EventToCommand.EventArgsConverter Property

Gets or sets an object that converts the event’s argument to a command’s parameter. This is a dependency property.

Namespace: DevExpress.WinUI.Core

Assembly: DevExpress.WinUI.Core.v22.1.dll

NuGet Package: DevExpress.WinUI

Declaration

C#

[DP(null)]
public IEventArgsConverter EventArgsConverter { get; set; }

VB.NET

<DP(Nothing)>
Public Property EventArgsConverter As IEventArgsConverter

Property Value

Type	Description
IEventArgsConverter	An object that implements the IEventArgsConverter interface.

Remarks

The EventToCommand behavior allows you to pass an event’s arguments to a command. If you want to maintain a clean MVVM pattern and convert the event’s arguments to an object suitable for the command, specify the EventArgsConverter property as follows:

XAML

<ListBox ...>
    <dx:Interaction.Behaviors>
        <dx:EventToCommand EventName="DoubleTapped" Command="{x:Bind EditCommand}">
            <dx:EventToCommand.EventArgsConverter>
                <local:CustomEventArgsConverter/>
            </dx:EventToCommand.EventArgsConverter>
        </dx:EventToCommand>
    </dx:Interaction.Behaviors>
</ListBox>

The defined EventArgsConverter should implement the IEventArgsConverter interface. You can also derive the converter from the EventArgsConverterBase<TArgs, TResult> class, which already implements the IEventArgsConverter interface.

C#

public interface IEventArgsConverter {
    object Convert(object sender, object args);
    void ConvertBack(object sender, object args, object parameter);
}
public abstract class EventArgsConverterBase<TArgs, TResult> : IEventArgsConverter {
    protected abstract TResult Convert(object sender, TArgs args);
    protected virtual void ConvertBack(object sender, TArgs args, TResult parameter) { }
}

VB.NET

Public Interface IEventArgsConverter
    Function Convert(ByVal sender As Object, ByVal args As Object) As Object
    Sub ConvertBack(ByVal sender As Object, ByVal args As Object, ByVal parameter As Object)
End Interface

Public MustInherit Class EventArgsConverterBase(Of TArgs, TResult)
    Implements IEventArgsConverter

    Protected MustOverride Function Convert(ByVal sender As Object, ByVal args As TArgs) As TResult
    Protected Overridable Sub ConvertBack(ByVal sender As Object, ByVal args As TArgs, ByVal parameter As TResult)
    End Sub
End Class

When you implement the converter, you can use the LayoutTreeHelper class that can search for nodes in an application’s visual tree:

C#

using DevExpress.WinUI.Core;
using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
using System.Linq;

public class ListBoxPointerEventArgsConverter : EventArgsConverterBase<RoutedEventArgs, SelectedItemInfo> {
    protected override SelectedItemInfo Convert(object sender, RoutedEventArgs args) {
        var listBox = (ListBox)sender;
        var originalSource = (DependencyObject)args.OriginalSource;
        var listBoxItem = LayoutTreeHelper.GetVisualParents(originalSource, listBox)
            .OfType<ListBoxItem>()
            .FirstOrDefault();
        var selectedItem = listBoxItem != null ? listBox.ItemFromContainer(listBoxItem) : null;
        return new SelectedItemInfo(selectedItem);
    }
}
public class SelectedItemInfo {
    public object Value { get; }
    public SelectedItemInfo(object value) {
        Value = value;
    }
}

VB.NET

Imports DevExpress.WinUI.Core
Imports Microsoft.UI.Xaml
Imports Microsoft.UI.Xaml.Controls
Imports System.Linq

Public Class ListBoxPointerEventArgsConverter
    Inherits EventArgsConverterBase(Of RoutedEventArgs, SelectedItemInfo)

    Protected Overrides Function Convert(ByVal sender As Object, ByVal args As RoutedEventArgs) As SelectedItemInfo
        Dim listBox = CType(sender, ListBox)
        Dim originalSource = CType(args.OriginalSource, DependencyObject)
        Dim listBoxItem = LayoutTreeHelper.GetVisualParents(originalSource, listBox).OfType(Of ListBoxItem)().FirstOrDefault()
        Dim selectedItem = If(listBoxItem IsNot Nothing, listBox.ItemFromContainer(listBoxItem), Nothing)
        Return New SelectedItemInfo(selectedItem)
    End Function
End Class

Public Class SelectedItemInfo
    Public ReadOnly Property Value As Object

    Public Sub New(ByVal value As Object)
        Value = value
    End Sub
End Class