Make SkImageFilter crop rects relative to the primitive origin, instead of relative to their parent

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
@@ skipping 17 matching lines @@
 
 bool SkImageFilterUtils::GetInputResultGPU(SkImageFilter* filter, SkImageFilter::Proxy* proxy,
                                            const SkBitmap& src, const SkMatrix& ctm,
                                            SkBitmap* result, SkIPoint* offset) {
     // Ensure that GrContext calls under filterImage and filterImageGPU below will see an identity
     // matrix with no clip and that the matrix, clip, and render target set before this function was
     // called are restored before we return to the caller.
     GrContext* context = src.getTexture()->getContext();
     GrContext::AutoWideOpenIdentityDraw awoid(context, NULL);
     if (!filter) {
+        offset->fX = offset->fY = 0;
         *result = src;
         return true;
     } else if (filter->canFilterImageGPU()) {
         return filter->filterImageGPU(proxy, src, ctm, result, offset);
     } else {
         if (filter->filterImage(proxy, src, ctm, result, offset)) {
             if (!result->getTexture()) {
                 SkImageInfo info;
                 if (!result->asImageInfo(&info)) {
                     return false;
                 }
                 GrTexture* resultTex = GrLockAndRefCachedBitmapTexture(context, *result, NULL);
                 result->setPixelRef(new SkGrPixelRef(info, resultTex))->unref();
                 GrUnlockAndUnrefCachedBitmapTexture(resultTex);
             }
             return true;
         } else {
             return false;
         }
     }
 }
 #endif