Allow Drag and Drop, Prevent reorder

[Datafyer]

I have a RadListBox that I am dragging items to a RadDiagram. This part works, but I can't figure out how to prevent reorder from within the RadListBox. I have tried several things. I just want to prevent the horizontal line from showing when the item is dragged away from the listboxand move to a different position within the list box.

 

This is my current code.

Xaml (Simplified to focus on problem)

01.<UserControl>
02.    <UserControl.Resources>
03.        <Style x:Key="DraggableListBoxItem" TargetType="telerik:RadListBoxItem" BasedOn="{StaticResource RadListBoxItemStyle}">
04.            <Setter Property="telerik:DragDropManager.AllowDrag" Value="True" />
05.        </Style>
06.    </UserControl.Resources>
07.
08.    <Grid Margin="5">
09.        <Grid.ColumnDefinitions>
10.            <ColumnDefinition Width="Auto" />
11.            <ColumnDefinition Width="*" />
12.        </Grid.ColumnDefinitions>
13.
14.        <Grid>
15.            <telerik:RadListBox Margin="0 10 0 0" Width="250" Grid.IsSharedSizeScope="True"
16.                            Background="Transparent" ScrollViewer.HorizontalScrollBarVisibility="Disabled" AllowDrop="False"
17.                            ItemContainerStyle="{StaticResource DraggableListBoxItem}"
18.                            ItemsSource="">
19.                <telerik:RadListBox.DragDropBehavior>
20.                    <behaviors:DatasourceDragDropBehavior AllowReorder="False" />
21.                </telerik:RadListBox.DragDropBehavior>
22.
23.                <telerik:RadListBox.DragVisualProvider>
24.                    <telerik:ScreenshotDragVisualProvider />
25.                </telerik:RadListBox.DragVisualProvider>
26.
27.                <telerik:RadListBox.ItemTemplate>
28.                    <DataTemplate>
29.                        <Grid>
30.                        </Grid>
31.                    </DataTemplate>
32.                </telerik:RadListBox.ItemTemplate>
33.            </telerik:RadListBox>
34.        </Grid>
35.
36.        <Grid>
37.            <telerik:RadDiagram IsSnapToGridEnabled="True" BorderThickness="1" BorderBrush="Black">
38.            </telerik:RadDiagram>
39.        </Grid>
40.    </Grid>
41.</UserControl>

Behavior

01.     class DatasourceDragDropBehavior : ListBoxDragDropBehavior
02.    {
03.        public override void DragDropCompleted(DragDropState state)
04.        {
05.            //implement some custom logic here
06.            //Do not call -> base.DragDropCompleted(state);
07.        }
08.
09.        public override bool CanDrop(DragDropState state)
10.        {
11.            return state.IsSameControl == false;
12.        }
13.    }

[Nasko]

Hello Patrick,

In order to prevent the horizontal line from visualization what we could suggest you is to create a custom DropVisualProvider and override the VisualizeDropPlaceholderEnded as demonstrated in the below code-snippet:

<telerik:RadListBox.DropVisualProvider>
    <local:NoDropVisualProvider/>
</telerik:RadListBox.DropVisualProvider>

and:

public class NoDropVisualProvider : LinearDropVisualProvider
{
    public override void VisualizeDropPlaceholderEnded(Telerik.Windows.Controls.RadListBoxItem container, System.Windows.Controls.Panel panel, object dataItem, System.Windows.FrameworkElement dropVisual)
    {
        //base.VisualizeDropPlaceholderEnded(container, panel, dataItem, dropVisual);
    }
}

We hope this will help you.

Regards,
Nasko
Telerik by Progress

[Datafyer]

Thanks. Very simple and works.