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* Copyright 2014 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef GrLayerCache_DEFINED
#define GrLayerCache_DEFINED
#include "GrAtlas.h"
#include "GrRect.h"
#include "SkChecksum.h"
#include "SkImageFilter.h"
#include "SkMessageBus.h"
#include "SkPicture.h"
#include "SkTDynamicHash.h"
// Set to 0 to disable caching of hoisted layers
// GrPictureInfo stores the atlas plots used by a single picture. A single
// plot may be used to store layers from multiple pictures.
struct GrPictureInfo {
static const int kNumPlots = 4;
// for SkTDynamicHash - just use the pictureID as the hash key
static const uint32_t& GetKey(const GrPictureInfo& pictInfo) { return pictInfo.fPictureID; }
static uint32_t Hash(const uint32_t& key) { return SkChecksum::Mix(key); }
// GrPictureInfo proper
GrPictureInfo(uint32_t pictureID) : fPictureID(pictureID) {
memset(fPlotUses, 0, sizeof(fPlotUses));
void incPlotUsage(int plotID) {
SkASSERT(plotID < kNumPlots);
void decPlotUsage(int plotID) {
SkASSERT(plotID < kNumPlots);
SkASSERT(fPlotUses[plotID] > 0);
int plotUsage(int plotID) const {
SkASSERT(plotID < kNumPlots);
return fPlotUses[plotID];
const uint32_t fPictureID;
GrAtlas::ClientPlotUsage fPlotUsage;
int fPlotUses[kNumPlots];
// GrCachedLayer encapsulates the caching information for a single saveLayer.
// Atlased layers get a ref to the backing GrTexture while non-atlased layers
// get a ref to the GrTexture in which they reside. In both cases 'fRect'
// contains the layer's extent in its texture.
// Atlased layers also get a pointer to the plot in which they reside.
// For non-atlased layers, the lock field just corresponds to locking in
// the resource cache. For atlased layers, it implements an additional level
// of locking to allow atlased layers to be reused multiple times.
struct GrCachedLayer {
// For SkTDynamicHash
struct Key {
Key(uint32_t pictureID, const SkMatrix& initialMat,
const unsigned* key, int keySize, bool copyKey = false)
: fKeySize(keySize)
, fFreeKey(copyKey) {
fIDMatrix.fPictureID = pictureID;
fIDMatrix.fInitialMat = initialMat;
fIDMatrix.fInitialMat.getType(); // force initialization of type so hashes match
if (copyKey) {
unsigned* tempKey = SkNEW_ARRAY(unsigned, keySize);
memcpy(tempKey, key, keySize*sizeof(unsigned));
fKey = tempKey;
} else {
fKey = key;
// The pictureID/matrix portion needs to be tightly packed.
GR_STATIC_ASSERT(sizeof(IDMatrix) == sizeof(uint32_t)+ // pictureID
9 * sizeof(SkScalar) + sizeof(uint32_t)); // matrix
~Key() {
if (fFreeKey) {
bool operator==(const Key& other) const {
if (fKeySize != other.fKeySize) {
return false;
return fIDMatrix.fPictureID == other.fIDMatrix.fPictureID &&
fIDMatrix.fInitialMat.cheapEqualTo(other.fIDMatrix.fInitialMat) &&
!memcmp(fKey, other.fKey, fKeySize * sizeof(int));
uint32_t pictureID() const { return fIDMatrix.fPictureID; }
// TODO: remove these when GrCachedLayer & ReplacementInfo fuse
const unsigned* key() const { SkASSERT(fFreeKey); return fKey; }
int keySize() const { SkASSERT(fFreeKey); return fKeySize; }
uint32_t hash() const {
uint32_t hash = SkChecksum::Murmur3(reinterpret_cast<const uint32_t*>(fKey),
fKeySize * sizeof(int));
return SkChecksum::Murmur3(reinterpret_cast<const uint32_t*>(&fIDMatrix),
sizeof(IDMatrix), hash);
struct IDMatrix {
// ID of the picture of which this layer is a part
uint32_t fPictureID;
// The initial matrix passed into drawPicture
SkMatrix fInitialMat;
} fIDMatrix;
const unsigned* fKey;
const int fKeySize;
bool fFreeKey;
static const Key& GetKey(const GrCachedLayer& layer) { return layer.fKey; }
static uint32_t Hash(const Key& key) { return key.hash(); }
// GrCachedLayer proper
GrCachedLayer(uint32_t pictureID, unsigned start, unsigned stop,
const SkIRect& srcIR, const SkIRect& dstIR,
const SkMatrix& ctm,
const unsigned* key, int keySize,
const SkPaint* paint)
: fKey(pictureID, ctm, key, keySize, true)
, fStart(start)
, fStop(stop)
, fSrcIR(srcIR)
, fDstIR(dstIR)
, fOffset(SkIPoint::Make(0, 0))
, fPaint(paint ? SkNEW_ARGS(SkPaint, (*paint)) : NULL)
, fFilter(NULL)
, fTexture(NULL)
, fRect(SkIRect::MakeEmpty())
, fPlot(NULL)
, fUses(0)
, fLocked(false) {
SkASSERT(SK_InvalidGenID != pictureID);
if (fPaint) {
if (fPaint->getImageFilter()) {
fFilter = SkSafeRef(fPaint->getImageFilter());
~GrCachedLayer() {
uint32_t pictureID() const { return fKey.pictureID(); }
// TODO: remove these when GrCachedLayer & ReplacementInfo fuse
const unsigned* key() const { return fKey.key(); }
int keySize() const { return fKey.keySize(); }
unsigned start() const { return fStart; }
// TODO: make bound debug only
const SkIRect& srcIR() const { return fSrcIR; }
const SkIRect& dstIR() const { return fDstIR; }
unsigned stop() const { return fStop; }
void setTexture(GrTexture* texture, const SkIRect& rect) {
SkRefCnt_SafeAssign(fTexture, texture);
fRect = rect;
if (!fTexture) {
fLocked = false;
GrTexture* texture() { return fTexture; }
const SkPaint* paint() const { return fPaint; }
const SkImageFilter* filter() const { return fFilter; }
const SkIRect& rect() const { return fRect; }
void setOffset(const SkIPoint& offset) { fOffset = offset; }
const SkIPoint& offset() const { return fOffset; }
void setPlot(GrPlot* plot) {
SkASSERT(NULL == plot || NULL == fPlot);
fPlot = plot;
GrPlot* plot() { return fPlot; }
bool isAtlased() const { return SkToBool(fPlot); }
void setLocked(bool locked) { fLocked = locked; }
bool locked() const { return fLocked; }
SkDEBUGCODE(const GrPlot* plot() const { return fPlot; })
SkDEBUGCODE(void validate(const GrTexture* backingTexture) const;)
const Key fKey;
// The "saveLayer" operation index of the cached layer
const unsigned fStart;
// The final "restore" operation index of the cached layer
const unsigned fStop;
// The layer's src rect (i.e., the portion of the source scene required
// for filtering).
const SkIRect fSrcIR;
// The layer's dest rect (i.e., where it will land in device space)
const SkIRect fDstIR;
// Offset sometimes required by image filters
SkIPoint fOffset;
// The paint used when dropping the layer down into the owning canvas.
// Can be NULL. This class makes a copy for itself.
SkPaint* fPaint;
// The imagefilter that needs to be applied to the layer prior to it being
// composited with the rest of the scene.
const SkImageFilter* fFilter;
// fTexture is a ref on the atlasing texture for atlased layers and a
// ref on a GrTexture for non-atlased textures.
GrTexture* fTexture;
// For both atlased and non-atlased layers 'fRect' contains the bound of
// the layer in whichever texture it resides. It is empty when 'fTexture'
// is NULL.
SkIRect fRect;
// For atlased layers, fPlot stores the atlas plot in which the layer rests.
// It is always NULL for non-atlased layers.
GrPlot* fPlot;
// The number of actively hoisted layers using this cached image (e.g.,
// extant GrHoistedLayers pointing at this object). This object will
// be unlocked when the use count reaches 0.
int fUses;
// For non-atlased layers 'fLocked' should always match "fTexture".
// (i.e., if there is a texture it is locked).
// For atlased layers, 'fLocked' is true if the layer is in a plot and
// actively required for rendering. If the layer is in a plot but not
// actively required for rendering, then 'fLocked' is false. If the
// layer isn't in a plot then is can never be locked.
bool fLocked;
void addUse() { ++fUses; }
void removeUse() { SkASSERT(fUses > 0); --fUses; }
int uses() const { return fUses; }
friend class GrLayerCache; // for access to usage methods
friend class TestingAccess; // for testing
// The GrLayerCache caches pre-computed saveLayers for later rendering.
// Non-atlased layers are stored in their own GrTexture while the atlased
// layers share a single GrTexture.
// Unlike the GrFontCache, the GrTexture atlas only has one GrAtlas (for 8888)
// and one GrPlot (for the entire atlas). As such, the GrLayerCache
// roughly combines the functionality of the GrFontCache and GrTextStrike
// classes.
class GrLayerCache {
// As a cache, the GrLayerCache can be ordered to free up all its cached
// elements by the GrContext
void freeAll();
GrCachedLayer* findLayer(uint32_t pictureID, const SkMatrix& ctm,
const unsigned* key, int keySize);
GrCachedLayer* findLayerOrCreate(uint32_t pictureID,
int start, int stop,
const SkIRect& srcIR,
const SkIRect& dstIR,
const SkMatrix& initialMat,
const unsigned* key, int keySize,
const SkPaint* paint);
// Attempt to place 'layer' in the atlas. Return true on success; false on failure.
// When true is returned, 'needsRendering' will indicate if the layer must be (re)drawn.
// Additionally, the GPU resources will be locked.
bool tryToAtlas(GrCachedLayer* layer, const GrSurfaceDesc& desc, bool* needsRendering);
// Attempt to lock the GPU resources required for a layer. Return true on success;
// false on failure. When true is returned 'needsRendering' will indicate if the
// layer must be (re)drawn.
// Note that atlased layers should already have been locked and rendered so only
// free floating layers will have 'needsRendering' set.
// Currently, this path always uses a new scratch texture for non-Atlased layers
// and (thus) doesn't cache anything. This can yield a lot of re-rendering.
// TODO: allow rediscovery of free-floating layers that are still in the resource cache.
bool lock(GrCachedLayer* layer, const GrSurfaceDesc& desc, bool* needsRendering);
// addUse is just here to keep the API symmetric
void addUse(GrCachedLayer* layer) { layer->addUse(); }
void removeUse(GrCachedLayer* layer) {
if (layer->uses() == 0) {
// If no one cares about the layer allow it to be recycled.
// Cleanup after any SkPicture deletions
void processDeletedPictures();
SkDEBUGCODE(void validate() const;)
void writeLayersToDisk(const SkString& dirName);
static bool PlausiblyAtlasable(int width, int height) {
return width <= kPlotWidth && height <= kPlotHeight;
void purgeAll();
static const int kAtlasTextureWidth = 1024;
static const int kAtlasTextureHeight = 1024;
static const int kNumPlotsX = 2;
static const int kNumPlotsY = 2;
static const int kPlotWidth = kAtlasTextureWidth / kNumPlotsX;
static const int kPlotHeight = kAtlasTextureHeight / kNumPlotsY;
GrContext* fContext; // pointer back to owning context
SkAutoTDelete<GrAtlas> fAtlas; // TODO: could lazily allocate
// We cache this information here (rather then, say, on the owning picture)
// because we want to be able to clean it up as needed (e.g., if a picture
// is leaked and never cleans itself up we still want to be able to
// remove the GrPictureInfo once its layers are purged from all the atlas
// plots).
SkTDynamicHash<GrPictureInfo, uint32_t> fPictureHash;
SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key> fLayerHash;
SkMessageBus<SkPicture::DeletionMessage>::Inbox fPictDeletionInbox;
// This implements a plot-centric locking mechanism (since the atlas
// backing texture is always locked). Each layer that is locked (i.e.,
// needed for the current rendering) in a plot increments the plot lock
// count for that plot. Similarly, once a rendering is complete all the
// layers used in it decrement the lock count for the used plots.
// Plots with a 0 lock count are open for recycling/purging.
int fPlotLocks[kNumPlotsX * kNumPlotsY];
// Inform the cache that layer's cached image is not currently required
void unlock(GrCachedLayer* layer);
void initAtlas();
GrCachedLayer* createLayer(uint32_t pictureID, int start, int stop,
const SkIRect& srcIR, const SkIRect& dstIR,
const SkMatrix& initialMat,
const unsigned* key, int keySize,
const SkPaint* paint);
// Remove all the layers (and unlock any resources) associated with 'pictureID'
void purge(uint32_t pictureID);
void purgePlot(GrPlot* plot);
// Try to find a purgeable plot and clear it out. Return true if a plot
// was purged; false otherwise.
bool purgePlot();
void incPlotLock(int plotIdx) { ++fPlotLocks[plotIdx]; }
void decPlotLock(int plotIdx) {
SkASSERT(fPlotLocks[plotIdx] > 0);
// for testing
friend class TestingAccess;
int numLayers() const { return fLayerHash.count(); }