gecko/layout/base/MaskLayerImageCache.h
2012-07-30 17:20:58 +03:00

216 lines
6.7 KiB
C++

/* -*- 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 "FrameLayerBuilder.h"
#include "nsPresContext.h"
#include "ImageLayers.h"
namespace mozilla {
/**
* 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;
public:
MaskLayerImageCache()
{
mMaskImageContainers.Init();
}
/**
* Representation of a rounded rectangle in device pixel coordinates, in
* contrast to FrameLayerBuilder::Clip::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 FrameLayerBuilder::Clip::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))
{
NS_FOR_CSS_HALF_CORNERS(corner) {
mRadii[corner] = aPresContext->AppUnitsToGfxUnits(aRRect.mRadii[corner]);
}
}
// 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 gfxMatrix& aTransform)
{
NS_ASSERTION(aTransform.xy == 0 && aTransform.yx == 0,
"Transform has a component other than scale and translate");
mRect = aTransform.Transform(mRect);
for (size_t i = 0; i < ArrayLength(mRadii); i += 2) {
mRadii[i] *= aTransform.xx;
mRadii[i + 1] *= aTransform.yy;
}
}
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;
}
gfxRect mRect;
// Indices into mRadii are the NS_CORNER_* constants in nsStyleConsts.h
gfxFloat mRadii[8];
};
/**
* 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.
*/
class MaskLayerImageKey
{
public:
MaskLayerImageKey(const nsTArray<PixelRoundedRect>& aRoundedClipRects)
: mLayerCount(0)
, mRoundedClipRects(aRoundedClipRects)
{}
void AddRef() const { ++mLayerCount; }
void Release() const
{
NS_ASSERTION(mLayerCount > 0, "Inconsistent layer count");
--mLayerCount;
}
PLDHashNumber Hash() const
{
PLDHashNumber hash = 0;
for (PRUint32 i = 0; i < mRoundedClipRects.Length(); ++i) {
hash = AddToHash(hash, mRoundedClipRects[i].Hash());
}
return hash;
}
bool operator==(const MaskLayerImageKey& aOther) const
{
return mRoundedClipRects == aOther.mRoundedClipRects;
}
mutable PRUint32 mLayerCount;
nsTArray<PixelRoundedRect> mRoundedClipRects;
};
// 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;
MaskLayerImageEntry(KeyTypePointer aKey) : mKey(aKey) {}
MaskLayerImageEntry(const MaskLayerImageEntry& aOther)
: mKey(aOther.mKey.get())
{
NS_ERROR("ALLOW_MEMMOVE == true, should never be called");
}
// 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;
nsRefPtr<ImageContainer> mContainer;
};
nsTHashtable<MaskLayerImageEntry> mMaskImageContainers;
// helper funtion for Sweep(), called for each entry in the hashtable
static PLDHashOperator SweepFunc(MaskLayerImageEntry* aEntry, void* aUserArg);
};
}
#endif