Use variable length key (rather than accumulated matrix) as save layer hoisting key

src/gpu/GrLayerCache.h

 /*
  * 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
 
@@ skipping 58 matching lines @@
 // 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 {
 public:
     // For SkTDynamicHash
     struct Key {
-        Key(uint32_t pictureID, int start, const SkIRect& bounds, const SkMatrix& ctm)
+        Key(uint32_t pictureID, int start, const SkIRect& bounds, const SkMatrix& ctm,
+            const int* key, int keySize)
         : fPictureID(pictureID)
         , fStart(start)
         , fBounds(bounds)
-        , fCTM(ctm) {
+        , fCTM(ctm)
+        , fKey(key)
+        , fKeySize(keySize) {
             fCTM.getType(); // force initialization of type so hashes match
 
+#if 0
             // Key needs to be tightly packed.
             GR_STATIC_ASSERT(sizeof(Key) == sizeof(uint32_t) +      // picture ID
                                             sizeof(int) +           // start index
                                             4 * sizeof(uint32_t) +  // bounds
                                             9 * sizeof(SkScalar) + sizeof(uint32_t)); // matrix
+#endif
         }
 
         bool operator==(const Key& other) const {
+            if (fKeySize != other.fKeySize) {
+                return false;
+            }
             return fPictureID == other.fPictureID &&
                    fStart == other.fStart &&
                    fBounds == other.fBounds &&
-                   fCTM.cheapEqualTo(other.fCTM);
+                   fCTM.cheapEqualTo(other.fCTM) &&
+                   !memcmp(fKey, other.fKey, fKeySize * sizeof(int));
         }
 
         uint32_t pictureID() const { return fPictureID; }
         int start() const { return fStart; }
         const SkIRect& bound() const { return fBounds; }
 
+        const int* key() const { return fKey; }
+        int keySize() const { return fKeySize; }
+
     private:
         // ID of the picture of which this layer is a part
         const uint32_t fPictureID;
         // The the index of the saveLayer command in the picture
         const int      fStart;
         // The bounds of the layer. The TL corner is its offset.
         const SkIRect  fBounds;
         // The 2x2 portion of the CTM applied to this layer in the picture
         SkMatrix       fCTM;
+
+        const int*     fKey;
+        const int      fKeySize;
     };
 
     static const Key& GetKey(const GrCachedLayer& layer) { return layer.fKey; }
     static uint32_t Hash(const Key& key) { 
-        return SkChecksum::Murmur3(reinterpret_cast<const uint32_t*>(&key), sizeof(Key));
+        return SkChecksum::Murmur3(reinterpret_cast<const uint32_t*>(key.key()), 
+                                   key.keySize() * sizeof(int));
     }
 
     // GrCachedLayer proper
     GrCachedLayer(uint32_t pictureID, int start, int stop,
                   const SkIRect& bounds, const SkMatrix& ctm,
+                  const int* key, int keySize,
                   const SkPaint* paint)
-        : fKey(pictureID, start, bounds, ctm)
+        : fKey(pictureID, start, bounds, ctm, key, keySize)
         , fStop(stop)
         , fPaint(paint ? SkNEW_ARGS(SkPaint, (*paint)) : NULL)
         , fTexture(NULL)
         , fRect(GrIRect16::MakeEmpty())
         , fPlot(NULL)
         , fUses(0)
         , fLocked(false) {
         SkASSERT(SK_InvalidGenID != pictureID && start >= 0 && stop >= 0);
     }
 
     ~GrCachedLayer() {
         SkSafeUnref(fTexture);
         SkDELETE(fPaint);
     }
 
     uint32_t pictureID() const { return fKey.pictureID(); }
     int start() const { return fKey.start(); }
+    const int* key() const { return fKey.key(); }
+    int keySize() const { return fKey.keySize(); }
+
     const SkIRect& bound() const { return fKey.bound(); }
 
     int stop() const { return fStop; }
     void setTexture(GrTexture* texture, const GrIRect16& rect) {
         SkRefCnt_SafeAssign(fTexture, texture);
         fRect = rect;
     }
     GrTexture* texture() { return fTexture; }
     const SkPaint* paint() const { return fPaint; }
     const GrIRect16& rect() const { return fRect; }
@@ skipping 65 matching lines @@
 // classes.
 class GrLayerCache {
 public:
     GrLayerCache(GrContext*);
     ~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, int start, 
-                             const SkIRect& bounds, const SkMatrix& ctm);
+    GrCachedLayer* findLayer(uint32_t pictureID, int start,
+                             const SkIRect& bounds, const SkMatrix& ctm,
+                             const int* key, int keySize);
     GrCachedLayer* findLayerOrCreate(uint32_t pictureID,
                                      int start, int stop, 
                                      const SkIRect& bounds,
                                      const SkMatrix& ctm,
+                                     const int* 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.
@@ skipping 60 matching lines @@
     // 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& bounds, const SkMatrix& ctm, 
+    GrCachedLayer* createLayer(uint32_t pictureID, int start, int stop,
+                               const SkIRect& bounds, const SkMatrix& ctm,
+                               const int* 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);
         --fPlotLocks[plotIdx];
     }
 
     // for testing
     friend class TestingAccess;
     int numLayers() const { return fLayerHash.count(); }
 };
 
 #endif