Image filters: implement offsets in GPU path.

src/core/SkImageFilterUtils.cpp

 /*
  * Copyright 2013 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMatrix.h"
 
 #if SK_SUPPORT_GPU
 #include "GrTexture.h"
 #include "SkImageFilterUtils.h"
 #include "SkBitmap.h"
 #include "SkGrPixelRef.h"
 #include "SkGr.h"
 
 bool SkImageFilterUtils::WrapTexture(GrTexture* texture, int width, int height, SkBitmap* result) {
     result->setConfig(SkBitmap::kARGB_8888_Config, width, height);
     result->setPixelRef(SkNEW_ARGS(SkGrPixelRef, (texture)))->unref();
     return true;
 }
 
-bool SkImageFilterUtils::GetInputResultGPU(SkImageFilter* filter, SkImageFilter::Proxy* proxy, const SkBitmap& src, SkBitmap* result) {
+bool SkImageFilterUtils::GetInputResultGPU(SkImageFilter* filter, SkImageFilter::Proxy* proxy,
+                                           const SkBitmap& src, SkBitmap* result,
+                                           SkIPoint* offset) {
     if (!filter) {
         *result = src;
         return true;
     } else if (filter->canFilterImageGPU()) {
-        return filter->filterImageGPU(proxy, src, result);
+        return filter->filterImageGPU(proxy, src, result, offset);
     } else {
-        SkIPoint offset;
-        if (filter->filterImage(proxy, src, SkMatrix(), result, &offset)) {
+        if (filter->filterImage(proxy, src, SkMatrix(), result, offset)) {
             if (!result->getTexture()) {
                 GrContext* context = ((GrTexture *) src.getTexture())->getContext();
                 GrTexture* resultTex = GrLockAndRefCachedBitmapTexture(context,
                     *result, NULL);
                 result->setPixelRef(new SkGrPixelRef(resultTex))->unref();
                 GrUnlockAndUnrefCachedBitmapTexture(resultTex);
             }
             return true;
         } else {
             return false;
         }
     }
 }
 #endif