How do I close a window(XAML) from the ViewModelHelper in c#?

Question

I want to perform onCloseCommand(object sender) method form onTimeOutCommand() method, but I don't know how to pass the required parameter passed from this method?

Plese refer the following code snippet.

XAML code:

x:name = "Recorder" // window name define in the begining


//below command is used for closing this window when user clicks on close button

Command = "{Binding CloseCommand}" CommandParameter="{Binding ElementName=Recorder}"

ViewModel Code:

CloseCommand = new DelegateCommand<object>(helper.onCloseCommand);

ViewModelHelper Code:

Note: onCloseCommand() methodis working as per expectation
onCloseCommand(object sender) // This method is used for closing the window on clicking on close button of this window
{
    if(sender != null && send is window)
    {
         (sender as window).close();
    }
}

onTimeOutCommand() // this method is used for closing the window (the window which is passed in onCloseCommand() method) automaticlly after time out of the recording
{
      how to perform onCloseCommand() from this method?
}

Answer 1

You should use AttachProperty to close your window.

public static class Attach
{
    #region CloseProperty
    public static DependencyProperty WindowCloseProperty = DependencyProperty.RegisterAttached("WindowClose",
        typeof(bool), typeof(Attach),
        new UIPropertyMetadata(false, WindowClosePropertyChangedCallback));

    private static void WindowClosePropertyChangedCallback(DependencyObject dependencyObject,
        DependencyPropertyChangedEventArgs eventArgs)
    {
        var window = (Window)dependencyObject;
        if (window != null && (bool)eventArgs.NewValue)
            window.Close();
    }

    public static bool GetWindowClose(DependencyObject obj)
        => (bool)obj.GetValue(WindowCloseProperty);

    public static void SetWindowClose(DependencyObject obj, bool value)
    {
        obj.SetValue(WindowCloseProperty, value);
    }

    #endregion
}

and in XAML

<Window x:Class="MyProject.MyWindow"
xmlns:helper="clr-namespace:MyProject.Helper;assembly=MyProject"
    helper:Attach.WindowClose="{Binding IsWindowClose}">

and in ViewModel when you set IsWindowClose to true your Window close

  public bool IsWindowClose
  {
      get => _isWindowClose;
      set => SetProperty(ref _isWindowClose, value);
  }

Answer 2

how to perform onCloseCommand() from this method?

You have multiple options, eg create an attached behavior that closes the window after a certain timeout and use that from xaml, effectively leaving the view model out of the equation.

I suggest you react to the window's Loaded event in the view model and store the window and use it later when you want to close it.

<Window x:Class="MyWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
        mc:Ignorable="d">
     <i:Interaction.Triggers>
         <i:EventTrigger EventName="Loaded">
             <i:InvokeCommandAction Command="{Binding WindowLoadedCommand}" CommandParameter="{Binding RelativeSource={RelativeSource AncestorType={x:Type Window}}}"/>
         </i:EventTrigger>
     </i:Interaction.Triggers>

     <!--- the rest of the window here --->
</Window>

But let me refer you to this answer for a more mvvm-friendly and, more importantly, testable way to close a window from the view model:

Make the window implement an interface and store and use that (not the full Window )!

So WindowLoadedCommand is of type DelegateCommand<IClosable> and stores the IClosable in a field. When the timeout occurs, fetch the IClosable from the field and call Close .