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

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

layout/base/FrameLayerBuilder.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: 20; 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 FRAMELAYERBUILDER_H_
 #define FRAMELAYERBUILDER_H_
 #include "nsTHashtable.h"
 #include "nsHashKeys.h"
 #include "nsTArray.h"
 #include "nsRegion.h"
 #include "nsIFrame.h"
 #include "ImageLayers.h"
 #include "DisplayItemClip.h"
 #include "mozilla/layers/LayersTypes.h"
 class nsDisplayListBuilder;
 class nsDisplayList;
 class nsDisplayItem;
 class gfxContext;
 class nsDisplayItemGeometry;
 namespace mozilla {
 namespace layers {
 class ContainerLayer;
 class LayerManager;
 class BasicLayerManager;
 class ThebesLayer;
 }
 class FrameLayerBuilder;
 class LayerManagerData;
 class ThebesLayerData;
 enum LayerState {
   LAYER_NONE,
   LAYER_INACTIVE,
   LAYER_ACTIVE,
   // Force an active layer even if it causes incorrect rendering, e.g.
   // when the layer has rounded rect clips.
   LAYER_ACTIVE_FORCE,
   // Special layer that is metadata only.
   LAYER_ACTIVE_EMPTY,
   // Inactive style layer for rendering SVG effects.
   LAYER_SVG_EFFECTS
 };
 class RefCountedRegion {
 public:
   NS_INLINE_DECL_REFCOUNTING(RefCountedRegion)
   RefCountedRegion() : mIsInfinite(false) {}
   nsRegion mRegion;
   bool mIsInfinite;
 };
 struct ContainerLayerParameters {
   ContainerLayerParameters() :
     mXScale(1), mYScale(1), mAncestorClipRect(nullptr),
     mInTransformedSubtree(false), mInActiveTransformedSubtree(false),
     mDisableSubpixelAntialiasingInDescendants(false)
   {}
   ContainerLayerParameters(float aXScale, float aYScale) :
     mXScale(aXScale), mYScale(aYScale), mAncestorClipRect(nullptr),
     mInTransformedSubtree(false), mInActiveTransformedSubtree(false),
     mDisableSubpixelAntialiasingInDescendants(false)
   {}
   ContainerLayerParameters(float aXScale, float aYScale,
                            const nsIntPoint& aOffset,
                            const ContainerLayerParameters& aParent) :
     mXScale(aXScale), mYScale(aYScale), mAncestorClipRect(nullptr),
     mOffset(aOffset),
     mInTransformedSubtree(aParent.mInTransformedSubtree),
     mInActiveTransformedSubtree(aParent.mInActiveTransformedSubtree),
     mDisableSubpixelAntialiasingInDescendants(aParent.mDisableSubpixelAntialiasingInDescendants)
   {}
   float mXScale, mYScale;
   /**
    * An ancestor clip rect that can be applied to restrict the visibility
    * of this container. Null if none available.
    */
   const nsIntRect* mAncestorClipRect;
   /**
    * An offset to append to the transform set on all child layers created.
    */
   nsIntPoint mOffset;
   bool mInTransformedSubtree;
   bool mInActiveTransformedSubtree;
   bool mDisableSubpixelAntialiasingInDescendants;
   /**
    * When this is false, ThebesLayer coordinates are drawn to with an integer
    * translation and the scale in mXScale/mYScale.
    */
   bool AllowResidualTranslation()
   {
     // If we're in a transformed subtree, but no ancestor transform is actively
     // changing, we'll use the residual translation when drawing into the
     // ThebesLayer to ensure that snapping exactly matches the ideal transform.
     return mInTransformedSubtree && !mInActiveTransformedSubtree;
   }
 };
 /**
  * The FrameLayerBuilder is responsible for converting display lists
  * into layer trees. Every LayerManager needs a unique FrameLayerBuilder
  * to build layers.
  *
  * The most important API in this class is BuildContainerLayerFor. This
  * method takes a display list as input and constructs a ContainerLayer
  * with child layers that render the contents of the display list. It
  * records the relationship between frames and layers.
  *
  * That data enables us to retain layer trees. When constructing a
  * ContainerLayer, we first check to see if there's an existing
  * ContainerLayer for the same frame that can be recycled. If we recycle
  * it, we also try to reuse its existing ThebesLayer children to render
  * the display items without layers of their own. The idea is that by
  * recycling layers deterministically, we can ensure that when nothing
  * changes in a display list, we will reuse the existing layers without
  * changes.
  *
  * We expose a GetLeafLayerFor method that can be called by display items
  * that make their own layers (e.g. canvas and video); this method
  * locates the last layer used to render the display item, if any, and
  * return it as a candidate for recycling.
  *
  * FrameLayerBuilder sets up ThebesLayers so that 0,0 in the Thebes layer
  * corresponds to the (pixel-snapped) top-left of the aAnimatedGeometryRoot.
  * It sets up ContainerLayers so that 0,0 in the container layer
  * corresponds to the snapped top-left of the display item reference frame.
  *
  * When we construct a container layer, we know the transform that will be
  * applied to the layer. If the transform scales the content, we can get
  * better results when intermediate buffers are used by pushing some scale
  * from the container's transform down to the children. For ThebesLayer
  * children, the scaling can be achieved by changing the size of the layer
  * and drawing into it with increased or decreased resolution. By convention,
  * integer types (nsIntPoint/nsIntSize/nsIntRect/nsIntRegion) are all in layer
  * coordinates, post-scaling, whereas appunit types are all pre-scaling.
  */
 class FrameLayerBuilder : public layers::LayerUserData {
 public:
   typedef layers::ContainerLayer ContainerLayer;
   typedef layers::Layer Layer;
   typedef layers::ThebesLayer ThebesLayer;
   typedef layers::ImageLayer ImageLayer;
   typedef layers::LayerManager LayerManager;
   typedef layers::BasicLayerManager BasicLayerManager;
   typedef layers::EventRegions EventRegions;
   FrameLayerBuilder() :
     mRetainingManager(nullptr),
     mDetectedDOMModification(false),
     mInvalidateAllLayers(false),
     mInLayerTreeCompressionMode(false),
     mContainerLayerGeneration(0),
     mMaxContainerLayerGeneration(0)
   {
     MOZ_COUNT_CTOR(FrameLayerBuilder);
   }
   ~FrameLayerBuilder()
   {
     MOZ_COUNT_DTOR(FrameLayerBuilder);
   }
   static void Shutdown();
   void Init(nsDisplayListBuilder* aBuilder, LayerManager* aManager,
             ThebesLayerData* aLayerData = nullptr);
   /**
    * Call this to notify that we have just started a transaction on the
    * retained layer manager aManager.
    */
   void DidBeginRetainedLayerTransaction(LayerManager* aManager);
   /**
    * Call this just before we end a transaction.
    */
   void WillEndTransaction();
   /**
    * Call this after we end a transaction.
    */
   void DidEndTransaction();
   enum {
     CONTAINER_NOT_CLIPPED_BY_ANCESTORS = 0x01
   };
   /**
    * Build a container layer for a display item that contains a child
    * list, either reusing an existing one or creating a new one. It
    * sets the container layer children to layers which together render
    * the contents of the display list. It reuses existing layers from
    * the retained layer manager if possible.
    * aContainer may be null, in which case we construct a root layer.
    * This gets called by display list code. It calls BuildLayer on the
    * items in the display list, making items with their own layers
    * children of the new container, and assigning all other items to
    * ThebesLayer children created and managed by the FrameLayerBuilder.
    * Returns a layer with clip rect cleared; it is the
    * caller's responsibility to add any clip rect. The visible region
    * is set based on what's in the layer.
    * The container layer is transformed by aTransform (if non-null), and
    * the result is transformed by the scale factors in aContainerParameters.
    */
   already_AddRefed<ContainerLayer>
   BuildContainerLayerFor(nsDisplayListBuilder* aBuilder,
                          LayerManager* aManager,
                          nsIFrame* aContainerFrame,
                          nsDisplayItem* aContainerItem,
                          const nsDisplayList& aChildren,
                          const ContainerLayerParameters& aContainerParameters,
                          const gfx3DMatrix* aTransform,
                          uint32_t aFlags = 0);
   /**
    * Get a retained layer for a display item that needs to create its own
    * layer for rendering (i.e. under nsDisplayItem::BuildLayer). Returns
    * null if no retained layer is available, which usually means that this
    * display item didn't have a layer before so the caller will
    * need to create one.
    * Returns a layer with clip rect cleared; it is the
    * caller's responsibility to add any clip rect and set the visible
    * region.
    */
   Layer* GetLeafLayerFor(nsDisplayListBuilder* aBuilder,
                          nsDisplayItem* aItem);
   /**
    * Call this to force all retained layers to be discarded and recreated at
    * the next paint.
    */
   static void InvalidateAllLayers(LayerManager* aManager);
   static void InvalidateAllLayersForFrame(nsIFrame *aFrame);
   /**
    * Call this to determine if a frame has a dedicated (non-Thebes) layer
    * for the given display item key. If there isn't one, we return null,
    * otherwise we return the layer.
    */
   static Layer* GetDedicatedLayer(nsIFrame* aFrame, uint32_t aDisplayItemKey);
   /**
    * This callback must be provided to EndTransaction. The callback data
    * must be the nsDisplayListBuilder containing this FrameLayerBuilder.
    * This function can be called multiple times in a row to draw
    * different regions.
    */
   static void DrawThebesLayer(ThebesLayer* aLayer,
                               gfxContext* aContext,
                               const nsIntRegion& aRegionToDraw,
                               mozilla::layers::DrawRegionClip aClip,
                               const nsIntRegion& aRegionToInvalidate,
                               void* aCallbackData);
 #ifdef MOZ_DUMP_PAINTING
   /**
    * Dumps this FrameLayerBuilder's retained layer manager's retained
    * layer tree. Defaults to dumping to stdout in non-HTML format.
    */
   static void DumpRetainedLayerTree(LayerManager* aManager, FILE* aFile = stdout, bool aDumpHtml = false);
 #endif
   /******* PRIVATE METHODS to FrameLayerBuilder.cpp ********/
   /* These are only in the public section because they need
    * to be called by file-scope helper functions in FrameLayerBuilder.cpp.
    */
   /**
    * Record aItem as a display item that is rendered by aLayer.
    *
    * @param aLayer Layer that the display item will be rendered into
    * @param aItem Display item to be drawn.
    * @param aLayerState What LayerState the item is using.
    * @param aTopLeft offset from active scrolled root to reference frame
    * @param aManager If the layer is in the LAYER_INACTIVE state,
    * then this is the temporary layer manager to draw with.
    */
   void AddLayerDisplayItem(Layer* aLayer,
                            nsDisplayItem* aItem,
                            const DisplayItemClip& aClip,
                            LayerState aLayerState,
                            const nsPoint& aTopLeft,
                            BasicLayerManager* aManager,
                            nsAutoPtr<nsDisplayItemGeometry> aGeometry);
   /**
    * Record aItem as a display item that is rendered by the ThebesLayer
    * aLayer, with aClipRect, where aContainerLayerFrame is the frame
    * for the container layer this ThebesItem belongs to.
    * aItem must have an underlying frame.
    * @param aTopLeft offset from active scrolled root to reference frame
    */
   void AddThebesDisplayItem(ThebesLayerData* aLayer,
                             nsDisplayItem* aItem,
                             const DisplayItemClip& aClip,
                             nsIFrame* aContainerLayerFrame,
                             LayerState aLayerState,
                             const nsPoint& aTopLeft,
                             nsAutoPtr<nsDisplayItemGeometry> aGeometry);
   /**
    * Gets the frame property descriptor for the given manager, or for the current
    * widget layer manager if nullptr is passed.
    */
   static const FramePropertyDescriptor* GetDescriptorForManager(LayerManager* aManager);
   /**
    * Calls GetOldLayerForFrame on the underlying frame of the display item,
    * and each subsequent merged frame if no layer is found for the underlying
    * frame.
    */
   Layer* GetOldLayerFor(nsDisplayItem* aItem,
                         nsDisplayItemGeometry** aOldGeometry = nullptr,
                         DisplayItemClip** aOldClip = nullptr,
                         nsTArray<nsIFrame*>* aChangedFrames = nullptr,
                         bool *aIsInvalid = nullptr);
   static Layer* GetDebugOldLayerFor(nsIFrame* aFrame, uint32_t aDisplayItemKey);
   /**
    * Destroy any stored LayerManagerDataProperty and the associated data for
    * aFrame.
    */
   static void DestroyDisplayItemDataFor(nsIFrame* aFrame);
   LayerManager* GetRetainingLayerManager() { return mRetainingManager; }
   /**
    * Returns true if the given display item was rendered during the previous
    * paint. Returns false otherwise.
    */
   static bool HasRetainedDataFor(nsIFrame* aFrame, uint32_t aDisplayItemKey);
   class DisplayItemData;
   typedef void (*DisplayItemDataCallback)(nsIFrame *aFrame, DisplayItemData* aItem);
   static void IterateRetainedDataFor(nsIFrame* aFrame, DisplayItemDataCallback aCallback);
   /**
    * Save transform that was in aLayer when we last painted, and the position
    * of the active scrolled root frame. It must be an integer
    * translation.
    */
   void SaveLastPaintOffset(ThebesLayer* aLayer);
   /**
    * Get the translation transform that was in aLayer when we last painted. It's either
    * the transform saved by SaveLastPaintTransform, or else the transform
    * that's currently in the layer (which must be an integer translation).
    */
   nsIntPoint GetLastPaintOffset(ThebesLayer* aLayer);
   /**
    * Return the resolution at which we expect to render aFrame's contents,
    * assuming they are being painted to retained layers. This takes into account
    * the resolution the contents of the ContainerLayer containing aFrame are
    * being rendered at, as well as any currently-inactive transforms between
    * aFrame and that container layer.
    */
   static gfxSize GetThebesLayerScaleForFrame(nsIFrame* aFrame);
   /**
    * Stores a Layer as the dedicated layer in the DisplayItemData for a given frame/key pair.
    *
    * Used when we optimize a ThebesLayer into an ImageLayer and want to retroactively update the
    * DisplayItemData so we can retrieve the layer from within layout.
    */
   void StoreOptimizedLayerForFrame(nsDisplayItem* aItem, Layer* aLayer);
   NS_DECLARE_FRAME_PROPERTY_WITH_FRAME_IN_DTOR(LayerManagerDataProperty,
                                                RemoveFrameFromLayerManager)
   /**
    * Retained data storage:
    *
    * Each layer manager (widget, and inactive) stores a LayerManagerData object
    * that keeps a hash-set of DisplayItemData items that were drawn into it.
    * Each frame also keeps a list of DisplayItemData pointers that were
    * created for that frame. DisplayItemData objects manage these lists automatically.
    *
    * During layer construction we update the data in the LayerManagerData object, marking
    * items that are modified. At the end we sweep the LayerManagerData hash-set and remove
    * all items that haven't been modified.
    */
   /**
    * Retained data for a display item.
    */
   class DisplayItemData MOZ_FINAL {
   public:
     friend class FrameLayerBuilder;
     uint32_t GetDisplayItemKey() { return mDisplayItemKey; }
     Layer* GetLayer() { return mLayer; }
     void Invalidate() { mIsInvalid = true; }
   private:
     DisplayItemData(LayerManagerData* aParent, uint32_t aKey, Layer* aLayer, LayerState aLayerState, uint32_t aGeneration);
     DisplayItemData(DisplayItemData &toCopy);
     /**
      * Removes any references to this object from frames
      * in mFrameList.
      */
     ~DisplayItemData();
     NS_INLINE_DECL_REFCOUNTING(DisplayItemData)
     /**
      * Associates this DisplayItemData with a frame, and adds it
      * to the LayerManagerDataProperty list on the frame.
      */
     void AddFrame(nsIFrame* aFrame);
     void RemoveFrame(nsIFrame* aFrame);
     void GetFrameListChanges(nsDisplayItem* aOther, nsTArray<nsIFrame*>& aOut);
     /**
      * Updates the contents of this item to a new set of data, instead of allocating a new
      * object.
      * Set the passed in parameters, and clears the opt layer, inactive manager, geometry
      * and clip.
      * Parent, frame list and display item key are assumed to be the same.
      */
     void UpdateContents(Layer* aLayer, LayerState aState,
                         uint32_t aContainerLayerGeneration, nsDisplayItem* aItem = nullptr);
     LayerManagerData* mParent;
     nsRefPtr<Layer> mLayer;
     nsRefPtr<Layer> mOptLayer;
     nsRefPtr<BasicLayerManager> mInactiveManager;
     nsAutoTArray<nsIFrame*, 1> mFrameList;
     nsAutoPtr<nsDisplayItemGeometry> mGeometry;
     DisplayItemClip mClip;
     uint32_t        mDisplayItemKey;
     uint32_t        mContainerLayerGeneration;
     LayerState      mLayerState;
     /**
      * Used to track if data currently stored in mFramesWithLayers (from an existing
      * paint) has been updated in the current paint.
      */
     bool            mUsed;
     bool            mIsInvalid;
   };
 protected:
   friend class LayerManagerData;
   static void RemoveFrameFromLayerManager(nsIFrame* aFrame, void* aPropertyValue);
   /**
    * Given a frame and a display item key that uniquely identifies a
    * display item for the frame, find the layer that was last used to
    * render that display item. Returns null if there is no such layer.
    * This could be a dedicated layer for the display item, or a ThebesLayer
    * that renders many display items.
    */
   DisplayItemData* GetOldLayerForFrame(nsIFrame* aFrame, uint32_t aDisplayItemKey);
   /**
    * Stores DisplayItemData associated with aFrame, stores the data in
    * mNewDisplayItemData.
    */
   DisplayItemData* StoreDataForFrame(nsDisplayItem* aItem, Layer* aLayer, LayerState aState);
   void StoreDataForFrame(nsIFrame* aFrame,
                          uint32_t aDisplayItemKey,
                          Layer* aLayer,
                          LayerState aState);
   // Flash the area within the context clip if paint flashing is enabled.
   static void FlashPaint(gfxContext *aContext);
   /*
    * Get the DisplayItemData array associated with this frame, or null if one
    * doesn't exist.
    *
    * Note that the pointer returned here is only valid so long as you don't
    * poke the LayerManagerData's mFramesWithLayers hashtable.
    */
   DisplayItemData* GetDisplayItemData(nsIFrame *aFrame, uint32_t aKey);
   /*
    * Get the DisplayItemData associated with this frame / display item pair,
    * using the LayerManager instead of FrameLayerBuilder.
    */
   static DisplayItemData* GetDisplayItemDataForManager(nsIFrame* aFrame,
                                                        uint32_t aDisplayItemKey,
                                                        LayerManager* aManager);
   static DisplayItemData* GetDisplayItemDataForManager(nsIFrame* aFrame,
                                                        uint32_t aDisplayItemKey);
   static DisplayItemData* GetDisplayItemDataForManager(nsDisplayItem* aItem, LayerManager* aManager);
   static DisplayItemData* GetDisplayItemDataForManager(nsIFrame* aFrame,
                                                        uint32_t aDisplayItemKey,
                                                        LayerManagerData* aData);
   static PLDHashOperator DumpDisplayItemDataForFrame(nsRefPtrHashKey<DisplayItemData>* aEntry,
                                                      void* aClosure);
   /**
    * We store one of these for each display item associated with a
    * ThebesLayer, in a hashtable that maps each ThebesLayer to an array
    * of ClippedDisplayItems. (ThebesLayerItemsEntry is the hash entry
    * for that hashtable.)
    * These are only stored during the paint process, so that the
    * DrawThebesLayer callback can figure out which items to draw for the
    * ThebesLayer.
    */
   struct ClippedDisplayItem {
     ClippedDisplayItem(nsDisplayItem* aItem, uint32_t aGeneration)
       : mItem(aItem), mContainerLayerGeneration(aGeneration)
     {
     }
     ~ClippedDisplayItem();
     nsDisplayItem* mItem;
     /**
      * If the display item is being rendered as an inactive
      * layer, then this stores the layer manager being
      * used for the inactive transaction.
      */
     nsRefPtr<LayerManager> mInactiveLayerManager;
     uint32_t mContainerLayerGeneration;
   };
   static void RecomputeVisibilityForItems(nsTArray<ClippedDisplayItem>& aItems,
                                           nsDisplayListBuilder* aBuilder,
                                           const nsIntRegion& aRegionToDraw,
                                           const nsIntPoint& aOffset,
                                           int32_t aAppUnitsPerDevPixel,
                                           float aXScale,
                                           float aYScale);
   void PaintItems(nsTArray<ClippedDisplayItem>& aItems,
                   const nsIntRect& aRect,
                   gfxContext* aContext,
                   nsRenderingContext* aRC,
                   nsDisplayListBuilder* aBuilder,
                   nsPresContext* aPresContext,
                   const nsIntPoint& aOffset,
                   float aXScale, float aYScale,
                   int32_t aCommonClipCount);
   /**
    * We accumulate ClippedDisplayItem elements in a hashtable during
    * the paint process. This is the hashentry for that hashtable.
    */
 public:
   class ThebesLayerItemsEntry : public nsPtrHashKey<ThebesLayer> {
   public:
     ThebesLayerItemsEntry(const ThebesLayer *key) :
         nsPtrHashKey<ThebesLayer>(key), mContainerLayerFrame(nullptr),
         mContainerLayerGeneration(0),
         mHasExplicitLastPaintOffset(false), mCommonClipCount(0) {}
     ThebesLayerItemsEntry(const ThebesLayerItemsEntry &toCopy) :
       nsPtrHashKey<ThebesLayer>(toCopy.mKey), mItems(toCopy.mItems)
     {
       NS_ERROR("Should never be called, since we ALLOW_MEMMOVE");
     }
     nsTArray<ClippedDisplayItem> mItems;
     nsIFrame* mContainerLayerFrame;
     // The translation set on this ThebesLayer before we started updating the
     // layer tree.
     nsIntPoint mLastPaintOffset;
     uint32_t mContainerLayerGeneration;
     bool mHasExplicitLastPaintOffset;
     /**
       * The first mCommonClipCount rounded rectangle clips are identical for
       * all items in the layer. Computed in ThebesLayerData.
       */
     uint32_t mCommonClipCount;
     enum { ALLOW_MEMMOVE = true };
   };
   /**
    * Get the ThebesLayerItemsEntry object associated with aLayer in this
    * FrameLayerBuilder
    */
   ThebesLayerItemsEntry* GetThebesLayerItemsEntry(ThebesLayer* aLayer)
   {
     return mThebesLayerItems.GetEntry(aLayer);
   }
   ThebesLayerData* GetContainingThebesLayerData()
   {
     return mContainingThebesLayer;
   }
   /**
    * Attempt to build the most compressed layer tree possible, even if it means
    * throwing away existing retained buffers.
    */
   void SetLayerTreeCompressionMode() { mInLayerTreeCompressionMode = true; }
   bool CheckInLayerTreeCompressionMode();
 protected:
   void RemoveThebesItemsAndOwnerDataForLayerSubtree(Layer* aLayer,
                                                     bool aRemoveThebesItems,
                                                     bool aRemoveOwnerData);
   static PLDHashOperator ProcessRemovedDisplayItems(nsRefPtrHashKey<DisplayItemData>* aEntry,
                                                     void* aUserArg);
   static PLDHashOperator RestoreDisplayItemData(nsRefPtrHashKey<DisplayItemData>* aEntry,
                                                 void *aUserArg);
   static PLDHashOperator RestoreThebesLayerItemEntries(ThebesLayerItemsEntry* aEntry,
                                                        void *aUserArg);
   /**
    * Returns true if the DOM has been modified since we started painting,
    * in which case we should bail out and not paint anymore. This should
    * never happen, but plugins can trigger it in some cases.
    */
   bool CheckDOMModified();
   /**
    * The layer manager belonging to the widget that is being retained
    * across paints.
    */
   LayerManager*                       mRetainingManager;
   /**
    * The root prescontext for the display list builder reference frame
    */
   nsRefPtr<nsRootPresContext>         mRootPresContext;
   /**
    * The display list builder being used.
    */
   nsDisplayListBuilder*               mDisplayListBuilder;
   /**
    * A map from ThebesLayers to the list of display items (plus
    * clipping data) to be rendered in the layer.
    */
   nsTHashtable<ThebesLayerItemsEntry> mThebesLayerItems;
   /**
    * When building layers for an inactive layer, this is where the
    * inactive layer will be placed.
    */
   ThebesLayerData*                    mContainingThebesLayer;
   /**
    * Saved generation counter so we can detect DOM changes.
    */
   uint32_t                            mInitialDOMGeneration;
   /**
    * Set to true if we have detected and reported DOM modification during
    * the current paint.
    */
   bool                                mDetectedDOMModification;
   /**
    * Indicates that the entire layer tree should be rerendered
    * during this paint.
    */
   bool                                mInvalidateAllLayers;
   bool                                mInLayerTreeCompressionMode;
   uint32_t                            mContainerLayerGeneration;
   uint32_t                            mMaxContainerLayerGeneration;
 };
 }
 #endif /* FRAMELAYERBUILDER_H_ */

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

layout/base/FrameLayerBuilder.h