Triton160/Common/Core/UI/MVVM/DelegateCommand.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Input;

namespace Aitex.Core.UI.MVVM
{
    public class DelegateCommand<T> : ICommand
    {
        readonly Action<T> _execute;
        readonly Predicate<T> _canExecute;
        public event EventHandler CanExecuteChanged;

        public DelegateCommand(Action<T> execute)
            : this(execute, null)
        {
        }

        public DelegateCommand(Action<T> execute, Predicate<T> canExecute)
        {
            if (execute == null)
                throw new ArgumentNullException("execute");

            _execute = execute;
            _canExecute = canExecute;
        }


        public bool CanExecute(object parameter)
        {
            return _canExecute == null ? true : _canExecute((T)parameter);
        }
        

        // The CanExecuteChanged is automatically registered by command binding, we can assume that it has some execution logic 
        // to update the button's enabled\disabled state(though we cannot see). So raises this event will cause the button's state be updated.
        public void RaiseCanExecuteChanged()
        {
            if (CanExecuteChanged != null)
                CanExecuteChanged(this, EventArgs.Empty);
        }

        public void Execute(object parameter)
        {
            _execute((T)parameter);
        }

    }

    public class DelegateCommand : ICommand
    {
        private readonly Action _execute;
        private readonly Func<bool> _canExecute;

        public DelegateCommand(Action execute) : this(execute, null) { }
        public DelegateCommand(Action execute, Func<bool> canExecute)
        {
            _execute = execute ?? throw new ArgumentNullException(nameof(execute));
            _canExecute = canExecute;
        }

        public void Execute(object parameter)
        {
            _execute();
        }
        public bool CanExecute(object parameter)
        {
            if (_canExecute == null) return true;
            return _canExecute();
        }


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