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1 // Copyright (c) 2009 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2009 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "skia/ext/skia_utils_gtk.h" | 5 #include "skia/ext/skia_utils_gtk.h" |
6 | 6 |
7 #include <gdk/gdkcolor.h> | 7 #include <gdk/gdkcolor.h> |
8 | 8 |
9 namespace skia { | 9 namespace skia { |
10 | 10 |
11 const int kSkiaToGDKMultiplier = 257; | 11 const int kSkiaToGDKMultiplier = 257; |
12 | 12 |
| 13 // GDK_COLOR_RGB multiplies by 257 (= 0x10001) to distribute the bits evenly |
| 14 // See: http://www.mindcontrol.org/~hplus/graphics/expand-bits.html |
| 15 // To get back, we can just right shift by eight |
| 16 // (or, formulated differently, i == (i*257)/256 for all i < 256). |
| 17 |
13 SkColor GdkColorToSkColor(GdkColor color) { | 18 SkColor GdkColorToSkColor(GdkColor color) { |
14 return SkColorSetRGB(color.red, color.green, color.blue); | 19 return SkColorSetRGB(color.red >> 8, color.green >> 8, color.blue >> 8); |
15 } | 20 } |
16 | 21 |
17 GdkColor SkColorToGdkColor(SkColor color) { | 22 GdkColor SkColorToGdkColor(SkColor color) { |
18 GdkColor gdk_color = { | 23 GdkColor gdk_color = { |
19 0, | 24 0, |
20 SkColorGetR(color) * kSkiaToGDKMultiplier, | 25 SkColorGetR(color) * kSkiaToGDKMultiplier, |
21 SkColorGetG(color) * kSkiaToGDKMultiplier, | 26 SkColorGetG(color) * kSkiaToGDKMultiplier, |
22 SkColorGetB(color) * kSkiaToGDKMultiplier | 27 SkColorGetB(color) * kSkiaToGDKMultiplier |
23 }; | 28 }; |
24 return gdk_color; | 29 return gdk_color; |
25 } | 30 } |
26 | 31 |
27 } // namespace | 32 } // namespace |
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