我想处理窗口的事件(当用户单击右上角的'X'按钮时)，最终显示确认消息和/或取消关闭。
我知道如何在代码后台中完成这个操作：订阅窗口的事件，然后使用属性。
但我正在使用MVVM，所以我不确定这是否是正确的方法。
我认为正确的方法是将事件绑定到我的ViewModel中的一个。
我尝试了一下：
<i:Interaction.Triggers>
<i:EventTrigger EventName="Closing">
<cmd:EventToCommand Command="{Binding CloseCommand}" />
</i:EventTrigger>
</i:Interaction.Triggers>
在我的ViewModel中有一个关联的RelayCommand，但它不起作用（命令代码未被执行）。
我会在视图构造函数中简单地关联处理程序：
MyWindow()
{
// Set up ViewModel, assign to DataContext etc.
Closing += viewModel.OnWindowClosing;
}
然后将处理程序添加到 ViewModel 中：
using System.ComponentModel;
public void OnWindowClosing(object sender, CancelEventArgs e)
{
// Handle closing logic, set e.Cancel as needed
}
这段代码完全正常：
ViewModel.cs:
public ICommand WindowClosing
{
get
{
return new RelayCommand<CancelEventArgs>(
(args) =>{
});
}
}
在XAML中：
<i:Interaction.Triggers>
<i:EventTrigger EventName="Closing">
<command:EventToCommand Command="{Binding WindowClosing}" PassEventArgsToCommand="True" />
</i:EventTrigger>
</i:Interaction.Triggers>
假设:
DataContext。xmlns:command="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Extras.SL5"xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"<i:Interaction.Triggers>中提到i是什么以及如何获取它会非常有帮助。 - Andrii Muzychukxmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"。 - StasEventToCommand的实现？答案应该是完整的，或者至少指导用户如何找到相关部分。您使用MVVM Light、Glue、Blend或其他实现之一吗？command命名空间是什么？这个答案只完成了一半。 - Alex这个选项甚至更加简单，也许适合你。在你的视图模型构造函数中，你可以像下面这样订阅主窗口关闭事件：
Application.Current.MainWindow.Closing += new CancelEventHandler(MainWindow_Closing);
void MainWindow_Closing(object sender, CancelEventArgs e)
{
//Your code to handle the event
}
祝你一切顺利。
如果您不想在ViewModel中使用Window（或其任何事件），则可以根据MVVM模式给出以下答案。
public interface IClosing
{
/// <summary>
/// Executes when window is closing
/// </summary>
/// <returns>Whether the windows should be closed by the caller</returns>
bool OnClosing();
}
public bool OnClosing()
{
bool close = true;
//Ask whether to save changes och cancel etc
//close = false; //If you want to cancel close
return close;
}
在窗口中我添加了关闭事件。这个代码不破坏MVVM模式。视图可以知道视图模型！
void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
IClosing context = DataContext as IClosing;
if (context != null)
{
e.Cancel = !context.OnClosing();
}
}
IClosing接口，而不仅仅是实现OnClosing方法。否则DataContext as IClosing转换将失败并返回null。 - Erik White哎呀，这里好像有很多代码啊。Stas上面的方法是最省力的。这是我的改编版本（使用MVVMLight但应该是可识别的）...哦，PassEventArgsToCommand="True" 绝对是需要的，就像上面所指出的。
（感谢Laurent Bugnionhttp://blog.galasoft.ch/archive/2009/10/18/clean-shutdown-in-silverlight-and-wpf-applications.aspx）
... MainWindow Xaml
...
WindowStyle="ThreeDBorderWindow"
WindowStartupLocation="Manual">
<i:Interaction.Triggers>
<i:EventTrigger EventName="Closing">
<cmd:EventToCommand Command="{Binding WindowClosingCommand}" PassEventArgsToCommand="True" />
</i:EventTrigger>
</i:Interaction.Triggers>
///<summary>
/// public RelayCommand<CancelEventArgs> WindowClosingCommand
///</summary>
public RelayCommand<CancelEventArgs> WindowClosingCommand { get; private set; }
...
...
...
// Window Closing
WindowClosingCommand = new RelayCommand<CancelEventArgs>((args) =>
{
ShutdownService.MainWindowClosing(args);
},
(args) => CanShutdown);
在ShutdownService中
/// <summary>
/// ask the application to shutdown
/// </summary>
public static void MainWindowClosing(CancelEventArgs e)
{
e.Cancel = true; /// CANCEL THE CLOSE - let the shutdown service decide what to do with the shutdown request
RequestShutdown();
}
RequestShutdown看起来像下面这样，但基本上它决定是否关闭应用程序（这将愉快地关闭窗口）：
...
...
...
/// <summary>
/// ask the application to shutdown
/// </summary>
public static void RequestShutdown()
{
// Unless one of the listeners aborted the shutdown, we proceed. If they abort the shutdown, they are responsible for restarting it too.
var shouldAbortShutdown = false;
Logger.InfoFormat("Application starting shutdown at {0}...", DateTime.Now);
var msg = new NotificationMessageAction<bool>(
Notifications.ConfirmShutdown,
shouldAbort => shouldAbortShutdown |= shouldAbort);
// recipients should answer either true or false with msg.execute(true) etc.
Messenger.Default.Send(msg, Notifications.ConfirmShutdown);
if (!shouldAbortShutdown)
{
// This time it is for real
Messenger.Default.Send(new NotificationMessage(Notifications.NotifyShutdown),
Notifications.NotifyShutdown);
Logger.InfoFormat("Application has shutdown at {0}", DateTime.Now);
Application.Current.Shutdown();
}
else
Logger.InfoFormat("Application shutdown aborted at {0}", DateTime.Now);
}
}
提问者应该使用STAS答案，但对于使用prism而没有galasoft/mvvmlight的读者，他们可能想尝试我使用的方法：
在窗口或用户控件等顶部的定义中，定义命名空间：
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
而就在该定义下面：
<i:Interaction.Triggers>
<i:EventTrigger EventName="Closing">
<i:InvokeCommandAction Command="{Binding WindowClosing}" CommandParameter="{Binding}" />
</i:EventTrigger>
</i:Interaction.Triggers>
你的视图模型中的属性：
public ICommand WindowClosing { get; private set; }
在您的ViewModel构造函数中附加DelegateCommand：
this.WindowClosing = new DelegateCommand<object>(this.OnWindowClosing);
最后，你想要在控件/窗口/其他东西关闭时到达的代码：
private void OnWindowClosing(object obj)
{
//put code here
}
我建议在您的App.xaml.cs文件中使用事件处理程序，以便您可以决定是否关闭应用程序。
例如，您可以在App.xaml.cs文件中添加以下代码：
protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
// Create the ViewModel to attach the window to
MainWindow window = new MainWindow();
var viewModel = new MainWindowViewModel();
// Create the handler that will allow the window to close when the viewModel asks.
EventHandler handler = null;
handler = delegate
{
//***Code here to decide on closing the application****
//***returns resultClose which is true if we want to close***
if(resultClose == true)
{
viewModel.RequestClose -= handler;
window.Close();
}
}
viewModel.RequestClose += handler;
window.DataContaxt = viewModel;
window.Show();
}
那么在您的MainWindowViewModel代码中，您可以有以下内容：
#region Fields
RelayCommand closeCommand;
#endregion
#region CloseCommand
/// <summary>
/// Returns the command that, when invoked, attempts
/// to remove this workspace from the user interface.
/// </summary>
public ICommand CloseCommand
{
get
{
if (closeCommand == null)
closeCommand = new RelayCommand(param => this.OnRequestClose());
return closeCommand;
}
}
#endregion // CloseCommand
#region RequestClose [event]
/// <summary>
/// Raised when this workspace should be removed from the UI.
/// </summary>
public event EventHandler RequestClose;
/// <summary>
/// If requested to close and a RequestClose delegate has been set then call it.
/// </summary>
void OnRequestClose()
{
EventHandler handler = this.RequestClose;
if (handler != null)
{
handler(this, EventArgs.Empty);
}
}
#endregion // RequestClose [event]
http://marlongrech.wordpress.com/2008/12/13/attachedcommandbehavior-v2-aka-acb/
我从这篇文章中获得了灵感，并将其改编成了一个我正在构建的库，供自己使用（但将公开位于此处：https://github.com/RFBCodeWorks/MvvmControls）。
虽然我的方法有点通过传递给处理程序的“sender”和“eventargs”向ViewModel暴露View，但我使用这种方法只是为了以防其他某些处理需要它。例如，如果处理程序不是ViewModel，而是记录打开/关闭窗口的某个服务，则该服务可能想要了解发送者。如果VM不想知道View，则它只需不检查发送者或参数。
以下是我想出的相关代码，它消除了Code-Behind，并允许在xaml中进行绑定：
Behaviors:WindowBehaviors.IWindowClosingHandler="{Binding ElementName=ThisWindow, Path=DataContext}"
/// <summary>
/// Interface that can be used to send a signal from the View to the ViewModel that the window is closing
/// </summary>
public interface IWindowClosingHandler
{
/// <summary>
/// Executes when window is closing
/// </summary>
void OnWindowClosing(object sender, System.ComponentModel.CancelEventArgs e);
/// <summary>
/// Occurs when the window has closed
/// </summary>
void OnWindowClosed(object sender, EventArgs e);
}
/// <summary>
/// Attached Properties for Windows that allow MVVM to react to a window Loading/Activating/Deactivating/Closing
/// </summary>
public static class WindowBehaviors
{
#region < IWindowClosing >
/// <summary>
/// Assigns an <see cref="IWindowClosingHandler"/> handler to a <see cref="Window"/>
/// </summary>
public static readonly DependencyProperty IWindowClosingHandlerProperty =
DependencyProperty.RegisterAttached(nameof(IWindowClosingHandler),
typeof(IWindowClosingHandler),
typeof(WindowBehaviors),
new PropertyMetadata(null, IWindowClosingHandlerPropertyChanged)
);
/// <summary>
/// Gets the assigned <see cref="IWindowLoadingHandler"/> from a <see cref="Window"/>
/// </summary>
public static IWindowClosingHandler GetIWindowClosingHandler(DependencyObject obj) => (IWindowClosingHandler)obj.GetValue(IWindowClosingHandlerProperty);
/// <summary>
/// Assigns an <see cref="IWindowClosingHandler"/> to a <see cref="Window"/>
/// </summary>
public static void SetIWindowClosingHandler(DependencyObject obj, IWindowClosingHandler value)
{
if (obj is not null and not Window) throw new ArgumentException($"{nameof(IWindowClosingHandler)} property can only be bound to a {nameof(Window)}");
obj.SetValue(IWindowClosingHandlerProperty, value);
}
private static void IWindowClosingHandlerPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
Window w = d as Window;
if (w is null) return;
if (e.NewValue != null)
{
w.Closing += W_Closing;
w.Closed += W_Closed;
}
else
{
w.Closing -= W_Closing;
w.Closed -= W_Closed;
}
}
private static void W_Closed(object sender, EventArgs e)
{
GetIWindowClosingHandler(sender as DependencyObject)?.OnWindowClosed(sender, e);
}
private static void W_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
GetIWindowClosingHandler(sender as DependencyObject)?.OnWindowClosing(sender, e);
}
#endregion
}