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(uint32_t pictureID, int layerID) 
+        : fPictureID(pictureID)
+        , fLayerID(layerID) {
+    }
+
+    uint32_t pictureID() const { return fPictureID; }
+    int layerID() const { return fLayerID; }
+
+    uint32_t getHash() const { return (fPictureID << 16) | fLayerID; }
+
+    static bool LessThan(const GrAtlasedLayer& layer, const PictureLayerKey& key) {
+        if (layer.pictureID() == key.pictureID()) {
+            return layer.layerID() < key.layerID();
+        }
+
+        return layer.pictureID() < key.pictureID();
+    }
+
+    static bool Equals(const GrAtlasedLayer& layer, const PictureLayerKey& key) {
+        return layer.pictureID() == key.pictureID() && layer.layerID() == key.layerID();
+    }
+
+private:
+    uint32_t fPictureID;
+    int      fLayerID;
+};
+
+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
+    SkISize textureSize = SkISize::Make(kAtlasTextureWidth, kAtlasTextureHeight);
+    fAtlasMgr.reset(SkNEW_ARGS(GrAtlasMgr, (fGpu, kSkia8888_GrPixelConfig,
+                                            textureSize, 1, 1)));
+}
+
+void GrLayerCache::freeAll() {
+    fLayerHash.deleteAll();
+    fAtlasMgr.free();
+}
+
+GrAtlasedLayer* GrLayerCache::createLayer(SkPicture* picture, int layerID) {
+    GrAtlasedLayer* layer = fLayerPool.alloc();
+
+    SkASSERT(picture->getGenerationID() != SkPicture::kInvalidGenID);
+    layer->init(picture->getGenerationID(), layerID);
+    fLayerHash.insert(PictureLayerKey(picture->getGenerationID(), layerID), layer);
+    return layer;
+}
+
+
+const GrAtlasedLayer* GrLayerCache::findLayerOrCreate(SkPicture* picture, int layerID) {
+    SkASSERT(picture->getGenerationID() != SkPicture::kInvalidGenID);
+    GrAtlasedLayer* layer = fLayerHash.find(PictureLayerKey(picture->getGenerationID(), layerID));
+    if (NULL == layer) {
+        layer = this->createLayer(picture, layerID);
+    }
+    return layer;
+}