use colortype instead of config

include/core/SkImageInfo.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImageInfo_DEFINED
 #define SkImageInfo_DEFINED
 
@@ skipping 171 matching lines @@
     SkAlphaType alphaType() const { return fAlphaType; }
 
     bool isEmpty() const { return fWidth <= 0 || fHeight <= 0; }
 
     bool isOpaque() const {
         return SkAlphaTypeIsOpaque(fAlphaType);
     }
 
     SkISize dimensions() const { return SkISize::Make(fWidth, fHeight); }
 
+    /**
+     *  Return a new ImageInfo with the same colortype and alphatype as this info,
+     *  but with the specified width and height.
+     */
+    SkImageInfo makeWH(int newWidth, int newHeight) const {
+        return SkImageInfo::Make(newWidth, newHeight, fColorType, fAlphaType);
+    }
+
     int bytesPerPixel() const {
         return SkColorTypeBytesPerPixel(fColorType);
     }
 
     uint64_t minRowBytes64() const {
         return sk_64_mul(fWidth, this->bytesPerPixel());
     }
 
     size_t minRowBytes() const {
         return (size_t)this->minRowBytes64();
@@ skipping 22 matching lines @@
 
     bool validRowBytes(size_t rowBytes) const {
         uint64_t rb = sk_64_mul(fWidth, this->bytesPerPixel());
         return rowBytes >= rb;
     }
 
     SkDEBUGCODE(void validate() const;)
 };
 
 #endif