WPF customize DelegateCommand 

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;

namespace WpfApp55.ViewModel
{
    public class VM : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        public void OnPropertyChanged(string propName)
        {
            var handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propName));
            }
        }

        private DelegateCommand UCCmdValue;
        public DelegateCommand UCCmd
        {
            get
            {
                if(UCCmdValue==null)
                {
                    UCCmdValue = new DelegateCommand(UCCmdExecuted, UCCmdCanExecute);
                }
                return UCCmdValue;
            }
        }

        private bool UCCmdCanExecute(object obj)
        {
            return true;
        }

        private void UCCmdExecuted(object obj)
        {
            MessageBox.Show("You had clicked the customized button!");
        }
    }
}

 

 1  public class DelegateCommand : ICommand
 2     {
 3         private readonly Predicate<object> _canExecute;
 4         private readonly Action<object> _execute;
 5 
 6         public event EventHandler CanExecuteChanged;
 7 
 8         public DelegateCommand(Action<object> execute)
 9                        : this(execute, null)
10         {
11         }
12 
13         public DelegateCommand(Action<object> execute,
14                        Predicate<object> canExecute)
15         {
16             _execute = execute;
17             _canExecute = canExecute;
18         }
19 
20         public  bool CanExecute(object parameter)
21         {
22             if (_canExecute == null)
23             {
24                 return true;
25             }
26 
27             return _canExecute(parameter);
28         }
29 
30         public  void Execute(object parameter)
31         {
32             _execute(parameter);
33         }
34 
35         public void RaiseCanExecuteChanged()
36         {
37             if (CanExecuteChanged != null)
38             {
39                 CanExecuteChanged(this, EventArgs.Empty);
40             }
41         }
42     }

 

posted @ 2019-11-24 17:02  FredGrit  阅读(477)  评论(0)    收藏  举报