Arrow cue - graphic problem

[Tim Tos]

Hello!

I am currently evaluating the DragAndDrop-Functionality - unfortunately I ran into some kind of graphic invalidation problem.
I am dragging from a custom usercontrol to a RadTreeView that's a child of a RadExpander. A snapshot of the result is attached as a png file. Has anyone experienced such a behavior? What am I doing wrong? Or is it a bug?

My code is very simple! I just activate the DragAndDrop-Functionality, register the events and then for the source and the destination in the code-behind:
Source:

private void OnDragQuery(object sender, DragDropQueryEventArgs e)
{
    e.Options.DragCue = RadDragAndDropManager.GenerateVisualCue();
    e.Options.ArrowCue = RadDragAndDropManager.GenerateArrowCue();
    e.Options.Payload = "Hello World";
    e.QueryResult = true;
    e.Handled = true;
}

Destination:

private void OnDropQuery(object sender, DragDropQueryEventArgs e)
{
    e.QueryResult = true;
    e.Handled = true;
}

private void OnDropInfo(object sender, DragDropEventArgs e)
{
    string payload = e.Options.Payload.ToString();

    if (e.Options.Status == DragStatus.DropComplete)
        this.myTreeView.Items.Add(payload);
}

That's all. Any ideas?
Thanks a lot,
Tim.

[Tsvyatko]

Hi Tim Tos,

Could you please try to wrap the logic for creating the Visual and Arrow Cue in this code:

  if (args.Options.Status == DragStatus.DragQuery){
...
}

Please, let me know, if you have further problems.

Best wishes,
Tsvyatko
the Telerik team

[Tim Tos]

Hello Tsvyatko,

thanks a lot!!! That did the trick!
Best wishes,
Tim.

[Andrew]

Hello,

I want to add ArrowCue to the RadTreeView. I do this in OnDragQuery event but e.Options.Status is always DropImpossible. Am I doing something wrong?

This is my code:

<Grid x:Name="LayoutRoot" Background="White">
   <Grid.RowDefinitions>
      <RowDefinition Height="*" />
      <RowDefinition Height="20" />
   </Grid.RowDefinitions>

   <Grid.ColumnDefinitions>
      <ColumnDefinition Width="*" />
      <ColumnDefinition Width="*" />
      <ColumnDefinition Width="*" />
      <ColumnDefinition Width="*" />
   </Grid.ColumnDefinitions>

   <telerik:RadTreeView Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="4" x:Name="radTreeView1">
      <telerik:RadTreeViewItem DropPosition="Inside" Header="Item 1" TabNavigation="Once" />
      <telerik:RadTreeViewItem DropPosition="Inside" Header="Item 2" TabNavigation="Once" />
      <telerik:RadTreeViewItem DropPosition="Inside" Header="Item 3" TabNavigation="Once" />
      <telerik:RadTreeViewItem DropPosition="Inside" Header="Item 4" TabNavigation="Once" />
      <telerik:RadTreeViewItem DropPosition="Inside" Header="Item 5" TabNavigation="Once" />
   </telerik:RadTreeView>

   <TextBlock Grid.Row="1" Grid.Column="0" x:Name="tbDragQuery" Text="DragQuery status: " />
   <TextBlock Grid.Row="1" Grid.Column="1" x:Name="tbDragInfo" Text="DragInfo status: " />
   <TextBlock Grid.Row="1" Grid.Column="2" x:Name="tbDropQuery" Text="DropQuery status: " />
   <TextBlock Grid.Row="1" Grid.Column="3" x:Name="tbDropInfo" Text="DropInfo status: " />
</Grid>

public MainPage()
{
   InitializeComponent();

   radTreeView1.IsDragDropEnabled = true;

   RadDragAndDropManager.AddDragQueryHandler(this.radTreeView1, OnDragQuery);
   RadDragAndDropManager.AddDragInfoHandler(this.radTreeView1, OnDragInfo);
   RadDragAndDropManager.AddDropQueryHandler(this.radTreeView1, OnDropQuery);
   RadDragAndDropManager.AddDropInfoHandler(this.radTreeView1, OnDropInfo);
}

private void OnDragQuery(object sender, DragDropQueryEventArgs e)
{
   tbDragQuery.Text = "DragQuery status: " + e.Options.Status.ToString();

   if (e.Options.Source is RadTreeViewItem)
   {
      RadTreeView tree = sender as RadTreeView;
      if (e.Options.Status == DragStatus.DragQuery && tree != null)
      {
         e.Options.Payload = tree.SelectedItems;
         e.Options.ArrowCue = RadDragAndDropManager.GenerateArrowCue();
         (e.Options.DragCue as TreeViewDragCue).ItemTemplate =
            (DataTemplate)System.Windows.Markup.XamlReader.Load("<DataTemplate xmlns=\"http://schemas.microsoft.com/winfx/2006/xaml/presentation\"><Image Source=\"/../../Img/Dashboard48.png\" Stretch=\"None\" VerticalAlignment=\"Top\" /></DataTemplate>");
      }
      e.QueryResult = true;
      e.Handled = true;
   }
}

private void OnDragInfo(object sender, DragDropEventArgs e)
{
   tbDragInfo.Text = "DragInfo status: " + e.Options.Status.ToString();
}

private void OnDropQuery(object sender, DragDropQueryEventArgs e)
{
   tbDropQuery.Text = "DropQuery status: " + e.Options.Status.ToString();
}

private void OnDropInfo(object sender, DragDropEventArgs e)
{
   tbDropInfo.Text = "DropInfo status: " + e.Options.Status.ToString();

   TreeViewDragCue cue = e.Options.DragCue as TreeViewDragCue;
   if (e.Options.Status == DragStatus.DropPossible)
   {
      cue.DragActionContent = String.Format("Move here: ");
      cue.IsDropPossible = true;
   }
   else if (e.Options.Status == DragStatus.DropImpossible)
   {
      cue.DragActionContent = null;
      cue.IsDropPossible = false;
   }
}

[Ivan Ivanov]

Hello Tim Tos,

I have prepared a sample project, similar to the one you have sent to me. Telerik RadTreeView internally handles drag and drop events. In order to subscribe to one, you should utilize the technique, demonstrated in the project. Please, have in mind that you should import Telerik.Windows namespace to enable the usage of our AddHandler(Telerik.Windows.RoutedEvent, ...) extension method, instead of AddHandler(System.Windows.RoutedEvent, ...).


All the best,
Ivan Ivanov
the Telerik team