Implement support for mixed sampled render targets

src/gpu/effects/GrPorterDuffXferProcessor.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "effects/GrPorterDuffXferProcessor.h"
 
 #include "GrBlend.h"
@@ skipping 384 matching lines @@
         } else {
             fDstBlend = kOne_GrBlendCoeff;
             return GrXferProcessor::kSkipDraw_OptFlag;
         }
     }
 
     // if we don't have coverage we can check whether the dst
     // has to read at all. If not, we'll disable blending.
     if (!hasCoverage) {
         if (dstCoeffIsZero) {
-            if (kOne_GrBlendCoeff == fSrcBlend) {
+            if (kOne_GrBlendCoeff == fSrcBlend &&
+                !colorPOI.needsCoverageModulation()) {
                 // if there is no coverage and coeffs are (1,0) then we
                 // won't need to read the dst at all, it gets replaced by src
                 fDstBlend = kZero_GrBlendCoeff;
                 return GrXferProcessor::kNone_Opt;
             } else if (kZero_GrBlendCoeff == fSrcBlend) {
                 // if the op is "clear" then we don't need to emit a color
                 // or blend, just write transparent black into the dst.
                 fSrcBlend = kOne_GrBlendCoeff;
                 fDstBlend = kZero_GrBlendCoeff;
                 return GrXferProcessor::kIgnoreColor_OptFlag |
@@ skipping 284 matching lines @@
 GR_DEFINE_XP_FACTORY_TEST(GrPorterDuffXPFactory);
 
 GrXPFactory* GrPorterDuffXPFactory::TestCreate(SkRandom* random,
                                                GrContext*,
                                                const GrDrawTargetCaps&,
                                                GrTexture*[]) {
     SkXfermode::Mode mode = SkXfermode::Mode(random->nextULessThan(SkXfermode::kLastCoeffMode));
     return GrPorterDuffXPFactory::Create(mode);
 }