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Support highlighting in truecolor, falling back to the closest xterm color if the terminal does not support it

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Fixes #758
This commit is contained in:
lazytype 2021-02-28 14:00:40 -05:00
parent c98dc566d5
commit 5de649b7aa
1 changed files with 118 additions and 24 deletions
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142
cli/src/highlight.rs
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@ -7,6 +7,7 @@ use serde::ser::SerializeMap;
use serde::{Deserialize, Deserializer, Serialize, Serializer};
use serde_json::{json, Value};
use std::collections::HashMap;
use std::fmt::Write;
use std::sync::atomic::AtomicUsize;
use std::time::Instant;
use std::{fs, io, path, str, usize};
@ -202,6 +203,12 @@ fn parse_style(style: &mut Style, json: Value) {
} else {
style.css = None;
}
if let Some(Color::RGB(red, green, blue)) = style.ansi.foreground {
if !terminal_supports_truecolor() {
style.ansi = style.ansi.fg(closest_xterm_color(red, green, blue));
}
}
}
fn parse_color(json: Value) -> Option<Color> {
@ -220,16 +227,8 @@ fn parse_color(json: Value) -> Option<Color> {
"white" => Some(Color::White),
"yellow" => Some(Color::Yellow),
s => {
if s.starts_with("#") && s.len() >= 7 {
if let (Ok(red), Ok(green), Ok(blue)) = (
u8::from_str_radix(&s[1..3], 16),
u8::from_str_radix(&s[3..5], 16),
u8::from_str_radix(&s[5..7], 16),
) {
Some(Color::RGB(red, green, blue))
} else {
None
}
if let Some((red, green, blue)) = hex_string_to_rgb(&s) {
Some(Color::RGB(red, green, blue))
} else {
None
}
@ -239,8 +238,23 @@ fn parse_color(json: Value) -> Option<Color> {
}
}
fn hex_string_to_rgb(s: &str) -> Option<(u8, u8, u8)> {
if s.starts_with("#") && s.len() >= 7 {
if let (Ok(red), Ok(green), Ok(blue)) = (
u8::from_str_radix(&s[1..3], 16),
u8::from_str_radix(&s[3..5], 16),
u8::from_str_radix(&s[5..7], 16),
) {
Some((red, green, blue))
} else {
None
}
} else {
None
}
}
fn style_to_css(style: ansi_term::Style) -> String {
use std::fmt::Write;
let mut result = "style='".to_string();
if style.is_underline {
write!(&mut result, "text-decoration: underline;").unwrap();
@ -252,27 +266,68 @@ fn style_to_css(style: ansi_term::Style) -> String {
write!(&mut result, "font-style: italic;").unwrap();
}
if let Some(color) = style.foreground {
write!(&mut result, "color: {};", color_to_css(color)).unwrap();
write_color(&mut result, color);
}
result.push('\'');
result
}
fn color_to_css(color: Color) -> &'static str {
match color {
Color::Black => "black",
Color::Blue => "blue",
Color::Red => "red",
Color::Green => "green",
Color::Yellow => "yellow",
Color::Cyan => "cyan",
Color::Purple => "purple",
Color::White => "white",
Color::Fixed(n) => CSS_STYLES_BY_COLOR_ID[n as usize].as_str(),
_ => panic!("Unsupported color type"),
fn write_color(buffer: &mut String, color: Color) {
if let Color::RGB(r, g, b) = &color {
write!(buffer, "color: #{:x?}{:x?}{:x?}", r, g, b).unwrap()
} else {
write!(
buffer,
"color: {}",
match color {
Color::Black => "black",
Color::Blue => "blue",
Color::Red => "red",
Color::Green => "green",
Color::Yellow => "yellow",
Color::Cyan => "cyan",
Color::Purple => "purple",
Color::White => "white",
Color::Fixed(n) => CSS_STYLES_BY_COLOR_ID[n as usize].as_str(),
_ => panic!("unreachable"),
}
)
.unwrap()
}
}
fn terminal_supports_truecolor() -> bool {
use std::env;
if let Ok(truecolor) = env::var("COLORTERM") {
truecolor == "truecolor" || truecolor == "24bit"
} else {
false
}
}
fn closest_xterm_color(red: u8, green: u8, blue: u8) -> Color {
use std::cmp::{max, min};
let colors = CSS_STYLES_BY_COLOR_ID
.iter()
.enumerate()
.map(|(color_id, hex)| (color_id as u8, hex_string_to_rgb(hex).unwrap()));
// Get the xterm color with the minimum Euclidean distance to the target color
// i.e. distance = √ (r2 - r1)² + (g2 - g1)² + (b2 - b1)²
let distances = colors.map(|(color_id, (r, g, b))| {
let r_delta: u32 = (max(r, red) - min(r, red)).into();
let g_delta: u32 = (max(g, green) - min(g, green)).into();
let b_delta: u32 = (max(b, blue) - min(b, blue)).into();
let distance = r_delta.pow(2) + g_delta.pow(2) + b_delta.pow(2);
// don't need to actually take the square root for the sake of comparison
(color_id, distance)
});
Color::Fixed(distances.min_by(|(_, d1), (_, d2)| d1.cmp(d2)).unwrap().0)
}
pub fn ansi(
loader: &Loader,
theme: &Theme,
@ -365,3 +420,42 @@ pub fn html(
Ok(())
}
#[cfg(test)]
mod tests {
use super::*;
use std::env;
const JUNGLE_GREEN: &'static str = "#26A69A";
const DARK_CYAN: &'static str = "#00AF87";
#[test]
fn test_parse_style() {
let original_environment_variable = env::var("COLORTERM");
let mut style = Style::default();
assert_eq!(style.ansi.foreground, None);
assert_eq!(style.css, None);
// darkcyan is an ANSI color and is preserved
parse_style(&mut style, Value::String(DARK_CYAN.to_string()));
assert_eq!(style.ansi.foreground, Some(Color::Fixed(36)));
assert_eq!(style.css, Some("style=\'color: #0af87\'".to_string()));
// junglegreen is not an ANSI color and is preserved when the terminal supports it
env::set_var("COLORTERM", "truecolor");
parse_style(&mut style, Value::String(JUNGLE_GREEN.to_string()));
assert_eq!(style.ansi.foreground, Some(Color::RGB(38, 166, 154)));
assert_eq!(style.css, Some("style=\'color: #26a69a\'".to_string()));
// junglegreen gets approximated as darkcyan when the terminal does not support it
env::set_var("COLORTERM", "");
parse_style(&mut style, Value::String(JUNGLE_GREEN.to_string()));
assert_eq!(style.ansi.foreground, Some(Color::Fixed(36)));
assert_eq!(style.css, Some("style=\'color: #26a69a\'".to_string()));
if let Ok(environment_variable) = original_environment_variable {
env::set_var("COLORTERM", environment_variable);
}
}
}