haussmann/graphics/
colours.rs

1// This file is part of "haussmann"
2// Under the MIT License
3// Copyright (c) 2023 Antonin Hérault
4
5//! Structures to store and convert hexadecimal to RGBA colour values, and
6//! colour constants.
7
8/// Blue colour constant (alpha = 255).
9pub const BLUE: RGBA = RGBA {
10    r: 0,
11    g: 0,
12    b: 255,
13    a: 255,
14};
15/// Green colour constant (alpha = 255).
16pub const GREEN: RGBA = RGBA {
17    r: 0,
18    g: 255,
19    b: 0,
20    a: 255,
21};
22/// Red colour constant (alpha = 255).
23pub const RED: RGBA = RGBA {
24    r: 255,
25    g: 0,
26    b: 0,
27    a: 255,
28};
29/// Transparent colour constant (alpha = 0).
30pub const TRANSPARENT: RGBA = RGBA {
31    r: 0,
32    g: 0,
33    b: 0,
34    a: 0,
35};
36
37/// Colour with red, green and blue values + an alpha channel.
38#[derive(Debug, Copy, Clone, Eq, PartialEq)]
39pub struct RGBA {
40    /// Red part of the colour corresponding to the first two bytes of an
41    /// hexadecimal colour value.
42    ///
43    /// Must be in range from 0 to 255.
44    pub r: u32,
45    /// Green part of the colour corresponding to the third and fourth bytes of
46    /// an hexadecimal colour value.
47    ///
48    /// Must be in range from 0 to 255.
49    pub g: u32,
50    /// Blue part of the colour corresponding to the fifth and sixth bytes of an
51    /// hexadecimal colour value.
52    ///
53    /// Must be in range from 0 to 255.
54    pub b: u32,
55    /// Alpha part of the colour corresponding to the seventh and eighth bytes
56    /// of an hexadecimal colour value.
57    ///
58    /// Must be in range from 0 to 255.
59    pub a: u32,
60}
61
62impl Default for RGBA {
63    fn default() -> Self {
64        RGBA {
65            r: 0,
66            g: 0,
67            b: 0,
68            a: 0,
69        }
70    }
71}
72
73impl RGBA {
74    /// Creates a new `RGBA` object.
75    ///
76    /// `r`, `g`, `b` and `a` are in range 0 to 255, where 0 is the non-colour
77    /// (black) and 255 the full colour (red, green or blue). For `a` being the
78    /// alpha channel, 0 transparent and 255 is completely visible.
79    pub fn new(r: u32, g: u32, b: u32, a: u32) -> Self {
80        Self { r, g, b, a }
81    }
82
83    /// Creates a new `RGBA` object from an hexadecimal value having an alpha
84    /// channel.
85    ///
86    /// Converts the hexadecimal `value` into a "RGBA" structure.
87    pub fn from_hex(value: u32) -> Self {
88        Self {
89            r: ((value >> 24) & 0xFF) / 255, // RR byte
90            g: ((value >> 16) & 0xFF) / 255, // GG byte
91            b: ((value >> 8) & 0xFF) / 255,  // BB byte
92            a: ((value) & 0xFF) / 255,       // AA byte
93        }
94    }
95
96    /// Converts the `RGBA` values into an hexadecimal value.
97    pub fn to_hex(&self) -> u32 {
98        (self.a << 24) | (self.b << 16) | (self.g << 8) | self.r
99    }
100}
haussmann/graphics/colours.rs

haussmann/graphics/
colours.rs
