Fix a unit test failure. One of the tests sends an empty bitmap through this...

skia/ext/image_operations.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 #define _USE_MATH_DEFINES
 #include <cmath>
 #include <limits>
 #include <vector>
 
 #include "skia/ext/image_operations.h"
@@ skipping 608 matching lines @@
 
       dst_row[x] = source_row[x_pix];
     }
   }
 
   return cropped;
 }
 
 // static
 SkBitmap ImageOperations::DownsampleByTwo(const SkBitmap& bitmap) {
-  DCHECK(bitmap.getConfig() == SkBitmap::kARGB_8888_Config);

[Peter Kasting, 2009/06/09 21:10:46]

Instead of removing this, the right fix seems like moving it below the "nop
case".  That will avoid DCHECKing unless we're actually going to do something
destructive, but still catch the bad case.  The unit tests would pass with that.

-
   // Handle the nop case.
   if (bitmap.width() <= 1 || bitmap.height() <= 1)
     return bitmap;
 
   SkBitmap result;
   result.setConfig(SkBitmap::kARGB_8888_Config,
                    (bitmap.width() + 1) / 2,
                    (bitmap.height() + 1) / 2);
   result.allocPixels();
 
@@ skipping 30 matching lines @@
       ag += (tmp >> 8) & 0xFF00FF;
       rb += tmp & 0xFF00FF;
       if (src_x < bitmap.width() - 1)
         cur_src += 1;
 
       // Bottom right pixel of the 2x2 block.
       tmp = *cur_src;
       ag += (tmp >> 8) & 0xFF00FF;
       rb += tmp & 0xFF00FF;
 
-      // PUt the channels back together, dividing each by 4 to get the average.
+      // Put the channels back together, dividing each by 4 to get the average.
       // |ag| has the alpha and green channels shifted right by 8 bits from
       // there they should end up, so shifting left by 6 gives them in the
       // correct position divided by 4.
       *result.getAddr32(dest_x, dest_y) =
           ((rb >> 2) & 0xFF00FF) | ((ag << 6) & 0xFF00FF00);
     }
   }
 
   return result;
 }
 
 // static
 SkBitmap ImageOperations::DownsampleByTwoUntilSize(const SkBitmap& bitmap,
                                                    int min_w, int min_h) {
   if (bitmap.width() <= min_w || bitmap.height() <= min_h ||
       min_w < 0 || min_h < 0)
     return bitmap;
 
   // Since bitmaps are refcounted, this copy will be fast.
   SkBitmap current = bitmap;
   while (current.width() >= min_w * 2 && current.height() >= min_h * 2 &&
          current.width() > 1 && current.height() > 1)
     current = DownsampleByTwo(current);
   return current;
 }
 
 }  // namespace skia