Add a GrLayerCache to GrContext

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
+
+#include "GrAllocPool.h"
+#include "GrTHashTable.h"
+#include "GrPictureUtils.h"
+#include "GrRect.h"
+
+class GrAtlasMgr;
+class GrGpu;
+class GrPlot;
+class SkPicture;
+
+// GrAtlasLocation captures an atlased item's position in the atlas. This
+// means the plot in which it resides and its bounds inside the plot.
+// TODO: Make GrGlyph use one of these?
+class GrAtlasLocation {
+public:
+    GrAtlasLocation() : fPlot(NULL) {}
+
+    void set(GrPlot* plot, const GrIRect16& bounds) {
+        fPlot = plot;
+        fBounds = bounds;
+    }
+
+    const GrPlot* plot() const {
+        return fPlot;
+    }
+
+    const GrIRect16& bounds() const {
+        return fBounds;
+    }
+
+private:
+    GrPlot*   fPlot;
+    GrIRect16 fBounds;  // only valid is fPlot != NULL
+};
+
+// A GrAtlasedLayer encapsulates the atlasing information for a single saveLayer.
+// It is roughly equivalent to a GrGlyph in the font caching system
+class GrAtlasedLayer {
+public:
+    GrAtlasedLayer() : fPictureID(SkPicture::kInvalidGenID) { }
+
+    uint32_t pictureID() const { return fPictureID; }
+    int layerID() const { return fLayerID; }
+
+    void init(uint32_t pictureID, int layerID) { 
+        fPictureID = pictureID;
+        fLayerID   = layerID; 
+    }
+
+private:
+    uint32_t        fPictureID;
+    int             fLayerID;        // only valid if fPicture != kInvalidGenID
+    GrAtlasLocation fLocation; 
+};
+
+// The GrLayerCache caches pre-computed saveLayers for later rendering.
+// Unlike the GrFontCache, this cache only has one GrAtlasMgr (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 {
+public:
+    GrLayerCache(GrGpu*);
+    ~GrLayerCache();
+
+    void freeAll();
+
+    const GrAtlasedLayer* findLayerOrCreate(SkPicture* picture, int id);
+
+private:
+    SkAutoTUnref<GrGpu>       fGpu;
+    SkAutoTDelete<GrAtlasMgr> fAtlasMgr; // TODO: could lazily allocate
+
+    class PictureLayerKey;
+    GrTHashTable<GrAtlasedLayer, PictureLayerKey, 7> fLayerHash;
+    GrTAllocPool<GrAtlasedLayer> fLayerPool;
+
+    void init();
+    GrAtlasedLayer* createLayer(SkPicture* picture, int id);
+
+};
+
+#endif