textui/ansi.ts

import { BufferLocation, BufferSize, Char, Color } from "./base.ts";
import { Display } from "./display.ts";

/**
 * ANSI terminal display
 */
export class AnsiTerminalDisplay implements Display {
  private palette_bg: readonly Uint8Array[] = [];
  private palette_fg: readonly Uint8Array[] = [];

  constructor(
    private writer: Deno.Writer = Deno.stdout,
    private reader: Deno.Reader = Deno.stdin,
  ) {
  }

  async getSize(): Promise<BufferSize> {
    const size = Deno.consoleSize(Deno.stdout.rid);
    return {
      w: size.columns,
      h: size.rows,
    };
  }

  async setupPalette(colors: readonly Color[]): Promise<readonly Color[]> {
    // TODO handle not fully rgb compatible terminals
    const cr = (x: number) => Math.round(x * 255);
    this.palette_bg = colors.map((col) =>
      escape(`[48;2;${cr(col.r)};${cr(col.g)};${cr(col.b)}m`)
    );
    this.palette_fg = colors.map((col) =>
      escape(`[38;2;${cr(col.r)};${cr(col.g)};${cr(col.b)}m`)
    );
    return colors;
  }

  async clear(): Promise<void> {
    await this.writer.write(CLEAR);
  }

  async setChar(at: BufferLocation, char: Char): Promise<void> {
    // TODO do not move the cursor if already at good location
    // TODO do not change the color if already good
    const fg = this.palette_fg[char.fg];
    const bg = this.palette_bg[char.bg];
    await this.writer.write(fg);
    await this.writer.write(bg);
    await this.writer.write(escape(`[${at.y};${at.x}H${char.ch}`));
  }
}

function escape(sequence: string): Uint8Array {
  return new Uint8Array([0x1B, ...new TextEncoder().encode(sequence)]);
}

const CLEAR = escape("[2J");