Add support for paths.

Rendering is implementing by rasterizing the paths into A8 textures.
This cna be extremely inefficient if the path changes often.

Change-Id: I609343f304ae38e0d319359403ee73b9b5b3c93a
diff --git a/libs/hwui/PathCache.h b/libs/hwui/PathCache.h
new file mode 100644
index 0000000..87a9141
--- /dev/null
+++ b/libs/hwui/PathCache.h
@@ -0,0 +1,144 @@
+/*
+ * 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_PATH_CACHE_H
+#define ANDROID_UI_PATH_CACHE_H
+
+#include <SkBitmap.h>
+#include <SkPaint.h>
+#include <SkPath.h>
+
+#include "Texture.h"
+#include "GenerationCache.h"
+
+namespace android {
+namespace uirenderer {
+
+/**
+ * Describe a path in the path cache.
+ */
+struct PathCacheEntry {
+    PathCacheEntry() {
+        path = NULL;
+        join = SkPaint::kDefault_Join;
+        cap = SkPaint::kDefault_Cap;
+        style = SkPaint::kFill_Style;
+        miter = 4.0f;
+        strokeWidth = 1.0f;
+    }
+
+    PathCacheEntry(const PathCacheEntry& entry):
+        path(entry.path), join(entry.join), cap(entry.cap),
+        style(entry.style), miter(entry.miter),
+        strokeWidth(entry.strokeWidth) {
+    }
+
+    PathCacheEntry(SkPath* path, SkPaint* paint) {
+        this->path = path;
+        join = paint->getStrokeJoin();
+        cap = paint->getStrokeCap();
+        miter = paint->getStrokeMiter();
+        strokeWidth = paint->getStrokeWidth();
+        style = paint->getStyle();
+    }
+
+    SkPath* path;
+    SkPaint::Join join;
+    SkPaint::Cap cap;
+    SkPaint::Style style;
+    float miter;
+    float strokeWidth;
+
+    bool operator<(const PathCacheEntry& rhs) const {
+        return memcmp(this, &rhs, sizeof(PathCacheEntry)) < 0;
+    }
+}; // struct PathCacheEntry
+
+/**
+ * Alpha texture used to represent a path.
+ */
+struct PathTexture: public Texture {
+    /**
+     * Left coordinate of the path bounds.
+     */
+    float left;
+    /**
+     * Top coordinate of the path bounds.
+     */
+    float top;
+    /**
+     * Offset to draw the path at the correct origin.
+     */
+    float offset;
+}; // struct PathTexture
+
+/**
+ * A simple LRU path cache. The cache has a maximum size expressed in bytes.
+ * Any texture added to the cache causing the cache to grow beyond the maximum
+ * allowed size will also cause the oldest texture to be kicked out.
+ */
+class PathCache: public OnEntryRemoved<PathCacheEntry, PathTexture*> {
+public:
+    PathCache(uint32_t maxByteSize);
+    ~PathCache();
+
+    /**
+     * Used as a callback when an entry is removed from the cache.
+     * Do not invoke directly.
+     */
+    void operator()(PathCacheEntry& path, PathTexture*& texture);
+
+    /**
+     * Returns the texture associated with the specified path. If the texture
+     * cannot be found in the cache, a new texture is generated.
+     */
+    PathTexture* get(SkPath* path, SkPaint* paint);
+    /**
+     * Clears the cache. This causes all textures 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:
+    /**
+     * Generates the texture from a bitmap into the specified texture structure.
+     */
+    void generateTexture(SkBitmap& bitmap, Texture* texture);
+
+    PathTexture* addTexture(const PathCacheEntry& entry, const SkPath *path, const SkPaint* paint);
+
+    GenerationCache<PathCacheEntry, PathTexture*> mCache;
+
+    uint32_t mSize;
+    uint32_t mMaxSize;
+}; // class PathCache
+
+}; // namespace uirenderer
+}; // namespace android
+
+#endif // ANDROID_UI_PATH_CACHE_H