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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 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 #ifndef UI_GFX_COLOR_UTILS_H_ | 5 #ifndef UI_GFX_COLOR_UTILS_H_ |
6 #define UI_GFX_COLOR_UTILS_H_ | 6 #define UI_GFX_COLOR_UTILS_H_ |
7 | 7 |
8 #include "base/basictypes.h" | 8 #include "base/basictypes.h" |
9 #include "third_party/skia/include/core/SkColor.h" | 9 #include "third_party/skia/include/core/SkColor.h" |
10 #include "ui/gfx/gfx_export.h" | 10 #include "ui/gfx/gfx_export.h" |
11 | 11 |
12 class SkBitmap; | 12 class SkBitmap; |
13 | 13 |
14 namespace color_utils { | 14 namespace color_utils { |
15 | 15 |
16 // Represents an HSL color. | 16 // Represents an HSL color. |
17 struct HSL { | 17 struct HSL { |
18 double h; | 18 double h; |
19 double s; | 19 double s; |
20 double l; | 20 double l; |
21 }; | 21 }; |
22 | 22 |
23 UI_EXPORT unsigned char GetLuminanceForColor(SkColor color); | 23 GFX_EXPORT unsigned char GetLuminanceForColor(SkColor color); |
24 | 24 |
25 // Calculated according to http://www.w3.org/TR/WCAG20/#relativeluminancedef | 25 // Calculated according to http://www.w3.org/TR/WCAG20/#relativeluminancedef |
26 UI_EXPORT double RelativeLuminance(SkColor color); | 26 GFX_EXPORT double RelativeLuminance(SkColor color); |
27 | 27 |
28 // Note: these transformations assume sRGB as the source color space | 28 // Note: these transformations assume sRGB as the source color space |
29 UI_EXPORT void SkColorToHSL(SkColor c, HSL* hsl); | 29 GFX_EXPORT void SkColorToHSL(SkColor c, HSL* hsl); |
30 UI_EXPORT SkColor HSLToSkColor(const HSL& hsl, SkAlpha alpha); | 30 GFX_EXPORT SkColor HSLToSkColor(const HSL& hsl, SkAlpha alpha); |
31 | 31 |
32 // HSL-Shift an SkColor. The shift values are in the range of 0-1, with the | 32 // HSL-Shift an SkColor. The shift values are in the range of 0-1, with the |
33 // option to specify -1 for 'no change'. The shift values are defined as: | 33 // option to specify -1 for 'no change'. The shift values are defined as: |
34 // hsl_shift[0] (hue): The absolute hue value - 0 and 1 map | 34 // hsl_shift[0] (hue): The absolute hue value - 0 and 1 map |
35 // to 0 and 360 on the hue color wheel (red). | 35 // to 0 and 360 on the hue color wheel (red). |
36 // hsl_shift[1] (saturation): A saturation shift, with the | 36 // hsl_shift[1] (saturation): A saturation shift, with the |
37 // following key values: | 37 // following key values: |
38 // 0 = remove all color. | 38 // 0 = remove all color. |
39 // 0.5 = leave unchanged. | 39 // 0.5 = leave unchanged. |
40 // 1 = fully saturate the image. | 40 // 1 = fully saturate the image. |
41 // hsl_shift[2] (lightness): A lightness shift, with the | 41 // hsl_shift[2] (lightness): A lightness shift, with the |
42 // following key values: | 42 // following key values: |
43 // 0 = remove all lightness (make all pixels black). | 43 // 0 = remove all lightness (make all pixels black). |
44 // 0.5 = leave unchanged. | 44 // 0.5 = leave unchanged. |
45 // 1 = full lightness (make all pixels white). | 45 // 1 = full lightness (make all pixels white). |
46 UI_EXPORT SkColor HSLShift(SkColor color, const HSL& shift); | 46 GFX_EXPORT SkColor HSLShift(SkColor color, const HSL& shift); |
47 | 47 |
48 // Determine if a given alpha value is nearly completely transparent. | 48 // Determine if a given alpha value is nearly completely transparent. |
49 bool IsColorCloseToTransparent(SkAlpha alpha); | 49 bool IsColorCloseToTransparent(SkAlpha alpha); |
50 | 50 |
51 // Determine if a color is near grey. | 51 // Determine if a color is near grey. |
52 bool IsColorCloseToGrey(int r, int g, int b); | 52 bool IsColorCloseToGrey(int r, int g, int b); |
53 | 53 |
54 // Builds a histogram based on the Y' of the Y'UV representation of | 54 // Builds a histogram based on the Y' of the Y'UV representation of |
55 // this image. | 55 // this image. |
56 UI_EXPORT void BuildLumaHistogram(const SkBitmap& bitmap, int histogram[256]); | 56 GFX_EXPORT void BuildLumaHistogram(const SkBitmap& bitmap, int histogram[256]); |
57 | 57 |
58 // Returns a blend of the supplied colors, ranging from |background| (for | 58 // Returns a blend of the supplied colors, ranging from |background| (for |
59 // |alpha| == 0) to |foreground| (for |alpha| == 255). The alpha channels of | 59 // |alpha| == 0) to |foreground| (for |alpha| == 255). The alpha channels of |
60 // the supplied colors are also taken into account, so the returned color may | 60 // the supplied colors are also taken into account, so the returned color may |
61 // be partially transparent. | 61 // be partially transparent. |
62 UI_EXPORT SkColor AlphaBlend(SkColor foreground, SkColor background, | 62 GFX_EXPORT SkColor AlphaBlend(SkColor foreground, SkColor background, |
63 SkAlpha alpha); | 63 SkAlpha alpha); |
64 | 64 |
65 // Makes a dark color lighter or a light color darker by blending |color| with | 65 // Makes a dark color lighter or a light color darker by blending |color| with |
66 // white or black depending on its current luminance. |alpha| controls the | 66 // white or black depending on its current luminance. |alpha| controls the |
67 // amount of white or black that will be alpha-blended into |color|. | 67 // amount of white or black that will be alpha-blended into |color|. |
68 UI_EXPORT SkColor BlendTowardOppositeLuminance(SkColor color, SkAlpha alpha); | 68 GFX_EXPORT SkColor BlendTowardOppositeLuminance(SkColor color, SkAlpha alpha); |
69 | 69 |
70 // Given an opaque foreground and background color, try to return a foreground | 70 // Given an opaque foreground and background color, try to return a foreground |
71 // color that is "readable" over the background color by luma-inverting the | 71 // color that is "readable" over the background color by luma-inverting the |
72 // foreground color and then picking whichever foreground color has higher | 72 // foreground color and then picking whichever foreground color has higher |
73 // contrast against the background color. You should not pass colors with | 73 // contrast against the background color. You should not pass colors with |
74 // non-255 alpha to this routine, since determining the correct behavior in such | 74 // non-255 alpha to this routine, since determining the correct behavior in such |
75 // cases can be impossible. | 75 // cases can be impossible. |
76 // | 76 // |
77 // NOTE: This won't do anything but waste time if the supplied foreground color | 77 // NOTE: This won't do anything but waste time if the supplied foreground color |
78 // has a luma value close to the midpoint (0.5 in the HSL representation). | 78 // has a luma value close to the midpoint (0.5 in the HSL representation). |
79 UI_EXPORT SkColor GetReadableColor(SkColor foreground, SkColor background); | 79 GFX_EXPORT SkColor GetReadableColor(SkColor foreground, SkColor background); |
80 | 80 |
81 // Invert a color. | 81 // Invert a color. |
82 UI_EXPORT SkColor InvertColor(SkColor color); | 82 GFX_EXPORT SkColor InvertColor(SkColor color); |
83 | 83 |
84 // Gets a Windows system color as a SkColor | 84 // Gets a Windows system color as a SkColor |
85 UI_EXPORT SkColor GetSysSkColor(int which); | 85 GFX_EXPORT SkColor GetSysSkColor(int which); |
86 | 86 |
87 } // namespace color_utils | 87 } // namespace color_utils |
88 | 88 |
89 #endif // UI_GFX_COLOR_UTILS_H_ | 89 #endif // UI_GFX_COLOR_UTILS_H_ |
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