Update documentation around drawBitmap and shaders

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 316 matching lines @@
 
     //////////////////////////////////////////////////////////////////////////
     //  Factory methods for stock shaders
 
     /** Call this to create a new shader that will draw with the specified bitmap.
      *
      *  If the bitmap cannot be used (e.g. has no pixels, or its dimensions
      *  exceed implementation limits (currently at 64K - 1)) then SkEmptyShader
      *  may be returned.
      *
+     *  If the src is kA8_Config then that mask will be colorized using the color on
+     *  the paint.
+     *
      *  @param src  The bitmap to use inside the shader
      *  @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.
      *  @return     Returns a new shader object. Note: this function never returns null.
     */
     static SkShader* CreateBitmapShader(const SkBitmap& src,
                                         TileMode tmx, TileMode tmy);
 
     SkDEVCODE(virtual void toString(SkString* str) const;)
 
@@ skipping 24 matching lines @@
     SkDEBUGCODE(SkBool8 fInSetContext;)
 
     static SkShader* CreateBitmapShader(const SkBitmap& src,
                                         TileMode, TileMode,
                                         void* storage, size_t storageSize);
     friend class SkAutoBitmapShaderInstall;
     typedef SkFlattenable INHERITED;
 };
 
 #endif