Tests animating the ANSI color palette

palettetest.rs

#!/usr/bin/env -S rust-script -t nightly
#![allow(dead_code)]
#![feature(unix_sigpipe)]

use std::io::Write;

fn title(t: &str) {
    println!("{}\n{:-<2$}", t, "", t.len())
}

fn reset() {
    print!("\x1B[m");
}

fn sgr(p: u32) {
    print!("\x1B[{}m", p);
}

fn fg_index_legacy(i: u32) {
    print!("\x1B[38;5;{}m", i);
}
fn bg_index_legacy(i: u32) {
    print!("\x1B[48;5;{}m", i);
}
fn fg_index_standard(i: u32) {
    print!("\x1B[38:5:{}m", i);
}
fn bg_index_standard(i: u32) {
    print!("\x1B[48:5:{}m", i);
}
fn fg_rgb_legacy(r: u8, g: u8, b: u8) {
    print!("\x1B[38;2;{};{};{}m", r, g, b);
}
fn bg_rgb_legacy(r: u8, g: u8, b: u8) {
    print!("\x1B[48;2;{};{};{}m", r, g, b);
}
fn fg_rgb_standard(r: u8, g: u8, b: u8) {
    print!("\x1B[38:2::{}:{}:{}m", r, g, b);
}
fn bg_rgb_standard(r: u8, g: u8, b: u8) {
    print!("\x1B[48:2::{}:{}:{}m", r, g, b);
}
fn reset_fgbg() {
    println!("\x1B[39;49m");
}

#[derive(Copy, Clone)]
struct RGB(u8, u8, u8);

const ANSI_COLORS: [RGB; 8] = [
    RGB(0, 0, 0),
    RGB(128, 0, 0),
    RGB(0, 128, 0),
    RGB(128, 128, 0),
    RGB(0, 0, 128),
    RGB(128, 0, 128),
    RGB(0, 128, 128),
    RGB(192, 192, 192),    
];

const AIX_COLORS: [RGB; 8] = [
    RGB(128, 128, 128),
    RGB(255, 0, 0),
    RGB(0, 255, 0),
    RGB(255, 255, 0),
    RGB(0, 0, 255),
    RGB(255, 0, 255),
    RGB(0, 255, 255),
    RGB(255, 255, 255),
];

fn setcolor(i: u8, rgb: &RGB) {
    print!("\x1B]4;{};rgb:{:02X}/{:02X}/{:02X}\x1B\\", i, rgb.0, rgb.1, rgb.2);
}

fn resetcolors() {
    print!("\x1B]104\x1B\\");
}

const fn mk_grayscale_ramp() -> [RGB; 24] {
    let mut ramp = [RGB(0, 0, 0); 24];
    let mut i = 0u8;
    while i < 24 {
        let level: u8 = i * 10 + 8;
        ramp[i as usize] = RGB(level, level, level);
        i += 1;
    }
    ramp
}

const GRAYSCALE_RAMP: [RGB; 24] = mk_grayscale_ramp();

#[unix_sigpipe = "inherit"]
fn main() -> std::io::Result<()> {
    title("Animate basic foreground");
    for i in 0..8 {
        sgr(30 + i);
        print!(" x ");
    }
    reset();
    println!("\n");

    title("Animate basic background");
    for i in 0..8 {
        sgr(40 + i);
        print!(" x ");
    }
    reset();   
    println!("\n");

    title("Animate AIX foreground");
    for i in 0..8 {
        sgr(90 + i);
        print!(" x ");
    }
    reset();   
    println!("\n");

    title("Animate AIX background");
    for i in 0..8 {
        sgr(100 + i);
        print!(" x ");
    }
    reset();   
    println!("\n");

    title("Animate xterm-256color grayscale ramp");
    for i in 0..24 {
        fg_index_legacy(232 + i);
        bg_index_legacy(232 + (i + 12) % 24);
        print!("x");
    }
    reset();
    println!("\n");

    for i in 0..40 {
        for j in 0..8 {
            setcolor(j, &ANSI_COLORS[((i + (7 - j)) & 7) as usize]);
        }
        for j in 0..8 {
            setcolor(8 + j, &AIX_COLORS[((i + (7 - j)) & 7) as usize]);
        }
        for j in 0..24 {
            setcolor(232 + j, &GRAYSCALE_RAMP[((i + (23 - j)) % 24) as usize]);
        }
        // xterm doesn't animate the palette changes without output.
        // WezTerm needs a new line, it seems.
        print!("\0");
        std::io::stdout().flush()?;
        std::thread::sleep(std::time::Duration::from_millis(100));
    }

    resetcolors();
    Ok(())
}