ListViews drag-drop + reorder

[mikemikk]

Hello, I have a windows form with two listview controls. I have finally gotten drag-n-drip working for the SourceListView to the DestListView. But after a drag operation is completed, if I then select a single item in the DestListView, all Items become selected.

Has anyone else noticed this... or is it just me.

 

[mikemikk]

I just tried listview.selecteditems.clear, and that left me with a weirder problem. The destination listview is also "orderable" using drag n drip (you can move items around into a different order). After the drag operation, DestListView does not respond to drag operations until I select another control, like the SourceListView, *then* I can select items in the DestListView and drag them into order.

weird...

 

[mikemikk]

Ok, I also tried SourceListView.Select. But I think I have a better description of what's going on:

After a drag operation from SourceListView to DestListView, DestListView does not fire a ItemDrag when you attempt to drag an item to a different position. But if you select any item in the SourceListView, DestListView begins to start triggering ItemDrag events like it should. Then drag n drip reordering of the items in DestListView is possible. But at least one item MUST be selected in SourceListView.

That make sense?

 

[mikemikk]

I pulled all of the drag n drip stuff out of the sub components classes, Bubbled-up the Drag events, and now handle everything from the main form. The previous problem has disappeared, but enough new ones have come up to justify another post...

 

[mikemikk]

ListView to ListView DragNDrop Problem

Hello, I have two ListView components on a form between which I have DragNDrop working. However, there is a funny issue: After dragging items between listview1 to listview2, I cannot drag anything in listview2 (re-order) until I first select *any* item in listview1 (single left click). Once I select an item in Listview1, listview2's ItemDrag starts responding to drags.

Any hints?

 

[JohnH]

Here's a sample to DragDrop one or more selected items between or within Listviews, both Copy and Move operation supported:

Private Sub ListView1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) _
Handles ListView1.MouseMove, ListView2.MouseMove

    If e.Button = Windows.Forms.MouseButtons.Left Then
        Dim lv As ListView = sender
        If lv.DoDragDrop(lv.SelectedItems, DragDropEffects.Move Or DragDropEffects.Copy) = DragDropEffects.Move Then
            For Each lvi As ListViewItem In lv.SelectedItems
                lv.Items.Remove(lvi)
            Next
        End If
    End If
End Sub

Private Sub ListView1_DragEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) _
Handles ListView1.DragEnter, ListView2.DragEnter

    If e.Data.GetDataPresent(GetType(ListView.SelectedListViewItemCollection)) Then
        Const CTRL As Integer = 8
        If (e.KeyState And CTRL) = CTRL Then
            e.Effect = DragDropEffects.Copy
        Else
            e.Effect = DragDropEffects.Move
        End If
    End If
End Sub

Private Sub ListView1_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) _
Handles ListView1.DragDrop, ListView2.DragDrop

    Dim lv As ListView = sender
    Dim pt As Point = lv.PointToClient(Cursor.Position)
    Dim hit As ListViewHitTestInfo = lv.HitTest(pt)
    Dim sel As ListView.SelectedListViewItemCollection
    sel = e.Data.GetData(GetType(ListView.SelectedListViewItemCollection))
    If hit.Item Is Nothing Then
        For Each lvi As ListViewItem In sel
            lv.Items.Add(lvi.Clone)
        Next
    Else
        For Each lvi As ListViewItem In sel
            lv.Items.Insert(hit.Item.Index, lvi.Clone)
        Next
    End If
End Sub

 

[mikemikk]

Great examples. Thanks.

I figured I was going to have to re-write these methods to figure this problem out. 8-(