Move willColorBlendWithDst from pipeline builder to GrPipelineOptimizations.

src/gpu/GrPrimitiveProcessor.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrPrimitiveProcessor_DEFINED
 #define GrPrimitiveProcessor_DEFINED
 
@@ skipping 95 matching lines @@
         if (SkToBool(kUseOverrideColor_Flag & fFlags)) {
             SkASSERT(SkToBool(kReadsColor_Flag & fFlags));
             if (overrideColor) {
                 *overrideColor = fOverrideColor;
             }
             return true;
         }
         return false;
     }
 
+    /**
+     * Returns true if the pipeline's color output will be affected by the existing render target
+     * destination pixel values (meaning we need to be careful with overlapping draws). Note that we
+     * can conflate coverage and color, so the destination color may still bleed into pixels that
+     * have partial coverage, even if this function returns false.
+     *
+     * The above comment seems incorrect for the use case. This funciton is used to turn two
+     * overlapping draws into a single draw (really to stencil multiple paths and do a single
+     * cover). It seems that what really matters is whether the dst is read for color OR for
+     * coverage.
+     */
+    bool willColorBlendWithDst() const { return SkToBool(kWillColorBlendWithDst_Flag & fFlags); }
+
 private:
     enum {
         // If this is not set the primitive processor need not produce a color output
         kReadsColor_Flag                = 0x1,
 
         // If this is not set the primitive processor need not produce a coverage output
         kReadsCoverage_Flag             = 0x2,
 
         // If this is not set the primitive processor need not produce local coordinates
         kReadsLocalCoords_Flag          = 0x4,
 
         // If this flag is set then the primitive processor may produce color*coverage as
         // its color output (and not output a separate coverage).
         kCanTweakAlphaForCoverage_Flag  = 0x8,
 
         // If this flag is set the GrPrimitiveProcessor must produce fOverrideColor as its
         // output color. If not set fOverrideColor is to be ignored.
         kUseOverrideColor_Flag          = 0x10,
+
+        kWillColorBlendWithDst_Flag     = 0x20,
     };
 
     uint32_t    fFlags;
     GrColor     fOverrideColor;
 
     friend class GrPipeline; // To initialize this
 };
 
 /*
  * This enum is shared by GrPrimitiveProcessors and GrGLPrimitiveProcessors to coordinate shaders
@@ skipping 100 matching lines @@
 
 private:
     virtual bool hasExplicitLocalCoords() const = 0;
 
     bool fIsPathRendering;
 
     typedef GrProcessor INHERITED;
 };
 
 #endif