Adding an option to render only the shadow in SkDropShadowImageFilter

gm/imagefiltersscaled.cpp

 /*
  * 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 "gm.h"
 #include "SkColor.h"
 #include "SkBitmapSource.h"
@@ skipping 92 matching lines @@
         SkScalar cutoffAngle = SkIntToScalar(15);
         SkScalar kd = SkIntToScalar(2);
         SkScalar surfaceScale = SkIntToScalar(1);
         SkColor white(0xFFFFFFFF);
         SkMatrix resizeMatrix;
         resizeMatrix.setScale(RESIZE_FACTOR, RESIZE_FACTOR);
 
         SkImageFilter* filters[] = {
             SkBlurImageFilter::Create(SkIntToScalar(4), SkIntToScalar(4)),
             SkDropShadowImageFilter::Create(SkIntToScalar(5), SkIntToScalar(10),
-                                            SkIntToScalar(3), SkIntToScalar(3),
-                                            SK_ColorYELLOW),
+                SkIntToScalar(3), SkIntToScalar(3), SK_ColorYELLOW,
+                SkDropShadowImageFilter::kDrawShadowAndForeground_ShadowMode),
             SkDisplacementMapEffect::Create(SkDisplacementMapEffect::kR_ChannelSelectorType,
                                             SkDisplacementMapEffect::kR_ChannelSelectorType,
                                             SkIntToScalar(12),
                                             gradient.get(),
                                             checkerboard.get()),
             SkDilateImageFilter::Create(1, 1, checkerboard.get()),
             SkErodeImageFilter::Create(1, 1, checkerboard.get()),
             SkOffsetImageFilter::Create(SkIntToScalar(32), 0),
             SkMatrixImageFilter::Create(resizeMatrix, SkPaint::kNone_FilterLevel),
             SkRectShaderImageFilter::Create(noise),
@@ skipping 50 matching lines @@
     SkBitmap fGradientCircle;
     typedef GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new ImageFiltersScaledGM; }
 static GMRegistry reg(MyFactory);
 
 }