Fix shadow blurs of RGBA bitmaps

src/core/SkMaskFilter.cpp

Index: src/core/SkMaskFilter.cpp
===================================================================
--- src/core/SkMaskFilter.cpp	(revision 3647)
+++ src/core/SkMaskFilter.cpp	(working copy)
@@ -8,6 +8,7 @@
 
 
 #include "SkMaskFilter.h"
+#include "SkBitmapProcShader.h"
 #include "SkBlitter.h"
 #include "SkBounder.h"
 #include "SkBuffer.h"
@@ -19,14 +20,15 @@
     return false;
 }
 
-bool SkMaskFilter::filterPath(const SkPath& devPath, const SkMatrix& matrix,
-                              const SkRasterClip& clip, SkBounder* bounder,
-                              SkBlitter* blitter, SkPaint::Style style) {
+bool SkMaskFilter::filterPath(const SkPath& devPath, const SkBitmap& devBitmap,
+                              const SkMatrix& matrix, const SkRasterClip& clip,
+                              SkBounder* bounder, const SkPaint& origPaint,
+                              SkPaint::Style style) {
     SkMask  srcM, dstM;
 
     if (!SkDraw::DrawToMask(devPath, &clip.getBounds(), this, &matrix, &srcM,
                             SkMask::kComputeBoundsAndRenderImage_CreateMode,
-                            style)) {
+                            style, origPaint.getShader())) {
         return false;
     }
     SkAutoMaskFreeImage autoSrc(srcM.fImage);
@@ -36,12 +38,17 @@
     }
     SkAutoMaskFreeImage autoDst(dstM.fImage);
 
+    SkPaint paint(origPaint);
+    paint.setShader(NULL);
+    SkBlitter* origBlitter = SkBlitter::Choose(devBitmap, matrix, paint);
+
     // if we get here, we need to (possibly) resolve the clip and blitter
-    SkAAClipBlitterWrapper wrapper(clip, blitter);
-    blitter = wrapper.getBlitter();
+    SkAAClipBlitterWrapper wrapper(clip, origBlitter);
+    SkBlitter* blitter = wrapper.getBlitter();
 
     SkRegion::Cliperator clipper(wrapper.getRgn(), dstM.fBounds);
 
+
     if (!clipper.done() && (bounder == NULL || bounder->doIRect(dstM.fBounds))) {
         const SkIRect& cr = clipper.rect();
         do {
@@ -49,6 +56,7 @@
             clipper.next();
         } while (!clipper.done());
     }
+    SkDELETE(origBlitter);
 
     return true;
 }