Getting a TreeViewItem from the Drop event in a TreeView when a different node is selected

问题

I have a drag and drop from a ListBox into a TreeView, the problem I have is that I can only see the "IsSelected" node that is returned from the TreeView sender under the Drop event, this is because I am selecting a property from the listbox of a TreeViewItem and dragging it into another TreeViewItem.

I hope that makes sense.

I can't get the data from the "dropped" TreeViewItem, I currently have these methods but I can't get the TreeViewItem I drop the ListBoxItem into.

private void nodeTree_Drop(object sender, DragEventArgs e)
{
    if (e.Data.GetDataPresent("copyProperty"))
    {
        BasePropertyTypeVM dragged = e.Data.GetData("copyProperty") as BasePropertyTypeVM;
    }
}

private void NodeTree_OnDragEnter(object sender, DragEventArgs e)
{
    if (!e.Data.GetDataPresent("copyProperty") ||
        sender == e.Source)
    {
        e.Effects = DragDropEffects.None;
    }
}

private void NodeTree_OnDragOver(object sender, DragEventArgs e)
{
    TreeViewItem treeViewItem = FindAncestor<TreeViewItem>((DependencyObject) e.OriginalSource);
    if (treeViewItem != null)
    {
        treeViewItem.Background = Brushes.Blue;
    }
}

private void NodeTree_OnDragLeave(object sender, DragEventArgs e)
{
    TreeViewItem treeViewItem = FindAncestor<TreeViewItem>((DependencyObject) e.OriginalSource);
    if (treeViewItem != null)
    {
        treeViewItem.Background = Brushes.White;
    }
}

回答1:

So I managed to do this. I used the find ancestor method to get the treeviewitem object and then used the header from this object and converted this to the NodeTreeVM object I had used to create the tree view.

private void nodeTree_Drop(object sender, DragEventArgs e)
    {
        //find the ancestor using the below method, this gets the TreeViewItem Object
        TreeViewItem treeViewItem = FindAncestor<TreeViewItem>((DependencyObject)e.OriginalSource);
        if (treeViewItem != null)
        {
           treeViewItem.Background = Brushes.White;
           //Convert the header into the origional object
           var droppedNode = (TreeNodeVM)treeViewItem.Header;
        }
    }

private static T FindAncestor<T>(DependencyObject current) where T : DependencyObject
    {
        // Search the VisualTree for specified type
        while (current != null)
        {
            if (current is T)
            {
                return (T) current;
            }
            current = VisualTreeHelper.GetParent(current);
        }
        return null;
    }

I hope this also helps someone else, please comment for more info :)

来源：https://stackoverflow.com/questions/28460343/getting-a-treeviewitem-from-the-drop-event-in-a-treeview-when-a-different-node-i

标签

wpf

listbox

treeview