Merge 20040 - Fix retarded bitmath. << 8 != * 255...

base/gfx/png_encoder.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.
 
 #include "base/basictypes.h"
 #include "base/gfx/png_encoder.h"
 #include "base/logging.h"
 #include "base/scoped_ptr.h"
 #include "third_party/skia/include/core/SkBitmap.h"
+#include "third_party/skia/include/core/SkUnPreMultiply.h"
 
 extern "C" {
 #include "third_party/libpng/png.h"
 }
 
 namespace {
 
 // Converts BGRA->RGBA and RGBA->BGRA.
 void ConvertBetweenBGRAandRGBA(const unsigned char* input, int pixel_width,
                                unsigned char* output) {
@@ skipping 187 matching lines @@
   scoped_array<unsigned char> divided(
       new unsigned char[input.width() * input.height() * bbp]);
 
   int i = 0;
   for (int y = 0; y < input.height(); y++) {
     for (int x = 0; x < input.width(); x++) {
       uint32 pixel = input.getAddr32(0, y)[x];
 
       int alpha = SkColorGetA(pixel);
       if (alpha != 0 && alpha != 255) {
-        divided[i + 0] = (SkColorGetR(pixel) << 8) / alpha;
-        divided[i + 1] = (SkColorGetG(pixel) << 8) / alpha;
-        divided[i + 2] = (SkColorGetB(pixel) << 8) / alpha;
+        SkColor unmultiplied = SkUnPreMultiply::PMColorToColor(pixel);
+        divided[i + 0] = SkColorGetR(unmultiplied);
+        divided[i + 1] = SkColorGetG(unmultiplied);
+        divided[i + 2] = SkColorGetB(unmultiplied);
         divided[i + 3] = alpha;
       } else {
         divided[i + 0] = SkColorGetR(pixel);
         divided[i + 1] = SkColorGetG(pixel);
         divided[i + 2] = SkColorGetB(pixel);
         divided[i + 3] = alpha;
       }
       i += bbp;
     }
   }
 
   return Encode(divided.get(),
                 PNGEncoder::FORMAT_RGBA, input.width(), input.height(),
                 input.width() * bbp, discard_transparency, output);
 }