/* -*- 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(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; } Maybe GetReferentId() const { MOZ_ASSERT(IsValid()); if (AtBottomLayer()) { return mLayer->AsRefLayer() ? Some(mLayer->AsRefLayer()->GetReferentId()) : Nothing(); } return Nothing(); } Maybe GetClipRect() const { MOZ_ASSERT(IsValid()); Maybe 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; } const ScrollThumbData& GetScrollThumbData() const { MOZ_ASSERT(IsValid()); return mLayer->GetScrollThumbData(); } FrameMetrics::ViewID GetScrollbarTargetContainerId() const { MOZ_ASSERT(IsValid()); return mLayer->GetScrollbarTargetContainerId(); } 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); } 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 */