DispatcherService

• Feb 26, 2021

The DispatcherService is an IDispatcherService implementation that allows you to perform actions in a ViewModel using the Dispatcher.

Getting Started with DispatcherService

Use the DispatcherService to perform an action in a ViewModel using the Dispatcher. Add the service to the view’s dxmvvmi:Interaction.Behaviors.

XAML

<UserControl
    xmlns:dxmvvmi="using:DevExpress.WinUI.Mvvm.UI.Interactivity"
    xmlns:dxmvvm="using:DevExpress.WinUI.Mvvm.UI"
    xmlns:ViewModel="using:WinUIApp.ViewModel" ...>
    <UserControl.DataContext>
        <ViewModel:ViewModel />
    </UserControl.DataContext>
    <dxmvvmi:Interaction.Behaviors>
        <dxmvvm:DispatcherService />
    </dxmvvmi:Interaction.Behaviors>
        ...
</UserControl>

Use the BeginInvoke method to perform the required actions. The example below uses the DispatcherService to execute the CalcCore method defined in the View Model.

C#

public class ViewModel {
    protected IDispatcherService DispatcherService { get { return this.GetService<IDispatcherService>(); } }
    ...
    void CalcCore() {
        ...
        DispatcherService.BeginInvoke(() => { ... });
        ...     
    }
    ...
}

VB.NET

Public Class ViewModel
    Protected ReadOnly Property DispatcherService() As IDispatcherService
        Get
            Return Me.GetService(Of IDispatcherService)()
        End Get
    End Property
    '...
    Private Sub CalcCore()
        '...
        DispatcherService.BeginInvoke(Sub()
            ...
        End Sub)
        '...
    End Sub
    '...
End Class

The DispatcherService has the following properties:

• DispatcherPriority - gets or sets the DispatcherService’s Dispatcher priority by which operations can be invoked by the Dispatcher.
• Delay - gets or sets the time delay (a TimeSpan object) before invoking the DispatcherService’s BeginInvoke method.