How do listen a keyboard event in dart console app?

Issue

All examples that I found about web and dart:html package. Can I get keyboard or mouse events from system in a desktop console program?

Solution

I don’t think you can read mouse events, but you can read pressed key codes from stdin. For this just have to switch it “raw” mode by setting both lineMode and echoMode to false and then listening on this stream.

Here is a simple example:

import 'dart:async';
import 'dart:convert';
import 'dart:io' as io;

Future main() async {
  io.stdin
    ..lineMode = false
    ..echoMode = false;
  StreamSubscription subscription;
  subscription = io.stdin.listen((List<int> codes) {
    var first = codes.first;
    var len = codes.length;
    var key;
    if (len == 1 && ((first > 0x01 && first < 0x20) || first == 0x7f)) {
      // Control code. For example:
      // 0x09 - Tab
      // 0x10 - Enter
      // 0x1b - ESC
      if (first == 0x09) {
        subscription.cancel();
      }
      key = codes.toString();
    } else if (len > 1 && first == 0x1b) {
      // ESC sequence.  For example:
      // [ 0x1b, 0x5b, 0x41 ] - Up Arrow
      // [ 0x1b, 0x5b, 0x42 ] - Down Arrow
      // [ 0x1b, 0x5b, 0x43 ] - Right Arrow
      // [ 0x1b, 0x5b, 0x44 ] - Left Arrow
      key = '${codes.toString()} ESC ${String.fromCharCodes(codes.skip(1))}';
    } else {
      key = utf8.decode(codes);
    }
    print(key);
  });
  print('Start listening');
}

You can also utilize dart_console package or adapt their readKey() method that parses control and esc codes.

Answered By – Styx

Answer Checked By – Marie Seifert (FlutterFixes Admin)