Initial push

MainWindow.axaml.cs

@@ -0,0 +1,76 @@
+using System;
+using System.ComponentModel;
+using Avalonia;
+using Avalonia.Controls;
+using System.Reactive.Linq;
+using Avalonia.Media;
+
+namespace SimpleNote;
+
+public partial class MainWindow : Window
+{
+    private MainViewModel ViewModel;
+    public MainWindow(string[]? args)
+    {
+        if (args == null || args.Length < 1)
+        {
+            Console.WriteLine("Call with Note as Argument!");
+            Environment.Exit(1);
+        }
+        InitializeComponent();
+        ViewModel = new MainViewModel();
+        DataContext = ViewModel;
+
+        this.GetObservable(Window.WidthProperty)
+            .Subscribe(width =>
+            {
+                if (DataContext is MainViewModel vm)
+                {
+                    vm.WindowWidth = (double)width;
+                }
+            });
+
+        init_TextField(args[0]);
+    }
+
+    public void init_TextField(string text)
+    {
+        var textBlock = new TextBlock
+        {
+            Text = text,
+            FontSize = ViewModel.FontSize,
+            FontFamily = new FontFamily(FontFamily.DefaultFontFamilyName)
+        };
+        textBlock.Measure(Size.Infinity);
+        ViewModel.WindowWidth = textBlock.DesiredSize.Width + 50;
+        Note.Text = text;
+    }
+}
+
+public class MainViewModel : INotifyPropertyChanged
+{
+    private double _windowWidth = 200;
+    private double _fontSize = 24;
+
+    public double WindowWidth
+    {
+        get => _windowWidth;
+        set
+        {
+            _windowWidth = value;
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(WindowWidth)));
+        }
+    }
+
+    public double FontSize
+    {
+        get => _fontSize;
+        set
+        {
+            _fontSize = value;
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(FontSize)));
+        }
+    }
+
+    public event PropertyChangedEventHandler? PropertyChanged;
+}