Add a GrLayerCache to GrContext

src/gpu/GrLayerCache.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "GrAtlas.h"
+#include "GrGpu.h"
+#include "GrLayerCache.h"
+
+/**
+ *  PictureLayerKey just wraps a saveLayer's id in the picture for GrTHashTable.
+ */
+class GrLayerCache::PictureLayerKey {
+public:
+    PictureLayerKey(SkPicture* picture, int id) : fPicture(picture), fID(id) {}
+
+    const SkPicture* picture() const { return fPicture; }
+    int id() const { return fID; }
+
+    uint32_t getHash() const { return ((int)fPicture) ^ fID; }
+
+    static bool LessThan(const GrAtlasedLayer& layer, const PictureLayerKey& key) {
+        if (layer.picture() == key.picture()) {
+            return layer.id() < key.id();
+        }
+
+        return layer.picture() < key.picture();
+    }
+
+    static bool Equals(const GrAtlasedLayer& layer, const PictureLayerKey& key) {
+        return layer.picture() == key.picture() && layer.id() == key.id();
+    }
+
+private:
+    SkPicture* fPicture;
+    int        fID;
+};
+
+GrLayerCache::GrLayerCache(GrGpu* gpu) 
+    : fGpu(SkRef(gpu))
+    , fLayerPool(16) {      // TODO: may need to increase this later
+}
+
+GrLayerCache::~GrLayerCache() {
+}
+
+void GrLayerCache::init() {
+    static const int kAtlasTextureWidth = 1024;
+    static const int kAtlasTextureHeight = 1024;
+
+    SkASSERT(NULL == fAtlasMgr.get());
+
+    // The layer cache only gets 1 plot
+    fAtlasMgr.reset(SkNEW_ARGS(GrAtlasMgr, (fGpu, kSkia8888_GrPixelConfig,
+                                            kAtlasTextureWidth, kAtlasTextureHeight,
+                                            1, 1)));
+}
+
+void GrLayerCache::freeAll() {
+    fLayerHash.deleteAll();
+    fAtlasMgr.free();
+}
+
+GrAtlasedLayer* GrLayerCache::createLayer(SkPicture* picture, int id) {
+    GrAtlasedLayer* layer = fLayerPool.alloc();
+
+    layer->init(picture, id);
+    fLayerHash.insert(PictureLayerKey(picture, id), layer);
+    return layer;
+}
+
+
+const GrAtlasedLayer* GrLayerCache::findLayer(SkPicture* picture, int id) {

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

Seems like this should be named something like findOrCreateLayer() since it
doesn't just find.

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

Done.

+    GrAtlasedLayer* layer = fLayerHash.find(PictureLayerKey(picture, id));
+    if (NULL == layer) {
+        layer = this->createLayer(picture, id);
+    }
+    return layer;
+}