Remove unpremul/remul from SkArithmeticMode, both raster and GPU, since the SVG spec actually defin…

include/effects/SkArithmeticMode.h

Index: include/effects/SkArithmeticMode.h
diff --git a/include/effects/SkArithmeticMode.h b/include/effects/SkArithmeticMode.h
index 9de332caef4016e414165549ae07b8eca8de6289..150503471ef9e0fdb36676653854c21d7701a095 100644
--- a/include/effects/SkArithmeticMode.h
+++ b/include/effects/SkArithmeticMode.h
@@ -21,9 +21,12 @@ public:
      *  k1=k2=k3=0, k4=1.0 results in returning opaque white
      *  k1=k3=k4=0, k2=1.0 results in returning the src
      *  k1=k2=k4=0, k3=1.0 results in returning the dst
+     *
+     *  unpremultiply causes the rgb values to be unpremultiplied by their
+     *  alpha before compositing, and remultiplied after.
      */
     static SkXfermode* Create(SkScalar k1, SkScalar k2,
-                              SkScalar k3, SkScalar k4);
+                              SkScalar k3, SkScalar k4, bool unpremultiply);

[reed1, 2013/06/11 21:45:40]

If we want a runtime param (which is fine with me), lets use an enum, so the
callsite can be more readable.

e.g.

enum Mode {
    kPremul_Mode,
    kUnpremul_Mode,
};

Or some other (better) name.

 
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP();