3074/Windows/Dialog/KeybindingDialog.xaml.cs

using System.ComponentModel;
using System.Windows.Input;

namespace tsf_3074.Windows.Dialog
{
	public partial class KeybindingDialog : System.Windows.Window
	{
		private readonly KeybindingDialogView _data = new KeybindingDialogView();

		public KeybindingDialog()
		{
			InitializeComponent();
			DataContext = _data;
		}

		private void KeybindingDialog_OnKeyDown(object sender, KeyEventArgs e)
		{
			if (e.Key == Key.Return || e.Key == Key.Escape)
			{
				Close();
				return;
			}

			var ctrl = Keyboard.IsKeyDown(Key.LeftCtrl);
			var alt = Keyboard.IsKeyDown(Key.LeftAlt);
			var shift = Keyboard.IsKeyDown(Key.LeftShift);

			var fs = ctrl ? VirtualKey.ModCtrl :
				alt ? VirtualKey.ModAlt :
				shift ? VirtualKey.ModShift : 0;

			_data.SetKey(e.Key, fs);
		}

		public static void OpenKeybindingDialog(out Key key, out uint fs, Key initKey = Key.None, uint initFs = 0)
		{
			var dialog = new KeybindingDialog
			{
				_data =
				{
					Key = initKey,
					Modifier = initFs
				}
			};

			// wait for exit, and put the values to the ref fields
			dialog.ShowDialog();
			
			key = dialog._data.Key;
			fs = dialog._data.Modifier;
		}
	}

	public class KeybindingDialogView : INotifyPropertyChanged
	{
		public event PropertyChangedEventHandler PropertyChanged;

		public string StatusText { get; set; } = "Press keys";

		internal Key Key { get; set; }
		internal uint Modifier { get; set; }

		public void SetKey(Key key, uint fsMod)
		{
			if (key == Key.LeftCtrl || key == Key.LeftAlt || key == Key.LeftShift || key == Key.System) return;

			Key = key;
			Modifier = fsMod;
			if (fsMod != 0)
			{
				var mod = fsMod == VirtualKey.ModCtrl ? "Ctrl" :
					fsMod == VirtualKey.ModAlt ? "Alt" :
					fsMod == VirtualKey.ModShift ? "Shift" : "Unknown";
				StatusText = $"{mod} + {Key}";
			}
			else
			{
				StatusText = $"{Key}";
			}

			PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(StatusText)));
		}
	}
}