Make SkImageFilter methods const.

include/core/SkImageFilter.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImageFilter_DEFINED
 #define SkImageFilter_DEFINED
 
@@ skipping 37 matching lines @@
         SkRect fRect;
         uint32_t fFlags;
     };
 
     class Proxy {
     public:
         virtual ~Proxy() {};
 
         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;
     };
 
     /**
      *  Request a new (result) image to be created from the src image.
      *  If the src has no pixels (isNull()) then the request just wants to
      *  receive the config and width/height of the result.
      *
      *  The matrix is the current matrix on the canvas.
      *
      *  Offset is the amount to translate the resulting image relative to the
      *  src when it is drawn. This is an out-param.
      *
      *  If the result image cannot be created, return false, in which case both
      *  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
      *  image after the filter has been applied.
      */
     bool filterBounds(const SkIRect& src, const SkMatrix& ctm, SkIRect* dst) const;
 
     /**
      *  Returns true if the filter can be processed on the GPU.  This is most
      *  often used for multi-pass effects, where intermediate results must be
      *  rendered to textures.  For single-pass effects, use asNewEffect().
      *  The default implementation returns asNewEffect(NULL, NULL, SkMatrix::I(),
      *  SkIRect()).
      */
     virtual bool canFilterImageGPU() const;
 
     /**
      *  Process this image filter on the GPU.  This is most often used for
      *  multi-pass effects, where intermediate results must be rendered to
      *  textures.  For single-pass effects, use asNewEffect().  src is the
      *  source image for processing, as a texture-backed bitmap.  result is
      *  the destination bitmap, which should contain a texture-backed pixelref
      *  on success.  offset is the amount to translate the resulting image
      *  relative to the src when it is drawn. The default implementation does
      *  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
      *  "filterPtr" parameter if it can. Does nothing otherwise.
      *  If this returns false, then the filterPtr is unchanged.
      *  If this returns true, then if filterPtr is not null, it must be set to a ref'd colorfitler
      *  (i.e. it may not be set to NULL).
      */
     virtual bool asColorFilter(SkColorFilter** filterPtr) const;
 
@@ skipping 61 matching lines @@
      *  The matrix is the current matrix on the canvas.
      *
      *  Offset is the amount to translate the resulting image relative to the
      *  src when it is drawn. This is an out-param.
      *
      *  If the result image cannot be created, this should false, in which
      *  case both the result and offset parameters will be ignored by the
      *  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).
     // Used for clipping and temp-buffer allocations, so the result need not
     // be exact, but should never be smaller than the real answer. The default
     // implementation recursively unions all input bounds, or returns false if
     // no inputs.
     virtual bool onFilterBounds(const SkIRect&, const SkMatrix&, SkIRect*) const;
 
     // Applies "matrix" to the crop rect, and sets "rect" to the intersection of
@@ skipping 22 matching lines @@
                              const SkIRect& bounds) const;
 
 private:
     typedef SkFlattenable INHERITED;
     int fInputCount;
     SkImageFilter** fInputs;
     CropRect fCropRect;
 };
 
 #endif