void MultiSourceTreeView_DragOverNode(object sender, DragOverNodeEventArgs e)
{
// Verify that the nodes are the correct type for this operation.
if (!(e.Node is MultiSourceTreeNode) || !(e.TargetNode is MultiSourceTreeNode))
{
return;
}
MultiSourceTreeNode node = (MultiSourceTreeNode)e.Node;
MultiSourceTreeNode targetNode = (MultiSourceTreeNode)e.TargetNode;
// For now, we are only allowing dropping of nodes that have a single info entry.
if (node.EntryCount != 1)
{
e.Cancel = true;
}
else if (targetNode.EntryCount != 1)
{
e.Cancel = true;
}
else
{
e.Cancel = !(node.InfoEntries[0].NodeType.ParentSource.CanDropInto(
targetNode.InfoEntries[0].NodeType, node.InfoEntries[0].NodeType));
}
}
private void BetterTreeView_DragOver(object sender, DragEventArgs e)
{
DragScroll();
// Compute drag position and move image
Point formP = PointToClient(new Point(e.X, e.Y));
DragHelper.ImageList_DragMove(formP.X - Left, formP.Y - Top);
// Get actual drop node
TreeNode dropNode = GetNodeAt(PointToClient(new Point(e.X, e.Y)));
// Make sure we have a node.
if (dropNode == null)
{
e.Effect = DragDropEffects.None;
return;
}
if (tempDropNode != dropNode)
{
DragHelper.ImageList_DragShowNolock(false);
SelectedNode = dropNode;
DragHelper.ImageList_DragShowNolock(true);
tempDropNode = dropNode;
}
// Make sure that we aren't dropping onto a child node.
TreeNode tmpNode = dropNode;
while (tmpNode.Parent != null)
{
if (tmpNode.Parent == dragNode)
{
e.Effect = DragDropEffects.None;
return;
}
tmpNode = tmpNode.Parent;
}
// Allow any event handlers a chance to cancel the drag/drop.
DragOverNodeEventArgs args = new DragOverNodeEventArgs(dragNode, dropNode);
if (DragOverNode != null)
{
DragOverNode(this, args);
}
if (args.Cancel)
{
e.Effect = DragDropEffects.None;
return;
}
e.Effect = DragDropEffects.All;
}