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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 */
#include <map>
#include <iosfwd>
#include "chrome/common/ipc_message_utils.h"
#include "FrameMetrics.h"
#include "ipc/IPCMessageUtils.h"
#include "LayersTypes.h"
#include "mozilla/Attributes.h"
#include "mozilla/GfxMessageUtils.h"
#include "mozilla/layers/FocusTarget.h"
#include "mozilla/layers/ScrollbarData.h"
#include "mozilla/layers/WebRenderMessageUtils.h"
#include "mozilla/webrender/WebRenderTypes.h"
#include "mozilla/HashTable.h"
#include "mozilla/Maybe.h"
#include "nsTArrayForwardDeclare.h"
namespace mozilla {
class nsDisplayItem;
class nsDisplayListBuilder;
struct ActiveScrolledRoot;
namespace layers {
class APZTestAccess;
class Layer;
class WebRenderLayerManager;
class WebRenderScrollData;
// Data needed by APZ, per layer. One instance of this class is created for
// each layer in the layer tree and sent over PWebRenderBridge to the APZ code.
// Each WebRenderLayerScrollData is conceptually associated with an "owning"
// WebRenderScrollData.
class WebRenderLayerScrollData final {
WebRenderLayerScrollData(); // needed for IPC purposes
WebRenderLayerScrollData(WebRenderLayerScrollData&& aOther) = default;
using ViewID = ScrollableLayerGuid::ViewID;
// Helper function for WebRenderScrollData::Validate().
bool ValidateSubtree(const WebRenderScrollData& aParent,
std::vector<size_t>& aVisitCounts,
size_t aCurrentIndex) const;
void InitializeRoot(int32_t aDescendantCount);
void Initialize(WebRenderScrollData& aOwner, nsDisplayItem* aItem,
int32_t aDescendantCount,
const ActiveScrolledRoot* aStopAtAsr,
const Maybe<gfx::Matrix4x4>& aAncestorTransform,
const ViewID& aAncestorTransformId);
int32_t GetDescendantCount() const;
size_t GetScrollMetadataCount() const;
void AppendScrollMetadata(WebRenderScrollData& aOwner,
const ScrollMetadata& aData);
// Return the ScrollMetadata object that used to be on the original Layer
// at the given index. Since we deduplicate the ScrollMetadata objects into
// the array in the owning WebRenderScrollData object, we need to be passed
// in a reference to that owner as well.
const ScrollMetadata& GetScrollMetadata(const WebRenderScrollData& aOwner,
size_t aIndex) const;
gfx::Matrix4x4 GetAncestorTransform() const { return mAncestorTransform; }
ViewID GetAncestorTransformId() const { return mAncestorTransformId; }
void SetTransform(const gfx::Matrix4x4& aTransform) {
mTransform = aTransform;
gfx::Matrix4x4 GetTransform() const { return mTransform; }
CSSTransformMatrix GetTransformTyped() const;
void SetTransformIsPerspective(bool aTransformIsPerspective) {
mTransformIsPerspective = aTransformIsPerspective;
bool GetTransformIsPerspective() const { return mTransformIsPerspective; }
void SetEventRegionsOverride(const EventRegionsOverride& aOverride) {
mEventRegionsOverride = aOverride;
EventRegionsOverride GetEventRegionsOverride() const {
return mEventRegionsOverride;
void SetVisibleRect(const LayerIntRect& aRect) { mVisibleRect = aRect; }
const LayerIntRect& GetVisibleRect() const { return mVisibleRect; }
void SetRemoteDocumentSize(const LayerIntSize& aRemoteDocumentSize) {
mRemoteDocumentSize = aRemoteDocumentSize;
const LayerIntSize& GetRemoteDocumentSize() const {
return mRemoteDocumentSize;
void SetReferentId(LayersId aReferentId) { mReferentId = Some(aReferentId); }
Maybe<LayersId> GetReferentId() const { return mReferentId; }
void SetScrollbarData(const ScrollbarData& aData) { mScrollbarData = aData; }
const ScrollbarData& GetScrollbarData() const { return mScrollbarData; }
void SetScrollbarAnimationId(const uint64_t& aId) {
mScrollbarAnimationId = Some(aId);
Maybe<uint64_t> GetScrollbarAnimationId() const {
return mScrollbarAnimationId;
void SetFixedPositionAnimationId(const uint64_t& aId) {
mFixedPositionAnimationId = Some(aId);
Maybe<uint64_t> GetFixedPositionAnimationId() const {
return mFixedPositionAnimationId;
void SetFixedPositionSides(const SideBits& aSideBits) {
mFixedPositionSides = aSideBits;
SideBits GetFixedPositionSides() const { return mFixedPositionSides; }
void SetFixedPositionScrollContainerId(ViewID aId) {
mFixedPosScrollContainerId = aId;
ViewID GetFixedPositionScrollContainerId() const {
return mFixedPosScrollContainerId;
void SetStickyPositionScrollContainerId(ViewID aId) {
mStickyPosScrollContainerId = aId;
ViewID GetStickyPositionScrollContainerId() const {
return mStickyPosScrollContainerId;
void SetStickyScrollRangeOuter(const LayerRectAbsolute& scrollRange) {
mStickyScrollRangeOuter = scrollRange;
const LayerRectAbsolute& GetStickyScrollRangeOuter() const {
return mStickyScrollRangeOuter;
void SetStickyScrollRangeInner(const LayerRectAbsolute& scrollRange) {
mStickyScrollRangeInner = scrollRange;
const LayerRectAbsolute& GetStickyScrollRangeInner() const {
return mStickyScrollRangeInner;
void SetStickyPositionAnimationId(const uint64_t& aId) {
mStickyPositionAnimationId = Some(aId);
Maybe<uint64_t> GetStickyPositionAnimationId() const {
return mStickyPositionAnimationId;
void SetZoomAnimationId(const uint64_t& aId) { mZoomAnimationId = Some(aId); }
Maybe<uint64_t> GetZoomAnimationId() const { return mZoomAnimationId; }
void SetAsyncZoomContainerId(const ViewID& aId) {
mAsyncZoomContainerId = Some(aId);
Maybe<ViewID> GetAsyncZoomContainerId() const {
return mAsyncZoomContainerId;
void Dump(std::ostream& aOut, const WebRenderScrollData& aOwner) const;
friend struct IPC::ParamTraits<WebRenderLayerScrollData>;
// For test use only
friend class APZTestAccess;
// For use by GTests in building WebRenderLayerScrollData trees.
// GTests don't have a display list so they can't use Initialize().
void InitializeForTest(int32_t aDescendantCount);
ScrollMetadata& GetScrollMetadataMut(WebRenderScrollData& aOwner,
size_t aIndex);
// The number of descendants this layer has (not including the layer itself).
// This is needed to reconstruct the depth-first layer tree traversal
// efficiently. Leaf layers should always have 0 descendants.
int32_t mDescendantCount;
// Handles to the ScrollMetadata objects that were on this layer. The values
// stored in this array are indices into the owning WebRenderScrollData's
// mScrollMetadatas array. This indirection is used to deduplicate the
// ScrollMetadata objects, since there is usually heavy duplication of them
// within a layer tree.
CopyableTArray<size_t> mScrollIds;
// Various data that we collect from the Layer in Initialize(), serialize
// over IPC, and use on the parent side in APZ.
gfx::Matrix4x4 mAncestorTransform;
ViewID mAncestorTransformId;
gfx::Matrix4x4 mTransform;
bool mTransformIsPerspective;
LayerIntRect mVisibleRect;
// The remote documents only need their size because their origin is always
// (0, 0).
LayerIntSize mRemoteDocumentSize;
Maybe<LayersId> mReferentId;
EventRegionsOverride mEventRegionsOverride;
ScrollbarData mScrollbarData;
Maybe<uint64_t> mScrollbarAnimationId;
Maybe<uint64_t> mFixedPositionAnimationId;
SideBits mFixedPositionSides;
ViewID mFixedPosScrollContainerId;
ViewID mStickyPosScrollContainerId;
LayerRectAbsolute mStickyScrollRangeOuter;
LayerRectAbsolute mStickyScrollRangeInner;
Maybe<uint64_t> mStickyPositionAnimationId;
Maybe<uint64_t> mZoomAnimationId;
Maybe<ViewID> mAsyncZoomContainerId;
#if defined(DEBUG) || defined(MOZ_DUMP_PAINTING)
// The display item for which this layer was built.
// This is only set on the content side.
nsDisplayItem* mInitializedFrom = nullptr;
// Data needed by APZ, for the whole layer tree. One instance of this class
// is created for each transaction sent over PWebRenderBridge. It is populated
// with information from the WebRender layer tree on the client side and the
// information is used by APZ on the parent side.
class WebRenderScrollData {
explicit WebRenderScrollData(WebRenderLayerManager* aManager,
nsDisplayListBuilder* aBuilder);
WebRenderScrollData(WebRenderScrollData&& aOther) = default;
WebRenderScrollData& operator=(WebRenderScrollData&& aOther) = default;
virtual ~WebRenderScrollData() = default;
// Validate that the scroll data is well-formed, and particularly that
// |mLayerScrollData| encodes a valid tree. This is necessary because
// the data can be sent over IPC from a less-trusted content process.
bool Validate() const;
WebRenderLayerManager* GetManager() const;
nsDisplayListBuilder* GetBuilder() const;
// Add the given ScrollMetadata if it doesn't already exist. Return an index
// that can be used to look up the metadata later.
size_t AddMetadata(const ScrollMetadata& aMetadata);
// Add the provided WebRenderLayerScrollData and return the index that can
// be used to look it up via GetLayerData.
size_t AddLayerData(WebRenderLayerScrollData&& aData);
size_t GetLayerCount() const;
// Return a pointer to the scroll data at the given index. Use with caution,
// as the pointer may be invalidated if this WebRenderScrollData is mutated.
const WebRenderLayerScrollData* GetLayerData(size_t aIndex) const;
WebRenderLayerScrollData* GetLayerData(size_t aIndex);
const ScrollMetadata& GetScrollMetadata(size_t aIndex) const;
Maybe<size_t> HasMetadataFor(
const ScrollableLayerGuid::ViewID& aScrollId) const;
void SetIsFirstPaint();
bool IsFirstPaint() const;
void SetPaintSequenceNumber(uint32_t aPaintSequenceNumber);
uint32_t GetPaintSequenceNumber() const;
void ApplyUpdates(ScrollUpdatesMap&& aUpdates, uint32_t aPaintSequenceNumber);
// Prepend the scroll position updates in the previous data to this data so
// that we can handle all scroll position updates in the proper order.
void PrependUpdates(const WebRenderScrollData& aPreviousData);
void SetWasUpdateSkipped() { mWasUpdateSkipped = true; }
bool GetWasUpdateSkipped() const { return mWasUpdateSkipped; }
friend struct IPC::ParamTraits<WebRenderScrollData>;
friend std::ostream& operator<<(std::ostream& aOut,
const WebRenderScrollData& aData);
// For test use only.
friend class WebRenderLayerScrollData;
ScrollMetadata& GetScrollMetadataMut(size_t aIndex);
// This is called by the ParamTraits implementation to rebuild mScrollIdMap
// based on mScrollMetadatas
bool RepopulateMap();
// This is a helper for the dumping code
void DumpSubtree(std::ostream& aOut, size_t aIndex,
const std::string& aIndent) const;
// Pointer back to the layer manager; if this is non-null, it will always be
// valid, because the WebRenderLayerManager that created |this| will
// outlive |this|.
WebRenderLayerManager* MOZ_NON_OWNING_REF mManager;
// Pointer to the display list builder; if this is non-null, it will always be
// valid, because the nsDisplayListBuilder that created the layer manager will
// outlive |this|.
nsDisplayListBuilder* MOZ_NON_OWNING_REF mBuilder;
// Internal data structure used to maintain uniqueness of mScrollMetadatas.
// This is not serialized/deserialized over IPC, but it is rebuilt on the
// parent side when mScrollMetadatas is deserialized. So it should always be
// valid on both the child and parent.
// The key into this map is the scrollId of a ScrollMetadata, and the value is
// an index into the mScrollMetadatas array.
HashMap<ScrollableLayerGuid::ViewID, size_t> mScrollIdMap;
// A list of all the unique ScrollMetadata objects from the layer tree. Each
// ScrollMetadata in this list must have a unique scroll id.
nsTArray<ScrollMetadata> mScrollMetadatas;
// A list of per-layer scroll data objects, generated via a depth-first,
// pre-order, last-to-first traversal of the layer tree (i.e. a recursive
// traversal where a node N first pushes itself, followed by its children in
// last-to-first order). Each layer's scroll data object knows how many
// descendants that layer had, which allows reconstructing the traversal on
// the other side.
nsTArray<WebRenderLayerScrollData> mLayerScrollData;
bool mIsFirstPaint;
uint32_t mPaintSequenceNumber;
// Wether this data was skipped to updated because the parent process hasn't
// yet gotten the referent LayersId for this data.
// Note this variable is not copied over IPC.
bool mWasUpdateSkipped = false;
} // namespace layers
} // namespace mozilla
namespace IPC {
template <>
struct ParamTraits<mozilla::layers::WebRenderLayerScrollData> {
typedef mozilla::layers::WebRenderLayerScrollData paramType;
static void Write(MessageWriter* aWriter, const paramType& aParam);
static bool Read(MessageReader* aReader, paramType* aResult);
template <>
struct ParamTraits<mozilla::layers::WebRenderScrollData> {
typedef mozilla::layers::WebRenderScrollData paramType;
static void Write(MessageWriter* aWriter, const paramType& aParam);
static bool Read(MessageReader* aReader, paramType* aResult);
} // namespace IPC