ecolor/
lib.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
//! Color conversions and types.
//!
//! If you want a compact color representation, use [`Color32`].
//! If you want to manipulate RGBA colors use [`Rgba`].
//! If you want to manipulate colors in a way closer to how humans think about colors, use [`HsvaGamma`].
//!
//! ## Feature flags
#![cfg_attr(feature = "document-features", doc = document_features::document_features!())]
//!

#![allow(clippy::wrong_self_convention)]

#[cfg(feature = "cint")]
mod cint_impl;

mod color32;
pub use color32::*;

mod hsva_gamma;
pub use hsva_gamma::*;

mod hsva;
pub use hsva::*;

#[cfg(feature = "color-hex")]
mod hex_color_macro;
#[cfg(feature = "color-hex")]
#[doc(hidden)]
pub use color_hex;

mod rgba;
pub use rgba::*;

mod hex_color_runtime;
pub use hex_color_runtime::*;

// ----------------------------------------------------------------------------
// Color conversion:

impl From<Color32> for Rgba {
    fn from(srgba: Color32) -> Self {
        Self([
            linear_f32_from_gamma_u8(srgba.0[0]),
            linear_f32_from_gamma_u8(srgba.0[1]),
            linear_f32_from_gamma_u8(srgba.0[2]),
            linear_f32_from_linear_u8(srgba.0[3]),
        ])
    }
}

impl From<Rgba> for Color32 {
    fn from(rgba: Rgba) -> Self {
        Self([
            gamma_u8_from_linear_f32(rgba.0[0]),
            gamma_u8_from_linear_f32(rgba.0[1]),
            gamma_u8_from_linear_f32(rgba.0[2]),
            linear_u8_from_linear_f32(rgba.0[3]),
        ])
    }
}

/// gamma [0, 255] -> linear [0, 1].
pub fn linear_f32_from_gamma_u8(s: u8) -> f32 {
    if s <= 10 {
        s as f32 / 3294.6
    } else {
        ((s as f32 + 14.025) / 269.025).powf(2.4)
    }
}

/// linear [0, 255] -> linear [0, 1].
/// Useful for alpha-channel.
#[inline(always)]
pub fn linear_f32_from_linear_u8(a: u8) -> f32 {
    a as f32 / 255.0
}

/// linear [0, 1] -> gamma [0, 255] (clamped).
/// Values outside this range will be clamped to the range.
pub fn gamma_u8_from_linear_f32(l: f32) -> u8 {
    if l <= 0.0 {
        0
    } else if l <= 0.0031308 {
        fast_round(3294.6 * l)
    } else if l <= 1.0 {
        fast_round(269.025 * l.powf(1.0 / 2.4) - 14.025)
    } else {
        255
    }
}

/// linear [0, 1] -> linear [0, 255] (clamped).
/// Useful for alpha-channel.
#[inline(always)]
pub fn linear_u8_from_linear_f32(a: f32) -> u8 {
    fast_round(a * 255.0)
}

fn fast_round(r: f32) -> u8 {
    (r + 0.5) as _ // rust does a saturating cast since 1.45
}

#[test]
pub fn test_srgba_conversion() {
    for b in 0..=255 {
        let l = linear_f32_from_gamma_u8(b);
        assert!(0.0 <= l && l <= 1.0);
        assert_eq!(gamma_u8_from_linear_f32(l), b);
    }
}

/// gamma [0, 1] -> linear [0, 1] (not clamped).
/// Works for numbers outside this range (e.g. negative numbers).
pub fn linear_from_gamma(gamma: f32) -> f32 {
    if gamma < 0.0 {
        -linear_from_gamma(-gamma)
    } else if gamma <= 0.04045 {
        gamma / 12.92
    } else {
        ((gamma + 0.055) / 1.055).powf(2.4)
    }
}

/// linear [0, 1] -> gamma [0, 1] (not clamped).
/// Works for numbers outside this range (e.g. negative numbers).
pub fn gamma_from_linear(linear: f32) -> f32 {
    if linear < 0.0 {
        -gamma_from_linear(-linear)
    } else if linear <= 0.0031308 {
        12.92 * linear
    } else {
        1.055 * linear.powf(1.0 / 2.4) - 0.055
    }
}

// ----------------------------------------------------------------------------

/// Cheap and ugly.
/// Made for graying out disabled `Ui`s.
pub fn tint_color_towards(color: Color32, target: Color32) -> Color32 {
    let [mut r, mut g, mut b, mut a] = color.to_array();

    if a == 0 {
        r /= 2;
        g /= 2;
        b /= 2;
    } else if a < 170 {
        // Cheapish and looks ok.
        // Works for e.g. grid stripes.
        let div = (2 * 255 / a as i32) as u8;
        r = r / 2 + target.r() / div;
        g = g / 2 + target.g() / div;
        b = b / 2 + target.b() / div;
        a /= 2;
    } else {
        r = r / 2 + target.r() / 2;
        g = g / 2 + target.g() / 2;
        b = b / 2 + target.b() / 2;
    }
    Color32::from_rgba_premultiplied(r, g, b, a)
}