Console color

In Rust, console colors can be used with external crates that have convenient syntax. But this is not always desirable.

With a short function, we can implement our own console coloring logic. This reduces an external dependency in the project, and can lead to further improvements.

Example

With ANSI codes, we can use numbers to indicate colors and whether text is bold. Other display features can be set, but colors and bolding are the most useful.

fn get_color_code(name: &str) -> &'static str {
    // Limited ANSI color converter.
    if name == "red" {
        "1"
    } else if name == "green" {
        "2"
    } else if name == "blue" {
        "4"
    } else if name == "white" {
        "7"
    } else {
        "0" // Black.
    }
}

fn get_color(value: &str, bold: bool, color: &str, background: &str) -> String {
    // Get string with console color information.
    let mut result = String::from("\u{1b}[");
    // [1;] means bold.
    if bold {
        result.push_str("1;");
    }
    // Handle foreground.
    if !color.is_empty() {
        result.push_str("38;5;"); // Codes for ANSI foreground.
        result.push_str(get_color_code(color));
        result.push(';');
    }
    // Handle background.
    if !background.is_empty() {
        result.push_str("48;5;"); // Codes for ANSI background.
        result.push_str(get_color_code(background));
        result.push(';');
    }
    result.push_str("7m"); // End token.
    result.push_str(value);
    result.push_str("\u{1b}[0m");
    result
}

fn main() {
    println!("{}", get_color("TEST", true, "blue", ""));
    println!("{}", get_color("TEST", true, "green", ""));
    println!("{}", get_color("OK", false, "black", ""));
    println!("{}", get_color("OK", false, "", ""));
    println!("{}", get_color("TEST", true, "blue", "white"));
    println!("{}", get_color("TEST", true, "green", ""));
    println!("{}", get_color("OK", false, "black", ""));
    println!("{}", get_color("OK", false, "", ""));
    println!("{}", get_color("RED", true, "red", ""));
    println!("{}", get_color("abc", true, "green", "black"));
}
TEST
TEST
OK
OK
TEST
TEST
OK
OK
RED
abc

Benefits

With these functions, we can often reduce a crate dependency and handle colors directly. And with the simple logic, we can make programs follow more unified themes.

Summary

Handling colors directly in Rust programs with a custom function can sometimes be desirable. The ANSI codes are understandable once we learn the syntax.