Implement crop rect for SkImageFilter

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 "SkFlattenable.h"
+#include "SkRect.h"
 
 class SkBitmap;
 class SkColorFilter;
 class SkDevice;
 class SkMatrix;
 struct SkIPoint;
-struct SkIRect;
 class SkShader;
 class GrEffectRef;
 class GrTexture;
 
 /**
  *  Experimental.
  *
  *  Base class for image filters. If one is installed in the paint, then
  *  all drawing occurs as usual, but it is as if the drawing happened into an
  *  offscreen (before the xfermode is applied). This offscreen bitmap will
@@ skipping 103 matching lines @@
 
     /**
      *  Returns the input filter at a given index, or NULL if no input is
      *  connected.  The indices used are filter-specific.
      */
     SkImageFilter* getInput(int i) const {
         SkASSERT(i < fInputCount);
         return fInputs[i];
     }
 
+    /**
+     *  Returns the crop rectangle of this filter. This is set at construction
+     *  time, and determines which pixels from the input image will
+     *  be processed. The size of this rectangle should be used as the size
+     *  of the destination image. The origin of this rect 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.)
+     */
+    const SkIRect& cropRect() const { return fCropRect; }
+
 protected:
-    SkImageFilter(int inputCount, SkImageFilter** inputs);
+    SkImageFilter(int inputCount, SkImageFilter** inputs, const SkIRect* cropRect = NULL);
 
     // Convenience constructor for 1-input filters.
-    explicit SkImageFilter(SkImageFilter* input);
+    explicit SkImageFilter(SkImageFilter* input, const SkIRect* cropRect = NULL);
 
     // Convenience constructor for 2-input filters.
-    SkImageFilter(SkImageFilter* input1, SkImageFilter* input2);
+    SkImageFilter(SkImageFilter* input1, SkImageFilter* input2, const SkIRect* cropRect = NULL);
 
     virtual ~SkImageFilter();
 
     explicit SkImageFilter(SkFlattenableReadBuffer& rb);
 
     virtual void flatten(SkFlattenableWriteBuffer& wb) const SK_OVERRIDE;
 
     // Default impl returns false
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
                                SkBitmap* result, SkIPoint* offset);
     // Default impl copies src into dst and returns true
     virtual bool onFilterBounds(const SkIRect&, const SkMatrix&, SkIRect*);
 
+    // Sets rect to the intersection of rect and the crop rect. If there
+    // is no overlap, returns false and leaves rect unchanged.
+    bool applyCropRect(SkIRect* rect) const;
+
 private:
     typedef SkFlattenable INHERITED;
     int fInputCount;
     SkImageFilter** fInputs;
+    SkIRect fCropRect;
 };
 
 #endif