How to handle closing window when pressing close icon on the top-right in WPF/MVVM?

Question

I am able to bind buttons and menu items with ICommand and close the windows. It is exactly as described in the tutorial WPF Apps With The Model-View-ViewModel Design Pattern - via the Command property accessible in XAML.

But it is not described or implemented in the tutorial how to close by pressing the standard 'Close' icon on the top-right of the window. I need to perform some clean up in my application. My question is how to bind a Command to the close event, so that it is executed when the user presses the close icon (not buttons or menu items - I know how to manage such cases).

How should this be handled to avoid violating the MVVM approach? Thanks!

Answer 1

I would bind a Command to the Application's Exit event

I like using the AttachedCommand behavior found here for binding Commands to Events, although I know you can also accomplish the same thing using Blend's Interaction Triggers.

Answer 2

The MVVM Light Toolkit contains a behaviour called EventToCommand, which gives you an easy way to bind a command to an event.

The following XAML snippet shows an example of how to get a command called "CloseCommand" to execute when the window's Closed event is raised:

<Window x:Class="EventToCommand.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" 
        xmlns:cmd="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Extras.WPF4"
    Title="MainWindow" Height="300" Width="500">

    <!-- Make sure to put this tag directly inside the Window, 
         and not inside a child element, since it is the Windows that has the Closed event -->
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="Closed">
            <cmd:EventToCommand Command="{Binding CloseCommand}"/>
        </i:EventTrigger>
    </i:Interaction.Triggers>

    <!-- Windows contents -->

</Window>

To get access to the EventToCommand behaviour, you need to download MVVM Light Toolkit from the project downloads page , and then reference the following DLLs:

• GalaSoft.MvvmLight.dll
• GalaSoft.MvvmLight.Extras.dll
• System.Windows.Interactivity.dll

That is all that is needed.

Further instructions of how to get started with the toolkit can be found here .