Fixes conversion from NSImage to ImageSkia when NSImageRep has size which isn't it's pixel size

ui/gfx/image/image_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 <Cocoa/Cocoa.h>
 
 #include "base/logging.h"
 #include "base/memory/scoped_nsobject.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/gfx/image/image.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/image/image_unittest_util.h"
 
 namespace {
 
 class ImageMacTest : public testing::Test {
  public:
   void CreateBitmapImageRep(int width, int height, NSImageRep** image_rep) {
+    // Create NSImageRep with point size |width|x|height|.
+    // Use resulting NSImageRep pixel size to detect device scale factor.
     scoped_nsobject<NSImage> image(
         [[NSImage alloc] initWithSize:NSMakeSize(width, height)]);
     [image lockFocus];
     [[NSColor redColor] set];
     NSRectFill(NSMakeRect(0, 0, width, height));
     [image unlockFocus];
     EXPECT_TRUE([[[image representations] lastObject]
         isKindOfClass:[NSImageRep class]]);
-    *image_rep = [[image representations] lastObject];
+    NSImageRep* point_sized_image_rep = [[image representations] lastObject];
+
+    // Create new NSBitmapImageRep with the correct size.
+    float x_scale = [point_sized_image_rep pixelsWide] / width;
+    float y_scale = [point_sized_image_rep pixelsHigh] / height;
+    NSRect request_rect = NSMakeRect(0, 0, static_cast<float>(width) / x_scale,

[Nico, 2012/06/11 05:05:14]

Remove static_cast<>, promotion rules do that implicitly

+        static_cast<float>(height) / y_scale);
+    [image lockFocus];
+    *image_rep = [[[NSBitmapImageRep alloc]
+        initWithFocusedViewRect:request_rect] autorelease];
+    [image unlockFocus];

[Nico, 2012/06/11 05:05:14]

…hm, this is pretty convoluted. Maybe it's simpler to create a NSBitmapImageRep
directly (
https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Applic...
) and then draw to it using graphicsContextWithBitmapImageRep: (
https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Applic...:
)?

   }
 };
 
 namespace gt = gfx::test;
 
+TEST_F(ImageMacTest, NSImageWithResizedNSImageRepToImageSkia) {
+  const int kWidth1x = 10;
+  const int kHeight1x = 12;
+  const int kWidth2x = 20;
+  const int kHeight2x = 24;
+
+  NSImageRep* image_rep;
+  CreateBitmapImageRep(kWidth2x, kHeight2x, &image_rep);
+
+  scoped_nsobject<NSImage> ns_image(
+      [[NSImage alloc] initWithSize:NSMakeSize(kWidth1x, kHeight1x)]);
+  [ns_image addRepresentation:image_rep];
+
+  [image_rep setSize:NSMakeSize(kWidth1x, kHeight1x)];
+
+  gfx::Image image(ns_image.release());
+  const gfx::ImageSkia* image_skia = image.ToImageSkia();
+
+  float scale_factor;
+  const SkBitmap& bitmap = image_skia->GetBitmapForScale(2.0f, 2.0f,
+                                                         &scale_factor);
+  EXPECT_EQ(2.0f, scale_factor);
+  EXPECT_EQ(kWidth2x, bitmap.width());
+  EXPECT_EQ(kHeight2x, bitmap.height());
+}
+
 TEST_F(ImageMacTest, MultiResolutionNSImageToImageSkia) {
-  const int width1x = 10;
-  const int height1x = 12;
-  const int width2x = 20;
-  const int height2x = 24;
+  const int kWidth1x = 10;
+  const int kHeight1x = 12;
+  const int kWidth2x = 20;
+  const int kHeight2x = 24;
 
   NSImageRep* image_rep_1;
-  CreateBitmapImageRep(width1x, height1x, &image_rep_1);
+  CreateBitmapImageRep(kWidth1x, kHeight1x, &image_rep_1);
   NSImageRep* image_rep_2;
-  CreateBitmapImageRep(width2x, height2x, &image_rep_2);
+  CreateBitmapImageRep(kWidth2x, kHeight2x, &image_rep_2);
   scoped_nsobject<NSImage> ns_image(
-      [[NSImage alloc] initWithSize:NSMakeSize(width1x, height1x)]);
+      [[NSImage alloc] initWithSize:NSMakeSize(kWidth1x, kHeight1x)]);
   [ns_image addRepresentation:image_rep_1];
   [ns_image addRepresentation:image_rep_2];
 
   gfx::Image image(ns_image.release());
 
   EXPECT_EQ(1u, image.RepresentationCount());
 
   const gfx::ImageSkia* image_skia = image.ToImageSkia();
   EXPECT_EQ(2u, image_skia->bitmaps().size());
 
   float scale_factor;
   const SkBitmap& bitmap1x = image_skia->GetBitmapForScale(1.0f, 1.0f,
                                                            &scale_factor);
   EXPECT_TRUE(!bitmap1x.isNull());
   EXPECT_EQ(1.0f, scale_factor);
-  EXPECT_EQ(width1x, bitmap1x.width());
-  EXPECT_EQ(height1x, bitmap1x.height());
+  EXPECT_EQ(kWidth1x, bitmap1x.width());
+  EXPECT_EQ(kHeight1x, bitmap1x.height());
 
   const SkBitmap& bitmap2x = image_skia->GetBitmapForScale(2.0f, 2.0f,
                                                            &scale_factor);
   EXPECT_TRUE(!bitmap2x.isNull());
   EXPECT_EQ(2.0f, scale_factor);
-  EXPECT_EQ(width2x, bitmap2x.width());
-  EXPECT_EQ(height2x, bitmap2x.height());
+  EXPECT_EQ(kWidth2x, bitmap2x.width());
+  EXPECT_EQ(kHeight2x, bitmap2x.height());
 
   // ToImageSkia should create a second representation.
   EXPECT_EQ(2u, image.RepresentationCount());
 }
 
 TEST_F(ImageMacTest, MultiResolutionImageSkiaToNSImage) {
-  const int width1x = 10;
-  const int height1x= 12;
-  const int width2x = 20;
-  const int height2x = 24;
+  const int kWidth1x = 10;
+  const int kHeight1x= 12;
+  const int kWidth2x = 20;
+  const int kHeight2x = 24;
 
   gfx::ImageSkia image_skia;
-  image_skia.AddBitmapForScale(gt::CreateBitmap(width1x, height1x), 1.0f);
-  image_skia.AddBitmapForScale(gt::CreateBitmap(width2x, height2x), 2.0f);
+  image_skia.AddBitmapForScale(gt::CreateBitmap(kWidth1x, kHeight1x), 1.0f);
+  image_skia.AddBitmapForScale(gt::CreateBitmap(kWidth2x, kHeight2x), 2.0f);
 
   gfx::Image image(image_skia);
 
   EXPECT_EQ(1u, image.RepresentationCount());
   EXPECT_EQ(2u, image.ToImageSkia()->bitmaps().size());
 
   NSImage* ns_image = image;
   EXPECT_TRUE(ns_image);
 
   // Image size should be the same as the 1x bitmap.
-  EXPECT_EQ([ns_image size].width, width1x);
-  EXPECT_EQ([ns_image size].height, height1x);
+  EXPECT_EQ([ns_image size].width, kWidth1x);
+  EXPECT_EQ([ns_image size].height, kHeight1x);
 
   EXPECT_EQ(2u, [[image representations] count]);
   NSImageRep* image_rep_1 = [[image representations] objectAtIndex:0];
   NSImageRep* image_rep_2 = [[image representations] objectAtIndex:1];
 
-  if ([image_rep_1 size].width == width1x) {
-    EXPECT_EQ([image_rep_1 size].width, width1x);
-    EXPECT_EQ([image_rep_1 size].height, height1x);
-    EXPECT_EQ([image_rep_2 size].width, width2x);
-    EXPECT_EQ([image_rep_2 size].height, height2x);
+  if ([image_rep_1 size].width == kWidth1x) {
+    EXPECT_EQ([image_rep_1 size].width, kWidth1x);
+    EXPECT_EQ([image_rep_1 size].height, kHeight1x);
+    EXPECT_EQ([image_rep_2 size].width, kWidth2x);
+    EXPECT_EQ([image_rep_2 size].height, kHeight2x);
   } else {
-    EXPECT_EQ([image_rep_1 size].width, width2x);
-    EXPECT_EQ([image_rep_1 size].height, height2x);
-    EXPECT_EQ([image_rep_2 size].width, width1x);
-    EXPECT_EQ([image_rep_2 size].height, height1x);
+    EXPECT_EQ([image_rep_1 size].width, kWidth2x);
+    EXPECT_EQ([image_rep_1 size].height, kHeight2x);
+    EXPECT_EQ([image_rep_2 size].width, kWidth1x);
+    EXPECT_EQ([image_rep_2 size].height, kHeight1x);
   }
 
   // Cast to NSImage* should create a second representation.
   EXPECT_EQ(2u, image.RepresentationCount());
 }
 
 } // namespace