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

src/effects/SkDisplacementMapEffect.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkDisplacementMapEffect.h"
 #include "SkFlattenableBuffers.h"
 #include "SkUnPreMultiply.h"
@@ skipping 203 matching lines @@
     }
 
     dst->setConfig(color.config(), bounds.width(), bounds.height());
     dst->allocPixels();
     if (!dst->getPixels()) {
         return false;
     }
 
     computeDisplacement(fXChannelSelector, fYChannelSelector, fScale, dst, &displ, &color, bounds);
 
-    offset->fX += bounds.left();
-    offset->fY += bounds.top();
+    offset->fX = bounds.left();
+    offset->fY = bounds.top();
     return true;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 #if SK_SUPPORT_GPU
 class GrGLDisplacementMapEffect : public GrGLEffect {
 public:
     GrGLDisplacementMapEffect(const GrBackendEffectFactory& factory,
                               const GrDrawEffect& drawEffect);
@@ skipping 113 matching lines @@
     displacementBM.getBounds(&displBounds);
     if (!this->applyCropRect(&displBounds, ctm)) {
         return false;
     }
     if (!bounds.intersect(displBounds)) {
         return false;
     }
     SkRect srcRect = SkRect::Make(bounds);
     SkRect dstRect = SkRect::MakeWH(srcRect.width(), srcRect.height());
     context->drawRectToRect(paint, dstRect, srcRect);
-    offset->fX += bounds.left();
-    offset->fY += bounds.top();
+    offset->fX = bounds.left();
+    offset->fY = bounds.top();
     return SkImageFilterUtils::WrapTexture(dst, bounds.width(), bounds.height(), result);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 GrDisplacementMapEffect::GrDisplacementMapEffect(
                              SkDisplacementMapEffect::ChannelSelectorType xChannelSelector,
                              SkDisplacementMapEffect::ChannelSelectorType yChannelSelector,
                              SkScalar scale,
                              GrTexture* displacement,
@@ skipping 168 matching lines @@
                                                         const GrGLCaps&) {
     const GrDisplacementMapEffect& displacementMap =
         drawEffect.castEffect<GrDisplacementMapEffect>();
 
     EffectKey xKey = displacementMap.xChannelSelector();
     EffectKey yKey = displacementMap.yChannelSelector() << SkDisplacementMapEffect::kKeyBits;
 
     return xKey | yKey;
 }
 #endif