gecko-dev/layout/painting/MaskLayerImageCache.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 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 KnowsCompositor;
} // 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::KnowsCompositor KnowsCompositor;
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() = delete;
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 enum HalfCorner constants in gfx/2d/Types.h
gfxFloat mRadii[8];
};
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, mKnowsCompositor.get());
return hash;
}
bool operator==(const MaskLayerImageKey& aOther) const
{
return mKnowsCompositor == aOther.mKnowsCompositor &&
mRoundedClipRects == aOther.mRoundedClipRects;
}
nsTArray<PixelRoundedRect> mRoundedClipRects;
RefPtr<KnowsCompositor> mKnowsCompositor;
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