Optimize CSS box-shadow performance by caching the SkMask of the blur effect.

src/effects/SkBlurMask.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkBlurMask_DEFINED
 #define SkBlurMask_DEFINED
+#include <map>
 
 #include "SkBlurTypes.h"
 #include "SkShader.h"
 #include "SkMask.h"
 #include "SkRRect.h"
 
 class SkBlurMask {
 public:
     static bool BlurRect(SkScalar sigma, SkMask *dst, const SkRect &src, SkBlurStyle,
                          SkIPoint *margin = NULL,
@@ skipping 48 matching lines @@
         will produce both the horizontal and vertical profiles of the blurry rectangle.
         @param pixels Location to store the resulting pixel data; allocated and managed by caller
         @param profile Precomputed blur profile computed by ComputeBlurProfile above.
         @param width Size of the pixels array.
         @param sigma Standard deviation of the gaussian blur kernel used to compute the profile;
                      this implicitly gives the size of the pixels array.
     */
 
     static void ComputeBlurredScanline(uint8_t* pixels, const uint8_t* profile,
                                        unsigned int width, SkScalar sigma);
+    static bool addDiscardableMemoryMaskToMap(SkMask*, SkDiscardableMemoryMask*);
+    static bool removeDiscardableMemoryMaskFromMap(SkMask*);
+    static SkDiscardableMemoryMask* getDiscardableMemoryMaskFromMap(SkMask*);

[Stephen White, 2014/06/09 18:03:57]

Naming nit: similarly, could this be getCachedMask()? No need to expose that
it's a map or that it's backed by discardable memory, AFAICT.

 
-
+private:
+    static std::map<SkMask*, SkDiscardableMemoryMask*> fDiscardableMemoryMaskMap;
 
 };
 
 #endif