blocks|key|1147334|text|我很想在您的App.xaml.cs文件中使用一个事件处理程序，它允许您决定是否关闭应用程序。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1147335|例如，您可以在App.xaml.cs文件中包含类似以下代码的内容：|1147336|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+%2B=+handler;

++++window.DataContaxt+=+viewModel;

++++window.Show();

}|code-block|syntax|javascript|1147337|然后，在您的MainWindowViewModel代码中，您可以拥有以下内容：|1147338|#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]|1147339|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

I would be tempted to use an event handler within your App.xaml.cs file that will allow you to decide on whether to close the application or not.

For example you could then have something like the following code in your App.xaml.cs file:

<pre><code>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();

}
</code></pre>

Then within your MainWindowViewModel code you could have the following:

<pre><code>#region Fields
RelayCommand closeCommand;
#endregion

#region CloseCommand
/// &lt;summary&gt;
/// Returns the command that, when invoked, attempts
/// to remove this workspace from the user interface.
/// &lt;/summary&gt;
public ICommand CloseCommand
{
 get
 {
 if (closeCommand == null)
 closeCommand = new RelayCommand(param =&gt; this.OnRequestClose());

 return closeCommand;
 }
}
#endregion // CloseCommand

#region RequestClose [event]

/// &lt;summary&gt;
/// Raised when this workspace should be removed from the UI.
/// &lt;/summary&gt;
public event EventHandler RequestClose;

/// &lt;summary&gt;
/// If requested to close and a RequestClose delegate has been set then call it.
/// &lt;/summary&gt;
void OnRequestClose()
{
 EventHandler handler = this.RequestClose;
 if (handler != null)
 {
 handler(this, EventArgs.Empty);
 }
}

#endregion // RequestClose [event]
</code></pre>

blocks|key|933024|text|基本上，窗口事件可能不会分配给MVVM。通常，关闭按钮会显示一个对话框，询问用户“保存:是/否/取消”，而这可能不是通过MVVM实现的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|933025|您可以保留OnClosing事件处理程序，您可以在其中调用Model.Close.CanExecute()并在event属性中设置布尔结果。因此，在CanExecute()调用(如果为真)之后，或者在OnClosed事件中，调用Model.Close.Execute()|933026|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Basically, window event may not be assigned to MVVM. In general, the Close button show a Dialog box to ask the user "save : yes/no/cancel", and this may not be achieved by the MVVM.

You may keep the OnClosing event handler, where you call the Model.Close.CanExecute() and set the boolean result in the event property.
So after the CanExecute() call if true, OR in the OnClosed event, call the Model.Close.Execute()

blocks|key|1147444|text|我没有做太多的测试，但它似乎是有效的。这是我想出来的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1147445|namespace+OrtzIRC.WPF
{
++++using+System;
++++using+System.Windows;
++++using+OrtzIRC.WPF.ViewModels;

++++///+<summary>
++++///+Interaction+logic+for+App.xaml
++++///+</summary>
++++public+partial+class+App+:+Application
++++{
++++++++private+MainViewModel+viewModel+=+new+MainViewModel();
++++++++private+MainWindow+window+=+new+MainWindow();

++++++++protected+override+void+OnStartup(StartupEventArgs+e)
++++++++{
++++++++++++base.OnStartup(e);

++++++++++++viewModel.RequestClose+%2B=+ViewModelRequestClose;

++++++++++++window.DataContext+=+viewModel;
++++++++++++window.Closing+%2B=+Window_Closing;
++++++++++++window.Show();
++++++++}

++++++++private+void+ViewModelRequestClose(object+sender,+EventArgs+e)
++++++++{
++++++++++++viewModel.RequestClose+-=+ViewModelRequestClose;
++++++++++++window.Close();
++++++++}

++++++++private+void+Window_Closing(object+sender,+System.ComponentModel.CancelEventArgs+e)
++++++++{
++++++++++++window.Closing+-=+Window_Closing;
++++++++++++viewModel.RequestClose+-=+ViewModelRequestClose;+//Otherwise+Close+gets+called+again
++++++++++++viewModel.CloseCommand.Execute(null);
++++++++}
++++}
}|code-block|syntax|javascript|1147446|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I haven't done much testing with this but it seems to work. Here's what I came up with:

<pre><code>namespace OrtzIRC.WPF
{
 using System;
 using System.Windows;
 using OrtzIRC.WPF.ViewModels;

 /// &lt;summary&gt;
 /// Interaction logic for App.xaml
 /// &lt;/summary&gt;
 public partial class App : Application
 {
 private MainViewModel viewModel = new MainViewModel();
 private MainWindow window = new MainWindow();

 protected override void OnStartup(StartupEventArgs e)
 {
 base.OnStartup(e);

 viewModel.RequestClose += ViewModelRequestClose;

 window.DataContext = viewModel;
 window.Closing += Window_Closing;
 window.Show();
 }

 private void ViewModelRequestClose(object sender, EventArgs e)
 {
 viewModel.RequestClose -= ViewModelRequestClose;
 window.Close();
 }

 private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
 {
 window.Closing -= Window_Closing;
 viewModel.RequestClose -= ViewModelRequestClose; //Otherwise Close gets called again
 viewModel.CloseCommand.Execute(null);
 }
 }
}
</code></pre>

blocks|key|933112|text|为此，我们使用AttachedCommandBehavior。您可以将任何事件附加到视图模型上的命令，从而避免任何代码隐藏。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|933113|我们在整个解决方案中都使用它，并且几乎没有任何代码|933114|http://marlongrech.wordpress.com/2008/12/13/attachedcommandbehavior-v2-aka-acb/|offset|length|933115|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|27|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Q|8|@]|9|@$F|R|G|S|1|T]]|A|$]]|$1|H|3|-4|5|6|7|U|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|E]]]]

We use AttachedCommandBehavior for this. You can attach any event to a command on your view model avoiding any code behind.

We use it throughout our solution and have almost zero code behind

<a href="http://marlongrech.wordpress.com/2008/12/13/attachedcommandbehavior-v2-aka-acb/" rel="nofollow noreferrer">http://marlongrech.wordpress.com/2008/12/13/attachedcommandbehavior-v2-aka-acb/</a>

blocks|key|933168|text|这个选项更简单，也许更适合你。在视图模型构造函数中，您可以订阅主窗口关闭事件，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|933169|Application.Current.MainWindow.Closing+%2B=+new+CancelEventHandler(MainWindow_Closing);

void+MainWindow_Closing(object+sender,+CancelEventArgs+e)
{
++++++++++++//Your+code+to+handle+the+event
}|code-block|syntax|javascript|933170|万事如意。|933171|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

This option is even easier, and maybe is suitable for you. In your View Model constructor, you can subscribe the Main Window closing event like this:

<pre><code>Application.Current.MainWindow.Closing += new CancelEventHandler(MainWindow_Closing);

void MainWindow_Closing(object sender, CancelEventArgs e)
{
 //Your code to handle the event
}
</code></pre>

All the best.

blocks|key|933252|text|如果你不想了解ViewModel中的窗口(或它的任何事件)，根据MVVM模式，这里有一个答案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|933253|public+interface+IClosing
{
++++///+<summary>
++++///+Executes+when+window+is+closing
++++///+</summary>
++++///+<returns>Whether+the+windows+should+be+closed+by+the+caller</returns>
++++bool+OnClosing();
}|code-block|syntax|javascript|933254|在ViewModel中添加接口和实现|933255|public+bool+OnClosing()
{
++++bool+close+=+true;

++++//Ask+whether+to+save+changes+och+cancel+etc
++++//close+=+false;+//If+you+want+to+cancel+close

++++return+close;
}|933256|在窗口中，我添加了关闭事件。此代码隐藏不会破坏MVVM模式。视图可以知道视图模型！|933257|void+Window_Closing(object+sender,+System.ComponentModel.CancelEventArgs+e)
{
++++IClosing+context+=+DataContext+as+IClosing;
++++if+(context+!=+null)
++++{
++++++++e.Cancel+=+!context.OnClosing();
++++}
}|933258|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Here is an answer according to the MVVM-pattern if you don't want to know about the Window (or any of its event) in the ViewModel.

<pre><code>public interface IClosing
{
 /// &lt;summary&gt;
 /// Executes when window is closing
 /// &lt;/summary&gt;
 /// &lt;returns&gt;Whether the windows should be closed by the caller&lt;/returns&gt;
 bool OnClosing();
}
</code></pre>

In the ViewModel add the interface and implementation

<pre><code>public bool OnClosing()
{
 bool close = true;

 //Ask whether to save changes och cancel etc
 //close = false; //If you want to cancel close

 return close;
}
</code></pre>

In the Window I add the Closing event. This code behind doesn't break the MVVM pattern. The View can know about the viewmodel!

<pre><code>void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
 IClosing context = DataContext as IClosing;
 if (context != null)
 {
 e.Cancel = !context.OnClosing();
 }
}
</code></pre>

blocks|key|1147755|text|发问者应该使用STAS+answer，但对于使用prism而不使用galasoft/mvvmlight的读者，他们可能想要尝试我使用的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1147756|在顶部的窗口或用户控件等定义中，定义名称空间：|1147757|xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"|code-block|syntax|javascript|1147758|就在这个定义之下：|1147759|<i:Interaction.Triggers>
++++++++<i:EventTrigger+EventName="Closing">
++++++++++++<i:InvokeCommandAction+Command="{Binding+WindowClosing}"+CommandParameter="{Binding}"+/>
++++++++</i:EventTrigger>
</i:Interaction.Triggers>|1147760|视图模型中的属性：|1147761|public+ICommand+WindowClosing+{+get;+private+set;+}|1147762|在视图模型构造函数中附加委托命令：|1147763|this.WindowClosing+=+new+DelegateCommand<object>(this.OnWindowClosing);|1147764|最后，您想要在关闭控件/窗口/任何东西时访问的代码：|1147765|private+void+OnWindowClosing(object+obj)
++++++++{
++++++++++++//put+code+here
++++++++}|1147766|entityMap^0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|12|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|13|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|14|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|15|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|16|8|@]|9|@]|A|$G|H]]|$1|Q|3|R|5|6|7|17|8|@]|9|@]|A|$]]|$1|S|3|T|5|F|7|18|8|@]|9|@]|A|$G|H]]|$1|U|3|V|5|6|7|19|8|@]|9|@]|A|$]]|$1|W|3|X|5|F|7|1A|8|@]|9|@]|A|$G|H]]|$1|Y|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|Z|$]]

The asker should use STAS answer, but for readers who use prism and no galasoft/mvvmlight, they may want to try what I used:

In the definition at the top for window or usercontrol, etc define namespace:

<pre><code>xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
</code></pre>

And just below that definition:

<pre><code>&lt;i:Interaction.Triggers&gt;
 &lt;i:EventTrigger EventName="Closing"&gt;
 &lt;i:InvokeCommandAction Command="{Binding WindowClosing}" CommandParameter="{Binding}" /&gt;
 &lt;/i:EventTrigger&gt;
&lt;/i:Interaction.Triggers&gt;
</code></pre>

Property in your viewmodel:

<pre><code>public ICommand WindowClosing { get; private set; }
</code></pre>

Attach delegatecommand in your viewmodel constructor:

<pre><code>this.WindowClosing = new DelegateCommand&lt;object&gt;(this.OnWindowClosing);
</code></pre>

Finally, your code you want to reach on close of the control/window/whatever:

<pre><code>private void OnWindowClosing(object obj)
 {
 //put code here
 }
</code></pre>

blocks|key|1147771|text|private+void+Window_Closing(object+sender,+System.ComponentModel.CancelEventArgs+e)
++++{
++++++++MessageBox.Show("closing");
++++}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1147772|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
 {
 MessageBox.Show("closing");
 }
</code></pre>

blocks|key|933453|text|您可以使用一些后台代码轻松完成此任务；在Main.xaml+set中：Closing="Window_Closing"|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|933454|在Main.cs中：|933455|+public+MainViewModel+dataContext+{+get;+set;+}
+public+ICommand+CloseApp+
+++{
++++++get+{+return+(ICommand)GetValue(CloseAppProperty);+}
++++++set+{+SetValue(CloseAppProperty,+value);+}
+++}
public+static+readonly+DependencyProperty+CloseAppProperty+=
DependencyProperty.Register("CloseApp",+typeof(ICommand),+typeof(MainWindow),+new+PropertyMetadata(null));|code-block|syntax|javascript|933456|在Main.OnLoading中：|933457|dataContext+=+DataContext+as+MainViewModel;|933458|在Main.Window_Closing中：|933459|+++if+(CloseApp+!=+null)
++++++CloseApp+.Execute(this);|933460|在MainWindowModel中：|933461|++++public+ICommand+CloseApp+=>+new+CloseApp+(this);|933462|最后：|933463|CloseApp类:+ICommand+{+public+event+EventHandler+CanExecuteChanged；|933464|++++private+MainViewModel+_viewModel;

++++public+CloseApp+(MainViewModel+viewModel)
++++{
++++++++_viewModel+=+viewModel;
++++}


++++public+bool+CanExecute(object+parameter)
++++{
++++++++return+true;
++++}

++++public+void+Execute(object+parameter)
++++{
++++++++Console.WriteLine();
++++}
}|933465|entityMap^0|Z|O|0|0|0|0|0|17|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|19|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1A|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1B|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|1C|8|@$9|1D|A|1E|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|6|7|1F|8|@]|D|@]|E|$]]|$1|S|3|T|5|J|7|1G|8|@]|D|@]|E|$K|L]]|$1|U|3|V|5|6|7|1H|8|@]|D|@]|E|$]]|$1|W|3|X|5|J|7|1I|8|@]|D|@]|E|$K|L]]|$1|Y|3|Z|5|6|7|1J|8|@]|D|@]|E|$]]|$1|10|3|11|5|6|7|1K|8|@]|D|@]|E|$]]|$1|12|3|13|5|J|7|1L|8|@]|D|@]|E|$K|L]]|$1|14|3|-4|5|6|7|1M|8|@]|D|@]|E|$]]]|15|$]]

You could easily do it with some code behind;
In Main.xaml set:
<code>Closing=&quot;Window_Closing&quot;</code>
In Main.cs:
<pre><code> public MainViewModel dataContext { get; set; }
 public ICommand CloseApp 
 {
 get { return (ICommand)GetValue(CloseAppProperty); }
 set { SetValue(CloseAppProperty, value); }
 }
public static readonly DependencyProperty CloseAppProperty =
DependencyProperty.Register(&quot;CloseApp&quot;, typeof(ICommand), typeof(MainWindow), new PropertyMetadata(null));
</code></pre>
In Main.OnLoading:
<code>dataContext = DataContext as MainViewModel;</code>
In Main.Window_Closing:
<pre><code> if (CloseApp != null)
 CloseApp .Execute(this);
</code></pre>
In MainWindowModel:
<pre><code> public ICommand CloseApp =&gt; new CloseApp (this);
</code></pre>
And finally:
class CloseApp : ICommand
{
public event EventHandler CanExecuteChanged;
<pre><code> private MainViewModel _viewModel;

 public CloseApp (MainViewModel viewModel)
 {
 _viewModel = viewModel;
 }


 public bool CanExecute(object parameter)
 {
 return true;
 }

 public void Execute(object parameter)
 {
 Console.WriteLine();
 }
}
</code></pre>

I'd like to handle the <code>Closing</code> event (when a user clicks the upper right 'X' button) of my window in order to eventually display a confirm message or/and cancel the closing.

I know how to do this in the code-behind: subscribe to the <code>Closing</code> event of the window then use the <code>CancelEventArgs.Cancel</code> property.

But I'm using MVVM so I'm not sure it's the good approach.

I think the good approach would be to bind the <code>Closing</code> event to a <code>Command</code> in my ViewModel.

I tried that:

<pre><code>&lt;i:Interaction.Triggers&gt;
 &lt;i:EventTrigger EventName="Closing"&gt;
 &lt;cmd:EventToCommand Command="{Binding CloseCommand}" /&gt;
 &lt;/i:EventTrigger&gt;
&lt;/i:Interaction.Triggers&gt;
</code></pre>

With an associated <code>RelayCommand</code> in my ViewModel but it doesn't work (the command's code is not executed).

Handling the window closing event with WPF / MVVM Light Toolkit

Windows

我希望处理窗口的Closing事件(当用户单击右上角的'X‘按钮时)，以便最终显示确认消息或/和取消关闭。我知道如何在代码隐藏中做到这一点:订阅窗口的Closing事件，然后使用CancelEventArgs.Cancel属性。但是我使用的是MVVM，所以我不确定这是不是一个好的方法。我认为最好的方法是将Closing...

问用WPF / MVVM Light Toolkit处理窗口关闭事件
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