RelayCommand.cs

using System;
using System.Diagnostics;
using System.Windows.Input;


namespace FFBitrateViewer
{
    // Source: https://docs.microsoft.com/en-us/archive/msdn-magazine/2009/february/patterns-wpf-apps-with-the-model-view-viewmodel-design-pattern#id0090030
    public class RelayCommand : ICommand
    {
        readonly Action<object?> _execute;
        readonly Predicate<object?>? _canExecute;

        public RelayCommand(Action<object?> execute) : this(execute, null) { }

        public RelayCommand(Action<object?> execute, Predicate<object?>? canExecute)
        {
            if (execute == null) throw new ArgumentNullException("execute");
            _execute = execute;
            _canExecute = canExecute;
        }

        [DebuggerStepThrough]
        public bool CanExecute(object? parameter) => _canExecute?.Invoke(parameter) ?? true;

        public event EventHandler? CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }

        public void RaiseCanExecuteChanged() => CommandManager.InvalidateRequerySuggested();

        public void Execute(object? parameter) => _execute(parameter);
    }
}