Change GR_COMPRESS_ALPHA_MASK from compile-time flag to run-time flag

include/gpu/GrContext.h

Index: include/gpu/GrContext.h
diff --git a/include/gpu/GrContext.h b/include/gpu/GrContext.h
index 39f5be728f85b171920d841b842f69791905fa77..07434425f972486620fa03bb06a51fdfb15e8dde 100644
--- a/include/gpu/GrContext.h
+++ b/include/gpu/GrContext.h
@@ -49,10 +49,19 @@ class SK_API GrContext : public SkRefCnt {
 public:
     SK_DECLARE_INST_COUNT(GrContext)
 
+    struct Options {
+        Options();
+
+        // EXPERIMENTAL
+        // May be removed in the future, or may become standard depending
+        // on the outcomes of a variety of internal tests.
+        bool fDrawPathToCompressedTexture;
+    };
+
     /**
      * Creates a GrContext for a backend context.
      */
-    static GrContext* Create(GrBackend, GrBackendContext);
+    static GrContext* Create(GrBackend, GrBackendContext, const Options* opts = NULL);
 
     virtual ~GrContext();
 
@@ -939,6 +948,14 @@ public:
                     GrPathRendererChain::DrawType drawType = GrPathRendererChain::kColor_DrawType,
                     GrPathRendererChain::StencilSupport* stencilSupport = NULL);
 
+    /**
+     *  This returns true if the underlying graphics device and system is
+     *  capable of drawing paths to compressed textures. This generally provides
+     *  a speedup on mobile devices with advanced GPUs, but it only gets turned
+     *  on when there is a clear speedup benefit.
+     */

[robertphillips, 2014/08/11 19:22:20]

drawPathsToCompressedTextures ?
compressCoverageMasks ?

[krajcevski, 2014/08/11 20:01:33]

Done.

+    bool supportsDrawPathToCompressedTexture() const;
+
 #if GR_CACHE_STATS
     void printCacheStats() const;
 #endif
@@ -986,9 +1003,10 @@ private:
     SkTDArray<CleanUpData>          fCleanUpData;
 
     int                             fMaxTextureSizeOverride;

[robertphillips, 2014/08/11 19:22:20]

Options fOptions; ?

[krajcevski, 2014/08/11 20:01:33]

Done.

+    bool                            fSupportsDrawPathToCompressed;
 
     GrContext(); // init must be called after the constructor.
-    bool init(GrBackend, GrBackendContext);
+    bool init(GrBackend, GrBackendContext, const Options& opts);
 
     void setupDrawBuffer();