Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 539 insertions, 0 deletions

diff --git a/gfx/layers/wr/WebRenderScrollDataWrapper.h b/gfx/layers/wr/WebRenderScrollDataWrapper.h
new file mode 100644
index 0000000000..8c432e0b61
--- /dev/null
+++ b/gfx/layers/wr/WebRenderScrollDataWrapper.h
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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 http://mozilla.org/MPL/2.0/. */
+
+#ifndef GFX_WEBRENDERSCROLLDATAWRAPPER_H
+#define GFX_WEBRENDERSCROLLDATAWRAPPER_H
+
+#include "FrameMetrics.h"
+#include "mozilla/layers/APZUpdater.h"
+#include "mozilla/layers/CompositorBridgeParent.h"
+#include "mozilla/layers/WebRenderBridgeParent.h"
+#include "mozilla/layers/WebRenderScrollData.h"
+
+namespace mozilla {
+namespace layers {
+
+/**
+ * A wrapper class around a target WebRenderLayerScrollData (henceforth,
+ * "layer") that allows user code to walk through the ScrollMetadata objects
+ * on the layer the same way it would walk through a layer tree.
+ * Consider the following layer tree:
+ *
+ *                    +---+
+ *                    | A |
+ *                    +---+
+ *                   /  |  \
+ *                  /   |   \
+ *                 /    |    \
+ *            +---+  +-----+  +---+
+ *            | B |  |  C  |  | D |
+ *            +---+  +-----+  +---+
+ *                   | SMn |
+ *                   |  .  |
+ *                   |  .  |
+ *                   |  .  |
+ *                   | SM1 |
+ *                   | SM0 |
+ *                   +-----+
+ *                   /     \
+ *                  /       \
+ *             +---+         +---+
+ *             | E |         | F |
+ *             +---+         +---+
+ *
+ * In this layer tree, there are six layers with A being the root and B,D,E,F
+ * being leaf nodes. Layer C is in the middle and has n+1 ScrollMetadata,
+ * labelled SM0...SMn. SM0 is the ScrollMetadata you get by calling
+ * c->GetScrollMetadata(0) and SMn is the ScrollMetadata you can obtain by
+ * calling c->GetScrollMetadata(c->GetScrollMetadataCount() - 1). This layer
+ * tree is conceptually equivalent to this one below:
+ *
+ *                    +---+
+ *                    | A |
+ *                    +---+
+ *                   /  |  \
+ *                  /   |   \
+ *                 /    |    \
+ *            +---+  +-----+  +---+
+ *            | B |  | Cn  |  | D |
+ *            +---+  +-----+  +---+
+ *                      |
+ *                      .
+ *                      .
+ *                      .
+ *                      |
+ *                   +-----+
+ *                   | C1  |
+ *                   +-----+
+ *                      |
+ *                   +-----+
+ *                   | C0  |
+ *                   +-----+
+ *                   /     \
+ *                  /       \
+ *             +---+         +---+
+ *             | E |         | F |
+ *             +---+         +---+
+ *
+ * In this layer tree, the layer C has been expanded into a stack of layers
+ * C1...Cn, where C1 has ScrollMetadata SM1 and Cn has ScrollMetdata Fn.
+ *
+ * The WebRenderScrollDataWrapper class allows client code to treat the first
+ * layer tree as though it were the second. That is, instead of client code
+ * having to iterate through the ScrollMetadata objects directly, it can use a
+ * WebRenderScrollDataWrapper to encapsulate that aspect of the layer tree and
+ * just walk the tree as if it were a stack of layers.
+ *
+ * The functions on this class do different things depending on which
+ * simulated layer is being wrapped. For example, if the
+ * WebRenderScrollDataWrapper is pretending to be C0, the GetPrevSibling()
+ * function will return null even though the underlying layer C does actually
+ * have a prev sibling. The WebRenderScrollDataWrapper pretending to be Cn will
+ * return B as the prev sibling.
+ *
+ * Implementation notes:
+ *
+ * The AtTopLayer() and AtBottomLayer() functions in this class refer to
+ * Cn and C0 in the second layer tree above; that is, they are predicates
+ * to test if the wrapper is simulating the topmost or bottommost layer, as
+ * those can have special behaviour.
+ *
+ * It is possible to wrap a nullptr in a WebRenderScrollDataWrapper, in which
+ * case the IsValid() function will return false. This is required to allow
+ * WebRenderScrollDataWrapper to be a MOZ_STACK_CLASS (desirable because it is
+ * used in loops and recursion).
+ *
+ * This class purposely does not expose the wrapped layer directly to avoid
+ * user code from accidentally calling functions directly on it. Instead
+ * any necessary functions should be wrapped in this class. It does expose
+ * the wrapped layer as a void* for printf purposes.
+ *
+ * The implementation may look like it special-cases mIndex == 0 and/or
+ * GetScrollMetadataCount() == 0. This is an artifact of the fact that both
+ * mIndex and GetScrollMetadataCount() are uint32_t and GetScrollMetadataCount()
+ * can return 0 but mIndex cannot store -1. This seems better than the
+ * alternative of making mIndex a int32_t that can store -1, but then having
+ * to cast to uint32_t all over the place.
+ *
+ * Note that WebRenderLayerScrollData objects are owned by WebRenderScrollData,
+ * which stores them in a flattened representation. The field mData,
+ * mLayerIndex, and mContainingSubtreeIndex are used to move around the "layers"
+ * given the flattened representation. The mMetadataIndex is used to move around
+ * the ScrollMetadata within a single layer.
+ *
+ * One important note here is that this class holds a pointer to the "owning"
+ * WebRenderScrollData. The caller must ensure that this class does not outlive
+ * the owning WebRenderScrollData, or this may result in use-after-free errors.
+ * This class being declared a MOZ_STACK_CLASS should help with that.
+ */
+class MOZ_STACK_CLASS WebRenderScrollDataWrapper final {
+ public:
+  // Basic constructor for external callers. Starts the walker at the root of
+  // the tree.
+  explicit WebRenderScrollDataWrapper(
+      const APZUpdater& aUpdater, const WebRenderScrollData* aData = nullptr)
+      : mUpdater(&aUpdater),
+        mData(aData),
+        mLayerIndex(0),
+        mContainingSubtreeLastIndex(0),
+        mLayer(nullptr),
+        mMetadataIndex(0) {
+    if (!mData) {
+      return;
+    }
+    mLayer = mData->GetLayerData(mLayerIndex);
+    if (!mLayer) {
+      return;
+    }
+
+    // sanity check on the data
+    MOZ_ASSERT(mData->GetLayerCount() ==
+               (size_t)(1 + mLayer->GetDescendantCount()));
+    mContainingSubtreeLastIndex = mData->GetLayerCount();
+
+    // See documentation in LayerMetricsWrapper.h about this. mMetadataIndex
+    // in this class is equivalent to mIndex in that class.
+    mMetadataIndex = mLayer->GetScrollMetadataCount();
+    if (mMetadataIndex > 0) {
+      mMetadataIndex--;
+    }
+  }
+
+ private:
+  // Internal constructor for walking from one WebRenderLayerScrollData to
+  // another. In this case we need to recompute the mMetadataIndex to be the
+  // "topmost" scroll metadata on the new layer.
+  WebRenderScrollDataWrapper(const APZUpdater* aUpdater,
+                             const WebRenderScrollData* aData,
+                             size_t aLayerIndex,
+                             size_t aContainingSubtreeLastIndex)
+      : mUpdater(aUpdater),
+        mData(aData),
+        mLayerIndex(aLayerIndex),
+        mContainingSubtreeLastIndex(aContainingSubtreeLastIndex),
+        mLayer(nullptr),
+        mMetadataIndex(0) {
+    MOZ_ASSERT(mData);
+    mLayer = mData->GetLayerData(mLayerIndex);
+    MOZ_ASSERT(mLayer);
+
+    // See documentation in LayerMetricsWrapper.h about this. mMetadataIndex
+    // in this class is equivalent to mIndex in that class.
+    mMetadataIndex = mLayer->GetScrollMetadataCount();
+    if (mMetadataIndex > 0) {
+      mMetadataIndex--;
+    }
+  }
+
+  // Internal constructor for walking from one metadata to another metadata on
+  // the same WebRenderLayerScrollData.
+  WebRenderScrollDataWrapper(const APZUpdater* aUpdater,
+                             const WebRenderScrollData* aData,
+                             size_t aLayerIndex,
+                             size_t aContainingSubtreeLastIndex,
+                             const WebRenderLayerScrollData* aLayer,
+                             uint32_t aMetadataIndex)
+      : mUpdater(aUpdater),
+        mData(aData),
+        mLayerIndex(aLayerIndex),
+        mContainingSubtreeLastIndex(aContainingSubtreeLastIndex),
+        mLayer(aLayer),
+        mMetadataIndex(aMetadataIndex) {
+    MOZ_ASSERT(mData);
+    MOZ_ASSERT(mLayer);
+    MOZ_ASSERT(mLayer == mData->GetLayerData(mLayerIndex));
+    MOZ_ASSERT(mMetadataIndex == 0 ||
+               mMetadataIndex < mLayer->GetScrollMetadataCount());
+  }
+
+ public:
+  bool IsValid() const { return mLayer != nullptr; }
+
+  explicit operator bool() const { return IsValid(); }
+
+  WebRenderScrollDataWrapper GetLastChild() const {
+    MOZ_ASSERT(IsValid());
+
+    if (!AtBottomLayer()) {
+      // If we're still walking around in the virtual container layers created
+      // by the ScrollMetadata array, we just need to update the metadata index
+      // and that's it.
+      return WebRenderScrollDataWrapper(mUpdater, mData, mLayerIndex,
+                                        mContainingSubtreeLastIndex, mLayer,
+                                        mMetadataIndex - 1);
+    }
+
+    // Otherwise, we need to walk to a different WebRenderLayerScrollData in
+    // mData.
+
+    // Since mData contains the layer in depth-first, last-to-first order,
+    // the index after mLayerIndex must be mLayerIndex's last child, if it
+    // has any children (indicated by GetDescendantCount() > 0). Furthermore
+    // we compute the first index outside the subtree rooted at this node
+    // (in |subtreeLastIndex|) and pass that in to the child wrapper to use as
+    // its mContainingSubtreeLastIndex.
+    if (mLayer->GetDescendantCount() > 0) {
+      size_t prevSiblingIndex = mLayerIndex + 1 + mLayer->GetDescendantCount();
+      size_t subtreeLastIndex =
+          std::min(mContainingSubtreeLastIndex, prevSiblingIndex);
+      return WebRenderScrollDataWrapper(mUpdater, mData, mLayerIndex + 1,
+                                        subtreeLastIndex);
+    }
+
+    // We've run out of descendants. But! If the original layer was a RefLayer,
+    // then it connects to another layer tree and we need to traverse that too.
+    // So return a WebRenderScrollDataWrapper for the root of the child layer
+    // tree.
+    if (mLayer->GetReferentId()) {
+      return WebRenderScrollDataWrapper(
+          *mUpdater, mUpdater->GetScrollData(*mLayer->GetReferentId()));
+    }
+
+    return WebRenderScrollDataWrapper(*mUpdater);
+  }
+
+  WebRenderScrollDataWrapper GetPrevSibling() const {
+    MOZ_ASSERT(IsValid());
+
+    if (!AtTopLayer()) {
+      // The virtual container layers don't have siblings
+      return WebRenderScrollDataWrapper(*mUpdater);
+    }
+
+    // Skip past the descendants to get to the previous sibling. However, we
+    // might be at the last sibling already.
+    size_t prevSiblingIndex = mLayerIndex + 1 + mLayer->GetDescendantCount();
+    if (prevSiblingIndex < mContainingSubtreeLastIndex) {
+      return WebRenderScrollDataWrapper(mUpdater, mData, prevSiblingIndex,
+                                        mContainingSubtreeLastIndex);
+    }
+    return WebRenderScrollDataWrapper(*mUpdater);
+  }
+
+  const ScrollMetadata& Metadata() const {
+    MOZ_ASSERT(IsValid());
+
+    if (mMetadataIndex >= mLayer->GetScrollMetadataCount()) {
+      return *ScrollMetadata::sNullMetadata;
+    }
+    return mLayer->GetScrollMetadata(*mData, mMetadataIndex);
+  }
+
+  const FrameMetrics& Metrics() const { return Metadata().GetMetrics(); }
+
+  AsyncPanZoomController* GetApzc() const { return nullptr; }
+
+  void SetApzc(AsyncPanZoomController* aApzc) const {}
+
+  const char* Name() const { return "WebRenderScrollDataWrapper"; }
+
+  gfx::Matrix4x4 GetTransform() const {
+    MOZ_ASSERT(IsValid());
+
+    // See WebRenderLayerScrollData::Initialize for more context.
+    //  * The ancestor transform is associated with whichever layer has scroll
+    //    id matching GetAncestorTransformId().
+    //  * The resolution is associated with the "topmost" layer.
+    //  * The transform is associated with the "bottommost" layer.
+    // Multiple transforms may apply to the same layer (e.g. if there is only
+    // one scrollmetadata on the layer, then it is both "topmost" and
+    // "bottommost"), so we may need to combine the transforms.
+
+    gfx::Matrix4x4 transform;
+    // The ancestor transform is usually emitted at the layer with the
+    // matching scroll id. However, sometimes the transform ends up on
+    // a node with no scroll metadata at all. In such cases we generate
+    // a single layer, and the ancestor transform needs to be on that layer,
+    // otherwise it will be lost.
+    bool emitAncestorTransform =
+        !Metrics().IsScrollable() ||
+        Metrics().GetScrollId() == mLayer->GetAncestorTransformId();
+    if (emitAncestorTransform) {
+      transform = mLayer->GetAncestorTransform();
+    }
+    if (AtTopLayer()) {
+      float resolution = mLayer->GetResolution();
+      transform =
+          transform * gfx::Matrix4x4::Scaling(resolution, resolution, 1.f);
+    }
+    if (AtBottomLayer()) {
+      transform = mLayer->GetTransform() * transform;
+    }
+    return transform;
+  }
+
+  CSSTransformMatrix GetTransformTyped() const {
+    return ViewAs<CSSTransformMatrix>(GetTransform());
+  }
+
+  bool TransformIsPerspective() const {
+    MOZ_ASSERT(IsValid());
+
+    // mLayer->GetTransformIsPerspective() tells us whether
+    // mLayer->GetTransform() is a perspective transform. Since
+    // mLayer->GetTransform() is only used at the bottom layer, we only
+    // need to check GetTransformIsPerspective() at the bottom layer too.
+    if (AtBottomLayer()) {
+      return mLayer->GetTransformIsPerspective();
+    }
+    return false;
+  }
+
+  LayerIntRegion GetVisibleRegion() const {
+    MOZ_ASSERT(IsValid());
+
+    if (AtBottomLayer()) {
+      return mLayer->GetVisibleRegion();
+    }
+
+    return ViewAs<LayerPixel>(
+        TransformBy(mLayer->GetTransformTyped(), mLayer->GetVisibleRegion()),
+        PixelCastJustification::MovingDownToChildren);
+  }
+
+  LayerIntSize GetRemoteDocumentSize() const {
+    MOZ_ASSERT(IsValid());
+
+    if (mLayer->GetReferentId().isNothing()) {
+      return LayerIntSize();
+    }
+
+    if (AtBottomLayer()) {
+      return mLayer->GetRemoteDocumentSize();
+    }
+
+    return ViewAs<LayerPixel>(mLayer->GetRemoteDocumentSize(),
+                              PixelCastJustification::MovingDownToChildren);
+  }
+
+  Maybe<LayersId> GetReferentId() const {
+    MOZ_ASSERT(IsValid());
+
+    if (AtBottomLayer()) {
+      return mLayer->GetReferentId();
+    }
+    return Nothing();
+  }
+
+  EventRegionsOverride GetEventRegionsOverride() const {
+    MOZ_ASSERT(IsValid());
+    // Only ref layers can have an event regions override.
+    if (GetReferentId()) {
+      return mLayer->GetEventRegionsOverride();
+    }
+    return EventRegionsOverride::NoOverride;
+  }
+
+  const ScrollbarData& GetScrollbarData() const {
+    MOZ_ASSERT(IsValid());
+    return mLayer->GetScrollbarData();
+  }
+
+  Maybe<uint64_t> GetScrollbarAnimationId() const {
+    MOZ_ASSERT(IsValid());
+    return mLayer->GetScrollbarAnimationId();
+  }
+
+  Maybe<uint64_t> GetFixedPositionAnimationId() const {
+    MOZ_ASSERT(IsValid());
+
+    if (AtBottomLayer()) {
+      return mLayer->GetFixedPositionAnimationId();
+    }
+    return Nothing();
+  }
+
+  ScrollableLayerGuid::ViewID GetFixedPositionScrollContainerId() const {
+    MOZ_ASSERT(IsValid());
+
+    if (AtBottomLayer()) {
+      return mLayer->GetFixedPositionScrollContainerId();
+    }
+    return ScrollableLayerGuid::NULL_SCROLL_ID;
+  }
+
+  SideBits GetFixedPositionSides() const {
+    MOZ_ASSERT(IsValid());
+
+    if (AtBottomLayer()) {
+      return mLayer->GetFixedPositionSides();
+    }
+    return SideBits::eNone;
+  }
+
+  ScrollableLayerGuid::ViewID GetStickyScrollContainerId() const {
+    MOZ_ASSERT(IsValid());
+
+    if (AtBottomLayer()) {
+      return mLayer->GetStickyPositionScrollContainerId();
+    }
+    return ScrollableLayerGuid::NULL_SCROLL_ID;
+  }
+
+  const LayerRectAbsolute& GetStickyScrollRangeOuter() const {
+    MOZ_ASSERT(IsValid());
+
+    if (AtBottomLayer()) {
+      return mLayer->GetStickyScrollRangeOuter();
+    }
+
+    static const LayerRectAbsolute empty;
+    return empty;
+  }
+
+  const LayerRectAbsolute& GetStickyScrollRangeInner() const {
+    MOZ_ASSERT(IsValid());
+
+    if (AtBottomLayer()) {
+      return mLayer->GetStickyScrollRangeInner();
+    }
+
+    static const LayerRectAbsolute empty;
+    return empty;
+  }
+
+  Maybe<uint64_t> GetStickyPositionAnimationId() const {
+    MOZ_ASSERT(IsValid());
+
+    if (AtBottomLayer()) {
+      return mLayer->GetStickyPositionAnimationId();
+    }
+    return Nothing();
+  }
+
+  Maybe<uint64_t> GetZoomAnimationId() const {
+    MOZ_ASSERT(IsValid());
+    return mLayer->GetZoomAnimationId();
+  }
+
+  Maybe<ScrollableLayerGuid::ViewID> GetAsyncZoomContainerId() const {
+    MOZ_ASSERT(IsValid());
+    return mLayer->GetAsyncZoomContainerId();
+  }
+
+  // Expose an opaque pointer to the layer. Mostly used for printf
+  // purposes. This is not intended to be a general-purpose accessor
+  // for the underlying layer.
+  const void* GetLayer() const {
+    MOZ_ASSERT(IsValid());
+    return mLayer;
+  }
+
+  template <int Level>
+  size_t Dump(gfx::TreeLog<Level>& aOut) const {
+    std::string result = "(invalid)";
+    if (!IsValid()) {
+      aOut << result;
+      return result.length();
+    }
+    if (AtBottomLayer()) {
+      if (mData != nullptr) {
+        const WebRenderLayerScrollData* layerData =
+            mData->GetLayerData(mLayerIndex);
+        if (layerData != nullptr) {
+          std::stringstream ss;
+          layerData->Dump(ss, *mData);
+          result = ss.str();
+          aOut << result;
+          return result.length();
+        }
+      }
+    }
+    return 0;
+  }
+
+ private:
+  bool AtBottomLayer() const { return mMetadataIndex == 0; }
+
+  bool AtTopLayer() const {
+    return mLayer->GetScrollMetadataCount() == 0 ||
+           mMetadataIndex == mLayer->GetScrollMetadataCount() - 1;
+  }
+
+ private:
+  const APZUpdater* mUpdater;
+  const WebRenderScrollData* mData;
+  // The index (in mData->mLayerScrollData) of the WebRenderLayerScrollData this
+  // wrapper is pointing to.
+  size_t mLayerIndex;
+  // The upper bound on the set of valid indices inside the subtree rooted at
+  // the parent of this "layer". That is, any layer index |i| in the range
+  // mLayerIndex <= i < mContainingSubtreeLastIndex is guaranteed to point to
+  // a layer that is a descendant of "parent", where "parent" is the parent
+  // layer of the layer at mLayerIndex. This is needed in order to implement
+  // GetPrevSibling() correctly.
+  size_t mContainingSubtreeLastIndex;
+  // The WebRenderLayerScrollData this wrapper is pointing to.
+  const WebRenderLayerScrollData* mLayer;
+  // The index of the scroll metadata within mLayer that this wrapper is
+  // pointing to.
+  uint32_t mMetadataIndex;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif /* GFX_WEBRENDERSCROLLDATAWRAPPER_H */