Image filters: implement offsets in GPU path.

include/effects/SkDisplacementMapEffect.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkDisplacementMapEffect_DEFINED
 #define SkDisplacementMapEffect_DEFINED
 
 #include "SkImageFilter.h"
 #include "SkBitmap.h"
 
 class SK_API SkDisplacementMapEffect : public SkImageFilter {
 public:
     enum ChannelSelectorType {
         kUnknown_ChannelSelectorType,
         kR_ChannelSelectorType,
         kG_ChannelSelectorType,
         kB_ChannelSelectorType,
         kA_ChannelSelectorType,
         kKeyBits = 3 // Max value is 4, so 3 bits are required at most
     };
 
-    SkDisplacementMapEffect(ChannelSelectorType xChannelSelector, ChannelSelectorType yChannelSelector, SkScalar scale, SkImageFilter* displacement, SkImageFilter* color = NULL);
+    SkDisplacementMapEffect(ChannelSelectorType xChannelSelector,
+                            ChannelSelectorType yChannelSelector,
+                            SkScalar scale, SkImageFilter* displacement,
+                            SkImageFilter* color = NULL);
 
     ~SkDisplacementMapEffect();
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkDisplacementMapEffect)
 
     virtual bool onFilterImage(Proxy* proxy,
                                const SkBitmap& src,
                                const SkMatrix& ctm,
                                SkBitmap* dst,
                                SkIPoint* offset) SK_OVERRIDE;
 #if SK_SUPPORT_GPU
     virtual bool canFilterImageGPU() const SK_OVERRIDE { return true; }
-    virtual bool filterImageGPU(Proxy* proxy, const SkBitmap& src, SkBitmap* result) SK_OVERRIDE;
+    virtual bool filterImageGPU(Proxy* proxy, const SkBitmap& src, SkBitmap* result,
+                                SkIPoint* offset) SK_OVERRIDE;
 #endif
 
 protected:
     explicit SkDisplacementMapEffect(SkFlattenableReadBuffer& buffer);
     virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
 
 private:
     ChannelSelectorType fXChannelSelector;
     ChannelSelectorType fYChannelSelector;
     SkScalar fScale;
     typedef SkImageFilter INHERITED;
     SkImageFilter* getDisplacementInput() { return getInput(0); }
     SkImageFilter* getColorInput() { return getInput(1); }
 };
 
 #endif