Fix alpha pre-multiplication error with custom cursor images

content/common/cursors/webcursor_unittest.cc

 // Copyright (c) 2012 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/pickle.h"
 #include "content/common/cursors/webcursor.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/WebKit/public/platform/WebCursorInfo.h"
 
 using blink::WebCursorInfo;
@@ skipping 132 matching lines @@
   ok_custom_pickle.WriteInt(2);
   // Scale
   ok_custom_pickle.WriteFloat(1.0);
   // Data len including enough data for a 2x2 image.
   ok_custom_pickle.WriteInt(4 * 4);
   for (size_t i = 0; i < 4; i++)
     ok_custom_pickle.WriteUInt32(0);
   // Custom Windows message.
   ok_custom_pickle.WriteUInt32(0);
   base::PickleIterator iter(ok_custom_pickle);
-  ASSERT_TRUE(custom_cursor.Deserialize(&iter));
+  EXPECT_TRUE(custom_cursor.Deserialize(&iter));
 
   // Convert to WebCursorInfo, make sure the hotspot got clamped.
   WebCursor::CursorInfo info;
   custom_cursor.GetCursorInfo(&info);
   EXPECT_EQ(gfx::Point(1, 1), info.hotspot);
 
   // Set hotspot to an invalid point again, pipe back through WebCursor,
   // and make sure the hotspot got clamped again.
   info.hotspot = gfx::Point(-1, -1);
   custom_cursor.InitFromCursorInfo(info);
@@ skipping 14 matching lines @@
   // Scale
   broken_cursor_pickle.WriteFloat(1.0);
   // No data for the image since the size is 0.
   broken_cursor_pickle.WriteInt(0);
   // Custom Windows message.
   broken_cursor_pickle.WriteInt(0);
 
   // Make sure we can read this on all platforms; it is technicaally a valid
   // cursor.
   base::PickleIterator iter(broken_cursor_pickle);
-  ASSERT_TRUE(custom_cursor.Deserialize(&iter));
+  EXPECT_TRUE(custom_cursor.Deserialize(&iter));
 }
 
 TEST(WebCursorTest, Scale2) {
   WebCursor custom_cursor;
   // This is a valid custom cursor.
   base::Pickle ok_custom_pickle;
   // Type and hotspots.
   ok_custom_pickle.WriteInt(WebCursorInfo::TypeCustom);
   ok_custom_pickle.WriteInt(0);
   ok_custom_pickle.WriteInt(0);
   // X & Y
   ok_custom_pickle.WriteInt(1);
   ok_custom_pickle.WriteInt(1);
   // Scale - 2 image pixels per UI pixel.
   ok_custom_pickle.WriteFloat(2.0);
   // Data len including enough data for a 1x1 image.
   ok_custom_pickle.WriteInt(4);
   ok_custom_pickle.WriteUInt32(0);
   // Custom Windows message.
   ok_custom_pickle.WriteUInt32(0);
   base::PickleIterator iter(ok_custom_pickle);
   EXPECT_TRUE(custom_cursor.Deserialize(&iter));
 }
 
+TEST(WebCursorTest, AlphaConversion) {
+  SkBitmap bitmap;
+  SkPMColor testColor = SkPreMultiplyARGB(10, 255, 255, 255);
+  bitmap.allocN32Pixels(1,1);
+  SkAutoLockPixels bitmap_lock(bitmap);
+  *bitmap.getAddr32(0, 0) = testColor;
+  WebCursor::CursorInfo cursor_info;
+  cursor_info.type = WebCursorInfo::TypeCustom;
+  cursor_info.custom_image = bitmap;
+  cursor_info.image_scale_factor = 1;
+  WebCursor custom_cursor;
+
+  // This round trip will convert the cursor to unpremultiplied form
+  custom_cursor.InitFromCursorInfo(cursor_info);
+  custom_cursor.GetCursorInfo(&cursor_info);
+  {
+    SkAutoLockPixels lock(cursor_info.custom_image);
+    EXPECT_EQ(kUnpremul_SkAlphaType, cursor_info.custom_image.alphaType());
+    EXPECT_EQ(testColor,
+              SkPreMultiplyColor(*cursor_info.custom_image.getAddr32(0,0)));
+  }
+
+  // Second round trip should not do any conversion because data is alread
+  // unpremultiplied
+  custom_cursor.InitFromCursorInfo(cursor_info);
+  custom_cursor.GetCursorInfo(&cursor_info);
+  {
+    SkAutoLockPixels lock(cursor_info.custom_image);
+    EXPECT_EQ(kUnpremul_SkAlphaType, cursor_info.custom_image.alphaType());
+    EXPECT_EQ(testColor,
+              SkPreMultiplyColor(*cursor_info.custom_image.getAddr32(0,0)));
+  }
+}
+
 }  // namespace content