Enable 8 bit color support, closes #11

src/main.rs

@@ -7,6 +7,8 @@ extern crate syntect;
 #[macro_use]
 extern crate clap;
 
+mod terminal;
+
 use std::collections::HashMap;
 use std::env;
 use std::io::{self, BufRead, ErrorKind, Result, StdoutLock, Write};
@@ -23,7 +25,12 @@ use git2::{DiffOptions, IntoCString, Repository};
 use syntect::easy::HighlightFile;
 use syntect::highlighting::{Theme, ThemeSet};
 use syntect::parsing::SyntaxSet;
-use syntect::util::as_24_bit_terminal_escaped;
+
+use terminal::as_terminal_escaped;
+
+struct Options {
+    true_color: bool,
+}
 
 #[derive(Copy, Clone, Debug)]
 enum LineChange {
@@ -52,6 +59,7 @@ fn print_horizontal_line(
 }
 
 fn print_file<P: AsRef<Path>>(
+    options: &Options,
     theme: &Theme,
     syntax_set: &SyntaxSet,
     filename: P,
@@ -101,7 +109,7 @@ fn print_file<P: AsRef<Path>>(
             Fixed(244).paint(format!("{:4}", line_nr)),
             line_change,
             Fixed(GRID_COLOR).paint("│"),
-            as_24_bit_terminal_escaped(&regions, false)
+            as_terminal_escaped(&regions, options.true_color)
         )?;
     }
 
@@ -169,6 +177,12 @@ fn run(matches: &ArgMatches) -> Result<()> {
         "Could not get home directory",
     ))?;
 
+    let colorterm = env::var("COLORTERM").unwrap_or("".into());
+
+    let options = Options {
+        true_color: colorterm == "truecolor" || colorterm == "24bit",
+    };
+
     let theme_dir = home_dir.join(".config").join("bat").join("themes");
     let theme_set = ThemeSet::load_from_folder(theme_dir)
         .map_err(|_| io::Error::new(ErrorKind::Other, "Could not load themes"))?;
@@ -179,7 +193,7 @@ fn run(matches: &ArgMatches) -> Result<()> {
     if let Some(files) = matches.values_of("FILE") {
         for file in files {
             let line_changes = get_git_diff(file.to_string());
-            print_file(theme, &syntax_set, file, line_changes)?;
+            print_file(&options, theme, &syntax_set, file, line_changes)?;
         }
     }
 

src/terminal.rs

@@ -0,0 +1,66 @@
+use std::fmt::Write;
+
+use ansi_term::Colour::{Fixed, RGB};
+use syntect::highlighting;
+
+/// Approximate a 24 bit color value by a 8 bit ANSI code
+fn rgb2ansi(r: u8, g: u8, b: u8) -> u8 {
+    const BLACK: u8 = 16;
+    const WHITE: u8 = 231;
+
+    if r == g && g == b {
+        if r < 8 {
+            BLACK
+        } else if r > 248 {
+            WHITE
+        } else {
+            let fr = r as f32;
+            (((fr - 8.) / 247.) * 24.) as u8 + 232
+        }
+    } else {
+        let fr = r as f32;
+        let fg = g as f32;
+        let fb = b as f32;
+        16 + (36 * (fr / 255. * 5.) as u8) + (6 * (fg / 255. * 5.) as u8) + (fb / 255. * 5.) as u8
+    }
+}
+
+pub fn as_terminal_escaped(v: &[(highlighting::Style, &str)], true_color: bool) -> String {
+    let mut s: String = String::new();
+    for &(ref style, text) in v.iter() {
+        let style = if true_color {
+            RGB(style.foreground.r, style.foreground.g, style.foreground.b)
+        } else {
+            let ansi = rgb2ansi(style.foreground.r, style.foreground.g, style.foreground.b);
+            Fixed(ansi)
+        };
+
+        write!(s, "{}", style.paint(text)).unwrap();
+    }
+
+    s
+}
+
+#[test]
+fn test_rgb2ansi_black_white() {
+    assert_eq!(16, rgb2ansi(0x00, 0x00, 0x00));
+    assert_eq!(231, rgb2ansi(0xff, 0xff, 0xff));
+}
+
+#[test]
+fn test_rgb2ansi_gray() {
+    assert_eq!(241, rgb2ansi(0x6c, 0x6c, 0x6c));
+    assert_eq!(233, rgb2ansi(0x1c, 0x1c, 0x1c));
+}
+
+#[test]
+fn test_rgb2ansi_color() {
+    assert_eq!(96, rgb2ansi(0x87, 0x5f, 0x87));
+    assert_eq!(141, rgb2ansi(0xaf, 0x87, 0xff));
+    assert_eq!(193, rgb2ansi(0xd7, 0xff, 0xaf));
+}
+
+#[test]
+fn test_rgb2ansi_approx() {
+    assert_eq!(231, rgb2ansi(0xfe, 0xfe, 0xfe));
+}