use colortype instead of config

src/core/SkBitmap_scroll.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkBitmap.h"
 #include "SkRegion.h"
 
 bool SkBitmap::scrollRect(const SkIRect* subset, int dx, int dy,
                           SkRegion* inval) const
 {
-    if (this->isImmutable()) {
+    if (this->isImmutable() || kUnknown_SkColorType == this->colorType()) {
         return false;
     }
 
     if (NULL != subset) {
         SkBitmap tmp;
 
         return  this->extractSubset(&tmp, *subset) &&
                 // now call again with no rectangle
                 tmp.scrollRect(NULL, dx, dy, inval);
     }
 
-    int shift;
-
-    switch (this->config()) {
-    case kIndex8_Config:
-    case kA8_Config:
-        shift = 0;
-        break;
-    case kARGB_4444_Config:
-    case kRGB_565_Config:
-        shift = 1;
-        break;
-    case kARGB_8888_Config:
-        shift = 2;
-        break;
-    default:
-        // can't scroll this config
-        return false;
-    }
-
+    int shift = this->bytesPerPixel() >> 1;
     int width = this->width();
     int height = this->height();
 
     // check if there's nothing to do
     if ((dx | dy) == 0 || width <= 0 || height <= 0) {
         if (NULL != inval) {
             inval->setEmpty();
         }
         return true;
     }
@@ skipping 59 matching lines @@
     width <<= shift;    // now width is the number of bytes to move per line
     while (--height >= 0) {
         memmove(dst, src, width);
         dst += rowBytes;
         src += rowBytes;
     }
 
     this->notifyPixelsChanged();
     return true;
 }