announce.dart

import 'dart:io';
import 'dart:math';

import 'package:dart_console/dart_console.dart';

final console = Console();
final startRow = (console.windowHeight / 3).round() - 1;

// Small demo app announcing dart2native.
//
// This uses package https://pub.dev/packages/dart_console,
// and was heavily inspired by examples/demo.dart from that package.
main() {
  progress('PREPARING ANNOUNCEMENT');
  stars();
  announce(
      'ANNOUNCING: dart2native',
      'Compile Dart to self-contained, native executables',
      'for macOS, Windows, and Linux');
  console
    ..resetColorAttributes()
    ..clearScreen();
}

progress(String text) {
  console
    ..setColors(ConsoleColor.blue, ConsoleColor.white)
    ..writeLineAt(text, Coordinate(startRow, 0))
    ..hideCursor();

  final barWidth = console.windowWidth - 8;
  for (int i = 0; i <= barWidth - 3; i++) {
    final bar = ('[' + ('#' * i)).padRight(barWidth - 2) + ']';
    console.writeAt(bar, Coordinate(startRow + 2, 4));
    sleep(Duration(milliseconds: 20));
  }
}

stars() {
  console
    ..setColors(ConsoleColor.black, ConsoleColor.red)
    ..hideCursor();
  final random = Random();

  for (int i = 0; i < 100; i++) {
    console
      ..writeAt('*', Coordinate(startRow, 20 + random.nextInt(40)))
      ..writeAt('   ', Coordinate(startRow, 18 + random.nextInt(42)));
    sleep(Duration(milliseconds: 10));
  }
}

announce(String announce1, String announce2, String announce3) {
  console
    ..setColors(ConsoleColor.black, ConsoleColor.brightRed)
    ..writeLineAt(announce2, Coordinate(startRow + 2, 0))
    ..writeLineAt(announce3, Coordinate(startRow + 3, 0))
    ..hideCursor();

  for (int i = 0; i < 50; i++) {
    console
      ..setForegroundExtendedColor(i * 3)
      ..writeLineAt(announce1, Coordinate(startRow, 0));
    sleep(Duration(milliseconds: 100));
  }
}

extension MyConsole on Console {
  setColors(ConsoleColor foreground, ConsoleColor background) {
    console
      ..resetColorAttributes()
      ..setBackgroundColor(foreground)
      ..setForegroundColor(background)
      ..clearScreen()
      ..showCursor();
  }

  writeLineAt(String text, Coordinate position) {
    console
      ..cursorPosition = position
      ..writeLine(text, TextAlignment.center);
  }

  writeAt(String text, Coordinate position) {
    console
      ..cursorPosition = position
      ..write(text);
  }
}

pubspec.yaml

name: announce
description: An announcement application.

environment:
  sdk: '>=2.6.0 <3.0.0'

dependencies:
  dart_console: ^0.4.0

pub get
dart2native bin/announce.dart -o announce
./announce