Make SkImageFilter methods const.

src/effects/SkBicubicImageFilter.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 "SkBicubicImageFilter.h"
 #include "SkBitmap.h"
 #include "SkColorPriv.h"
@@ skipping 67 matching lines @@
     return SkPackARGB32(SkScalarRoundToInt(a),
                         SkScalarRoundToInt(SkScalarClampMax(r, a)),
                         SkScalarRoundToInt(SkScalarClampMax(g, a)),
                         SkScalarRoundToInt(SkScalarClampMax(b, a)));
 }
 
 bool SkBicubicImageFilter::onFilterImage(Proxy* proxy,
                                          const SkBitmap& source,
                                          const SkMatrix& matrix,
                                          SkBitmap* result,
-                                         SkIPoint* offset) {
+                                         SkIPoint* offset) const {
     SkBitmap src = source;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
     if (getInput(0) && !getInput(0)->filterImage(proxy, source, matrix, &src, &srcOffset)) {
         return false;
     }
 
     if (src.config() != SkBitmap::kARGB_8888_Config) {
         return false;
     }
 
@@ skipping 64 matching lines @@
     offset->fX = dstIRect.fLeft;
     offset->fY = dstIRect.fTop;
     return true;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 #if SK_SUPPORT_GPU
 
 bool SkBicubicImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                          SkBitmap* result, SkIPoint* offset) {
+                                          SkBitmap* result, SkIPoint* offset) const {
     SkBitmap srcBM;
     if (!SkImageFilterUtils::GetInputResultGPU(getInput(0), proxy, src, ctm, &srcBM, offset)) {
         return false;
     }
     GrTexture* srcTexture = srcBM.getTexture();
     GrContext* context = srcTexture->getContext();
 
     SkRect dstRect = SkRect::MakeWH(srcBM.width() * fScale.fWidth,
                                     srcBM.height() * fScale.fHeight);
 
@@ skipping 12 matching lines @@
     GrPaint paint;
     paint.addColorEffect(GrBicubicEffect::Create(srcTexture, fCoefficients))->unref();
     SkRect srcRect;
     srcBM.getBounds(&srcRect);
     context->drawRectToRect(paint, dstRect, srcRect);
     return SkImageFilterUtils::WrapTexture(dst, desc.fWidth, desc.fHeight, result);
 }
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////