1 files changed, 198 insertions, 0 deletions
diff --git a/libs/hwui/pipeline/skia/VectorDrawableAtlas.h b/libs/hwui/pipeline/skia/VectorDrawableAtlas.h
new file mode 100644
index 000000000000..496c55742748
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+++ b/libs/hwui/pipeline/skia/VectorDrawableAtlas.h
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+/*
+ * Copyright (C) 2017 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.
+ */
+
+#pragma once
+
+#include <map>
+#include <SkSurface.h>
+#include <utils/FatVector.h>
+#include <utils/RefBase.h>
+#include <list>
+
+class GrRectanizer;
+
+namespace android {
+namespace uirenderer {
+namespace skiapipeline {
+
+typedef uintptr_t AtlasKey;
+
+#define INVALID_ATLAS_KEY 0
+
+struct AtlasEntry {
+    sk_sp<SkSurface> surface;
+    SkRect rect;
+    AtlasKey key = INVALID_ATLAS_KEY;
+};
+
+/**
+ * VectorDrawableAtlas provides offscreen buffers used to draw VD and AnimatedVD.
+ * VectorDrawableAtlas can allocate a standalone surface or provide a subrect from a shared surface.
+ * VectorDrawableAtlas is owned by the CacheManager and weak pointers are kept by each
+ * VectorDrawable that is using it. VectorDrawableAtlas and its surface can be deleted at any time,
+ * except during a renderFrame call. VectorDrawable does not contain a pointer to atlas SkSurface
+ * nor any coordinates into the atlas, but instead holds a rectangle "id", which is resolved only
+ * when drawing. This design makes VectorDrawableAtlas free to move the data internally.
+ * At draw time a VectorDrawable may find, that its atlas has been deleted, which will make it
+ * draw in a standalone cache surface not part of an atlas. In this case VD won't use
+ * VectorDrawableAtlas until the next frame.
+ * VectorDrawableAtlas tries to fit VDs in the atlas SkSurface. If there is not enough space in
+ * the atlas, VectorDrawableAtlas creates a standalone surface for each VD.
+ * When a VectorDrawable is deleted, it invokes VectorDrawableAtlas::releaseEntry, which is keeping
+ * track of free spaces and allow to reuse the surface for another VD.
+ */
+ //TODO: Check if not using atlas for AnimatedVD is more efficient.
+ //TODO: For low memory situations, when there are no paint effects in VD, we may render without an
+ //TODO: offscreen surface.
+class VectorDrawableAtlas : public virtual RefBase {
+public:
+    enum class StorageMode {
+        allowSharedSurface,
+        disallowSharedSurface
+    };
+
+    VectorDrawableAtlas(size_t surfaceArea,
+            StorageMode storageMode = StorageMode::allowSharedSurface);
+
+    /**
+     * "prepareForDraw" may allocate a new surface if needed. It may schedule to repack the
+     * atlas at a later time.
+     */
+    void prepareForDraw(GrContext* context);
+
+    /**
+     * Repack the atlas if needed, by moving used rectangles into a new atlas surface.
+     * The goal of repacking is to fix a fragmented atlas.
+     */
+    void repackIfNeeded(GrContext* context);
+
+    /**
+     * Returns true if atlas is fragmented and repack is needed.
+     */
+    bool isFragmented();
+
+    /**
+     * "requestNewEntry" is called by VectorDrawable to allocate a new rectangle area from the atlas
+     * or create a standalone surface if atlas is full.
+     * On success it returns a non-negative unique id, which can be used later with "getEntry" and
+     * "releaseEntry".
+     */
+    AtlasEntry requestNewEntry(int width, int height, GrContext* context);
+
+    /**
+     * "getEntry" extracts coordinates and surface of a previously created rectangle.
+     * "atlasKey" is an unique id created by "requestNewEntry". Passing a non-existing "atlasKey" is
+     * causing an undefined behaviour.
+     * On success it returns a rectangle Id -> may be same or different from "atlasKey" if
+     * implementation decides to move the record internally.
+     */
+    AtlasEntry getEntry(AtlasKey atlasKey);
+
+    /**
+     * "releaseEntry" is invoked when a VectorDrawable is deleted. Passing a non-existing "atlasKey"
+     * is causing an undefined behaviour.
+     */
+    void releaseEntry(AtlasKey atlasKey);
+
+    void setStorageMode(StorageMode mode);
+
+private:
+    struct CacheEntry {
+        CacheEntry(const SkRect& newVDrect, const SkRect& newRect,
+                const sk_sp<SkSurface>& newSurface)
+                : VDrect(newVDrect)
+                , rect(newRect)
+                , surface(newSurface) { }
+
+        /**
+         * size and position of VectorDrawable into the atlas or in "this.surface"
+         */
+        SkRect VDrect;
+
+        /**
+         * rect allocated in atlas surface or "this.surface". It may be bigger than "VDrect"
+         */
+        SkRect rect;
+
+        /**
+         * this surface is used if atlas is full or VD is too big
+         */
+        sk_sp<SkSurface> surface;
+
+        /**
+         * iterator is used to delete self with a constant complexity (without traversing the list)
+         */
+        std::list<CacheEntry>::iterator eraseIt;
+    };
+
+    /**
+     * atlas surface shared by all VDs
+     */
+    sk_sp<SkSurface> mSurface;
+
+    std::unique_ptr<GrRectanizer> mRectanizer;
+    const int mWidth;
+    const int mHeight;
+
+    /**
+     * "mRects" keeps records only for rectangles used by VDs. List has nice properties: constant
+     * complexity to insert and erase and references are not invalidated by insert/erase.
+     */
+    std::list<CacheEntry> mRects;
+
+    /**
+     * Rectangles freed by "releaseEntry" are removed from "mRects" and added to "mFreeRects".
+     * "mFreeRects" is using for an index the rectangle area. There could be more than one free
+     * rectangle with the same area, which is the reason to use "multimap" instead of "map".
+     */
+    std::multimap<size_t, SkRect> mFreeRects;
+
+    /**
+     * area in atlas used by VectorDrawables (area in standalone surface not counted)
+     */
+    int mPixelUsedByVDs = 0;
+
+    /**
+     * area allocated in mRectanizer
+     */
+    int mPixelAllocated = 0;
+
+    /**
+     * Consecutive times we had to allocate standalone surfaces, because atlas was full.
+     */
+    int mConsecutiveFailures = 0;
+
+    /**
+     * mStorageMode allows using a shared surface to store small vector drawables.
+     * Using a shared surface can boost the performance by allowing GL ops to be batched, but may
+     * consume more memory.
+     */
+    StorageMode mStorageMode;
+
+    sk_sp<SkSurface> createSurface(int width, int height, GrContext* context);
+
+    inline bool fitInAtlas(int width, int height) {
+        return 2*width < mWidth && 2*height < mHeight;
+    }
+
+    void repack(GrContext* context);
+
+    static bool compareCacheEntry(const CacheEntry& first, const CacheEntry& second);
+};
+
+} /* namespace skiapipeline */
+} /* namespace uirenderer */
+} /* namespace android */