GrabWindowSnapshotTest.TestGrabWindowSnapshot fails in HighDPI

chrome/browser/ui/window_snapshot/window_snapshot_mac_unittest.mm

 // 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 "chrome/browser/ui/window_snapshot/window_snapshot.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/memory/scoped_nsobject.h"
 #include "base/memory/scoped_ptr.h"
 #include "testing/platform_test.h"
 #include "ui/gfx/rect.h"
 
+#if !defined(MAC_OS_X_VERSION_10_7) || \
+    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7
+
+@interface NSWindow (LionAPI)
+- (CGFloat)backingScaleFactor;
+@end
+
+#endif  // 10.7
+
 namespace chrome {
 namespace {
 
 typedef PlatformTest GrabWindowSnapshotTest;
 
 TEST_F(GrabWindowSnapshotTest, TestGrabWindowSnapshot) {
   // Launch a test window so we can take a snapshot.
   NSRect frame = NSMakeRect(0, 0, 400, 400);
   scoped_nsobject<NSWindow> window(
       [[NSWindow alloc] initWithContentRect:frame
                                   styleMask:NSBorderlessWindowMask
                                     backing:NSBackingStoreBuffered
                                       defer:NO]);
   [window setBackgroundColor:[NSColor whiteColor]];
   [window makeKeyAndOrderFront:NSApp];
 
   scoped_ptr<std::vector<unsigned char> > png_representation(
       new std::vector<unsigned char>);
   gfx::Rect bounds = gfx::Rect(0, 0, frame.size.width, frame.size.height);
   EXPECT_TRUE(internal::GrabWindowSnapshot(window, png_representation.get(),
                                            bounds));
 
   // Copy png back into NSData object so we can make sure we grabbed a png.
   scoped_nsobject<NSData> image_data(
       [[NSData alloc] initWithBytes:&(*png_representation)[0]
                              length:png_representation->size()]);
   NSBitmapImageRep* rep = [NSBitmapImageRep imageRepWithData:image_data.get()];
   EXPECT_TRUE([rep isKindOfClass:[NSBitmapImageRep class]]);
-  EXPECT_TRUE(CGImageGetWidth([rep CGImage]) == 400);
-  NSColor* color = [rep colorAtX:200 y:200];
+  CGFloat scaleFactor = 1.0f;
+  if ([window respondsToSelector:@selector(backingScaleFactor)])
+    scaleFactor = [window backingScaleFactor];
+  EXPECT_EQ(400UL * scaleFactor, CGImageGetWidth([rep CGImage]));

[Nico, 2012/09/21 03:37:44]

Do you need the UL? It's multiplied by a float, the result's float too.

[dhollowa, 2012/09/21 04:06:51]

Ah yes, I'd converted to UL prior to adding the scale factor fix.  Done.

On 2012/09/21 03:37:44, Nico wrote:

+  NSColor* color = [rep colorAtX:200 * scaleFactor y:200 * scaleFactor];
   CGFloat red = 0, green = 0, blue = 0, alpha = 0;
   [color getRed:&red green:&green blue:&blue alpha:&alpha];
   EXPECT_GE(red + green + blue, 3.0);
 }
 
 }  // namespace
 }  // namespace chrome