Question

I have two ListView’s. One has options that are to be dragged into the other. This is the “fields” ListView. The other one is the “builder” ListView. The problem I am having is that I cannot have ListViewItem’s inserted where the user drags it AND also be added to the bottom if they drag it to whitespace. I can do one or the other at this time. I need a solution for this.

private void builder_DragEnter(object sender, DragEventArgs e)
{
    e.Effect = DragDropEffects.Move;
}

private void fields_DragEnter(object sender, DragEventArgs e)
{
    e.Effect = DragDropEffects.Move;
}

private void fields_ItemDrag(object sender, ItemDragEventArgs e)
{
    fromBuilder = false;
    fields.DoDragDrop(e.Item, DragDropEffects.Move);
}

private void builder_ItemDrag(object sender, ItemDragEventArgs e)
{
    fromBuilder = true;
    builder.DoDragDrop(e.Item, DragDropEffects.Move);
}

private void builderAndFields_DragDrop(object sender, DragEventArgs e)
{
    ListViewItem i = new ListViewItem();
    i = e.Data.GetData(typeof(ListViewItem)) as ListViewItem;

    // Since this function works for both the builder and the fields,
    // we have to check to see where we are dropping, the sender
    // is the ListView we are dropping onto
    if (sender.Equals(builder))
    {
        ListViewItem c = new ListViewItem();
        c = (ListViewItem)i.Clone();
        Point cp = builder.PointToClient(new Point(e.X, e.Y));
        Console.WriteLine("cp: " + cp);
        ListViewItem dragToItem = builder.GetItemAt(cp.X, cp.Y);
        Console.WriteLine("dragToItem: " + dragToItem);
        int dropIndex = dragToItem.Index;
        // Now, we have to check to see if we are reordering or adding
        // So, we check the flag to see if the dragDrop was initiated 
        // on the builder or on the fields ListView
        if (fromBuilder)
        {
            builder.Items.Insert(dropIndex, c);
            builder.Items.Remove(i);
        }
        else
        {
            // ## Problem - Attempted solution ##
            if (String.IsNullOrWhiteSpace(dragToItem.ToString()))
                builder.Items.Add(c);
            else
            {
                Console.WriteLine(dropIndex);
                builder.Items.Insert(dropIndex, c);
            }
        }
    }
    // If the sender is the fields listView, the user is trying to remove
    // the item from the builder.
    else
    {
        builder.Items.Remove(i);
    }
}

Answer 1

Thank you for your comment Hans. It was very helpful! Here is the solution to two problems I was having. The other was being able to reorder the ListView and drag items to the bottom of the list.

// Generic DragEnter
private void ddEnter_DragEnter(object sender, DragEventArgs e)
{
    e.Effect = DragDropEffects.Move;
}

// ItemDrag Events
private void fields_ItemDrag(object sender, ItemDragEventArgs e)
{
    fromBuilder = false;
    fields.DoDragDrop(e.Item, DragDropEffects.Move);
}

private void builder_ItemDrag(object sender, ItemDragEventArgs e)
{
    fromBuilder = true;
    packetBuilder.DoDragDrop(e.Item, DragDropEffects.Move);
}

// DragDrop Events
private void builderAndFields_DragDrop(object sender, DragEventArgs e)
{
    ListViewItem i = new ListViewItem();
    i = e.Data.GetData(typeof(ListViewItem)) as ListViewItem;

    // Since this function works for both the builder and the fields,
    // we have to check to see where we are dropping, the sender
    // is the ListView we are dropping onto
    Console.WriteLine(sender.Equals(packetBuilder));
    if (sender.Equals(packetBuilder))
    {
        ListViewItem c = new ListViewItem();
        c = (ListViewItem)i.Clone();
        Point cp = packetBuilder.PointToClient(new Point(e.X, e.Y));
        // Now, we have to check to see if we are reordering or adding
        // So, we check the flag to see if the dragDrop was initiated 
        // on the builder or on the fields ListView
        Console.WriteLine(fromBuilder);
        if (fromBuilder)
        {
            if (packetBuilder.HitTest(cp).Location.ToString() == "None")
            {
                packetBuilder.Items.Add(c);
                packetBuilder.Items.Remove(i);
            }
            else
            {
                ListViewItem dragToItem = packetBuilder.GetItemAt(cp.X, cp.Y);
                int dropIndex = dragToItem.Index;
                packetBuilder.Items.Insert(dropIndex, c);
                packetBuilder.Items.Remove(i);
            }

        }
        else
        {
            if (packetBuilder.HitTest(cp).Location.ToString() == "None")
                packetBuilder.Items.Add(c);
            else
            {

                ListViewItem dragToItem = packetBuilder.GetItemAt(cp.X, cp.Y);
                int dropIndex = dragToItem.Index;
                packetBuilder.Items.Insert(dropIndex, c);
            }
        }
    }
    // If the sender is the fields listView, the user is trying to remove
    // the item from the builder.
    else
    {
        packetBuilder.Items.Remove(i);
    }
}