFE_WANT_IMAGE_SURFACE = 1 << 0,
     /* Whether to extract the first frame (as opposed to the
        current frame) in the case that the element is an image. */
     SFE_WANT_FIRST_FRAME = 1 << 1,
     /* Whether we should skip colorspace/gamma conversion */
     SFE_NO_COLORSPACE_CONVERSION = 1 << 2,
     /* Specifies that the caller wants unpremultiplied pixel data.
        If this is can be done efficiently, the result will be a
        DataSourceSurface and mIsPremultiplied with be set to false. */
     SFE_PREFER_NO_PREMULTIPLY_ALPHA = 1 << 3,
     /* Whether we should skip getting a surface for vector images and
        return a DirectDrawInfo containing an imgIContainer instead. */
     SFE_NO_RASTERIZING_VECTORS = 1 << 4
   };
   struct DirectDrawInfo {
     /* imgIContainer to directly draw to a context */
     nsCOMPtr<imgIContainer> mImgContainer;
     /* which frame to draw */
     uint32_t mWhichFrame;
     /* imgIContainer flags to use when drawing */
     uint32_t mDrawingFlags;
   };
   struct SurfaceFromElementResult {
     SurfaceFromElementResult();
     /* mSurface will contain the resulting surface, or will be nullptr on error */
     nsRefPtr<gfxASurface> mSurface;
     mozilla::RefPtr<SourceSurface> mSourceSurface;
     /* Contains info for drawing when there is no mSourceSurface. */
     DirectDrawInfo mDrawInfo;
     /* The size of the surface */
     gfxIntSize mSize;
     /* The principal associated with the element whose surface was returned.
        If there is a surface, this will never be null. */
     nsCOMPtr<nsIPrincipal> mPrincipal;
     /* The image request, if the element is an nsIImageLoadingContent */
     nsCOMPtr<imgIRequest> mImageRequest;
     /* Whether the element was "write only", that is, the bits should not be exposed to content */
     bool mIsWriteOnly;
     /* Whether the element was still loading.  Some consumers need to handle
        this case specially. */
     bool mIsStillLoading;
     /* Whether the element used CORS when loading. */
     bool mCORSUsed;
     /* Whether the returned image contains premultiplied pixel data */
     bool mIsPremultiplied;
   };
   static SurfaceFromElementResult SurfaceFromElement(mozilla::dom::Element *aElement,
                                                      uint32_t aSurfaceFlags = 0,
                                                      DrawTarget *aTarget = nullptr);
   static SurfaceFromElementResult SurfaceFromElement(nsIImageLoadingContent *aElement,
                                                      uint32_t aSurfaceFlags = 0,
                                                      DrawTarget *aTarget = nullptr);
   // Need an HTMLImageElement overload, because otherwise the
   // nsIImageLoadingContent and mozilla::dom::Element overloads are ambiguous
   // for HTMLImageElement.
   static SurfaceFromElementResult SurfaceFromElement(mozilla::dom::HTMLImageElement *aElement,
                                                      uint32_t aSurfaceFlags = 0,
                                                      DrawTarget *aTarget = nullptr);
   static SurfaceFromElementResult SurfaceFromElement(mozilla::dom::HTMLCanvasElement *aElement,
                                                      uint32_t aSurfaceFlags = 0,
                                                      DrawTarget *aTarget = nullptr);
   static SurfaceFromElementResult SurfaceFromElement(mozilla::dom::HTMLVideoElement *aElement,
                                                      uint32_t aSurfaceFlags = 0,
                                                      DrawTarget *aTarget = nullptr);
   /**
    * When the document is editable by contenteditable attribute of its root
    * content or body content.
    *
    * Be aware, this returns nullptr if it's in designMode.
    *
    * For example:
    *
    *  <html contenteditable="true"><body></body></html>
    *    returns the <html>.
    *
    *  <html><body contenteditable="true"></body></html>
    *  <body contenteditable="true"></body>
    *    With these cases, this returns the <body>.
    *    NOTE: The latter case isn't created normally, however, it can be
    *          created by script with XHTML.
    *
    *  <body><p contenteditable="true"></p></body>
    *    returns nullptr because <body> isn't editable.
    */
   static nsIContent*
     GetEditableRootContentByContentEditable(nsIDocument* aDocument);
   /**
    * Returns true if the passed in prescontext needs the dark grey background
    * that goes behind the page of a print preview presentation.
    */
   static bool NeedsPrintPreviewBackground(nsPresContext* aPresContext);
   /**
    * Adds all font faces used in the frame tree starting from aFrame
    * to the list aFontFaceList.
    */
   static nsresult GetFontFacesForFrames(nsIFrame* aFrame,
                                         nsFontFaceList* aFontFaceList);
   /**
    * Adds all font faces used within the specified range of text in aFrame,
    * and optionally its continuations, to the list in aFontFaceList.
    * Pass 0 and INT32_MAX for aStartOffset and aEndOffset to specify the
    * entire text is to be considered.
    */
   static nsresult GetFontFacesForText(nsIFrame* aFrame,
                                       int32_t aStartOffset,
                                       int32_t aEndOffset,
                                       bool aFollowContinuations,
                                       nsFontFaceList* aFontFaceList);
   /**
    * Walks the frame tree starting at aFrame looking for textRuns.
    * If |clear| is true, just clears the TEXT_RUN_MEMORY_ACCOUNTED flag
    * on each textRun found (and |aMallocSizeOf| is not used).
    * If |clear| is false, adds the storage used for each textRun to the
    * total, and sets the TEXT_RUN_MEMORY_ACCOUNTED flag to avoid double-
    * accounting. (Runs with this flag already set will be skipped.)
    * Expected usage pattern is therefore to call twice:
    *    (void)SizeOfTextRunsForFrames(rootFrame, nullptr, true);
    *    total = SizeOfTextRunsForFrames(rootFrame, mallocSizeOf, false);
    */
   static size_t SizeOfTextRunsForFrames(nsIFrame* aFrame,
                                         mozilla::MallocSizeOf aMallocSizeOf,
                                         bool clear);
   /**
    * Returns true if the content node has animations or transitions that can be
    * performed on the compositor.
    */
   static bool HasAnimationsForCompositor(nsIContent* aContent,
                                          nsCSSProperty aProperty);
   /**
    * Returns true if the content node has animations or transitions for the
    * property.
    */
   static bool HasAnimations(nsIContent* aContent, nsCSSProperty aProperty);
   /**
    * Checks if off-main-thread animations are enabled.
    */
   static bool AreAsyncAnimationsEnabled();
   /**
    * Checks if we should warn about animations that can't be async
    */
   static bool IsAnimationLoggingEnabled();
   /**
    * Find a suitable scale for an element (aContent) over the course of any
    * animations and transitions on the element.
    * It will check the maximum and minimum scale during the animations and
    * transitions and return a suitable value for performance and quality.
    * Will return scale(1,1) if there is no animated scaling.
    * Always return positive value.
    */
   static gfxSize ComputeSuitableScaleForAnimation(nsIContent* aContent);
   /**
    * Checks if we should forcibly use nearest pixel filtering for the
    * background.
    */
   static bool UseBackgroundNearestFiltering();
   /**
    * Checks whether we want to use the GPU to scale images when
    * possible.
    */
   static bool GPUImageScalingEnabled();
   /**
    * Checks whether we want to layerize animated images whenever possible.
    */
   static bool AnimatedImageLayersEnabled();
   /**
    * Checks if we should enable parsing for CSS Filters.
    */
   static bool CSSFiltersEnabled();
   /**
    * Checks whether support for the CSS-wide "unset" value is enabled.
    */
   static bool UnsetValueEnabled();
   /**
    * Checks whether support for the CSS text-align (and -moz-text-align-last)
    * 'true' value is enabled.
    */
   static bool IsTextAlignTrueValueEnabled();
   /**
    * Checks if CSS variables are currently enabled.
    */
   static bool CSSVariablesEnabled()
   {
     return sCSSVariablesEnabled;
   }
   static bool InterruptibleReflowEnabled()
   {
     return sInterruptibleReflowEnabled;
   }
   /**
    * Unions the overflow areas of the children of aFrame with aOverflowAreas.
    * aSkipChildLists specifies any child lists that should be skipped.
    * kSelectPopupList and kPopupList are always skipped.
    */
   static void UnionChildOverflow(nsIFrame* aFrame,
                                  nsOverflowAreas& aOverflowAreas,
                                  mozilla::layout::FrameChildListIDs aSkipChildLists =
                                      mozilla::layout::FrameChildListIDs());
   /**
    * Return the font size inflation *ratio* for a given frame.  This is
    * the factor by which font sizes should be inflated; it is never
    * smaller than 1.
    */
   static float FontSizeInflationFor(const nsIFrame *aFrame);
   /**
    * Perform the first half of the computation of FontSizeInflationFor
    * (see above).
    * This includes determining whether inflation should be performed
    * within this container and returning 0 if it should not be.
    *
    * The result is guaranteed not to vary between line participants
    * (inlines, text frames) within a line.
    *
    * The result should not be used directly since font sizes slightly
    * above the minimum should always be adjusted as done by
    * FontSizeInflationInner.
    */
   static nscoord InflationMinFontSizeFor(const nsIFrame *aFrame);
   /**
    * Perform the second half of the computation done by
    * FontSizeInflationFor (see above).
    *
    * aMinFontSize must be the result of one of the
    *   InflationMinFontSizeFor methods above.
    */
   static float FontSizeInflationInner(const nsIFrame *aFrame,
                                       nscoord aMinFontSize);
   static bool FontSizeInflationEnabled(nsPresContext *aPresContext);
   /**
    * See comment above "font.size.inflation.maxRatio" in
    * modules/libpref/src/init/all.js .
    */
   static uint32_t FontSizeInflationMaxRatio() {
     return sFontSizeInflationMaxRatio;
   }
   /**
    * See comment above "font.size.inflation.emPerLine" in
    * modules/libpref/src/init/all.js .
    */
   static uint32_t FontSizeInflationEmPerLine() {
     return sFontSizeInflationEmPerLine;
   }
   /**
    * See comment above "font.size.inflation.minTwips" in
    * modules/libpref/src/init/all.js .
    */
   static uint32_t FontSizeInflationMinTwips() {
     return sFontSizeInflationMinTwips;
   }
   /**
    * See comment above "font.size.inflation.lineThreshold" in
    * modules/libpref/src/init/all.js .
    */
   static uint32_t FontSizeInflationLineThreshold() {
     return sFontSizeInflationLineThreshold;
   }
   static bool FontSizeInflationForceEnabled() {
     return sFontSizeInflationForceEnabled;
   }
   static bool FontSizeInflationDisabledInMasterProcess() {
     return sFontSizeInflationDisabledInMasterProcess;
   }
   /**
    * See comment above "font.size.inflation.mappingIntercept" in
    * modules/libpref/src/init/all.js .
    */
   static int32_t FontSizeInflationMappingIntercept() {
     return sFontSizeInflationMappingIntercept;
   }
   /**
    * Returns true if the nglayout.debug.invalidation pref is set to true.
    * Note that sInvalidationDebuggingIsEnabled is declared outside this function to
    * allow it to be accessed an manipulated from breakpoint conditions.
    */
   static bool InvalidationDebuggingIsEnabled() {
     return sInvalidationDebuggingIsEnabled || getenv("MOZ_DUMP_INVALIDATION") != 0;
   }
   static void Initialize();
   static void Shutdown();
   /**
    * Register an imgIRequest object with a refresh driver.
    *
    * @param aPresContext The nsPresContext whose refresh driver we want to
    *        register with.
    * @param aRequest A pointer to the imgIRequest object which the client wants
    *        to register with the refresh driver.
    * @param aRequestRegistered A pointer to a boolean value which indicates
    *        whether the given image request is registered. If
    *        *aRequestRegistered is true, then this request will not be
    *        registered again. If the request is registered by this function,
    *        then *aRequestRegistered will be set to true upon the completion of
    *        this function.
    *
    */
   static void RegisterImageRequest(nsPresContext* aPresContext,
                                    imgIRequest* aRequest,
                                    bool* aRequestRegistered);
   /**
    * Register an imgIRequest object with a refresh driver, but only if the
    * request is for an image that is animated.
    *
    * @param aPresContext The nsPresContext whose refresh driver we want to
    *        register with.
    * @param aRequest A pointer to the imgIRequest object which the client wants
    *        to register with the refresh driver.
    * @param aRequestRegistered A pointer to a boolean value which indicates
    *        whether the given image request is registered. If
    *        *aRequestRegistered is true, then this request will not be
    *        registered again. If the request is registered by this function,
    *        then *aRequestRegistered will be set to true upon the completion of
    *        this function.
    *
    */
   static void RegisterImageRequestIfAnimated(nsPresContext* aPresContext,
                                              imgIRequest* aRequest,
                                              bool* aRequestRegistered);
   /**
    * Deregister an imgIRequest object from a refresh driver.
    *
    * @param aPresContext The nsPresContext whose refresh driver we want to
    *        deregister from.
    * @param aRequest A pointer to the imgIRequest object with which the client
    *        previously registered and now wants to deregister from the refresh
    *        driver.
    * @param aRequestRegistered A pointer to a boolean value which indicates
    *        whether the given image request is registered. If
    *        *aRequestRegistered is false, then this request will not be
    *        deregistered. If the request is deregistered by this function,
    *        then *aRequestRegistered will be set to false upon the completion of
    *        this function.
    */
   static void DeregisterImageRequest(nsPresContext* aPresContext,
                                      imgIRequest* aRequest,
                                      bool* aRequestRegistered);
   /**
    * Shim to nsCSSFrameConstructor::PostRestyleEvent. Exists so that we
    * can avoid including nsCSSFrameConstructor.h and all its dependencies
    * in content files.
    */
   static void PostRestyleEvent(mozilla::dom::Element* aElement,
                                nsRestyleHint aRestyleHint,
                                nsChangeHint aMinChangeHint);
   /**
    * Updates a pair of x and y distances if a given point is closer to a given
    * rectangle than the original distance values.  If aPoint is closer to
    * aRect than aClosestXDistance and aClosestYDistance indicate, then those
    * two variables are updated with the distance between aPoint and aRect,
    * and true is returned.  If aPoint is not closer, then aClosestXDistance
    * and aClosestYDistance are left unchanged, and false is returned.
    *
    * Distances are measured in the two dimensions separately; a closer x
    * distance beats a closer y distance.
    */
   template<typename PointType, typename RectType, typename CoordType>
   static bool PointIsCloserToRect(PointType aPoint, const RectType& aRect,
                                   CoordType& aClosestXDistance,
                                   CoordType& aClosestYDistance);
   /**
    * Computes the box shadow rect for the frame, or returns an empty rect if
    * there are no shadows.
    *
    * @param aFrame Frame to compute shadows for.
    * @param aFrameSize Size of aFrame (in case it hasn't been set yet).
    */
   static nsRect GetBoxShadowRectForFrame(nsIFrame* aFrame, const nsSize& aFrameSize);
 #ifdef DEBUG
   /**
    * Assert that there are no duplicate continuations of the same frame
    * within aFrameList.  Optimize the tests by assuming that all frames
    * in aFrameList have parent aContainer.
    */
   static void
   AssertNoDuplicateContinuations(nsIFrame* aContainer,
                                  const nsFrameList& aFrameList);
   /**
    * Assert that the frame tree rooted at |aSubtreeRoot| is empty, i.e.,
    * that it contains no first-in-flows.
    */
   static void
   AssertTreeOnlyEmptyNextInFlows(nsIFrame *aSubtreeRoot);
 #endif
   /**
    * Determine if aImageFrame (which is an nsImageFrame, nsImageControlFrame, or
    * nsSVGImageFrame) is visible or close to being visible via scrolling and
    * update the presshell with this knowledge.
    */
   static void
   UpdateImageVisibilityForFrame(nsIFrame* aImageFrame);
  /**
   * Calculate the compostion size for a frame. See FrameMetrics.h for
   * defintion of composition size (or bounds).
   */
   static nsSize
   CalculateCompositionSizeForFrame(nsIFrame* aFrame);
  /**
   * Calculate the composition size for the root scroll frame of the root
   * content document.
   * @param aFrame A frame in the root content document (or a descendant of it).
   * @param aIsRootContentDocRootScrollFrame Whether aFrame is already the root
   *          scroll frame of the root content document. In this case we just
   *          use aFrame's own composition size.
   * @param aMetrics A partially populated FrameMetrics for aFrame. Must have at
   *          least mCompositionBounds, mCumulativeResolution, and
   *          mDevPixelsPerCSSPixel set.
   */
   static CSSSize
   CalculateRootCompositionSize(nsIFrame* aFrame,
                                bool aIsRootContentDocRootScrollFrame,
                                const FrameMetrics& aMetrics);
  /**
   * Calculate the scrollable rect for a frame. See FrameMetrics.h for
   * defintion of scrollable rect. aScrollableFrame is the scroll frame to calculate
   * the scrollable rect for. If it's null then we calculate the scrollable rect
   * as the rect of the root frame.
   */
   static nsRect
   CalculateScrollableRectForFrame(nsIScrollableFrame* aScrollableFrame, nsIFrame* aRootFrame);
  /**
   * Calculate the expanded scrollable rect for a frame. See FrameMetrics.h for
   * defintion of expanded scrollable rect.
   */
   static nsRect
   CalculateExpandedScrollableRect(nsIFrame* aFrame);
   /**
    * Return whether we want to use APZ for subframes in this process.
    * Currently we don't support APZ for the parent process on B2G.
    */
   static bool WantSubAPZC();
  /**
    * Get the display port for |aScrollFrame|'s content. If |aScrollFrame|
    * WantsAsyncScroll() and we don't have a scrollable displayport yet (as
    * tracked by |aBuilder|), calculate and set a display port. Returns true if
    * there is (now) a displayport, and if so the displayport is returned in
    * |aOutDisplayport|.
    *
    * Note that a displayport can either be stored as a rect, or as a base
    * rect + margins. If it is stored as a base rect + margins, the base rect
    * is updated to |aDisplayPortBase|, and the rect assembled from the
    * base rect and margins is returned. If this function creates a displayport,
    * it computes margins and stores |aDisplayPortBase| as the base rect.
    *
    * This is intended to be called during display list building.
    */
   static bool GetOrMaybeCreateDisplayPort(nsDisplayListBuilder& aBuilder,
                                           nsIFrame* aScrollFrame,
                                           nsRect aDisplayPortBase,
                                           nsRect* aOutDisplayport);
 private:
   static uint32_t sFontSizeInflationEmPerLine;
   static uint32_t sFontSizeInflationMinTwips;
   static uint32_t sFontSizeInflationLineThreshold;
   static int32_t  sFontSizeInflationMappingIntercept;
   static uint32_t sFontSizeInflationMaxRatio;
   static bool sFontSizeInflationForceEnabled;
   static bool sFontSizeInflationDisabledInMasterProcess;
   static bool sInvalidationDebuggingIsEnabled;
   static bool sCSSVariablesEnabled;
   static bool sInterruptibleReflowEnabled;
 };
 MOZ_FINISH_NESTED_ENUM_CLASS(nsLayoutUtils::RepaintMode)
 template<typename PointType, typename RectType, typename CoordType>
 /* static */ bool
 nsLayoutUtils::PointIsCloserToRect(PointType aPoint, const RectType& aRect,
                                    CoordType& aClosestXDistance,
                                    CoordType& aClosestYDistance)
 {
   CoordType fromLeft = aPoint.x - aRect.x;
   CoordType fromRight = aPoint.x - aRect.XMost();
   CoordType xDistance;
   if (fromLeft >= 0 && fromRight <= 0) {
     xDistance = 0;
   } else {
     xDistance = std::min(abs(fromLeft), abs(fromRight));
   }
   if (xDistance <= aClosestXDistance) {
     if (xDistance < aClosestXDistance) {
       aClosestYDistance = std::numeric_limits<CoordType>::max();
     }
     CoordType fromTop = aPoint.y - aRect.y;
     CoordType fromBottom = aPoint.y - aRect.YMost();
     CoordType yDistance;
     if (fromTop >= 0 && fromBottom <= 0) {
       yDistance = 0;
     } else {
       yDistance = std::min(abs(fromTop), abs(fromBottom));
     }
     if (yDistance < aClosestYDistance) {
       aClosestXDistance = xDistance;
       aClosestYDistance = yDistance;
       return true;
     }
   }
   return false;
 }
 namespace mozilla {
   namespace layout {
     /**
      * An RAII class which will, for the duration of its lifetime,
      * **if** the frame given is a container for font size inflation,
      * set the current inflation container on the pres context to null
      * (and then, in its destructor, restore the old value).
      */
     class AutoMaybeDisableFontInflation {
     public:
       AutoMaybeDisableFontInflation(nsIFrame *aFrame);
       ~AutoMaybeDisableFontInflation();
     private:
       nsPresContext *mPresContext;
       bool mOldValue;
     };
   }
 }
 class nsSetAttrRunnable : public nsRunnable
 {
 public:
   nsSetAttrRunnable(nsIContent* aContent, nsIAtom* aAttrName,
                     const nsAString& aValue);
   nsSetAttrRunnable(nsIContent* aContent, nsIAtom* aAttrName,
                     int32_t aValue);
   NS_DECL_NSIRUNNABLE
   nsCOMPtr<nsIContent> mContent;
   nsCOMPtr<nsIAtom> mAttrName;
   nsAutoString mValue;
 };
 class nsUnsetAttrRunnable : public nsRunnable
 {
 public:
   nsUnsetAttrRunnable(nsIContent* aContent, nsIAtom* aAttrName);
   NS_DECL_NSIRUNNABLE
   nsCOMPtr<nsIContent> mContent;
   nsCOMPtr<nsIAtom> mAttrName;
 };
 #endif // nsLayoutUtils_h__

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