rot-js/lib/display/term.js

A roguelike toolkit in JavaScript

import Backend from "./backend.js";
import * as Color from "../color.js";
function clearToAnsi(bg) {
    return `\x1b[0;48;5;${termcolor(bg)}m\x1b[2J`;
}
function colorToAnsi(fg, bg) {
    return `\x1b[0;38;5;${termcolor(fg)};48;5;${termcolor(bg)}m`;
}
function positionToAnsi(x, y) {
    return `\x1b[${y + 1};${x + 1}H`;
}
function termcolor(color) {
    const SRC_COLORS = 256.0;
    const DST_COLORS = 6.0;
    const COLOR_RATIO = DST_COLORS / SRC_COLORS;
    let rgb = Color.fromString(color);
    let r = Math.floor(rgb[0] * COLOR_RATIO);
    let g = Math.floor(rgb[1] * COLOR_RATIO);
    let b = Math.floor(rgb[2] * COLOR_RATIO);
    return r * 36 + g * 6 + b * 1 + 16;
}
export default class Term extends Backend {
    constructor() {
        super();
        this._offset = [0, 0];
        this._cursor = [-1, -1];
        this._lastColor = "";
    }
    schedule(cb) { setTimeout(cb, 1000 / 60); }
    setOptions(options) {
        super.setOptions(options);
        let size = [options.width, options.height];
        let avail = this.computeSize();
        this._offset = avail.map((val, index) => Math.floor((val - size[index]) / 2));
    }
    clear() {
        process.stdout.write(clearToAnsi(this._options.bg));
    }
    draw(data, clearBefore) {
        // determine where to draw what with what colors
        let [x, y, ch, fg, bg] = data;
        // determine if we need to move the terminal cursor
        let dx = this._offset[0] + x;
        let dy = this._offset[1] + y;
        let size = this.computeSize();
        if (dx < 0 || dx >= size[0]) {
            return;
        }
        if (dy < 0 || dy >= size[1]) {
            return;
        }
        if (dx !== this._cursor[0] || dy !== this._cursor[1]) {
            process.stdout.write(positionToAnsi(dx, dy));
            this._cursor[0] = dx;
            this._cursor[1] = dy;
        }
        // terminals automatically clear, but if we're clearing when we're
        // not otherwise provided with a character, just use a space instead
        if (clearBefore) {
            if (!ch) {
                ch = " ";
            }
        }
        // if we're not clearing and not provided with a character, do nothing
        if (!ch) {
            return;
        }
        // determine if we need to change colors
        let newColor = colorToAnsi(fg, bg);
        if (newColor !== this._lastColor) {
            process.stdout.write(newColor);
            this._lastColor = newColor;
        }
        if (ch != '\t') {
            // write the provided symbol to the display
            let chars = [].concat(ch);
            process.stdout.write(chars[0]);
        }
        // update our position, given that we wrote a character
        this._cursor[0]++;
        if (this._cursor[0] >= size[0]) {
            this._cursor[0] = 0;
            this._cursor[1]++;
        }
    }
    computeFontSize() { throw new Error("Terminal backend has no notion of font size"); }
    eventToPosition(x, y) { return [x, y]; }
    computeSize() { return [process.stdout.columns, process.stdout.rows]; }
}