emitChild() takes an outputColor instead of generating one

src/core/SkComposeShader.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkComposeShader.h"
@@ skipping 265 matching lines @@
 
     // Store alpha of input color and un-premultiply the input color by its alpha. We will
     // re-multiply by this alpha after blending the output colors of the two child procs.
     // This is because we don't want the paint's alpha to affect either child proc's output
     // before the blend; we want to apply the paint's alpha AFTER the blend. This mirrors the
     // software implementation of SkComposeShader.
     SkString inputAlpha("inputAlpha");
     fsBuilder->codeAppendf("float %s = %s.a;", inputAlpha.c_str(), args.fInputColor);
     fsBuilder->codeAppendf("%s /= %s.a;", args.fInputColor, args.fInputColor);
 
-    // emit the code of the two child shaders
-    SkString mangledOutputColorA;
-    this->emitChild(0, args.fInputColor, &mangledOutputColorA, args);
-    SkString mangledOutputColorB;
-    this->emitChild(1, args.fInputColor, &mangledOutputColorB, args);
+    // declare outputColor and emit the code for each of the two children
+    SkString outputColorA(args.fOutputColor);
+    outputColorA.append("_dst");
+    fsBuilder->codeAppendf("vec4 %s;\n", outputColorA.c_str());
+    this->emitChild(0, args.fInputColor, outputColorA.c_str(), args);
+
+    SkString outputColorB(args.fOutputColor);
+    outputColorB.append("_src");
+    fsBuilder->codeAppendf("vec4 %s;\n", outputColorB.c_str());
+    this->emitChild(1, args.fInputColor, outputColorB.c_str(), args);
 
     // emit blend code
     SkXfermode::Mode mode = cs.getMode();
     fsBuilder->codeAppend("{");
     fsBuilder->codeAppendf("// Compose Xfer Mode: %s\n", SkXfermode::ModeName(mode));
-    GrGLBlend::AppendPorterDuffBlend(fsBuilder, mangledOutputColorB.c_str(),
-                                     mangledOutputColorA.c_str(), args.fOutputColor, mode);
+    GrGLBlend::AppendPorterDuffBlend(fsBuilder, outputColorB.c_str(),
+                                     outputColorA.c_str(), args.fOutputColor, mode);
     fsBuilder->codeAppend("}");
 
     // re-multiply the output color by the input color's alpha
     fsBuilder->codeAppendf("%s *= %s;", args.fOutputColor, inputAlpha.c_str());
 }
 
 /////////////////////////////////////////////////////////////////////
 
 const GrFragmentProcessor* SkComposeShader::asFragmentProcessor(GrContext* context,
                                                             const SkMatrix& viewM,
@@ skipping 47 matching lines @@
     if (fMode) {
         str->append(" Xfermode: ");
         fMode->toString(str);
     }
 
     this->INHERITED::toString(str);
 
     str->append(")");
 }
 #endif