Change GR_COMPRESS_ALPHA_MASK from compile-time flag to run-time. We do this by introducing an Options struct to be passed to a GrContext on creation.

R=robertphillips@google.com, bsalomon@google.com

Author: krajcevski@google.com

Review URL: https://codereview.chromium.org/459033002

gyp/gpu.gyp

@@ -74,9 +74,6 @@
         '../include/gpu',
       ],
     },
-    'defines': [
-      'GR_COMPRESS_ALPHA_MASK=0',
-    ],
   },
   'targets': [
     {

include/gpu/GrContext.h

@@ -49,10 +49,19 @@ class SK_API GrContext : public SkRefCnt {
 public:
     SK_DECLARE_INST_COUNT(GrContext)
 
+    struct Options {
+        Options() : fDrawPathToCompressedTexture(false) { }
+
+        // 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 +948,12 @@ public:
                     GrPathRendererChain::DrawType drawType = GrPathRendererChain::kColor_DrawType,
                     GrPathRendererChain::StencilSupport* stencilSupport = NULL);
 
+    /**
+     *  This returns a copy of the the GrContext::Options that was passed to the
+     *  constructor of this class.
+     */
+    const Options& getOptions() const { return fOptions; }
+
 #if GR_CACHE_STATS
     void printCacheStats() const;
 #endif
@@ -987,7 +1002,9 @@ private:
 
     int                             fMaxTextureSizeOverride;
 
-    GrContext(); // init must be called after the constructor.
+    const Options                   fOptions;
+
+    GrContext(const Options&); // init must be called after the constructor.
     bool init(GrBackend, GrBackendContext);
 
     void setupDrawBuffer();

src/gpu/GrContext.cpp

@@ -84,8 +84,15 @@ private:
     GrContext* fContext;
 };
 
-GrContext* GrContext::Create(GrBackend backend, GrBackendContext backendContext) {
-    GrContext* context = SkNEW(GrContext);
+GrContext* GrContext::Create(GrBackend backend, GrBackendContext backendContext,
+                             const Options* opts) {
+    GrContext* context;
+    if (NULL == opts) {
+        context = SkNEW_ARGS(GrContext, (Options()));
+    } else {
+        context = SkNEW_ARGS(GrContext, (*opts));
+    }
+
     if (context->init(backend, backendContext)) {
         return context;
     } else {
@@ -94,7 +101,7 @@ GrContext* GrContext::Create(GrBackend backend, GrBackendContext backendContext)
     }
 }
 
-GrContext::GrContext() {
+GrContext::GrContext(const Options& opts) : fOptions(opts) {
     fDrawState = NULL;
     fGpu = NULL;
     fClip = NULL;

src/gpu/GrSWMaskHelper.cpp

@@ -66,7 +66,6 @@ static inline GrPixelConfig fmt_to_config(SkTextureCompressor::Format fmt) {
     return config;
 }
 
-#if GR_COMPRESS_ALPHA_MASK
 static bool choose_compressed_fmt(const GrDrawTargetCaps* caps,
                                   SkTextureCompressor::Format *fmt) {
     if (NULL == fmt) {
@@ -95,7 +94,6 @@ static bool choose_compressed_fmt(const GrDrawTargetCaps* caps,
 
     return false;
 }
-#endif
 
 }
 
@@ -171,11 +169,10 @@ bool GrSWMaskHelper::init(const SkIRect& resultBounds,
     SkIRect bounds = SkIRect::MakeWH(resultBounds.width(),
                                      resultBounds.height());
 
-#if GR_COMPRESS_ALPHA_MASK
-    if (choose_compressed_fmt(fContext->getGpu()->caps(), &fCompressedFormat)) {
+    if (fContext->getOptions().fDrawPathToCompressedTexture &&
+        choose_compressed_fmt(fContext->getGpu()->caps(), &fCompressedFormat)) {
         fCompressionMode = kCompress_CompressionMode;
     }
-#endif
 
     // Make sure that the width is a multiple of the desired block dimensions
     // to allow for specialized SIMD instructions that compress multiple blocks at a time.