原文
[WPF疑难]Hide me! not close
周银辉 有朋友遇到这样的一个问题,在WPF中,当Closing一个窗体时,将e.Cancel=true,然后再调用Hide()方法,以便隐藏窗口而不是关 闭,但报异常了:“当Window Closing时不能设置Visibility,或调用Show(),Close(),Hide()方法”。OK,本随笔将帮你解决该问题。 问题的关键在于不能再Closing方法中调用Close等,那么只要我们知道用户有意图关闭窗体时,仅仅再Closing方法中取消关闭,然后在 Closing紧接着的某个方法中调用Hide就OK了。为了体现这个“紧接着的某个方法”,让我联想到方法排队,比如多个线程中的方法使用同一个对象 时,这些方法将被排队,否则异常。那么就用Invoke来帮我们实现这个排队就OK了。 假设我们的Window类型的win2时一个需要隐藏的窗口,企图关闭该窗体时其会被隐藏,点击主窗口上的btnShowWin2按钮时窗体会再次被显示。 我们实现一个Delegate,其代理的方法将异常窗体: delegate void WillHide(); // private WillHide willHide; // this .willHide = new WillHide( this .HideWin2); // private void HideWin2() { this.win2.Hide();}
当Closing时我们这样:
void win2_Closing( object sender, CancelEventArgs e) { e.Cancel = true; Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Normal, this.willHide); }
Everything is OK!
整体的代码: using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Windows;using System.Windows.Controls;using System.Windows.Data;using System.Windows.Documents;using System.Windows.Input;using System.Windows.Media;using System.Windows.Media.Imaging;using System.Windows.Navigation;using System.Windows.Shapes;using System.ComponentModel;namespace ClosingDemo{ /// <summary> /// Interaction logic for Window1.xaml /// </summary> public partial class Window1 : Window { delegate void WillHide(); private Window2 win2 = new Window2(); private WillHide willHide; public Window1() { InitializeComponent(); Test(); } private void HideWin2() { this.win2.Hide(); } private void Test() { App.Current.MainWindow = this; App.Current.ShutdownMode = ShutdownMode.OnMainWindowClose; this.willHide = new WillHide(this.HideWin2); this.win2.Closing += new CancelEventHandler(win2_Closing); this.btnShowWin2.Click += new RoutedEventHandler(btnShowWin2_Click); this.win2.Show(); } void btnShowWin2_Click(object sender, RoutedEventArgs e) { this.win2.Show(); } void win2_Closing(object sender, CancelEventArgs e) { e.Cancel = true; Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Normal, this.willHide); } }}