Add XferProcessor factory in GrPaint and GrDrawState.

src/gpu/effects/GrPorterDuffXferProcessor.cpp

Index: src/gpu/effects/GrPorterDuffXferProcessor.cpp
diff --git a/src/gpu/effects/GrPorterDuffXferProcessor.cpp b/src/gpu/effects/GrPorterDuffXferProcessor.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..fdbcbbe656d266305cc08612a85dc0e2f22c6abd
--- /dev/null
+++ b/src/gpu/effects/GrPorterDuffXferProcessor.cpp
@@ -0,0 +1,76 @@
+/*
+ * 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 "GrPorterDuffXferProcessor.h"
+
+#include "GrBackendProcessorFactory.h"
+#include "GrDrawState.h"
+#include "GrInvariantOutput.h"
+#include "GrProcessor.h"
+#include "GrTBackendProcessorFactory.h"
+#include "GrTypes.h"
+#include "GrXferProcessor.h"
+#include "gl/GrGLProcessor.h"
+#include "gl/builders/GrGLFragmentShaderBuilder.h"
+#include "gl/builders/GrGLProgramBuilder.h"
+
+class GrGLPorterDuffXferProcessor : public GrGLXferProcessor {
+public:
+    GrGLPorterDuffXferProcessor(const GrBackendProcessorFactory& factory, const GrProcessor&)
+        : INHERITED(factory) {}
+
+    virtual ~GrGLPorterDuffXferProcessor() {}
+
+    virtual void emitCode(GrGLFPBuilder* builder,
+                          const GrFragmentProcessor& fp,
+                          const char* outputColor,
+                          const char* inputColor,
+                          const TransformedCoordsArray& coords,
+                          const TextureSamplerArray& samplers) SK_OVERRIDE {
+        GrGLFPFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
+        fsBuilder->codeAppendf("%s = %s;", outputColor, inputColor);
+    }
+
+    virtual void setData(const GrGLProgramDataManager&, const GrProcessor&) SK_OVERRIDE {};
+
+    static void GenKey(const GrProcessor&, const GrGLCaps& caps, GrProcessorKeyBuilder* b) {};
+
+private:
+    typedef GrGLXferProcessor INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+GrPorterDuffXferProcessor::GrPorterDuffXferProcessor(GrBlendCoeff srcBlend, GrBlendCoeff dstBlend)
+    : fSrcBlend(srcBlend), fDstBlend(dstBlend) {}
+
+GrPorterDuffXferProcessor::~GrPorterDuffXferProcessor() {
+}
+
+const GrBackendFragmentProcessorFactory& GrPorterDuffXferProcessor::getFactory() const {
+    return GrTBackendFragmentProcessorFactory<GrPorterDuffXferProcessor>::getInstance();
+}
+
+void GrPorterDuffXferProcessor::onComputeInvariantOutput(GrInvariantOutput* inout) const {
+    inout->setToUnknown(GrInvariantOutput::kWillNot_ReadInput);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+const GrXferProcessor* GrPorterDuffXPFactory::createXferProcessor() const {
+    return GrPorterDuffXferProcessor::Create(fSrc, fDst);
+}
+
+bool GrPorterDuffXPFactory::supportsRGBCoverage(GrColor /*knownColor*/,
+                                                uint32_t knownColorFlags) const {
+    if (kOne_GrBlendCoeff == fSrc && kISA_GrBlendCoeff == fDst &&
+        kRGBA_GrColorComponentFlags == knownColorFlags) {
+        return true;
+    }
+    return false;
+}
+