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) {}
+
+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() : fPicture(NULL) { }
+
+    const SkPicture* picture() const { return fPicture; }
+    int id() const { return fID; }
+
+    void init(SkPicture* picture, int id) { 
+        fPicture = picture;
+        fID = id; 
+    }
+
+private:
+    SkPicture*      fPicture;

[bsalomon, 2014/04/01 15:26:35]

A bare ptr?

[robertphillips, 2014/04/01 16:51:49]

I would greatly prefer a GenID on pictures.

[bsalomon, 2014/04/01 16:59:04]

Is that something that could reasonably be done first? This seems really unsafe.
A new picture could easily have the same address as a deleted picture. I kind
feel like we let in bare ptrs for clipstacks thinking we'd fix in not too long
and it's been in there forever now.

+    int             fID;        // only valid if fPicture != NULL
+    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* findLayer(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