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implement FromStr and Display for Color

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misaka10987 2025-05-09 22:05:19 +08:00 • committed by Héctor Ramón Jiménez
parent 42d6549ed1
commit e2f5d36cee
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1 changed files with 82 additions and 35 deletions
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117
core/src/color.rs
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@ -1,4 +1,15 @@
use std::{fmt::Display, num::ParseIntError, str::FromStr};
use thiserror::Error;
/// A color in the `sRGB` color space.
///
/// # String Representation
///
/// A color can be represented in either of the following valid formats: `#rrggbb`, `#rrggbbaa`, `#rgb`, and `#rgba`.
/// Both uppercase and lowercase letters are supported.
///
/// If `a` (transparency) is not specified, `1.0` (completely opaque) would be used by default.
#[derive(Debug, Clone, Copy, PartialEq, Default)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct Color {
@ -108,41 +119,7 @@ impl Color {
///
/// [`color!`]: crate::color!
pub fn parse(s: &str) -> Option<Color> {
let hex = s.strip_prefix('#').unwrap_or(s);
let parse_channel = |from: usize, to: usize| {
let num =
usize::from_str_radix(&hex[from..=to], 16).ok()? as f32 / 255.0;
// If we only got half a byte (one letter), expand it into a full byte (two letters)
Some(if from == to { num + num * 16.0 } else { num })
};
Some(match hex.len() {
3 => Color::from_rgb(
parse_channel(0, 0)?,
parse_channel(1, 1)?,
parse_channel(2, 2)?,
),
4 => Color::from_rgba(
parse_channel(0, 0)?,
parse_channel(1, 1)?,
parse_channel(2, 2)?,
parse_channel(3, 3)?,
),
6 => Color::from_rgb(
parse_channel(0, 1)?,
parse_channel(2, 3)?,
parse_channel(4, 5)?,
),
8 => Color::from_rgba(
parse_channel(0, 1)?,
parse_channel(2, 3)?,
parse_channel(4, 5)?,
parse_channel(6, 7)?,
),
_ => None?,
})
s.parse().ok()
}
/// Converts the [`Color`] into its RGBA8 equivalent.
@ -232,6 +209,76 @@ impl From<[f32; 4]> for Color {
}
}
/// An error which can be returned when parsing color from an RGB hexadecimal string.
///
/// See [`Color`] for specifications for the string.
#[derive(Debug, Error)]
pub enum ParseColorError {
/// The string could not be parsed to valid integers.
#[error(transparent)]
ParseIntError(#[from] ParseIntError),
/// The string is of invalid length.
#[error(
"expected hex string of length 3, 4, 6 or 8 excluding optional prefix '#', found {0}"
)]
InvalidLength(usize),
}
impl FromStr for Color {
type Err = ParseColorError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let hex = s.strip_prefix('#').unwrap_or(s);
let parse_channel =
|from: usize, to: usize| -> Result<f32, ParseIntError> {
let num =
usize::from_str_radix(&hex[from..=to], 16)? as f32 / 255.0;
// If we only got half a byte (one letter), expand it into a full byte (two letters)
Ok(if from == to { num + num * 16.0 } else { num })
};
let val = match hex.len() {
3 => Color::from_rgb(
parse_channel(0, 0)?,
parse_channel(1, 1)?,
parse_channel(2, 2)?,
),
4 => Color::from_rgba(
parse_channel(0, 0)?,
parse_channel(1, 1)?,
parse_channel(2, 2)?,
parse_channel(3, 3)?,
),
6 => Color::from_rgb(
parse_channel(0, 1)?,
parse_channel(2, 3)?,
parse_channel(4, 5)?,
),
8 => Color::from_rgba(
parse_channel(0, 1)?,
parse_channel(2, 3)?,
parse_channel(4, 5)?,
parse_channel(6, 7)?,
),
_ => return Err(ParseColorError::InvalidLength(hex.len())),
};
Ok(val)
}
}
impl Display for Color {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let [r, g, b, a] = self.into_rgba8();
if self.a == 1.0 {
return write!(f, "#{r:02x}{g:02x}{b:02x}");
}
write!(f, "#{r:02x}{g:02x}{b:02x}{a:02x}")
}
}
/// Creates a [`Color`] with shorter and cleaner syntax.
///
/// # Examples