speed up maprect for scale+trans case

include/core/SkMatrix.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkMatrix_DEFINED
@@ skipping 543 matching lines @@
         bottom-right, and bottom-left points transformed by the matrix.
         @param dst  Where the transformed quad is written.
         @param rect The original rectangle to be transformed.
     */
     void mapRectToQuad(SkPoint dst[4], const SkRect& rect) const {
         // This could potentially be faster if we only transformed each x and y of the rect once.
         rect.toQuad(dst);
         this->mapPoints(dst, 4);
     }
 
+    /**
+     *  Maps a rect to another rect, asserting (in debug mode) that the matrix only contains
+     *  scale and translate elements. If it contains other elements, the results are undefined.
+     */
+    void mapRectScaleTranslate(SkRect* dst, const SkRect& src) const;
+    
     /** Return the mean radius of a circle after it has been mapped by
         this matrix. NOTE: in perspective this value assumes the circle
         has its center at the origin.
     */
     SkScalar mapRadius(SkScalar radius) const;
 
     typedef void (*MapXYProc)(const SkMatrix& mat, SkScalar x, SkScalar y,
                                  SkPoint* result);
 
     static MapXYProc GetMapXYProc(TypeMask mask) {
@@ skipping 256 matching lines @@
 
     static void Affine_vpts(const SkMatrix&, SkPoint dst[], const SkPoint[], int);
 
     static const MapPtsProc gMapPtsProcs[];
 
     friend class SkPerspIter;
 };
 SK_END_REQUIRE_DENSE
 
 #endif