Wsrtjtyk

I have 2 ListViews, I can drag an item from ListView1 and drop it on to ListView2. If I drop the item between other items I want the item to be added in that same location.

So the question is: How do I get the position/index where I dropped my item?

I would expect to find the index somewhere in the DragEventArgs of the Drop event, but I can't find it anywhere:

private async void ListView2_Drop(object sender, DragEventArgs e)

{



}

Anyway: I have tinkered around with this code and finally got it to work to my needs:

    private async void MyListView_Drop(object sender, DragEventArgs e)

    {

        var scrollViewer = VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(MyListView, 0), 0) as ScrollViewer;

        var position = e.GetPosition((ListView)sender);

        var positionY = scrollViewer.VerticalOffset + position.Y;

        var index = GetItemIndex(positionY, MyListView);



        // do something useful with the index... 

    }



    int GetItemIndex(double positionY, ListView targetListView)

    {

        var index = 0;

        double height = 0;



        foreach (var item in targetListView.Items)

        {

            height += GetRowHeight(item, targetListView);

            if (height > positionY) return index;

            index++;

        }



        return index;

    }



    double GetRowHeight(object listItem, ListView targetListView)

    { 

        var listItemContainer = targetListView.ContainerFromItem(listItem) as ListViewItem;

        var height = listItemContainer.ActualHeight;

        var marginTop = listItemContainer.Margin.Top;

        return marginTop + height;

    }

Thank you for pointing me in the right direction!

How do I get the position/index where I dropped my item?

Currently, Drop event does not provide the index of your dropped item. But you could get the drop position with GetPosition method and calculate the index of your current dropped item. I have implement it based on official drag and drop code sample. And you could use the following code directly.

private double rowHeight;

private async void TargetListView_Drop(object sender, DragEventArgs e)

{

    // This test is in theory not needed as we returned DataPackageOperation.None if

    // the DataPackage did not contained text. However, it is always better if each

    // method is robust by itself

    if (e.DataView.Contains(StandardDataFormats.Text))

    {

        var position = e.GetPosition((UIElement)sender);



        var targetListView = sender as ListView;

        if (targetListView.Items.Count != 0)

        {

            var listItem = targetListView.Items[0];

            var listItemContainer = targetListView.ContainerFromItem(listItem) as ListViewItem;

            var height = listItemContainer.ActualHeight;

            var marginTop = listItemContainer.Margin.Top;

            rowHeight = marginTop + height;

        }



        if (position.Y > rowHeight * targetListView.Items.Count)

        {

            var def = e.GetDeferral();

            var s = await e.DataView.GetTextAsync();

            var items = s.Split('n');

            foreach (var item in items)

            {

                _selection.Add(item);

            }

            e.AcceptedOperation = DataPackageOperation.Copy;

            def.Complete();



        }

        else

        {

            double index = position.Y / rowHeight;

            var mathIndex = Math.Round(index, MidpointRounding.AwayFromZero);

            var def = e.GetDeferral();

            var s = await e.DataView.GetTextAsync();

            var items = s.Split('n');

            foreach (var item in items)

            {

                _selection.Insert(Convert.ToInt32(mathIndex), item);

            }

            e.AcceptedOperation = DataPackageOperation.Copy;

            def.Complete();

        }



    }

}