[Solved] Nested Drag and Drop

[Frustrated Dev]

Please Disregard. I figured it out. I was not casting the destination properly.

Hello,

I have an ItemsControl where each item is a TreeView. Below this ItemsControl is a GridView with a list of items. I'm trying to allow a user to drag items from the GridView into one of the TreeViews in the ItemsControl. When a user drops the item from the GridView onto a TreeView, the item would get added to that specific TreeView.  My XAML looks like the following:

<Grid>
  <Grid.RowDefinitions>
    <RowDefinition />
    <RowDefinition />
  </Grid.RowDefinitions>

  <Grid>
    <Grid.RowDefinitions>
      <RowDefinition Height="Auto" />
      <RowDefinition />
    </Grid.RowDefinitions>

    <StackPanel Orientation="Horizontal">
      <TextBlock Text="Tasks" VerticalAlignment="Center" />
    </StackPanel>

    <ItemsControl x:Name="myItemsControl" Grid.Row="1"
      telerikDragDrop:RadDragAndDropManager.AllowDrag="True"
      Loaded="myItemsControl_Loaded">
      <ItemsControl.ItemTemplate>
        <DataTemplate>
          <navigation:RadTreeView x:Name="myTree" HorizontalAlignment="Stretch" HorizontalContentAlignment="Stretch" Loaded="myTree_Loaded">
            <navigation:RadTreeViewItem Header="{Binding}">
              <navigation:RadTreeViewItem.ItemTemplate>
                <DataTemplate>
                  <TextBlock Text="{Binding}" />
                </DataTemplate>
              </navigation:RadTreeViewItem.ItemTemplate>
            </navigation:RadTreeViewItem>
          </navigation:RadTreeView>
        </DataTemplate>
      </ItemsControl.ItemTemplate>
    </ItemsControl>
  </Grid>

  <Grid Grid.Row="1">
    <Grid.RowDefinitions>
      <RowDefinition Height="Auto" />
      <RowDefinition />
    </Grid.RowDefinitions>

    <StackPanel Orientation="Horizontal">
      <TextBlock Text="Days" />
    </StackPanel>

    <telerik:RadGridView x:Name="myGridView" UseAlternateRowStyle="True"
      AutoGenerateColumns="False" ShowGroupPanel="False" Grid.Row="1"
      telerikDragDrop:RadDragAndDropManager.AllowDrop="True"
      Loaded="myGridView_Loaded">
      <telerik:RadGridView.RowStyle>
        <Style TargetType="gridview:GridViewRow">
          <Setter Property="telerikDragDrop:RadDragAndDropManager.AllowDrag" Value="True" />
        </Style>
       </telerik:RadGridView.RowStyle>
     <telerik:RadGridView.Columns>
     <telerik:GridViewDataColumn Header="Day" DataMemberBinding="{Binding}" IsReadOnly="True" IsFilterable="False" IsGroupable="False"  />
   </telerik:RadGridView.Columns>
 </telerik:RadGridView>
 </Grid>
 </Grid>

I can drag items from the GridView. But I cannot identify how to drop it on one of the TreeViews in the ItemsControl.  I have a message box that should say "dropped". But it is not triggering. I'm not sure what I'm doing wrong. My C# code is provided below. What am I doing wrong? How can I accomplish this?

Thank you for your help,

private void myTree_Loaded(object sender, RoutedEventArgs e)
{
  RadTreeView myTreeView = (RadTreeView)(sender);
  RadDragAndDropManager.SetAllowDrop(myTreeView, true);

  RadDragAndDropManager.AddDropQueryHandler(myTreeView, myTreeView_OnDropQuery);
  RadDragAndDropManager.AddDropInfoHandler(myTreeView, myTreeView_OnDropInfo);
}

private void myTreeView_OnDropQuery(object sender, Telerik.Windows.Controls.DragDrop.DragDropQueryEventArgs e)
{
  RadGridView destination = sender as RadGridView;
  if (destination != null)
  {
    e.Handled = true;
    e.QueryResult = true;
  }
}

private void myTreeView_OnDropInfo(object sender, Telerik.Windows.Controls.DragDrop.DragDropEventArgs e)
{
  RadGridView destination = sender as RadGridView;
  if (e.Options.Status == Telerik.Windows.Controls.DragDrop.DragStatus.DropComplete)
  {
    MessageBox.Show("dropped!");
  }
}

private void myItemsControl_Loaded(object sender, RoutedEventArgs e)
{
  List<string> tasks = new List<string>();
  tasks.Add("Sweep Floor");
  tasks.Add("Task out Garbage");
  tasks.Add("Clean Windows");

  myItemsControl.ItemsSource = tasks;
}

private void myGridView_Loaded(object sender, RoutedEventArgs e)
{
  RadDragAndDropManager.AddDropQueryHandler(myGridView, myGridView_OnDropQuery);
  RadDragAndDropManager.AddDropInfoHandler(myGridView, myGridView_OnDropInfo);
  RadDragAndDropManager.AddDragQueryHandler(myGridView, myGridView_OnDragQuery);
  RadDragAndDropManager.AddDragInfoHandler(myGridView, myGridView_OnDragInfo);

  List<string> days = new List<string>();
  days.Add("Sunday");
  days.Add("Monday");
  days.Add("Tuesday");
  days.Add("Wednesday");
  days.Add("Thursday");
  days.Add("Friday");
  days.Add("Saturday");
  myGridView.ItemsSource = days;
}

private void myGridView_OnDragQuery(object sender, DragDropQueryEventArgs e)
{
  RadGridView gridView = sender as RadGridView;
  if (gridView != null)
    e.Options.Payload = gridView.SelectedItem;

   // Inform the event handlers that we have programmatically handled it
   e.QueryResult = true;
   e.Handled = true;
}

private void myGridView_OnDragInfo(object sender, DragDropEventArgs e)
{
  RadGridView gridView = sender as RadGridView;
  string draggedItem = e.Options.Payload as string;

  if (e.Options.Status == DragStatus.DragInProgress)
  {
    //Setting up a drag cue:
    ContentControl cue = new ContentControl();
    //Choosing a template for the items:
    cue.ContentTemplate = this.Resources["MyTemplate"] as DataTemplate;
    cue.Content = draggedItem;
    e.Options.DragCue = cue;
  }
  else if (e.Options.Status == DragStatus.DragComplete)
  {
    //deleting the dragged item from the RadGridView
    //                IList source = gridView.ItemsSource as IList;
    //                source.Remove(draggedItem);
  }
}

private void myGridView_OnDropQuery(object sender, Telerik.Windows.Controls.DragDrop.DragDropQueryEventArgs e)
{
  RadGridView destination = sender as RadGridView;
  if (destination != null)
  {
    e.Handled = true;
    e.QueryResult = true;
  }
}

private void myGridView_OnDropInfo(object sender, Telerik.Windows.Controls.DragDrop.DragDropEventArgs e)
{
  RadGridView destination = sender as RadGridView;
  if (e.Options.Status == Telerik.Windows.Controls.DragDrop.DragStatus.DropComplete)
   {
   }
}

[Tina Stancheva]

Hello Frustrated Dev,

We are glad to hear that.

Please let us know if you need more info.

All the best,
Tina Stancheva
the Telerik team

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