Added GrGLBlend.h|cpp with helper function AppendPorterDuffBlend() in preparation for SkComposeShad…

src/gpu/gl/GrGLBlend.h

Index: src/gpu/gl/GrGLBlend.h
diff --git a/src/gpu/gl/GrGLBlend.h b/src/gpu/gl/GrGLBlend.h
new file mode 100644
index 0000000000000000000000000000000000000000..9c1d80b82045123e55d34f4eb37ee9d49f57a38f
--- /dev/null
+++ b/src/gpu/gl/GrGLBlend.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrGLBlend_DEFINED
+#define GrGLBlend_DEFINED
+
+#include "SkXfermode.h"
+
+class GrGLFragmentBuilder;
+
+namespace GrGLBlend {
+    void AppendPorterDuffBlend(GrGLFragmentBuilder* fsBuilder, const char* srcColor,

[egdaniel, 2015/07/24 18:14:30]

Add a comment on this function to describe what it does.

[wangyix, 2015/07/24 20:18:15]

Done.

+                               const char* dstColor, const char* outColor, SkXfermode::Mode mode);
+};
+
+#endif