Add isUnblended query to GrDrawState.

src/gpu/GrDrawState.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrDrawState.h"
 
 #include "GrOptDrawState.h"
@@ skipping 724 matching lines @@
         }
 
         // Since the shader will multiply coverage and color, the only way the final A==1 is if
         // coverage and color both have A==1.
         return (inoutColor.isOpaque() && inoutCoverage.isOpaque());
     }
 
     return inoutColor.isOpaque();
 }
 
+bool GrDrawState::isUnblended() const {
+    if (!this->hasSolidCoverage()) {
+        return false;
+    }
+
+    bool srcAIsOne = this->srcAlphaWillBeOne();
+    GrBlendCoeff srcCoeff = this->getSrcBlendCoeff();
+    GrBlendCoeff dstCoeff = this->getDstBlendCoeff();
+    bool dstCoeffIsZero = kZero_GrBlendCoeff == dstCoeff ||

[bsalomon, 2014/11/11 20:49:56]

The fact that the blend opts code doesn't directly update the coeffs is weird.
Can we make this something like

if (kISA_GrBlendCoeff == dstCoeff && srcAIsOne) {
    dstCoeff == kZero_GrBlendCoeff;
}

[egdaniel, 2014/11/11 21:05:55]

Done.

+                          (kISA_GrBlendCoeff == dstCoeff && srcAIsOne);
+    if (kOne_GrBlendCoeff != srcCoeff || !dstCoeffIsZero || this->willEffectReadDstColor()) {
+        return false;
+    }
+
+    return true;
+}
+