CODEWITHSUNDEEP
c#xamlwin-universal-app
Tom Kitch
Tom Kitch

Reputation: 21

UWP Drag and Drop between Multiple ListViews

I'm having some trouble with Drag and Drop between different ListViews. I have a GridView that contains multiple ListView all from the same ObservableCollection. Basically, I want to be able to drag items from one ListView into another Listview but within the same GridView.

Below is the ListView Which is part of the DataTemplate for the GridView. The ListView is Bound to a ObservableCollection of string. Which is a Property or the ObservableCollection the GridView is bound too.

<ListView Name="ListingView"  Height="200"  HorizontalAlignment="Center" Grid.Row="1" CanDragItems="True" AllowDrop="True"
                      DragItemsStarting="ListView_DragItemsStarting"
                      DragOver="ListView_DragOver"
                      CanReorderItems="True"
                      DragItemsCompleted="ListView_DragItemsCompleted"
                      Drop="ListView_Drop" ItemsSource="{Binding Listing}" 
                      />

And here is the Code Behind for the ListView

    private void ListView_DragItemsStarting(object sender, DragItemsStartingEventArgs e)
    {

        var item = string.Join(",", e.Items.Cast<string>());

        e.Data.SetText(item);
        e.Data.RequestedOperation = DataPackageOperation.Move;



    }

    private void ListView_DragOver(object sender, DragEventArgs e)
    {
        if (e.DataView.Contains(StandardDataFormats.Text))
        {


            e.AcceptedOperation = DataPackageOperation.Move;


        }
    }

    private async void ListView_Drop(object sender, DragEventArgs e)
    {
        if (e.DataView.Contains(StandardDataFormats.Text))
        {
            var item = await e.DataView.GetTextAsync();

            var destinationListView = sender as ListView;
            var listViewItemsSource = destinationListView?.ItemsSource as ObservableCollection<string>;

            if (listViewItemsSource != null)
            {


                listViewItemsSource.Add(item);



            }


        }
    }

    private void ListView_DragItemsCompleted(ListViewBase sender, DragItemsCompletedEventArgs args)
    {

        var item = string.Join(",", args.Items.Cast<string>());

        var destinationListView = sender as ListView;
        var listViewItemsSource = destinationListView?.ItemsSource as ObservableCollection<string>;



        listViewItemsSource.Remove(item);
    }
}

The Problem I have is finding a way to stop a ListView from becoming completely empty if I drag all the items out of the a ListView. Once the ListView becomes empty I can't go back and drag something into it.

The Second problem is when I drag an item and then let go of it in the same ListView it was dragged from then it deletes and does no re-add the item. I think I need to add an If statement to the DragItemCompleted method to see If the source is the same as the target before removing the item.

Edit I seem to have fixed" the second problem by removing the CanReorderItemsProperty from the listView. I'm not sure why but it seems to have fixed up that issue. But now i can't reorder the lists :(

Upvotes: 1

Views: 2383

Answers (1)

Kiran Paul
Kiran Paul

Reputation: 885

Look into this windows sample program https://github.com/Microsoft/Windows-universal-samples/tree/master/Samples/XamlDragAndDrop/cs

Upvotes: 0

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