ultraviolet 0.1.1+1

Core cell/buffer/style types for terminal rendering.

Ultraviolet

ultraviolet is a high-performance terminal rendering/runtime package for Dart. It provides the low-level primitives you need to build interactive terminal applications: screen buffers, styled cells, diff-based rendering, typed input events, and terminal capability handling.

Features

• Cell/buffer-based rendering model
• High-performance diff renderer (UvTerminalRenderer)
• Typed keyboard/mouse/focus/resize events
• Style + color primitives (UvStyle, UvColor)
• ANSI helpers (Ansi) and renderer-level ANSI sequences (UvAnsi)
• Terminal capability detection
• Image protocol support (Kitty, iTerm2, Sixel, fallback drawables)

Installation

This package is currently configured as workspace/private (publish_to: none).

Workspace usage:

dependencies:
  ultraviolet:

Git dependency usage:

dependencies:
  ultraviolet:
    git:
      url: https://github.com/kingwill101/artisanal.git
      path: pkgs/ultraviolet

Quick Start

import 'package:ultraviolet/ultraviolet.dart';

Future<void> main() async {
  final terminal = Terminal();
  await terminal.start();
  try {
    terminal.enterAltScreen();
    terminal.hideCursor();

    terminal.setCell(2, 1, Cell(content: 'U'));
    terminal.setCell(3, 1, Cell(content: 'V'));
    terminal.draw();

    await for (final event in terminal.events) {
      if (event is KeyEvent && event.matchString('q', 'esc', 'ctrl+c')) {
        break;
      }
    }
  } finally {
    terminal.showCursor();
    terminal.exitAltScreen();
    await terminal.stop();
  }
}

Demo Captures

Raycast maze:

Conway's Game of Life:

Metaballs / marching squares:

Layout example (example/layout.dart):

Performance Tips

• Prefer incremental updates over full-screen redraws.
• For resize-heavy or animation-heavy apps, consider:
  • terminal.setScrollOptim(false)
  • terminal.setSynchronizedOutput(true)

API Surface

• Terminal
  Runtime entrypoint: lifecycle, event stream, capability queries, and drawing.
• Buffer
  2D grid of cells representing screen state for a frame.
• Cell
  A single rendered glyph plus style/link metadata.
• UvStyle / UvColor
  Text attributes and color model for foreground/background styling.
• UvTerminalRenderer
  Diff-based renderer that minimizes terminal output between frames.
• Ansi / UvAnsi
  ANSI escape sequence helpers (Ansi) and UV renderer ANSI controls (UvAnsi).
• Event types (KeyEvent, MouseEvent, WindowSizeEvent, etc.)
  Typed input and terminal-state events from terminal.events.

Small How-Tos

Write ANSI sequences directly:

import 'dart:io';
import 'package:ultraviolet/ultraviolet.dart';

stdout.write(Ansi.clearScreen);
stdout.write(Ansi.cursorTo(1, 1));
stdout.write('${Ansi.bold}Ultraviolet${Ansi.reset}');

Draw a styled label:

terminal.setCell(
  2,
  2,
  Cell(
    content: 'H',
    style: const UvStyle(
      fg: UvColor.rgb(255, 210, 120),
      attrs: Attr.bold,
    ),
  ),
);
terminal.setCell(3, 2, Cell(content: 'i'));
terminal.draw();

Fill an area:

final panel = rect(0, 0, 20, 6);
terminal.fillArea(
  Cell(content: ' ', style: const UvStyle(bg: UvColor.rgb(24, 32, 48))),
  panel,
);
terminal.draw();

Handle resize safely:

await for (final event in terminal.events) {
  if (event is WindowSizeEvent) {
    terminal.resize(event.width, event.height);
    terminal.clearScreen();
    terminal.draw();
  }
}

Run a simple animation loop:

final timer = Timer.periodic(const Duration(milliseconds: 33), (_) {
  // update state
  terminal.clear();
  // redraw frame
  terminal.draw();
});

Pick best image protocol automatically:

final drawable = terminal.bestImageDrawableForTerminal(
  image,
  columns: 40,
  rows: 20,
);
drawable.draw(terminal, rect(2, 2, 40, 20));
terminal.draw();

Use synchronized output for heavy redraws:

terminal.setScrollOptim(false);
terminal.setSynchronizedOutput(true);

Examples

See:

• pkgs/ultraviolet/example/