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

include/core/SkMask.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 SkMask_DEFINED
@@ skipping 118 matching lines @@
     static uint8_t* AllocImage(size_t bytes);
     static void FreeImage(void* image);
 
     enum CreateMode {
         kJustComputeBounds_CreateMode,      //!< compute bounds and return
         kJustRenderImage_CreateMode,        //!< render into preallocate mask
         kComputeBoundsAndRenderImage_CreateMode  //!< compute bounds, alloc image and render into it
     };
 };
 
+struct SkDiscardableMemoryMask {

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

Naming nit: instead of baking "discardable memory" into the name, maybe this
could be something a bit more generic, like SkCachedMask?

+    SkMask fMask;
+    uint32_t fPixelGenerationID;
+    void*    fCacheId;
+};
+
 ///////////////////////////////////////////////////////////////////////////////
 
 /**
  *  \class SkAutoMaskImage
  *
  *  Stack class used to manage the fImage buffer in a SkMask.
  *  When this object loses scope, the buffer is freed with SkMask::FreeImage().
  */
 class SkAutoMaskFreeImage {
 public:
     SkAutoMaskFreeImage(uint8_t* maskImage) {
         fImage = maskImage;
     }
 
     ~SkAutoMaskFreeImage() {
         SkMask::FreeImage(fImage);
     }
 
 private:
     uint8_t* fImage;
 };
 #define SkAutoMaskFreeImage(...) SK_REQUIRE_LOCAL_VAR(SkAutoMaskFreeImage)
 
 #endif