Add a layer (FBO) cache.

The cache is used to draw layers so that a new
texture does not have to be recreated every time
a call to saveLayer() happens.

The FBO cache used a KeyedVector, which is a bad
idea. The cache should be able to store several
FBOs of the same size (this happens a lot during
scrolling with fading edges for instance.) This
will be changed in a future CL.

Change-Id: Ic316189e625f0dbcf0d273a71cc981a433d48726

1 files changed, 78 insertions, 0 deletions

diff --git a/libs/hwui/LayerCache.h b/libs/hwui/LayerCache.h
new file mode 100644
index 0000000..3696848
--- /dev/null
+++ b/libs/hwui/LayerCache.h
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_UI_LAYER_CACHE_H
+#define ANDROID_UI_LAYER_CACHE_H
+
+#include "Layer.h"
+#include "GenerationCache.h"
+
+namespace android {
+namespace uirenderer {
+
+class LayerCache: public OnEntryRemoved<LayerSize, Layer*> {
+public:
+    LayerCache(uint32_t maxByteSize);
+    ~LayerCache();
+
+    /**
+     * Used as a callback when an entry is removed from the cache.
+     * Do not invoke directly.
+     */
+    void operator()(LayerSize& bitmap, Layer*& texture);
+
+    /**
+     * Returns the layer of specified dimensions, NULL if cannot be found.
+     */
+    Layer* get(LayerSize& size);
+    /**
+     * Adds the layer to the cache. The layer will not be added if there is
+     * not enough space available.
+     *
+     * @return True if the layer was added, false otherwise.
+     */
+    bool put(LayerSize& size, Layer* layer);
+    /**
+     * Clears the cache. This causes all layers to be deleted.
+     */
+    void clear();
+
+    /**
+     * Sets the maximum size of the cache in bytes.
+     */
+    void setMaxSize(uint32_t maxSize);
+    /**
+     * Returns the maximum size of the cache in bytes.
+     */
+    uint32_t getMaxSize();
+    /**
+     * Returns the current size of the cache in bytes.
+     */
+    uint32_t getSize();
+
+private:
+    void deleteLayer(Layer* layer);
+
+    GenerationCache<LayerSize, Layer*> mCache;
+
+    uint32_t mSize;
+    uint32_t mMaxSize;
+}; // class LayerCache
+
+}; // namespace uirenderer
+}; // namespace android
+
+#endif // ANDROID_UI_LAYER_CACHE_H