Fix premultiplication mismatch

chrome/renderer/extensions/extension_process_bindings.cc

 // Copyright (c) 2009 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 <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "chrome/renderer/extensions/extension_process_bindings.h"
@@ skipping 416 matching lines @@
       return v8::Undefined();
     }
 
     SkBitmap bitmap;
     bitmap.setConfig(SkBitmap::kARGB_8888_Config, width, height);
     bitmap.allocPixels();
     bitmap.eraseARGB(0, 0, 0, 0);
 
     uint32_t* pixels = bitmap.getAddr32(0, 0);
     for (int t = 0; t < width*height; t++) {
-      // |data| is RGBA, pixels is ARGB.
-      pixels[t] =
-          ((data->Get(v8::Integer::New(4*t + 3))->Int32Value() & 0xFF) << 24) |
-          ((data->Get(v8::Integer::New(4*t + 0))->Int32Value() & 0xFF) << 16) |
-          ((data->Get(v8::Integer::New(4*t + 1))->Int32Value() & 0xFF) << 8) |
-          ((data->Get(v8::Integer::New(4*t + 2))->Int32Value() & 0xFF) << 0);
+      // |data| is RGBA not premutiplied, pixels is ARGB premultiplied.

[tony, 2009/10/23 16:52:17]

Drive-by-nit: third_party/skia/include/core/SkColor.h has SkPreMultiply*
methods.  SkUnPreMultiply.h has the reverse.

+      uint32_t r = data->Get(v8::Integer::New(4*t + 0))->Int32Value();
+      uint32_t g = data->Get(v8::Integer::New(4*t + 1))->Int32Value();
+      uint32_t b = data->Get(v8::Integer::New(4*t + 2))->Int32Value();
+      uint32_t a = data->Get(v8::Integer::New(4*t + 3))->Int32Value();
+      pixels[t] = (a & 0xFF) << 24 |
+                  (r * a / 0xFF & 0xFF) << 16 |
+                  (g * a / 0xFF & 0xFF) << 8 |
+                  (b * a / 0xFF & 0xFF);
     }
 
     // Construct the Value object.
     IPC::Message bitmap_pickle;
     IPC::WriteParam(&bitmap_pickle, bitmap);
     Value* bitmap_value = BinaryValue::CreateWithCopiedBuffer(
         static_cast<const char*>(bitmap_pickle.data()), bitmap_pickle.size());
 
     DictionaryValue* dict = new DictionaryValue();
     dict->Set(L"imageData", bitmap_value);
@@ skipping 151 matching lines @@
     return;
 
   v8::HandleScope handle_scope;
   WebFrame* frame = view->mainFrame();
   v8::Local<v8::Context> context = frame->mainWorldScriptContext();
   v8::Handle<v8::Value> argv[1];
   argv[0] = v8::String::New(type_str);
   bindings_utils::CallFunctionInContext(context, "setViewType",
                                         arraysize(argv), argv);
 }