Fast blurred rectangles on GPU

include/core/SkMaskFilter.h

Index: include/core/SkMaskFilter.h
diff --git a/include/core/SkMaskFilter.h b/include/core/SkMaskFilter.h
index f4448ddddb453e9502f075f928303a0c9fb428f0..4d2536297a275f8b03b0727226dde878e951e9b1 100644
--- a/include/core/SkMaskFilter.h
+++ b/include/core/SkMaskFilter.h
@@ -15,6 +15,7 @@
 #include "SkPaint.h"
 
 class GrContext;
+class GrPaint;
 class SkBitmap;
 class SkBlitter;
 class SkBounder;
@@ -89,6 +90,15 @@ public:
                                   SkRect* maskRect) const;
 
     /**
+     *  Try to directly render the mask filter into the target.  Returns
+     *  true if drawing was successful.
+     */
+    virtual bool directFilterMaskGPU(GrContext *context,

[bsalomon, 2013/12/21 02:50:09]

minor style nit: type* var 

Also, is there a reason to make the path mutable? I guess the current calling
code always has a mutable path but is that a contract we want to commit to? 

Also for future implementors of this virtual it might be nice to provide
SkStrokeRec rather than doFill. That way the stroking parameters are available
to do a stroke fast-path. (It also can communicate that the path is filled
rather than stroked).

[humper, 2013/12/23 13:26:58]

Done.

+                                     GrPaint *grp,
+                                     bool doFill,
+                                     SkPath* path) const;
+
+    /**
      *  Perform this mask filter on the GPU.  This is most often used for
      *  multi-pass effects, where intermediate results must be rendered to
      *  textures.  For single-pass effects, use asNewEffect().  'src' is the