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

base/gfx/png_decoder.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/gfx/png_decoder.h"
 
 #include "base/logging.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
 extern "C" {
@@ skipping 311 matching lines @@
   std::vector<unsigned char> decoded_data;
   if (PNGDecoder::Decode(&data->front(), data->size(), PNGDecoder::FORMAT_BGRA,
                          &decoded_data, &width, &height)) {
     bitmap->setConfig(SkBitmap::kARGB_8888_Config, width, height);
     bitmap->allocPixels();
     unsigned char* bitmap_data =
         reinterpret_cast<unsigned char*>(bitmap->getAddr32(0, 0));
     for (int i = width * height * 4 - 4; i >= 0; i -= 4) {
       unsigned char alpha = decoded_data[i + 3];
       if (alpha != 0 && alpha != 255) {
+        SkColor premultiplied = SkPreMultiplyARGB(alpha,
+            decoded_data[i], decoded_data[i + 1], decoded_data[i + 2]);
         bitmap_data[i + 3] = alpha;
-        bitmap_data[i] = (decoded_data[i] * alpha) >> 8;
-        bitmap_data[i + 1] = (decoded_data[i + 1] * alpha) >> 8;
-        bitmap_data[i + 2] = (decoded_data[i + 2] * alpha) >> 8;
+        bitmap_data[i] = SkColorGetR(premultiplied);
+        bitmap_data[i + 1] = SkColorGetG(premultiplied);
+        bitmap_data[i + 2] = SkColorGetB(premultiplied);
       } else {
         bitmap_data[i + 3] = alpha;
         bitmap_data[i] = decoded_data[i];
         bitmap_data[i + 1] = decoded_data[i + 1];
         bitmap_data[i + 2] = decoded_data[i + 2];
       }
     }
     return true;
   }
   return false;
@@ skipping 16 matching lines @@
     }
     bitmap_data[i + 3] = alpha;
     bitmap_data[i] = (bgra[i] * alpha) >> 8;
     bitmap_data[i + 1] = (bgra[i + 1] * alpha) >> 8;
     bitmap_data[i + 2] = (bgra[i + 2] * alpha) >> 8;
   }
 
   bitmap->setIsOpaque(opaque);
   return bitmap;
 }