refactor code to apply the croprect

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 14 matching lines @@
 
 /**
  *  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
  *  then be handed to the imagefilter, who in turn creates a new bitmap which
  *  is what will finally be drawn to the device (using the original xfermode).
  */
 class SK_API SkImageFilter : public SkFlattenable {
 public:
-    class CropRect {
-    public:
-        enum CropEdge {
-            kHasLeft_CropEdge   = 0x01,
-            kHasTop_CropEdge    = 0x02,
-            kHasRight_CropEdge  = 0x04,
-            kHasBottom_CropEdge = 0x08,
-            kHasAll_CropEdge    = 0x0F,
-        };
-        CropRect() {}
-        explicit CropRect(const SkRect& rect, uint32_t flags = kHasAll_CropEdge) : fRect(rect), fFlags(flags) {}
-        uint32_t flags() const { return fFlags; }
-        const SkRect& rect() const { return fRect; }
-    private:
-        SkRect fRect;
-        uint32_t fFlags;
-    };
-
     // This cache maps from (filter's unique ID + CTM + clipBounds + src bitmap generation ID) to
     // (result, offset).
     class Cache : public SkRefCnt {
     public:
         struct Key;
         virtual ~Cache() {}
         static Cache* Create(size_t maxBytes);
         static Cache* Get();
         virtual bool get(const Key& key, SkBitmap* result, SkIPoint* offset) const = 0;
         virtual void set(const Key& key, const SkBitmap& result, const SkIPoint& offset) = 0;
         virtual void purge() {}
     };
 
     class Context {
     public:
         Context(const SkMatrix& ctm, const SkIRect& clipBounds, Cache* cache) :
             fCTM(ctm), fClipBounds(clipBounds), fCache(cache) {
         }
         const SkMatrix& ctm() const { return fCTM; }
         const SkIRect& clipBounds() const { return fClipBounds; }
         Cache* cache() const { return fCache; }
     private:
         SkMatrix fCTM;
         SkIRect  fClipBounds;
         Cache*   fCache;
     };
 
+    class CropRect {
+    public:
+        enum CropEdge {
+            kHasLeft_CropEdge   = 0x01,
+            kHasTop_CropEdge    = 0x02,
+            kHasRight_CropEdge  = 0x04,
+            kHasBottom_CropEdge = 0x08,
+            kHasAll_CropEdge    = 0x0F,
+        };
+        CropRect() {}
+        explicit CropRect(const SkRect& rect, uint32_t flags = kHasAll_CropEdge)
+            : fRect(rect), fFlags(flags) {}
+        uint32_t flags() const { return fFlags; }
+        const SkRect& rect() const { return fRect; }
+#ifndef SK_IGNORE_TO_STRING
+        void toString(SkString* str) const;
+#endif
+
+        /**
+         *  Apply this cropRect to the imageBounds. If a given edge of the cropRect is not
+         *  set, then the corresponding edge from imageBounds will be used.
+         *
+         *  Note: imageBounds is in "device" space, as the output cropped rectangle will be,
+         *  so the context's CTM is ignore for those. It is only applied the croprect's bounds.
+         *
+         *  The resulting rect will be intersected with the context's clip. If that intersection is
+         *  empty, then this returns false and cropped is unmodified.
+         */
+        bool applyTo(const SkIRect& imageBounds, const Context&, SkIRect* cropped) const;
+
+    private:
+        SkRect fRect;
+        uint32_t fFlags;
+    };
+
     class Proxy {
     public:
         Proxy(SkBaseDevice* device) : fDevice(device) { }
 
         SkBaseDevice* createDevice(int width, int height);
 
         // Returns true if the proxy handled the filter itself. If this returns
         // false then the filter's code will be called.
         bool filterImage(const SkImageFilter*, const SkBitmap& src, const SkImageFilter::Context&,
                          SkBitmap* result, SkIPoint* offset);
@@ skipping 85 matching lines @@
      *  connected.  The indices used are filter-specific.
      */
     SkImageFilter* getInput(int i) const {
         SkASSERT(i < fInputCount);
         return fInputs[i];
     }
 
     /**
      *  Returns whether any edges of the crop rect have been set. The crop
      *  rect is set at construction time, and determines which pixels from the
-     *  input image will be processed. The size of the crop rect should be
+     *  input image will be processed, and which pixels in the output image will be allowed.
+     *  The size of the crop rect 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.)
      */
     bool cropRectIsSet() const { return fCropRect.flags() != 0x0; }
 
     CropRect getCropRect() const { return fCropRect; }
 
@@ skipping 167 matching lines @@
  */
 #define SK_IMAGEFILTER_UNFLATTEN_COMMON(localVar, expectedCount)    \
     Common localVar;                                                \
     do {                                                            \
         if (!localVar.unflatten(buffer, expectedCount)) {           \
             return NULL;                                            \
         }                                                           \
     } while (0)
 
 #endif