carnelian/
color.rs

1// Copyright 2020 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use anyhow::Error;
6use fidl_fuchsia_ui_gfx::ColorRgba;
7
8pub(crate) fn srgb_to_linear(l: u8) -> f32 {
9    let l = l as f32 * 255.0f32.recip();
10
11    if l <= 0.04045 {
12        l * 12.92f32.recip()
13    } else {
14        ((l + 0.055) * 1.055f32.recip()).powf(2.4)
15    }
16}
17
18/// Struct representing an RGBA color value in un-premultiplied non-linear sRGB space
19#[derive(Hash, Eq, PartialEq, Debug, Clone, Copy)]
20pub struct Color {
21    /// Red
22    pub r: u8,
23    /// Green
24    pub g: u8,
25    /// Blue
26    pub b: u8,
27    /// Alpha
28    pub a: u8,
29}
30
31impl Color {
32    /// Create a new color set to black with full alpha
33    pub const fn new() -> Color {
34        Color { r: 0, g: 0, b: 0, a: 255 }
35    }
36
37    /// Create a new color set to white with full alpha
38    pub const fn white() -> Color {
39        Color { r: 255, g: 255, b: 255, a: 255 }
40    }
41
42    /// Create a new color set to red with full alpha
43    pub const fn red() -> Color {
44        Color { r: 255, g: 0, b: 0, a: 255 }
45    }
46
47    /// Create a new color set to green with full alpha
48    pub const fn green() -> Color {
49        Color { r: 0, g: 255, b: 0, a: 255 }
50    }
51
52    /// Create a new color set to blue with full alpha
53    pub const fn blue() -> Color {
54        Color { r: 0, g: 0, b: 255, a: 255 }
55    }
56
57    /// Create a new color set to Fuchsia with full alpha
58    pub const fn fuchsia() -> Color {
59        Color { r: 255, g: 0, b: 255, a: 255 }
60    }
61
62    fn extract_hex_slice(hash_code: &str, start_index: usize) -> Result<u8, Error> {
63        Ok(u8::from_str_radix(&hash_code[start_index..start_index + 2], 16)?)
64    }
65
66    /// Create a color from a six or height hexadecimal digit string like '#EBD5B3'
67    pub fn from_hash_code(hash_code: &str) -> Result<Color, Error> {
68        let mut new_color = Color::new();
69        new_color.r = Color::extract_hex_slice(&hash_code, 1)?;
70        new_color.g = Color::extract_hex_slice(&hash_code, 3)?;
71        new_color.b = Color::extract_hex_slice(&hash_code, 5)?;
72        if hash_code.len() > 8 {
73            new_color.a = Color::extract_hex_slice(&hash_code, 7)?;
74        }
75        Ok(new_color)
76    }
77
78    /// Create a Scenic-compatible [`ColorRgba`]
79    pub fn make_color_rgba(&self) -> ColorRgba {
80        ColorRgba { red: self.r, green: self.g, blue: self.b, alpha: self.a }
81    }
82
83    /// Create a linear, premultiplied RGBA representation
84    pub fn to_linear_premult_rgba(&self) -> [f32; 4] {
85        let alpha = self.a as f32 * 255.0f32.recip();
86
87        [
88            srgb_to_linear(self.r) * alpha,
89            srgb_to_linear(self.g) * alpha,
90            srgb_to_linear(self.b) * alpha,
91            alpha,
92        ]
93    }
94
95    /// Create a linear BGRA representation
96    pub fn to_linear_bgra(&self) -> [f32; 4] {
97        [
98            srgb_to_linear(self.b),
99            srgb_to_linear(self.g),
100            srgb_to_linear(self.r),
101            self.a as f32 * 255.0f32.recip(),
102        ]
103    }
104
105    /// Create a premultiplied SRGB representation
106    pub fn to_srgb_premult_rgba(&self) -> [f32; 4] {
107        let recip = 255.0f32.recip();
108        let alpha = self.a as f32 * recip;
109
110        [
111            self.r as f32 * recip * alpha,
112            self.g as f32 * recip * alpha,
113            self.b as f32 * recip * alpha,
114            alpha,
115        ]
116    }
117}
118
119impl Default for Color {
120    fn default() -> Self {
121        Color::new()
122    }
123}
carnelian/color.rs

carnelian/
color.rs
