How to set default size of macos app in flutter?

Question

I am trying to build a macOS desktop app with flutter. I want the app to be full-width, edge-to-edge. However, when I run the app via the simulator, or after the build, it always launches the app with size 800x600.

I have set the height and width of the root container to double.infinity. In fact, even if I set the height and width to 10.0, it always launches the app with 800x600. I am new to flutter, so probably missing some fundamentals. Most tutorials I have come across talk about building a mobile app where this is never a problem because the app always launches to its full width.

Here is my entire test app code:

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
      decoration: BoxDecoration(color: Colors.white),
      height: double.infinity,
      width: double.infinity,
      child: Center(
        child: Text(
          'Hello World',
          textDirection: TextDirection.ltr,
          style: TextStyle(
              fontSize: 32, fontWeight: FontWeight.bold, color: Colors.black),
        ),
      ),
    );
  }
}

Answer 1

Currently the only way to control the initial size is in native code (follow these issues: 1 and 2 to find out when that changes). You'd most likely want to set it in macos/Runner/MainFlutterWindow.swift.

It's not clear from your description whether you want to launch into full-screen mode, or just have a standard window the size of the client area of the screen; the code involved would be different depending on which you are trying to accomplish.