Disable blending when there is an effect that reads the dst and draw state blend is 1,0.

R=robertphillips@google.com

Review URL: https://codereview.chromium.org/15199008

git-svn-id: http://skia.googlecode.com/svn/trunk@9147 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 7 insertions, 0 deletions

diff --git a/src/gpu/GrDrawState.cpp b/src/gpu/GrDrawState.cpp
index 591e157129..a3850b087e 100644
--- a/src/gpu/GrDrawState.cpp
+++ b/src/gpu/GrDrawState.cpp
@@ -371,6 +371,13 @@ GrDrawState::BlendOptFlags GrDrawState::getBlendOpts(bool forceCoverage,
             return  kCoverageAsAlpha_BlendOptFlag;
         }
     }
+    if (kOne_GrBlendCoeff == *srcCoeff &&
+        kZero_GrBlendCoeff == *dstCoeff &&
+        this->willEffectReadDstColor()) {
+        // In this case the shader will fully resolve the color, coverage, and dst and we don't
+        // need blending.
+        return kDisableBlend_BlendOptFlag;
+    }
     return kNone_BlendOpt;
 }