Add SkImage->draw() call with src and dst rects.

src/image/SkImagePriv.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkImagePriv.h"
 #include "SkCanvas.h"
 #include "SkPicture.h"
@@ skipping 123 matching lines @@
         canvas->saveLayer(&bounds, paint);
         canvas->translate(x, y);
     } else if (x || y) {
         canvas->save();
         canvas->translate(x, y);
     }
 
     canvas->drawPicture(*picture);
     canvas->restoreToCount(saveCount);
 }
+
+void SkImagePrivDrawPicture(SkCanvas* canvas, SkPicture* picture,
+                            const SkRect* src,  const SkRect& dst, const SkPaint* paint) {  
+    int saveCount = canvas->getSaveCount();  
+
+    SkMatrix     matrix;
+    SkRect       pictureBounds, tmpSrc;
+
+    pictureBounds.set(0, 0,

[reed1, 2013/07/19 20:28:52]

minor, but might move the initialization of pictureBounds inside the else where
it is used, to avoid the cost of the int-to-float conversion when not needed.

+                      SkIntToScalar(picture->width()),
+                      SkIntToScalar(picture->height()));
+    if (NULL != src) {
+        tmpSrc = *src;
+    } else {
+        tmpSrc = pictureBounds;
+    }
+
+    matrix.setRectToRect(tmpSrc, dst, SkMatrix::kFill_ScaleToFit);
+    if (paint && needs_layer(*paint)) {
+        canvas->saveLayer(&dst, paint);
+    } else {
+        canvas->save();
+    }
+    canvas->concat(matrix);
+    if (!paint || !needs_layer(*paint)) {
+        canvas->clipRect(tmpSrc);
+    }
+    
+    canvas->drawPicture(*picture);
+    canvas->restoreToCount(saveCount);
+}