Explicit tile bounds for SkPictureShader

include/core/SkShader.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 SkShader_DEFINED
 #define SkShader_DEFINED
@@ skipping 410 matching lines @@
                                         const SkMatrix* localMatrix = NULL);
 
     /** Call this to create a new shader that will draw with the specified picture.
      *
      *  @param src  The picture to use inside the shader (if not NULL, its ref count
      *              is incremented). The SkPicture must not be changed after
      *              successfully creating a picture shader.
      *              FIXME: src cannot be const due to SkCanvas::drawPicture
      *  @param tmx  The tiling mode to use when sampling the bitmap in the x-direction.
      *  @param tmy  The tiling mode to use when sampling the bitmap in the y-direction.
+     *  @param tile The tile rectangle in picture coordinates: this represents the subset
+     *              (or superset) of the picture used when building a tile. It is not
+     *              affected by localMatrix and does not imply scaling (only translation
+     *              and cropping). If null, the tile rect is considered equal to the picture
+     *              bounds.
      *  @return     Returns a new shader object. Note: this function never returns null.
     */
-    static SkShader* CreatePictureShader(SkPicture* src, TileMode tmx, TileMode tmy,
-                                         const SkMatrix* localMatrix = NULL);
+    static SkShader* CreatePictureShader(SkPicture* src,
+                                         TileMode tmx, TileMode tmy,
+                                         const SkMatrix* localMatrix,
+                                         const SkRect* tile);
 
     /**
      *  Return a shader that will apply the specified localMatrix to the proxy shader.
      *  The specified matrix will be applied before any matrix associated with the proxy.
      *
      *  Note: ownership of the proxy is not transferred (though a ref is taken).
      */
     static SkShader* CreateLocalMatrixShader(SkShader* proxy, const SkMatrix& localMatrix);
 
     /**
@@ skipping 25 matching lines @@
     // constructors.
     SkMatrix fLocalMatrix;
 
     // So the SkLocalMatrixShader can whack fLocalMatrix in its SkReadBuffer constructor.
     friend class SkLocalMatrixShader;
 
     typedef SkFlattenable INHERITED;
 };
 
 #endif