Make SkImageFilter methods const.

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 "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
@@ skipping 177 matching lines @@
     this->INHERITED::flatten(buffer);
     buffer.writeInt((int) fXChannelSelector);
     buffer.writeInt((int) fYChannelSelector);
     buffer.writeScalar(fScale);
 }
 
 bool SkDisplacementMapEffect::onFilterImage(Proxy* proxy,
                                             const SkBitmap& src,
                                             const SkMatrix& ctm,
                                             SkBitmap* dst,
-                                            SkIPoint* offset) {
+                                            SkIPoint* offset) const {
     SkBitmap displ = src, color = src;
-    SkImageFilter* colorInput = getColorInput();
-    SkImageFilter* displInput = getDisplacementInput();
+    const SkImageFilter* colorInput = getColorInput();
+    const SkImageFilter* displInput = getDisplacementInput();
     SkIPoint colorOffset = SkIPoint::Make(0, 0), displOffset = SkIPoint::Make(0, 0);
     if ((colorInput && !colorInput->filterImage(proxy, src, ctm, &color, &colorOffset)) ||
         (displInput && !displInput->filterImage(proxy, src, ctm, &displ, &displOffset))) {
         return false;
     }
     if ((displ.config() != SkBitmap::kARGB_8888_Config) ||
         (color.config() != SkBitmap::kARGB_8888_Config)) {
         return false;
     }
 
@@ skipping 129 matching lines @@
     GrCoordTransform            fColorTransform;
     GrTextureAccess             fColorAccess;
     SkDisplacementMapEffect::ChannelSelectorType fXChannelSelector;
     SkDisplacementMapEffect::ChannelSelectorType fYChannelSelector;
     SkVector fScale;
 
     typedef GrEffect INHERITED;
 };
 
 bool SkDisplacementMapEffect::filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                             SkBitmap* result, SkIPoint* offset) {
+                                             SkBitmap* result, SkIPoint* offset) const {
     SkBitmap colorBM;
     SkIPoint colorOffset = SkIPoint::Make(0, 0);
     if (!SkImageFilterUtils::GetInputResultGPU(getColorInput(), proxy, src, ctm, &colorBM,
                                                &colorOffset)) {
         return false;
     }
     GrTexture* color = colorBM.getTexture();
     SkBitmap displacementBM;
     SkIPoint displacementOffset = SkIPoint::Make(0, 0);
     if (!SkImageFilterUtils::GetInputResultGPU(getDisplacementInput(), proxy, src, ctm,
@@ skipping 237 matching lines @@
                                                         const GrGLCaps&) {
     const GrDisplacementMapEffect& displacementMap =
         drawEffect.castEffect<GrDisplacementMapEffect>();
 
     EffectKey xKey = displacementMap.xChannelSelector();
     EffectKey yKey = displacementMap.yChannelSelector() << SkDisplacementMapEffect::kKeyBits;
 
     return xKey | yKey;
 }
 #endif