Re: JTree model reload : prevent collapse
Luc Van Bogaert wrote:
Hi,
I'm having difficulty finding a solution for the following problem :
I have some leaf nodes in a JTree that are rendered by a JLabel
subclass, actually DefaultTreeCellRenderer.
I have written a custom function to modify the text of the leaf
nodes. After the change, I could call repaint() on the tree. But, if
the new text of a leaf node is longer than the original text, the
text is truncated with "..." to fit into the original label width.
You should not call repaint. How ever you modify the text, that process
should fire an TreeModelEvent which will cause the JTree to redraw itself.
Example:
"Original text" becomes "This is the ne..." instead of "This is the
new text".
I have found a solution using treemodel.reload(), but the problem
with this is that it collapses the whole tree, and I would like to
avoid that. Expanded branches should keep their expanded state after
the node text has changed.
I have tried adding a TreeWillExpandListener, but that doesn't seem
to work. I suspect because the collapse after reload() isn't
triggered by a mouse click or another UI event.
So, does anyone have any suggestions on how to solve this problem?
A properly designed UI should only ever need to call repaint for
animations. It should rarely call validate or invalidate, and it should
never call paint* directly (not implying that you did, but just noting
common mistakes).
My suggestion to you is to make sure your text-change dispatches the
proper event. Look up TreeModelListener.treeNodesChanged. There is a
great tutorial called How to use Trees:
<http://java.sun.com/docs/books/tutorial/uiswing/components/tree.html>
Hope this helps.
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