diff options
Diffstat (limited to 'gfx/layers/LayerMetricsWrapper.h')
| -rw-r--r-- | gfx/layers/LayerMetricsWrapper.h | 516 |
1 files changed, 516 insertions, 0 deletions
diff --git a/gfx/layers/LayerMetricsWrapper.h b/gfx/layers/LayerMetricsWrapper.h new file mode 100644 index 000000000..d26915633 --- /dev/null +++ b/gfx/layers/LayerMetricsWrapper.h @@ -0,0 +1,516 @@ +/* -*- 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 GFX_LAYERMETRICSWRAPPER_H +#define GFX_LAYERMETRICSWRAPPER_H + +#include "Layers.h" +#include "UnitTransforms.h" + +namespace mozilla { +namespace layers { + +/** + * A wrapper class around a target Layer with that allows user code to + * walk through the FrameMetrics objects on the layer the same way it + * would walk through a ContainerLayer hierarchy. Consider the following + * layer tree: + * + * +---+ + * | A | + * +---+ + * / | \ + * / | \ + * / | \ + * +---+ +-----+ +---+ + * | B | | C | | D | + * +---+ +-----+ +---+ + * | FMn | + * | . | + * | . | + * | . | + * | FM1 | + * | FM0 | + * +-----+ + * / \ + * / \ + * +---+ +---+ + * | 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 FrameMetrics, labelled + * FM0...FMn. FM0 is the FrameMetrics you get by calling c->GetFrameMetrics(0) + * and FMn is the FrameMetrics you can obtain by calling + * c->GetFrameMetrics(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 container + * layers C1...Cn, where C1 has FrameMetrics FM1 and Cn has FrameMetrics Fn. + * Although in this example C (in the first layer tree) and C0 (in the second + * layer tree) are both ContainerLayers (because they have children), they + * do not have to be. They may just be PaintedLayers or ColorLayers, for example, + * which do not have any children. However, the type of C will always be the + * same as the type of C0. + * + * The LayerMetricsWrapper 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 FrameMetrics objects directly, it can use a + * LayerMetricsWrapper to encapsulate that aspect of the layer tree and just + * walk the tree as if it were a stack of ContainerLayers. + * + * The functions on this class do different things depending on which + * simulated ContainerLayer is being wrapped. For example, if the + * LayerMetricsWrapper is pretending to be C0, the GetNextSibling() function + * will return null even though the underlying layer C does actually have + * a next sibling. The LayerMetricsWrapper pretending to be Cn will return + * D as the next 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 LayerMetricsWrapper is simulating the topmost or bottommost + * layer, as those will have special behaviour. + * + * It is possible to wrap a nullptr in a LayerMetricsWrapper, in which case + * the IsValid() function will return false. This is required to allow + * LayerMetricsWrapper 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. + */ +class MOZ_STACK_CLASS LayerMetricsWrapper { +public: + enum StartAt { + TOP, + BOTTOM, + }; + + LayerMetricsWrapper() + : mLayer(nullptr) + , mIndex(0) + { + } + + explicit LayerMetricsWrapper(Layer* aRoot, StartAt aStart = StartAt::TOP) + : mLayer(aRoot) + , mIndex(0) + { + if (!mLayer) { + return; + } + + switch (aStart) { + case StartAt::TOP: + mIndex = mLayer->GetScrollMetadataCount(); + if (mIndex > 0) { + mIndex--; + } + break; + case StartAt::BOTTOM: + mIndex = 0; + break; + default: + MOZ_ASSERT_UNREACHABLE("Unknown startAt value"); + break; + } + } + + explicit LayerMetricsWrapper(Layer* aLayer, uint32_t aMetricsIndex) + : mLayer(aLayer) + , mIndex(aMetricsIndex) + { + MOZ_ASSERT(mLayer); + MOZ_ASSERT(mIndex == 0 || mIndex < mLayer->GetScrollMetadataCount()); + } + + bool IsValid() const + { + return mLayer != nullptr; + } + + explicit operator bool() const + { + return IsValid(); + } + + bool IsScrollInfoLayer() const + { + MOZ_ASSERT(IsValid()); + + // If we are not at the bottommost layer then it's + // a stack of container layers all the way down to + // mLayer, which we can ignore. We only care about + // non-container descendants. + return Metrics().IsScrollable() + && mLayer->AsContainerLayer() + && !mLayer->GetFirstChild(); + } + + LayerMetricsWrapper GetParent() const + { + MOZ_ASSERT(IsValid()); + + if (!AtTopLayer()) { + return LayerMetricsWrapper(mLayer, mIndex + 1); + } + if (mLayer->GetParent()) { + return LayerMetricsWrapper(mLayer->GetParent(), StartAt::BOTTOM); + } + return LayerMetricsWrapper(nullptr); + } + + LayerMetricsWrapper GetFirstChild() const + { + MOZ_ASSERT(IsValid()); + + if (!AtBottomLayer()) { + return LayerMetricsWrapper(mLayer, mIndex - 1); + } + return LayerMetricsWrapper(mLayer->GetFirstChild()); + } + + LayerMetricsWrapper GetLastChild() const + { + MOZ_ASSERT(IsValid()); + + if (!AtBottomLayer()) { + return LayerMetricsWrapper(mLayer, mIndex - 1); + } + return LayerMetricsWrapper(mLayer->GetLastChild()); + } + + LayerMetricsWrapper GetPrevSibling() const + { + MOZ_ASSERT(IsValid()); + + if (AtTopLayer()) { + return LayerMetricsWrapper(mLayer->GetPrevSibling()); + } + return LayerMetricsWrapper(nullptr); + } + + LayerMetricsWrapper GetNextSibling() const + { + MOZ_ASSERT(IsValid()); + + if (AtTopLayer()) { + return LayerMetricsWrapper(mLayer->GetNextSibling()); + } + return LayerMetricsWrapper(nullptr); + } + + const ScrollMetadata& Metadata() const + { + MOZ_ASSERT(IsValid()); + + if (mIndex >= mLayer->GetScrollMetadataCount()) { + return *ScrollMetadata::sNullMetadata; + } + return mLayer->GetScrollMetadata(mIndex); + } + + const FrameMetrics& Metrics() const + { + return Metadata().GetMetrics(); + } + + AsyncPanZoomController* GetApzc() const + { + MOZ_ASSERT(IsValid()); + + if (mIndex >= mLayer->GetScrollMetadataCount()) { + return nullptr; + } + return mLayer->GetAsyncPanZoomController(mIndex); + } + + void SetApzc(AsyncPanZoomController* aApzc) const + { + MOZ_ASSERT(IsValid()); + + if (mLayer->GetScrollMetadataCount() == 0) { + MOZ_ASSERT(mIndex == 0); + MOZ_ASSERT(aApzc == nullptr); + return; + } + MOZ_ASSERT(mIndex < mLayer->GetScrollMetadataCount()); + mLayer->SetAsyncPanZoomController(mIndex, aApzc); + } + + const char* Name() const + { + MOZ_ASSERT(IsValid()); + + if (AtBottomLayer()) { + return mLayer->Name(); + } + return "DummyContainerLayer"; + } + + LayerManager* Manager() const + { + MOZ_ASSERT(IsValid()); + + return mLayer->Manager(); + } + + gfx::Matrix4x4 GetTransform() const + { + MOZ_ASSERT(IsValid()); + + if (AtBottomLayer()) { + return mLayer->GetTransform(); + } + return gfx::Matrix4x4(); + } + + 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; + } + + EventRegions GetEventRegions() const + { + MOZ_ASSERT(IsValid()); + + if (AtBottomLayer()) { + return mLayer->GetEventRegions(); + } + return EventRegions(); + } + + bool HasTransformAnimation() const + { + MOZ_ASSERT(IsValid()); + + if (AtBottomLayer()) { + return mLayer->HasTransformAnimation(); + } + return false; + } + + RefLayer* AsRefLayer() const + { + MOZ_ASSERT(IsValid()); + + if (AtBottomLayer()) { + return mLayer->AsRefLayer(); + } + return nullptr; + } + + LayerIntRegion GetVisibleRegion() const + { + MOZ_ASSERT(IsValid()); + + if (AtBottomLayer()) { + return mLayer->GetVisibleRegion(); + } + LayerIntRegion region = mLayer->GetVisibleRegion(); + region.Transform(mLayer->GetTransform()); + return region; + } + + Maybe<ParentLayerIntRect> GetClipRect() const + { + MOZ_ASSERT(IsValid()); + + Maybe<ParentLayerIntRect> result; + + // The layer can have a clip rect and a scrolled clip, which are considered + // to apply only to the bottommost LayerMetricsWrapper. + // TODO: These actually apply in a different coordinate space than the + // scroll clip of the bottommost metrics, so we shouldn't be intersecting + // them with the scroll clip; bug 1269537 tracks fixing this. + if (AtBottomLayer()) { + result = mLayer->GetClipRect(); + result = IntersectMaybeRects(result, mLayer->GetScrolledClipRect()); + } + + // The scroll metadata can have a clip rect as well. + result = IntersectMaybeRects(result, Metadata().GetClipRect()); + + return result; + } + + float GetPresShellResolution() const + { + MOZ_ASSERT(IsValid()); + + if (AtTopLayer() && mLayer->AsContainerLayer()) { + return mLayer->AsContainerLayer()->GetPresShellResolution(); + } + + return 1.0f; + } + + EventRegionsOverride GetEventRegionsOverride() const + { + MOZ_ASSERT(IsValid()); + + if (mLayer->AsContainerLayer()) { + return mLayer->AsContainerLayer()->GetEventRegionsOverride(); + } + return EventRegionsOverride::NoOverride; + } + + Layer::ScrollDirection GetScrollbarDirection() const + { + MOZ_ASSERT(IsValid()); + + return mLayer->GetScrollbarDirection(); + } + + FrameMetrics::ViewID GetScrollbarTargetContainerId() const + { + MOZ_ASSERT(IsValid()); + + return mLayer->GetScrollbarTargetContainerId(); + } + + int32_t GetScrollbarSize() const + { + if (GetScrollbarDirection() == Layer::VERTICAL) { + return mLayer->GetVisibleRegion().GetBounds().height; + } else { + return mLayer->GetVisibleRegion().GetBounds().width; + } + } + + bool IsScrollbarContainer() const + { + MOZ_ASSERT(IsValid()); + return mLayer->IsScrollbarContainer(); + } + + FrameMetrics::ViewID GetFixedPositionScrollContainerId() const + { + MOZ_ASSERT(IsValid()); + + return mLayer->GetFixedPositionScrollContainerId(); + } + + // 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 (void*)mLayer; + } + + bool operator==(const LayerMetricsWrapper& aOther) const + { + return mLayer == aOther.mLayer + && mIndex == aOther.mIndex; + } + + bool operator!=(const LayerMetricsWrapper& aOther) const + { + return !(*this == aOther); + } + + static const FrameMetrics& TopmostScrollableMetrics(Layer* aLayer) + { + for (uint32_t i = aLayer->GetScrollMetadataCount(); i > 0; i--) { + if (aLayer->GetFrameMetrics(i - 1).IsScrollable()) { + return aLayer->GetFrameMetrics(i - 1); + } + } + return ScrollMetadata::sNullMetadata->GetMetrics(); + } + + static const FrameMetrics& BottommostScrollableMetrics(Layer* aLayer) + { + for (uint32_t i = 0; i < aLayer->GetScrollMetadataCount(); i++) { + if (aLayer->GetFrameMetrics(i).IsScrollable()) { + return aLayer->GetFrameMetrics(i); + } + } + return ScrollMetadata::sNullMetadata->GetMetrics(); + } + + static const FrameMetrics& BottommostMetrics(Layer* aLayer) + { + if (aLayer->GetScrollMetadataCount() > 0) { + return aLayer->GetFrameMetrics(0); + } + return ScrollMetadata::sNullMetadata->GetMetrics(); + } + +private: + bool AtBottomLayer() const + { + return mIndex == 0; + } + + bool AtTopLayer() const + { + return mLayer->GetScrollMetadataCount() == 0 || mIndex == mLayer->GetScrollMetadataCount() - 1; + } + +private: + Layer* mLayer; + uint32_t mIndex; +}; + +} // namespace layers +} // namespace mozilla + +#endif /* GFX_LAYERMETRICSWRAPPER_H */ |