UWP drag and drop custom type/class

Question

Hy there, I'm trying to enable drag & drop between 2 GridViews, I managed to do it with the custom types of the "DataPackage" class (SetText, SetBitmap, etc..) but I can't figure out how to do this with a custom class/type. Both GridViews are data-bound to the same custom class (only a couple of properties, int, string, bitmapimage), I simply would like to drag directly this data items from one GridView to the other. Thank you very much for your help!

Answer 1

So to summarize for the benefit of others, I added these to event handlers to DataTemplate content, as I only wanted items of a certain (ViewModel) type to be draggable.

    private void Grid_Drop(object sender, DragEventArgs e)
    {
        if (sender is FrameworkElement)
        {
            var fe = sender as FrameworkElement;
            var targetIvm = fe.DataContext as ItemViewModel;
            object obj = null;
            if(e.DataView.Properties.TryGetValue("ItemViewModel", out obj))
            {
                var sourceIvm = obj as ItemViewModel;
                vm.MoveItem(sourceIvm, targetIvm);
            }
        }
    }

    private void Grid_DragStarting(Windows.UI.Xaml.UIElement sender, DragStartingEventArgs args)
    {
        if (sender is FrameworkElement)
        {
            var fe = sender as FrameworkElement;
            var item = new KeyValuePair<string, object>("ItemViewModel", fe.DataContext);
            args.Data.RequestedOperation = DataPackageOperation.Move;
            args.Data.Properties.Add("ItemViewModel", fe.DataContext);
        }
    }

Answer 2

I had the same issue please check this example I used Behaviors because I used MVVM pattern but I did this for ListView but is the same for GridView with small changes.

Change the Behaviors <ListView> to <GridView>

This behavior is attached in the ListView where you want drag the item

public class StartingDragBehavior:Behavior<ListView>
{
    protected override void OnAttached()
    {
        base.OnAttached();
        this.AssociatedObject.CanDragItems = true;
        this.AssociatedObject.DragItemsStarting += AssociatedObject_DragItemsStarting;
    }


    private void AssociatedObject_DragItemsStarting(object sender, DragItemsStartingEventArgs e)
    {
        e.Data.RequestedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.Copy;
        if(e.Items!=null && e.Items.Any())
        {
            e.Data.Properties.Add("item", e.Items.FirstOrDefault());

        }
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        this.AssociatedObject.DragItemsStarting -= AssociatedObject_DragItemsStarting;

    }
}

This behavior is attached in the ListView where you want to drop the item Here another Behavior to catch the drop event.

public class EndDropBehavior : Behavior<ListView>
{
    protected override void OnAttached()
    {
        base.OnAttached();
        this.AssociatedObject.AllowDrop = true;
        this.AssociatedObject.Drop += AssociatedObject_Drop;
        this.AssociatedObject.DragOver += AssociatedObject_DragOver;
    }

    private void AssociatedObject_Drop(object sender, Windows.UI.Xaml.DragEventArgs e)
    {
        if (e.DataView != null &&
            e.DataView.Properties != null &&
            e.DataView.Properties.Any(x => x.Key == "item" && x.Value.GetType() == typeof(MyObject)))
        {
            try
            {
                var def = e.GetDeferral();

                var item = e.Data.Properties.FirstOrDefault(x => x.Key == "item");
                var card = item.Value as MyObject;


                    var list = sender as ListView;
                    var vm = list.DataContext as Infrastructure.ViewModels.CreditCardsViewModel;


                        vm.MyCollection.Add(card);

                def.Complete();
            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex.ToString());

            }

        }
        else
        {
            e.AcceptedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.None;
        }
    }

    private void AssociatedObject_DragOver(object sender, Windows.UI.Xaml.DragEventArgs e)
    {
        if (e.DataView != null &&
            e.DataView.Properties != null &&
            e.DataView.Properties.Any(x => x.Key == "item" && x.Value.GetType() == typeof(MyObject)))
        {

            e.AcceptedOperation = e.AcceptedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.Copy;

        }
        else
        {
            e.AcceptedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.None;
        }
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        this.AssociatedObject.Drop -= AssociatedObject_Drop;

        this.AssociatedObject.DragOver -= AssociatedObject_DragOver;
    }
}

If you are not using MVVM pattern just check the events of the to Behaviors.