So I'm trying to make a tree which can reorder its nodes by dragging
them. One of the things I wanted to do is prevent a parent item from
being dragged on to any of its children, and to show that during the
dragOver event.
In order to calculate whether the source is being dragged on to any
of its offspring, I've been comparing the
event.dragSource.dataForFormat("treeItems") first to
firstValue=event.target.getDropParent().getTreeNodeAt
(event.target.getDropLocation()) then recursively to the parents of
firstValue.
This apparently doesn't work because dataForFormat seems to hand me a
copy of the items being dragged instead of an actual reference, so
the two values are never equal. I did note that the items that
dataForFormat give me, do contain references to the real parents,
data and other objects, it is just that the items themselves are
copies for some reason.
What I ended up doing is something like the following:
if(checkParentDrop(myowncustom.TreeUtils.findDataItemNode
(view.TemplateAssemblyTree, dragItems[i].getData())
, event.target.getDropParent().getTreeNodeAt
(event.target.getDropLocation())))
action = DragManager.NONE;
private function checkParentDrop(source, node):Boolean
{
if(source == node)
return true;
if(node.getParent()!=null)
return checkParentDrop(source, node.getParent());
else
return false;
}
public static function findDataItemNode(tree:mx.controls.Tree,
o:Object):TreeNode
... recursively check the entire tree for the same getData()
reference ...
So basically instead of comparing items from
event.dragSource.dataForFormat("treeItems"), i have to recursively
look them up by the reference they contain to their getData()
information, to get the actual reference to the TreeNode which I then
compare to the drop target and its ancestors for referential equality.
This is horribly ugly, but it works. Is there a better way that
people have stumbled across to validate tree->self drags? I wish that
dataForFormat handed over references instead of copies!
(sorry if this was discussed before; I'm apparently bad at finding
previously discussed topics in this list!)
Sean
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