/* -*- 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 MASKLAYERIMAGECACHE_H_ #define MASKLAYERIMAGECACHE_H_ #include "DisplayItemClip.h" #include "nsAutoPtr.h" #include "nsPresContext.h" #include "mozilla/gfx/Matrix.h" namespace mozilla { namespace layers { class ImageContainer; class ShadowLayerForwarder; } // namespace layers /** * Keeps a record of image containers for mask layers, containers are mapped * from the rounded rects used to create them. * The cache stores MaskLayerImageEntries indexed by MaskLayerImageKeys. * Each MaskLayerImageEntry owns a heap-allocated MaskLayerImageKey * (heap-allocated so that a mask layer's userdata can keep a pointer to the * key for its image, in spite of the hashtable moving its entries around). * The key consists of the rounded rects used to create the mask, * an nsRefPtr to the ImageContainer containing the image, and a count * of the number of layers currently using this ImageContainer. * When the key's layer count is zero, the cache * may remove the entry, which deletes the key object. */ class MaskLayerImageCache { typedef mozilla::layers::ImageContainer ImageContainer; typedef mozilla::layers::ShadowLayerForwarder ShadowLayerForwarder; public: MaskLayerImageCache(); ~MaskLayerImageCache(); /** * Representation of a rounded rectangle in device pixel coordinates, in * contrast to DisplayItemClip::RoundedRect, which uses app units. * In particular, our internal representation uses a gfxRect, rather than * an nsRect, so this class is easier to use with transforms. */ struct PixelRoundedRect { PixelRoundedRect(const DisplayItemClip::RoundedRect& aRRect, nsPresContext* aPresContext) : mRect(aPresContext->AppUnitsToGfxUnits(aRRect.mRect.x), aPresContext->AppUnitsToGfxUnits(aRRect.mRect.y), aPresContext->AppUnitsToGfxUnits(aRRect.mRect.width), aPresContext->AppUnitsToGfxUnits(aRRect.mRect.height)) { MOZ_COUNT_CTOR(PixelRoundedRect); NS_FOR_CSS_HALF_CORNERS(corner) { mRadii[corner] = aPresContext->AppUnitsToGfxUnits(aRRect.mRadii[corner]); } } PixelRoundedRect(const PixelRoundedRect& aPRR) : mRect(aPRR.mRect) { MOZ_COUNT_CTOR(PixelRoundedRect); NS_FOR_CSS_HALF_CORNERS(corner) { mRadii[corner] = aPRR.mRadii[corner]; } } ~PixelRoundedRect() { MOZ_COUNT_DTOR(PixelRoundedRect); } // Applies the scale and translate components of aTransform. // It is an error to pass a matrix which does more than just scale // and translate. void ScaleAndTranslate(const gfx::Matrix& aTransform) { NS_ASSERTION(aTransform._12 == 0 && aTransform._21 == 0, "Transform has a component other than scale and translate"); mRect = aTransform.TransformBounds(mRect); for (size_t i = 0; i < ArrayLength(mRadii); i += 2) { mRadii[i] *= aTransform._11; mRadii[i + 1] *= aTransform._22; } } bool operator==(const PixelRoundedRect& aOther) const { if (!mRect.IsEqualInterior(aOther.mRect)) { return false; } NS_FOR_CSS_HALF_CORNERS(corner) { if (mRadii[corner] != aOther.mRadii[corner]) { return false; } } return true; } bool operator!=(const PixelRoundedRect& aOther) const { return !(*this == aOther); } // Create a hash for this object. PLDHashNumber Hash() const { PLDHashNumber hash = HashBytes(&mRect.x, 4*sizeof(gfxFloat)); hash = AddToHash(hash, HashBytes(mRadii, 8*sizeof(gfxFloat))); return hash; } gfx::Rect mRect; // Indices into mRadii are the NS_CORNER_* constants in nsStyleConsts.h gfxFloat mRadii[8]; private: PixelRoundedRect() = delete; }; struct MaskLayerImageKeyRef; /** * A key to identify cached image containers. * The const-ness of this class is with respect to its use as a key into a * hashtable, so anything not used to create the hash is mutable. * mLayerCount counts the number of mask layers which have a reference to * MaskLayerImageEntry::mContainer; it is maintained by MaskLayerUserData, * which keeps a reference to the key. There will usually be mLayerCount + 1 * pointers to a key object (the +1 being from the hashtable entry), but this * invariant may be temporarily broken. */ struct MaskLayerImageKey { friend struct MaskLayerImageKeyRef; MaskLayerImageKey(); MaskLayerImageKey(const MaskLayerImageKey& aKey); ~MaskLayerImageKey(); bool HasZeroLayerCount() const { return mLayerCount == 0; } PLDHashNumber Hash() const { PLDHashNumber hash = 0; for (uint32_t i = 0; i < mRoundedClipRects.Length(); ++i) { hash = AddToHash(hash, mRoundedClipRects[i].Hash()); } hash = AddToHash(hash, mForwarder.get()); return hash; } bool operator==(const MaskLayerImageKey& aOther) const { return mForwarder == aOther.mForwarder && mRoundedClipRects == aOther.mRoundedClipRects; } nsTArray<PixelRoundedRect> mRoundedClipRects; RefPtr<ShadowLayerForwarder> mForwarder; private: void IncLayerCount() const { ++mLayerCount; } void DecLayerCount() const { NS_ASSERTION(mLayerCount > 0, "Inconsistent layer count"); --mLayerCount; } mutable uint32_t mLayerCount; }; /** * This struct maintains a reference to a MaskLayerImageKey, via a variant on * refcounting. When a key is passed in via Reset(), we increment the * passed-in key's mLayerCount, and we decrement its mLayerCount when we're * destructed (or when the key is replaced via a second Reset() call). * * However, unlike standard refcounting smart-pointers, this object does * *not* delete the tracked MaskLayerImageKey -- instead, deletion happens * in MaskLayerImageCache::Sweep(), for any keys whose mLayerCount is 0. */ struct MaskLayerImageKeyRef { ~MaskLayerImageKeyRef() { if (mRawPtr) { mRawPtr->DecLayerCount(); } } MaskLayerImageKeyRef() : mRawPtr(nullptr) {} MaskLayerImageKeyRef(const MaskLayerImageKeyRef&) = delete; void operator=(const MaskLayerImageKeyRef&) = delete; void Reset(const MaskLayerImageKey* aPtr) { MOZ_ASSERT(aPtr, "Cannot initialize a MaskLayerImageKeyRef with a null pointer"); aPtr->IncLayerCount(); if (mRawPtr) { mRawPtr->DecLayerCount(); } mRawPtr = aPtr; } private: const MaskLayerImageKey* mRawPtr; }; // Find an image container for aKey, returns nullptr if there is no suitable // cached image. If there is an image, then aKey is set to point at the stored // key for the image. ImageContainer* FindImageFor(const MaskLayerImageKey** aKey); // Add an image container with a key to the cache // The image container used will be set as the container in aKey and aKey // itself will be linked from this cache void PutImage(const MaskLayerImageKey* aKey, ImageContainer* aContainer); // Sweep the cache for old image containers that can be deleted void Sweep(); protected: class MaskLayerImageEntry : public PLDHashEntryHdr { public: typedef const MaskLayerImageKey& KeyType; typedef const MaskLayerImageKey* KeyTypePointer; explicit MaskLayerImageEntry(KeyTypePointer aKey) : mKey(aKey) { MOZ_COUNT_CTOR(MaskLayerImageEntry); } MaskLayerImageEntry(const MaskLayerImageEntry& aOther) : mKey(aOther.mKey.get()) { NS_ERROR("ALLOW_MEMMOVE == true, should never be called"); } ~MaskLayerImageEntry() { MOZ_COUNT_DTOR(MaskLayerImageEntry); } // KeyEquals(): does this entry match this key? bool KeyEquals(KeyTypePointer aKey) const { return *mKey == *aKey; } // KeyToPointer(): Convert KeyType to KeyTypePointer static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; } // HashKey(): calculate the hash number static PLDHashNumber HashKey(KeyTypePointer aKey) { return aKey->Hash(); } // ALLOW_MEMMOVE can we move this class with memmove(), or do we have // to use the copy constructor? enum { ALLOW_MEMMOVE = true }; bool operator==(const MaskLayerImageEntry& aOther) const { return KeyEquals(aOther.mKey); } nsAutoPtr<const MaskLayerImageKey> mKey; RefPtr<ImageContainer> mContainer; }; nsTHashtable<MaskLayerImageEntry> mMaskImageContainers; }; } // namespace mozilla #endif