Modifies GetPlatformImageColor() to check the color of a given point.

ui/gfx/image/image_unittest_util.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.
 
 // Because the unit tests for gfx::Image are spread across multiple
 // implementation files, this header contains the reusable components.
 
 #include "base/memory/scoped_ptr.h"
 #include "ui/base/layout.h"
 #include "ui/gfx/image/image_unittest_util.h"
@@ skipping 121 matching lines @@
 #elif defined(TOOLKIT_GTK)
   return image.CopyGdkPixbuf();
 #else
   return *image.ToSkBitmap();
 #endif
 }
 
 #if defined(OS_MACOSX)
 // Defined in image_unittest_util_mac.mm.
 #elif defined(TOOLKIT_GTK)
-SkColor GetPlatformImageColor(PlatformImage image) {
+SkColor GetPlatformImageColor(PlatformImage image, int x, int y) {
+  int n_channels = gdk_pixbuf_get_n_channels(image);
+  int rowstride = gdk_pixbuf_get_rowstride(image);
   guchar* gdk_pixels = gdk_pixbuf_get_pixels(image);
-  guchar alpha = gdk_pixbuf_get_has_alpha(image) ? gdk_pixels[3] : 255;
-  return SkColorSetARGB(alpha, gdk_pixels[0], gdk_pixels[1], gdk_pixels[2]);
+
+  guchar* pixel = gdk_pixels + (y * rowstride) + (x * n_channels);

[Elliot Glaysher, 2012/09/19 17:47:11]

This is probably correct everywhere. (At least you took care of the main gotcha:
rowstride can sometimes != x * n_channels; it's usually rounded up to the
nearest word.

+  guchar alpha = gdk_pixbuf_get_has_alpha(image) ? pixel[3] : 255;
+  return SkColorSetARGB(alpha, pixel[0], pixel[1], pixel[2]);
 }
 #else
-SkColor GetPlatformImageColor(PlatformImage image) {
+SkColor GetPlatformImageColor(PlatformImage image, int x, int y) {
   SkAutoLockPixels auto_lock(image);
-  return image.getColor(10, 10);
+  return image.getColor(x, y);
 }
 #endif
 
 void CheckColor(SkColor color, bool is_red) {
   // Be tolerant of floating point rounding and lossy color space conversions.
   if (is_red) {
     EXPECT_GT(SkColorGetR(color), 0.95);
     EXPECT_LT(SkColorGetG(color), 0.05);
   } else {
     EXPECT_GT(SkColorGetG(color), 0.95);
@@ skipping 14 matching lines @@
 bool PlatformImagesEqual(PlatformImage image1, PlatformImage image2) {
 #if defined(OS_MACOSX) || defined(TOOLKIT_GTK)
   return image1 == image2;
 #else
   return image1.getPixels() == image2.getPixels();
 #endif
 }
 
 }  // namespace test
 }  // namespace gfx