Make SkImageFilter methods const.

SkImageFilter had some non-const methods that could all be made const.
This is a first step towards making SkImageFilter immutable.

BUG=skia:2097
R=mtklein@google.com, reed@google.com, robertphillips@google.com

Author: dominikg@chromium.org

Review URL: https://codereview.chromium.org/148883011

git-svn-id: http://skia.googlecode.com/svn/trunk@13330 2bbb7eff-a529-9590-31e7-b0007b416f81

54 files changed, 107 insertions, 109 deletions

diff --git a/gm/imagefiltersbase.cpp b/gm/imagefiltersbase.cpp
index 109be6a1e0..4794b02699 100644
--- a/gm/imagefiltersbase.cpp
+++ b/gm/imagefiltersbase.cpp
@@ -23,7 +23,7 @@ public:
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(FailImageFilter)
 protected:
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset) {
+                               SkBitmap* result, SkIPoint* offset) const {
         return false;
     }
 
@@ -46,7 +46,7 @@ public:
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(IdentityImageFilter)
 protected:
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset) {
+                               SkBitmap* result, SkIPoint* offset) const {
         *result = src;
         return true;
     }
diff --git a/gm/imagefiltersgraph.cpp b/gm/imagefiltersgraph.cpp
index 40b673cb42..6d5105e304 100644
--- a/gm/imagefiltersgraph.cpp
+++ b/gm/imagefiltersgraph.cpp
@@ -29,7 +29,7 @@ public:
     : SkImageFilter(input), fDX(dx), fDY(dy) {}
 
     virtual bool onFilterImage(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                               SkBitmap* dst, SkIPoint* offset) SK_OVERRIDE {
+                               SkBitmap* dst, SkIPoint* offset) const SK_OVERRIDE {
         SkBitmap source = src;
         SkImageFilter* input = getInput(0);
         SkIPoint srcOffset = SkIPoint::Make(0, 0);
diff --git a/include/core/SkBitmapDevice.h b/include/core/SkBitmapDevice.h
index 945ffbfca4..e4f9b88a5e 100644
--- a/include/core/SkBitmapDevice.h
+++ b/include/core/SkBitmapDevice.h
@@ -227,7 +227,7 @@ protected:
      *  some subclasses that do not support pixel manipulations after drawing
      *  has occurred (e.g. printing). The default implementation returns true.
      */
-    virtual bool allowImageFilter(SkImageFilter*) SK_OVERRIDE;
+    virtual bool allowImageFilter(const SkImageFilter*) SK_OVERRIDE;
 
     /**
      *  Override and return true for filters that the device can handle
@@ -236,7 +236,7 @@ protected:
      *  Returning false means the SkCanvas will have apply the filter itself,
      *  and just pass the resulting image to the device.
      */
-    virtual bool canHandleImageFilter(SkImageFilter*) SK_OVERRIDE;
+    virtual bool canHandleImageFilter(const SkImageFilter*) SK_OVERRIDE;
 
     /**
      *  Related (but not required) to canHandleImageFilter, this method returns
@@ -245,7 +245,7 @@ protected:
      *  If the device does not recognize or support this filter,
      *  it just returns false and leaves result and offset unchanged.
      */
-    virtual bool filterImage(SkImageFilter*, const SkBitmap&, const SkMatrix&,
+    virtual bool filterImage(const SkImageFilter*, const SkBitmap&, const SkMatrix&,
                              SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
 
 private:
diff --git a/include/core/SkDevice.h b/include/core/SkDevice.h
index 7c83f448d4..016e2babc8 100644
--- a/include/core/SkDevice.h
+++ b/include/core/SkDevice.h
@@ -341,7 +341,7 @@ protected:
      *  some subclasses that do not support pixel manipulations after drawing
      *  has occurred (e.g. printing). The default implementation returns true.
      */
-    virtual bool allowImageFilter(SkImageFilter*) = 0;
+    virtual bool allowImageFilter(const SkImageFilter*) = 0;
 
     /**
      *  Override and return true for filters that the device can handle
@@ -350,7 +350,7 @@ protected:
      *  Returning false means the SkCanvas will have apply the filter itself,
      *  and just pass the resulting image to the device.
      */
-    virtual bool canHandleImageFilter(SkImageFilter*) = 0;
+    virtual bool canHandleImageFilter(const SkImageFilter*) = 0;
 
     /**
      *  Related (but not required) to canHandleImageFilter, this method returns
@@ -359,7 +359,7 @@ protected:
      *  If the device does not recognize or support this filter,
      *  it just returns false and leaves result and offset unchanged.
      */
-    virtual bool filterImage(SkImageFilter*, const SkBitmap&, const SkMatrix&,
+    virtual bool filterImage(const SkImageFilter*, const SkBitmap&, const SkMatrix&,
                              SkBitmap* result, SkIPoint* offset) = 0;
 
     // This is equal kBGRA_Premul_Config8888 or kRGBA_Premul_Config8888 if
diff --git a/include/core/SkImageFilter.h b/include/core/SkImageFilter.h
index 6b53987891..a3e5a62ee5 100644
--- a/include/core/SkImageFilter.h
+++ b/include/core/SkImageFilter.h
@@ -55,10 +55,10 @@ public:
 
         virtual SkBaseDevice* createDevice(int width, int height) = 0;
         // returns true if the proxy can handle this filter natively
-        virtual bool canHandleImageFilter(SkImageFilter*) = 0;
+        virtual bool canHandleImageFilter(const SkImageFilter*) = 0;
         // returns true if the proxy handled the filter itself. if this returns
         // false then the filter's code will be called.
-        virtual bool filterImage(SkImageFilter*, const SkBitmap& src,
+        virtual bool filterImage(const SkImageFilter*, const SkBitmap& src,
                                  const SkMatrix& ctm,
                                  SkBitmap* result, SkIPoint* offset) = 0;
     };
@@ -77,7 +77,7 @@ public:
      *  the result and offset parameters will be ignored by the caller.
      */
     bool filterImage(Proxy*, const SkBitmap& src, const SkMatrix& ctm,
-                     SkBitmap* result, SkIPoint* offset);
+                     SkBitmap* result, SkIPoint* offset) const;
 
     /**
      *  Given the src bounds of an image, this returns the bounds of the result
@@ -105,7 +105,7 @@ public:
      *  single-pass processing using asNewEffect().
      */
     virtual bool filterImageGPU(Proxy*, const SkBitmap& src, const SkMatrix& ctm,
-                                SkBitmap* result, SkIPoint* offset);
+                                SkBitmap* result, SkIPoint* offset) const;
 
     /**
      *  Returns whether this image filter is a color filter and puts the color filter into the
@@ -187,7 +187,7 @@ protected:
      *  caller.
      */
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset);
+                               SkBitmap* result, SkIPoint* offset) const;
     // Given the bounds of the destination rect to be filled in device
     // coordinates (first parameter), and the CTM, compute (conservatively)
     // which rect of the source image would be required (third parameter).
diff --git a/include/core/SkImageFilterUtils.h b/include/core/SkImageFilterUtils.h
index b3921cdaf6..b533c3bca2 100644
--- a/include/core/SkImageFilterUtils.h
+++ b/include/core/SkImageFilterUtils.h
@@ -28,7 +28,7 @@ public:
      * this function returns src.  If the filter has no GPU implementation, it
      * will be processed in software and uploaded to the GPU.
      */
-    static bool GetInputResultGPU(SkImageFilter* filter, SkImageFilter::Proxy* proxy,
+    static bool GetInputResultGPU(const SkImageFilter* filter, SkImageFilter::Proxy* proxy,
                                   const SkBitmap& src, const SkMatrix& ctm, SkBitmap* result,
                                   SkIPoint* offset);
 };
diff --git a/include/effects/SkBicubicImageFilter.h b/include/effects/SkBicubicImageFilter.h
index d321169b71..48105b1c5b 100644
--- a/include/effects/SkBicubicImageFilter.h
+++ b/include/effects/SkBicubicImageFilter.h
@@ -39,12 +39,12 @@ protected:
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* loc) const SK_OVERRIDE;
 
 #if SK_SUPPORT_GPU
     virtual bool canFilterImageGPU() const SK_OVERRIDE { return true; }
     virtual bool filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                                SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 #endif
 
 private:
diff --git a/include/effects/SkBitmapSource.h b/include/effects/SkBitmapSource.h
index fa6dafc3a5..fcc1db97bc 100644
--- a/include/effects/SkBitmapSource.h
+++ b/include/effects/SkBitmapSource.h
@@ -23,7 +23,7 @@ protected:
     explicit SkBitmapSource(SkReadBuffer& buffer);
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
     virtual bool onFilterBounds(const SkIRect& src, const SkMatrix& ctm, SkIRect* dst) const SK_OVERRIDE;
 
 private:
diff --git a/include/effects/SkBlurImageFilter.h b/include/effects/SkBlurImageFilter.h
index f35269179b..60dab729b4 100644
--- a/include/effects/SkBlurImageFilter.h
+++ b/include/effects/SkBlurImageFilter.h
@@ -26,13 +26,13 @@ protected:
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
     virtual bool onFilterBounds(const SkIRect& src, const SkMatrix&,
                                 SkIRect* dst) const SK_OVERRIDE;
 
     bool canFilterImageGPU() const SK_OVERRIDE { return true; }
     virtual bool filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                                SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 
 private:
     SkSize   fSigma;
diff --git a/include/effects/SkColorFilterImageFilter.h b/include/effects/SkColorFilterImageFilter.h
index c04e418f29..d127f36db3 100755
--- a/include/effects/SkColorFilterImageFilter.h
+++ b/include/effects/SkColorFilterImageFilter.h
@@ -26,7 +26,7 @@ protected:
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* loc) const SK_OVERRIDE;
 
     virtual bool asColorFilter(SkColorFilter**) const SK_OVERRIDE;
 
diff --git a/include/effects/SkComposeImageFilter.h b/include/effects/SkComposeImageFilter.h
index 9cf7465a42..9e024ef84e 100644
--- a/include/effects/SkComposeImageFilter.h
+++ b/include/effects/SkComposeImageFilter.h
@@ -21,7 +21,7 @@ protected:
     explicit SkComposeImageFilter(SkReadBuffer& buffer);
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* loc) const SK_OVERRIDE;
     virtual bool onFilterBounds(const SkIRect&, const SkMatrix&, SkIRect*) const SK_OVERRIDE;
 
 private:
diff --git a/include/effects/SkDisplacementMapEffect.h b/include/effects/SkDisplacementMapEffect.h
index de07fe4ca4..5de4814951 100644
--- a/include/effects/SkDisplacementMapEffect.h
+++ b/include/effects/SkDisplacementMapEffect.h
@@ -36,7 +36,7 @@ public:
                                const SkBitmap& src,
                                const SkMatrix& ctm,
                                SkBitmap* dst,
-                               SkIPoint* offset) SK_OVERRIDE;
+                               SkIPoint* offset) const SK_OVERRIDE;
     virtual void computeFastBounds(const SkRect& src, SkRect* dst) const SK_OVERRIDE;
 
     virtual bool onFilterBounds(const SkIRect& src, const SkMatrix&,
@@ -45,7 +45,7 @@ public:
 #if SK_SUPPORT_GPU
     virtual bool canFilterImageGPU() const SK_OVERRIDE { return true; }
     virtual bool filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                                SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 #endif
 
 protected:
@@ -57,8 +57,6 @@ private:
     ChannelSelectorType fYChannelSelector;
     SkScalar fScale;
     typedef SkImageFilter INHERITED;
-    SkImageFilter* getDisplacementInput() { return getInput(0); }
-    SkImageFilter* getColorInput() { return getInput(1); }
     const SkImageFilter* getDisplacementInput() const { return getInput(0); }
     const SkImageFilter* getColorInput() const { return getInput(1); }
 };
diff --git a/include/effects/SkDropShadowImageFilter.h b/include/effects/SkDropShadowImageFilter.h
index cfcad8c33b..aba2017eef 100644
--- a/include/effects/SkDropShadowImageFilter.h
+++ b/include/effects/SkDropShadowImageFilter.h
@@ -19,7 +19,7 @@ public:
 protected:
     explicit SkDropShadowImageFilter(SkReadBuffer&);
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
-    virtual bool onFilterImage(Proxy*, const SkBitmap& source, const SkMatrix&, SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
+    virtual bool onFilterImage(Proxy*, const SkBitmap& source, const SkMatrix&, SkBitmap* result, SkIPoint* loc) const SK_OVERRIDE;
     virtual bool onFilterBounds(const SkIRect& src, const SkMatrix&,
                                 SkIRect* dst) const SK_OVERRIDE;
 
diff --git a/include/effects/SkMagnifierImageFilter.h b/include/effects/SkMagnifierImageFilter.h
index 222abd1283..44f0d0d689 100644
--- a/include/effects/SkMagnifierImageFilter.h
+++ b/include/effects/SkMagnifierImageFilter.h
@@ -23,7 +23,7 @@ protected:
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 #if SK_SUPPORT_GPU
     virtual bool asNewEffect(GrEffectRef** effect, GrTexture* texture, const SkMatrix& matrix, const SkIRect& bounds) const SK_OVERRIDE;
 #endif
diff --git a/include/effects/SkMatrixConvolutionImageFilter.h b/include/effects/SkMatrixConvolutionImageFilter.h
index 8da556e918..59af83e025 100644
--- a/include/effects/SkMatrixConvolutionImageFilter.h
+++ b/include/effects/SkMatrixConvolutionImageFilter.h
@@ -68,7 +68,7 @@ protected:
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* loc) const SK_OVERRIDE;
 
 #if SK_SUPPORT_GPU
     virtual bool asNewEffect(GrEffectRef** effect,
@@ -91,20 +91,20 @@ private:
     void filterPixels(const SkBitmap& src,
                       SkBitmap* result,
                       const SkIRect& rect,
-                      const SkIRect& bounds);
+                      const SkIRect& bounds) const;
     template <class PixelFetcher>
     void filterPixels(const SkBitmap& src,
                       SkBitmap* result,
                       const SkIRect& rect,
-                      const SkIRect& bounds);
+                      const SkIRect& bounds) const;
     void filterInteriorPixels(const SkBitmap& src,
                               SkBitmap* result,
                               const SkIRect& rect,
-                              const SkIRect& bounds);
+                              const SkIRect& bounds) const;
     void filterBorderPixels(const SkBitmap& src,
                             SkBitmap* result,
                             const SkIRect& rect,
-                            const SkIRect& bounds);
+                            const SkIRect& bounds) const;
 };
 
 #endif
diff --git a/include/effects/SkMergeImageFilter.h b/include/effects/SkMergeImageFilter.h
index 74cf561fd7..36eaaf3df1 100755
--- a/include/effects/SkMergeImageFilter.h
+++ b/include/effects/SkMergeImageFilter.h
@@ -29,7 +29,7 @@ protected:
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* loc) const SK_OVERRIDE;
 private:
     uint8_t*            fModes; // SkXfermode::Mode
 
diff --git a/include/effects/SkMorphologyImageFilter.h b/include/effects/SkMorphologyImageFilter.h
index c2b0d13eb3..4d60180aeb 100644
--- a/include/effects/SkMorphologyImageFilter.h
+++ b/include/effects/SkMorphologyImageFilter.h
@@ -32,14 +32,14 @@ public:
 protected:
     bool filterImageGeneric(Proc procX, Proc procY,
                             Proxy*, const SkBitmap& src, const SkMatrix&,
-                            SkBitmap* result, SkIPoint* offset);
+                            SkBitmap* result, SkIPoint* offset) const;
     SkMorphologyImageFilter(SkReadBuffer& buffer);
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 #if SK_SUPPORT_GPU
     virtual bool canFilterImageGPU() const SK_OVERRIDE { return true; }
     bool filterImageGPUGeneric(bool dilate, Proxy* proxy, const SkBitmap& src,
                                const SkMatrix& ctm, SkBitmap* result,
-                               SkIPoint* offset);
+                               SkIPoint* offset) const;
 #endif
 
     SkISize    radius() const { return fRadius; }
@@ -57,10 +57,10 @@ public:
     : INHERITED(radiusX, radiusY, input, cropRect) {}
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 #if SK_SUPPORT_GPU
     virtual bool filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                                SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 #endif
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkDilateImageFilter)
@@ -80,10 +80,10 @@ public:
     : INHERITED(radiusX, radiusY, input, cropRect) {}
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 #if SK_SUPPORT_GPU
     virtual bool filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                                SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 #endif
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkErodeImageFilter)
diff --git a/include/effects/SkOffsetImageFilter.h b/include/effects/SkOffsetImageFilter.h
index aef158c539..31eead3ded 100644
--- a/include/effects/SkOffsetImageFilter.h
+++ b/include/effects/SkOffsetImageFilter.h
@@ -25,7 +25,7 @@ protected:
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* loc) const SK_OVERRIDE;
     virtual bool onFilterBounds(const SkIRect&, const SkMatrix&, SkIRect*) const SK_OVERRIDE;
 
 private:
diff --git a/include/effects/SkPictureImageFilter.h b/include/effects/SkPictureImageFilter.h
index ccda85d3ac..eeaf1d2e46 100644
--- a/include/effects/SkPictureImageFilter.h
+++ b/include/effects/SkPictureImageFilter.h
@@ -31,7 +31,7 @@ protected:
     explicit SkPictureImageFilter(SkReadBuffer& buffer);
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 
 private:
     SkPicture* fPicture;
diff --git a/include/effects/SkRectShaderImageFilter.h b/include/effects/SkRectShaderImageFilter.h
index 28d98cc49a..23c538e688 100644
--- a/include/effects/SkRectShaderImageFilter.h
+++ b/include/effects/SkRectShaderImageFilter.h
@@ -38,7 +38,7 @@ protected:
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* loc) const SK_OVERRIDE;
 
 private:
     SkRectShaderImageFilter(SkShader* s, const CropRect* rect);
diff --git a/include/effects/SkResizeImageFilter.h b/include/effects/SkResizeImageFilter.h
index e2747e7bf4..cc02a01d03 100644
--- a/include/effects/SkResizeImageFilter.h
+++ b/include/effects/SkResizeImageFilter.h
@@ -40,7 +40,7 @@ protected:
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* loc) const SK_OVERRIDE;
 
 private:
     SkScalar              fSx, fSy;
diff --git a/include/effects/SkTestImageFilters.h b/include/effects/SkTestImageFilters.h
index 66ef5b1e68..abbaa92593 100755
--- a/include/effects/SkTestImageFilters.h
+++ b/include/effects/SkTestImageFilters.h
@@ -16,7 +16,7 @@ protected:
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* loc) const SK_OVERRIDE;
 
 private:
     SkScalar fScale;
diff --git a/include/effects/SkTileImageFilter.h b/include/effects/SkTileImageFilter.h
index 095b976445..390e00c9a4 100644
--- a/include/effects/SkTileImageFilter.h
+++ b/include/effects/SkTileImageFilter.h
@@ -23,7 +23,7 @@ public:
         : INHERITED(input), fSrcRect(srcRect), fDstRect(dstRect) {}
 
     virtual bool onFilterImage(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                               SkBitmap* dst, SkIPoint* offset) SK_OVERRIDE;
+                               SkBitmap* dst, SkIPoint* offset) const SK_OVERRIDE;
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkTileImageFilter)
 
diff --git a/include/effects/SkXfermodeImageFilter.h b/include/effects/SkXfermodeImageFilter.h
index e2724c3507..602dc48404 100644
--- a/include/effects/SkXfermodeImageFilter.h
+++ b/include/effects/SkXfermodeImageFilter.h
@@ -32,11 +32,11 @@ public:
                                const SkBitmap& src,
                                const SkMatrix& ctm,
                                SkBitmap* dst,
-                               SkIPoint* offset) SK_OVERRIDE;
+                               SkIPoint* offset) const SK_OVERRIDE;
 #if SK_SUPPORT_GPU
     virtual bool canFilterImageGPU() const SK_OVERRIDE { return !cropRectIsSet(); }
     virtual bool filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                                SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 #endif
 
 protected:
diff --git a/include/gpu/SkGpuDevice.h b/include/gpu/SkGpuDevice.h
index 151a6dcd65..8b2170da6d 100644
--- a/include/gpu/SkGpuDevice.h
+++ b/include/gpu/SkGpuDevice.h
@@ -131,8 +131,8 @@ public:
      */
     virtual void makeRenderTargetCurrent();
 
-    virtual bool canHandleImageFilter(SkImageFilter*) SK_OVERRIDE;
-    virtual bool filterImage(SkImageFilter*, const SkBitmap&, const SkMatrix&,
+    virtual bool canHandleImageFilter(const SkImageFilter*) SK_OVERRIDE;
+    virtual bool filterImage(const SkImageFilter*, const SkBitmap&, const SkMatrix&,
                              SkBitmap*, SkIPoint*) SK_OVERRIDE;
 
     class SkAutoCachedTexture; // used internally
diff --git a/include/pdf/SkPDFDevice.h b/include/pdf/SkPDFDevice.h
index 51d046de60..9b21f8f90a 100644
--- a/include/pdf/SkPDFDevice.h
+++ b/include/pdf/SkPDFDevice.h
@@ -213,7 +213,7 @@ protected:
     virtual bool onReadPixels(const SkBitmap& bitmap, int x, int y,
                               SkCanvas::Config8888) SK_OVERRIDE;
 
-    virtual bool allowImageFilter(SkImageFilter*) SK_OVERRIDE;
+    virtual bool allowImageFilter(const SkImageFilter*) SK_OVERRIDE;
 
 private:
     // TODO(vandebo): push most of SkPDFDevice's state into a core object in
diff --git a/src/core/SkBitmapDevice.cpp b/src/core/SkBitmapDevice.cpp
index 5e70b1ab1b..9dde6e172e 100644
--- a/src/core/SkBitmapDevice.cpp
+++ b/src/core/SkBitmapDevice.cpp
@@ -95,17 +95,17 @@ const SkBitmap& SkBitmapDevice::onAccessBitmap() {
     return fBitmap;
 }
 
-bool SkBitmapDevice::canHandleImageFilter(SkImageFilter*) {
+bool SkBitmapDevice::canHandleImageFilter(const SkImageFilter*) {
     return false;
 }
 
-bool SkBitmapDevice::filterImage(SkImageFilter* filter, const SkBitmap& src,
+bool SkBitmapDevice::filterImage(const SkImageFilter* filter, const SkBitmap& src,
                                  const SkMatrix& ctm, SkBitmap* result,
                                  SkIPoint* offset) {
     return false;
 }
 
-bool SkBitmapDevice::allowImageFilter(SkImageFilter*) {
+bool SkBitmapDevice::allowImageFilter(const SkImageFilter*) {
     return true;
 }
 
diff --git a/src/core/SkDeviceImageFilterProxy.h b/src/core/SkDeviceImageFilterProxy.h
index 03fcb68125..800e42c1f6 100644
--- a/src/core/SkDeviceImageFilterProxy.h
+++ b/src/core/SkDeviceImageFilterProxy.h
@@ -18,10 +18,10 @@ public:
         return fDevice->createCompatibleDevice(SkBitmap::kARGB_8888_Config,
                                                w, h, false);
     }
-    virtual bool canHandleImageFilter(SkImageFilter* filter) SK_OVERRIDE {
+    virtual bool canHandleImageFilter(const SkImageFilter* filter) SK_OVERRIDE {
         return fDevice->canHandleImageFilter(filter);
     }
-    virtual bool filterImage(SkImageFilter* filter, const SkBitmap& src,
+    virtual bool filterImage(const SkImageFilter* filter, const SkBitmap& src,
                              const SkMatrix& ctm,
                              SkBitmap* result, SkIPoint* offset) SK_OVERRIDE {
         return fDevice->filterImage(filter, src, ctm, result, offset);
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index 384f2dce6b..cd7c01b4e6 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -94,7 +94,7 @@ void SkImageFilter::flatten(SkWriteBuffer& buffer) const {
 
 bool SkImageFilter::filterImage(Proxy* proxy, const SkBitmap& src,
                                 const SkMatrix& ctm,
-                                SkBitmap* result, SkIPoint* offset) {
+                                SkBitmap* result, SkIPoint* offset) const {
     SkASSERT(result);
     SkASSERT(offset);
     /*
@@ -135,7 +135,7 @@ void SkImageFilter::computeFastBounds(const SkRect& src, SkRect* dst) const {
 }
 
 bool SkImageFilter::onFilterImage(Proxy*, const SkBitmap&, const SkMatrix&,
-                                  SkBitmap*, SkIPoint*) {
+                                  SkBitmap*, SkIPoint*) const {
     return false;
 }
 
@@ -144,7 +144,7 @@ bool SkImageFilter::canFilterImageGPU() const {
 }
 
 bool SkImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                   SkBitmap* result, SkIPoint* offset) {
+                                   SkBitmap* result, SkIPoint* offset) const {
 #if SK_SUPPORT_GPU
     SkBitmap input;
     SkASSERT(fInputCount == 1);
diff --git a/src/core/SkImageFilterUtils.cpp b/src/core/SkImageFilterUtils.cpp
index 204f38d65b..c6c534e71d 100644
--- a/src/core/SkImageFilterUtils.cpp
+++ b/src/core/SkImageFilterUtils.cpp
@@ -21,7 +21,7 @@ bool SkImageFilterUtils::WrapTexture(GrTexture* texture, int width, int height,
     return true;
 }
 
-bool SkImageFilterUtils::GetInputResultGPU(SkImageFilter* filter, SkImageFilter::Proxy* proxy,
+bool SkImageFilterUtils::GetInputResultGPU(const 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
diff --git a/src/effects/SkAlphaThresholdFilter.cpp b/src/effects/SkAlphaThresholdFilter.cpp
index d3d9093050..6b55fdf90e 100644
--- a/src/effects/SkAlphaThresholdFilter.cpp
+++ b/src/effects/SkAlphaThresholdFilter.cpp
@@ -22,7 +22,7 @@ protected:
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 #if SK_SUPPORT_GPU
     virtual bool asNewEffect(GrEffectRef** effect, GrTexture* texture,
                              const SkMatrix& matrix, const SkIRect& bounds) const SK_OVERRIDE;
@@ -305,7 +305,7 @@ void SkAlphaThresholdFilterImpl::flatten(SkWriteBuffer& buffer) const {
 
 bool SkAlphaThresholdFilterImpl::onFilterImage(Proxy*, const SkBitmap& src,
                                                const SkMatrix& matrix, SkBitmap* dst,
-                                               SkIPoint* offset) {
+                                               SkIPoint* offset) const {
     SkASSERT(src.config() == SkBitmap::kARGB_8888_Config);
 
     if (src.config() != SkBitmap::kARGB_8888_Config) {
diff --git a/src/effects/SkBicubicImageFilter.cpp b/src/effects/SkBicubicImageFilter.cpp
index e44b717003..cf71435cde 100644
--- a/src/effects/SkBicubicImageFilter.cpp
+++ b/src/effects/SkBicubicImageFilter.cpp
@@ -85,7 +85,7 @@ 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)) {
@@ -170,7 +170,7 @@ bool SkBicubicImageFilter::onFilterImage(Proxy* proxy,
 #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;
diff --git a/src/effects/SkBitmapSource.cpp b/src/effects/SkBitmapSource.cpp
index f318c91a73..ec4fcd16fb 100644
--- a/src/effects/SkBitmapSource.cpp
+++ b/src/effects/SkBitmapSource.cpp
@@ -43,7 +43,7 @@ void SkBitmapSource::flatten(SkWriteBuffer& buffer) const {
 }
 
 bool SkBitmapSource::onFilterImage(Proxy* proxy, const SkBitmap&, const SkMatrix& matrix,
-                                   SkBitmap* result, SkIPoint* offset) {
+                                   SkBitmap* result, SkIPoint* offset) const {
     SkRect bounds, dstRect;
     fBitmap.getBounds(&bounds);
     matrix.mapRect(&dstRect, fDstRect);
diff --git a/src/effects/SkBlurImageFilter.cpp b/src/effects/SkBlurImageFilter.cpp
index 67b0511480..a08b9c5675 100644
--- a/src/effects/SkBlurImageFilter.cpp
+++ b/src/effects/SkBlurImageFilter.cpp
@@ -136,7 +136,7 @@ static void getBox3Params(SkScalar s, int *kernelSize, int* kernelSize3, int *lo
 
 bool SkBlurImageFilter::onFilterImage(Proxy* proxy,
                                       const SkBitmap& source, const SkMatrix& ctm,
-                                      SkBitmap* dst, SkIPoint* offset) {
+                                      SkBitmap* dst, SkIPoint* offset) const {
     SkBitmap src = source;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
     if (getInput(0) && !getInput(0)->filterImage(proxy, source, ctm, &src, &srcOffset)) {
@@ -252,7 +252,7 @@ bool SkBlurImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,
 }
 
 bool SkBlurImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                       SkBitmap* result, SkIPoint* offset) {
+                                       SkBitmap* result, SkIPoint* offset) const {
 #if SK_SUPPORT_GPU
     SkBitmap input;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
diff --git a/src/effects/SkColorFilterImageFilter.cpp b/src/effects/SkColorFilterImageFilter.cpp
index da494bb294..1f92d1683d 100755
--- a/src/effects/SkColorFilterImageFilter.cpp
+++ b/src/effects/SkColorFilterImageFilter.cpp
@@ -101,7 +101,7 @@ SkColorFilterImageFilter::~SkColorFilterImageFilter() {
 bool SkColorFilterImageFilter::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)) {
diff --git a/src/effects/SkComposeImageFilter.cpp b/src/effects/SkComposeImageFilter.cpp
index cb513766cc..842ff48b82 100644
--- a/src/effects/SkComposeImageFilter.cpp
+++ b/src/effects/SkComposeImageFilter.cpp
@@ -17,7 +17,7 @@ bool SkComposeImageFilter::onFilterImage(Proxy* proxy,
                                          const SkBitmap& src,
                                          const SkMatrix& ctm,
                                          SkBitmap* result,
-                                         SkIPoint* offset) {
+                                         SkIPoint* offset) const {
     SkImageFilter* outer = getInput(0);
     SkImageFilter* inner = getInput(1);
 
diff --git a/src/effects/SkDisplacementMapEffect.cpp b/src/effects/SkDisplacementMapEffect.cpp
index 555f795a51..a563a6ef85 100644
--- a/src/effects/SkDisplacementMapEffect.cpp
+++ b/src/effects/SkDisplacementMapEffect.cpp
@@ -195,10 +195,10 @@ 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))) {
@@ -348,7 +348,7 @@ private:
 };
 
 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,
diff --git a/src/effects/SkDropShadowImageFilter.cpp b/src/effects/SkDropShadowImageFilter.cpp
index 7cb515265c..6d68a24d43 100644
--- a/src/effects/SkDropShadowImageFilter.cpp
+++ b/src/effects/SkDropShadowImageFilter.cpp
@@ -58,7 +58,7 @@ void SkDropShadowImageFilter::flatten(SkWriteBuffer& buffer) const
     buffer.writeColor(fColor);
 }
 
-bool SkDropShadowImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& source, const SkMatrix& matrix, SkBitmap* result, SkIPoint* offset)
+bool SkDropShadowImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& source, const SkMatrix& matrix, SkBitmap* result, SkIPoint* offset) const
 {
     SkBitmap src = source;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
diff --git a/src/effects/SkLightingImageFilter.cpp b/src/effects/SkLightingImageFilter.cpp
index d16ecb1bb3..f4f1ae1707 100644
--- a/src/effects/SkLightingImageFilter.cpp
+++ b/src/effects/SkLightingImageFilter.cpp
@@ -272,7 +272,7 @@ protected:
     explicit SkDiffuseLightingImageFilter(SkReadBuffer& buffer);
     virtual void flatten(SkWriteBuffer& buffer) const SK_OVERRIDE;
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 #if SK_SUPPORT_GPU
     virtual bool asNewEffect(GrEffectRef** effect, GrTexture*, const SkMatrix& matrix, const SkIRect& bounds) const SK_OVERRIDE;
 #endif
@@ -294,7 +294,7 @@ protected:
     explicit SkSpecularLightingImageFilter(SkReadBuffer& buffer);
     virtual void flatten(SkWriteBuffer& buffer) const SK_OVERRIDE;
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 #if SK_SUPPORT_GPU
     virtual bool asNewEffect(GrEffectRef** effect, GrTexture*, const SkMatrix& matrix, const SkIRect& bounds) const SK_OVERRIDE;
 #endif
@@ -925,7 +925,7 @@ bool SkDiffuseLightingImageFilter::onFilterImage(Proxy* proxy,
                                                  const SkBitmap& source,
                                                  const SkMatrix& ctm,
                                                  SkBitmap* dst,
-                                                 SkIPoint* offset) {
+                                                 SkIPoint* offset) const {
     SkImageFilter* input = getInput(0);
     SkBitmap src = source;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
@@ -1018,7 +1018,7 @@ bool SkSpecularLightingImageFilter::onFilterImage(Proxy* proxy,
                                                   const SkBitmap& source,
                                                   const SkMatrix& ctm,
                                                   SkBitmap* dst,
-                                                  SkIPoint* offset) {
+                                                  SkIPoint* offset) const {
     SkImageFilter* input = getInput(0);
     SkBitmap src = source;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
diff --git a/src/effects/SkMagnifierImageFilter.cpp b/src/effects/SkMagnifierImageFilter.cpp
index a1c62b7720..2fed24dc74 100644
--- a/src/effects/SkMagnifierImageFilter.cpp
+++ b/src/effects/SkMagnifierImageFilter.cpp
@@ -281,7 +281,7 @@ void SkMagnifierImageFilter::flatten(SkWriteBuffer& buffer) const {
 
 bool SkMagnifierImageFilter::onFilterImage(Proxy*, const SkBitmap& src,
                                            const SkMatrix&, SkBitmap* dst,
-                                           SkIPoint* offset) {
+                                           SkIPoint* offset) const {
     SkASSERT(src.config() == SkBitmap::kARGB_8888_Config);
     SkASSERT(fSrcRect.width() < src.width());
     SkASSERT(fSrcRect.height() < src.height());
diff --git a/src/effects/SkMatrixConvolutionImageFilter.cpp b/src/effects/SkMatrixConvolutionImageFilter.cpp
index b73f623aec..43ebc6ce66 100644
--- a/src/effects/SkMatrixConvolutionImageFilter.cpp
+++ b/src/effects/SkMatrixConvolutionImageFilter.cpp
@@ -152,7 +152,7 @@ template<class PixelFetcher, bool convolveAlpha>
 void SkMatrixConvolutionImageFilter::filterPixels(const SkBitmap& src,
                                                   SkBitmap* result,
                                                   const SkIRect& rect,
-                                                  const SkIRect& bounds) {
+                                                  const SkIRect& bounds) const {
     for (int y = rect.fTop; y < rect.fBottom; ++y) {
         SkPMColor* dptr = result->getAddr32(rect.fLeft - bounds.fLeft, y - bounds.fTop);
         for (int x = rect.fLeft; x < rect.fRight; ++x) {
@@ -192,7 +192,7 @@ template<class PixelFetcher>
 void SkMatrixConvolutionImageFilter::filterPixels(const SkBitmap& src,
                                                   SkBitmap* result,
                                                   const SkIRect& rect,
-                                                  const SkIRect& bounds) {
+                                                  const SkIRect& bounds) const {
     if (fConvolveAlpha) {
         filterPixels<PixelFetcher, true>(src, result, rect, bounds);
     } else {
@@ -203,14 +203,14 @@ void SkMatrixConvolutionImageFilter::filterPixels(const SkBitmap& src,
 void SkMatrixConvolutionImageFilter::filterInteriorPixels(const SkBitmap& src,
                                                           SkBitmap* result,
                                                           const SkIRect& rect,
-                                                          const SkIRect& bounds) {
+                                                          const SkIRect& bounds) const {
     filterPixels<UncheckedPixelFetcher>(src, result, rect, bounds);
 }
 
 void SkMatrixConvolutionImageFilter::filterBorderPixels(const SkBitmap& src,
                                                         SkBitmap* result,
                                                         const SkIRect& rect,
-                                                        const SkIRect& bounds) {
+                                                        const SkIRect& bounds) const {
     switch (fTileMode) {
         case kClamp_TileMode:
             filterPixels<ClampPixelFetcher>(src, result, rect, bounds);
@@ -253,7 +253,7 @@ bool SkMatrixConvolutionImageFilter::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)) {
diff --git a/src/effects/SkMergeImageFilter.cpp b/src/effects/SkMergeImageFilter.cpp
index d0a153fa50..5f66244084 100755
--- a/src/effects/SkMergeImageFilter.cpp
+++ b/src/effects/SkMergeImageFilter.cpp
@@ -67,7 +67,7 @@ SkMergeImageFilter::~SkMergeImageFilter() {
 
 bool SkMergeImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& src,
                                        const SkMatrix& ctm,
-                                       SkBitmap* result, SkIPoint* offset) {
+                                       SkBitmap* result, SkIPoint* offset) const {
     if (countInputs() < 1) {
         return false;
     }
diff --git a/src/effects/SkMorphologyImageFilter.cpp b/src/effects/SkMorphologyImageFilter.cpp
index 46302ad520..f2eeb2d6ff 100644
--- a/src/effects/SkMorphologyImageFilter.cpp
+++ b/src/effects/SkMorphologyImageFilter.cpp
@@ -143,7 +143,7 @@ bool SkMorphologyImageFilter::filterImageGeneric(SkMorphologyImageFilter::Proc p
                                                  const SkBitmap& source,
                                                  const SkMatrix& ctm,
                                                  SkBitmap* dst,
-                                                 SkIPoint* offset) {
+                                                 SkIPoint* offset) const {
     SkBitmap src = source;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
     if (getInput(0) && !getInput(0)->filterImage(proxy, source, ctm, &src, &srcOffset)) {
@@ -214,7 +214,7 @@ bool SkMorphologyImageFilter::filterImageGeneric(SkMorphologyImageFilter::Proc p
 
 bool SkErodeImageFilter::onFilterImage(Proxy* proxy,
                                        const SkBitmap& source, const SkMatrix& ctm,
-                                       SkBitmap* dst, SkIPoint* offset) {
+                                       SkBitmap* dst, SkIPoint* offset) const {
     Proc erodeXProc = SkMorphologyGetPlatformProc(kErodeX_SkMorphologyProcType);
     if (!erodeXProc) {
         erodeXProc = erode<kX>;
@@ -228,7 +228,7 @@ bool SkErodeImageFilter::onFilterImage(Proxy* proxy,
 
 bool SkDilateImageFilter::onFilterImage(Proxy* proxy,
                                         const SkBitmap& source, const SkMatrix& ctm,
-                                        SkBitmap* dst, SkIPoint* offset) {
+                                        SkBitmap* dst, SkIPoint* offset) const {
     Proc dilateXProc = SkMorphologyGetPlatformProc(kDilateX_SkMorphologyProcType);
     if (!dilateXProc) {
         dilateXProc = dilate<kX>;
@@ -540,7 +540,7 @@ bool SkMorphologyImageFilter::filterImageGPUGeneric(bool dilate,
                                                     const SkBitmap& src,
                                                     const SkMatrix& ctm,
                                                     SkBitmap* result,
-                                                    SkIPoint* offset) {
+                                                    SkIPoint* offset) const {
     SkBitmap input;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
     if (!SkImageFilterUtils::GetInputResultGPU(getInput(0), proxy, src, ctm, &input, &srcOffset)) {
@@ -582,12 +582,12 @@ bool SkMorphologyImageFilter::filterImageGPUGeneric(bool dilate,
 }
 
 bool SkDilateImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                         SkBitmap* result, SkIPoint* offset) {
+                                         SkBitmap* result, SkIPoint* offset) const {
     return this->filterImageGPUGeneric(true, proxy, src, ctm, result, offset);
 }
 
 bool SkErodeImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                        SkBitmap* result, SkIPoint* offset) {
+                                        SkBitmap* result, SkIPoint* offset) const {
     return this->filterImageGPUGeneric(false, proxy, src, ctm, result, offset);
 }
 
diff --git a/src/effects/SkOffsetImageFilter.cpp b/src/effects/SkOffsetImageFilter.cpp
index e19a3275d1..b36ef8a3ed 100644
--- a/src/effects/SkOffsetImageFilter.cpp
+++ b/src/effects/SkOffsetImageFilter.cpp
@@ -17,7 +17,7 @@
 bool SkOffsetImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& source,
                                         const SkMatrix& matrix,
                                         SkBitmap* result,
-                                        SkIPoint* offset) {
+                                        SkIPoint* offset) const {
     SkImageFilter* input = getInput(0);
     SkBitmap src = source;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
diff --git a/src/effects/SkPictureImageFilter.cpp b/src/effects/SkPictureImageFilter.cpp
index ae9576043f..c78b2499ec 100644
--- a/src/effects/SkPictureImageFilter.cpp
+++ b/src/effects/SkPictureImageFilter.cpp
@@ -45,7 +45,7 @@ void SkPictureImageFilter::flatten(SkWriteBuffer& buffer) const {
 }
 
 bool SkPictureImageFilter::onFilterImage(Proxy* proxy, const SkBitmap&, const SkMatrix& matrix,
-                                   SkBitmap* result, SkIPoint* offset) {
+                                   SkBitmap* result, SkIPoint* offset) const {
     if (!fPicture) {
         offset->fX = offset->fY = 0;
         return true;
diff --git a/src/effects/SkRectShaderImageFilter.cpp b/src/effects/SkRectShaderImageFilter.cpp
index 272a4af2b9..18e38470bc 100644
--- a/src/effects/SkRectShaderImageFilter.cpp
+++ b/src/effects/SkRectShaderImageFilter.cpp
@@ -54,7 +54,7 @@ bool SkRectShaderImageFilter::onFilterImage(Proxy* proxy,
                                             const SkBitmap& source,
                                             const SkMatrix& ctm,
                                             SkBitmap* result,
-                                            SkIPoint* offset) {
+                                            SkIPoint* offset) const {
     SkIRect bounds;
     source.getBounds(&bounds);
     if (!this->applyCropRect(&bounds, ctm)) {
diff --git a/src/effects/SkResizeImageFilter.cpp b/src/effects/SkResizeImageFilter.cpp
index 983dd157cc..4a3f4b56ee 100644
--- a/src/effects/SkResizeImageFilter.cpp
+++ b/src/effects/SkResizeImageFilter.cpp
@@ -44,7 +44,7 @@ bool SkResizeImageFilter::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)) {
diff --git a/src/effects/SkTestImageFilters.cpp b/src/effects/SkTestImageFilters.cpp
index 96226f5d25..69279324ca 100755
--- a/src/effects/SkTestImageFilters.cpp
+++ b/src/effects/SkTestImageFilters.cpp
@@ -23,7 +23,7 @@ public:
 
 bool SkDownSampleImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& src,
                                             const SkMatrix&,
-                                            SkBitmap* result, SkIPoint*) {
+                                            SkBitmap* result, SkIPoint*) const {
     SkScalar scale = fScale;
     if (scale > SK_Scalar1 || scale <= 0) {
         return false;
diff --git a/src/effects/SkTileImageFilter.cpp b/src/effects/SkTileImageFilter.cpp
index f0b7fda869..f17e2eac93 100644
--- a/src/effects/SkTileImageFilter.cpp
+++ b/src/effects/SkTileImageFilter.cpp
@@ -17,7 +17,7 @@
 #include "SkValidationUtils.h"
 
 bool SkTileImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                      SkBitmap* dst, SkIPoint* offset) {
+                                      SkBitmap* dst, SkIPoint* offset) const {
     SkBitmap source = src;
     SkImageFilter* input = getInput(0);
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
diff --git a/src/effects/SkXfermodeImageFilter.cpp b/src/effects/SkXfermodeImageFilter.cpp
index b3ab9ffa93..d43699db64 100644
--- a/src/effects/SkXfermodeImageFilter.cpp
+++ b/src/effects/SkXfermodeImageFilter.cpp
@@ -47,7 +47,7 @@ bool SkXfermodeImageFilter::onFilterImage(Proxy* proxy,
                                             const SkBitmap& src,
                                             const SkMatrix& ctm,
                                             SkBitmap* dst,
-                                            SkIPoint* offset) {
+                                            SkIPoint* offset) const {
     SkBitmap background = src, foreground = src;
     SkImageFilter* backgroundInput = getInput(0);
     SkImageFilter* foregroundInput = getInput(1);
@@ -100,7 +100,7 @@ bool SkXfermodeImageFilter::filterImageGPU(Proxy* proxy,
                                            const SkBitmap& src,
                                            const SkMatrix& ctm,
                                            SkBitmap* result,
-                                           SkIPoint* offset) {
+                                           SkIPoint* offset) const {
     SkBitmap background;
     SkIPoint backgroundOffset = SkIPoint::Make(0, 0);
     if (!SkImageFilterUtils::GetInputResultGPU(getInput(0), proxy, src, ctm, &background,
diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index 8c272f947a..a3af3c3d08 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -1515,7 +1515,7 @@ void SkGpuDevice::internalDrawBitmap(const SkBitmap& bitmap,
 }
 
 static bool filter_texture(SkBaseDevice* device, GrContext* context,
-                           GrTexture* texture, SkImageFilter* filter,
+                           GrTexture* texture, const SkImageFilter* filter,
                            int w, int h, const SkMatrix& ctm, SkBitmap* result,
                            SkIPoint* offset) {
     SkASSERT(filter);
@@ -1694,11 +1694,11 @@ void SkGpuDevice::drawDevice(const SkDraw& draw, SkBaseDevice* device,
     fContext->drawRectToRect(grPaint, dstRect, srcRect);
 }
 
-bool SkGpuDevice::canHandleImageFilter(SkImageFilter* filter) {
+bool SkGpuDevice::canHandleImageFilter(const SkImageFilter* filter) {
     return filter->canFilterImageGPU();
 }
 
-bool SkGpuDevice::filterImage(SkImageFilter* filter, const SkBitmap& src,
+bool SkGpuDevice::filterImage(const SkImageFilter* filter, const SkBitmap& src,
                               const SkMatrix& ctm,
                               SkBitmap* result, SkIPoint* offset) {
     // want explicitly our impl, so guard against a subclass of us overriding it
diff --git a/src/pdf/SkPDFDevice.cpp b/src/pdf/SkPDFDevice.cpp
index ff83aadeee..0f0c38c0b1 100644
--- a/src/pdf/SkPDFDevice.cpp
+++ b/src/pdf/SkPDFDevice.cpp
@@ -2330,6 +2330,6 @@ bool SkPDFDevice::onReadPixels(const SkBitmap& bitmap, int x, int y,
     return false;
 }
 
-bool SkPDFDevice::allowImageFilter(SkImageFilter*) {
+bool SkPDFDevice::allowImageFilter(const SkImageFilter*) {
     return false;
 }
diff --git a/src/utils/SkGatherPixelRefsAndRects.h b/src/utils/SkGatherPixelRefsAndRects.h
index 795378f3e5..5159525939 100644
--- a/src/utils/SkGatherPixelRefsAndRects.h
+++ b/src/utils/SkGatherPixelRefsAndRects.h
@@ -299,9 +299,9 @@ protected:
     }
     virtual void lockPixels() SK_OVERRIDE { NothingToDo(); }
     virtual void unlockPixels() SK_OVERRIDE { NothingToDo(); }
-    virtual bool allowImageFilter(SkImageFilter*) SK_OVERRIDE { return false; }
-    virtual bool canHandleImageFilter(SkImageFilter*) SK_OVERRIDE { return false; }
-    virtual bool filterImage(SkImageFilter*, const SkBitmap&, const SkMatrix&,
+    virtual bool allowImageFilter(const SkImageFilter*) SK_OVERRIDE { return false; }
+    virtual bool canHandleImageFilter(const SkImageFilter*) SK_OVERRIDE { return false; }
+    virtual bool filterImage(const SkImageFilter*, const SkBitmap&, const SkMatrix&,
                              SkBitmap* result, SkIPoint* offset) SK_OVERRIDE {
         return false;
     }
diff --git a/src/utils/SkPictureUtils.cpp b/src/utils/SkPictureUtils.cpp
index 4af8da8ecf..92d0487c54 100644
--- a/src/utils/SkPictureUtils.cpp
+++ b/src/utils/SkPictureUtils.cpp
@@ -75,9 +75,9 @@ public:
     }
     virtual void lockPixels() SK_OVERRIDE { nothing_to_do(); }
     virtual void unlockPixels() SK_OVERRIDE { nothing_to_do(); }
-    virtual bool allowImageFilter(SkImageFilter*) SK_OVERRIDE { return false; }
-    virtual bool canHandleImageFilter(SkImageFilter*) SK_OVERRIDE { return false; }
-    virtual bool filterImage(SkImageFilter*, const SkBitmap&, const SkMatrix&,
+    virtual bool allowImageFilter(const SkImageFilter*) SK_OVERRIDE { return false; }
+    virtual bool canHandleImageFilter(const SkImageFilter*) SK_OVERRIDE { return false; }
+    virtual bool filterImage(const SkImageFilter*, const SkBitmap&, const SkMatrix&,
                              SkBitmap* result, SkIPoint* offset) SK_OVERRIDE {
         return false;
     }