Move SkMatrixImageFilter into core, and add a factory fn for it.

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
 
+#include "SkFilterQuality.h"
 #include "SkFlattenable.h"
 #include "SkMatrix.h"
 #include "SkRect.h"
 #include "SkTemplates.h"
 
 class SkBitmap;
 class SkColorFilter;
 class SkBaseDevice;
 class SkSurfaceProps;
 struct SkIPoint;
@@ skipping 164 matching lines @@
      *  should be used to offset access to the input images, and should also
      *  be added to the "offset" parameter in onFilterImage and
      *  filterImageGPU(). (The latter ensures that the resulting buffer is
      *  drawn in the correct location.)
      */
     bool cropRectIsSet() const { return fCropRect.flags() != 0x0; }
 
     // Default impl returns union of all input bounds.
     virtual void computeFastBounds(const SkRect&, SkRect*) const;
 
+    /**
+     * Create an SkMatrixImageFilter, which transforms its input by the given matrix.
+     */
+    static SkImageFilter* CreateMatrix(const SkMatrix& matrix,

[Stephen White, 2015/03/19 18:47:42]

BTW, I was thinking of changing this to CreateMatrixFilter(), since
CreateMatrix() is somewhat ambiguous. CreateMatrixImageFilter() seems a bit
long, but I could go with that too.

[reed1, 2015/03/19 20:50:01]

Agreed, CreateMatrixFilter is more consistent with other std factories in
SkColorFilter and SkShader.

+                                       SkFilterQuality,
+                                       SkImageFilter* input = NULL);
+
 #if SK_SUPPORT_GPU
     /**
      * Wrap the given texture in a texture-backed SkBitmap.
      */
     static void WrapTexture(GrTexture* texture, int width, int height, SkBitmap* result);
 
     /**
      * Recursively evaluate this filter on the GPU. If the filter has no GPU
      * implementation, it will be processed in software and uploaded to the GPU.
      */
@@ skipping 144 matching lines @@
  */
 #define SK_IMAGEFILTER_UNFLATTEN_COMMON(localVar, expectedCount)    \
     Common localVar;                                                \
     do {                                                            \
         if (!localVar.unflatten(buffer, expectedCount)) {           \
             return NULL;                                            \
         }                                                           \
     } while (0)
 
 #endif