GWT Tree, opening event.

Question

I'm using the tree control in GWT. I have a custom widget that I add as a TreeItem:

Tree testTree = new Tree();
testTree.addItem(myWidget);

I would like to retrieve myWidget instance on the node opening event. Is it possible ? Does anybody knows which event should I be using ?

I tried the openHandler<TreeItem> but what I retrieve is the... tree item.

Answer 1

In almost every case in which you're using GWT's Tree, you really want to be using the GWT Incubator's FastTree, which has an addBeforeOpenHandler() method, which takes a BeforeOpenHandler<FastTreeItem> which passes a BeforeOpenEvent to onBeforeOpen() making available the source of the event (that was a mouthful...)

Long story short, FastTree > Tree, and you want to use addBeforeOpenHandler() on the FastTree itself.

To add widgets to your tree (instead of just FastTreeItems) you can add your widget to the enclosing FastTreeItem, or just subclass FastTreeItem to do what you want.

Answer 2

I was looking to far.

To answer my original question: The event we retrieve in the openHandler has all the info I needed.

public void onOpen(OpenEvent<TreeItem> event) {
// The TreeItem
TreeItem ti = event.getTarget();

// The widget added in the treeItem
CustomWidget cw = (CustomWidget)event.getTarget().getWidget();
}

Just for info:

Instead of adding a widget (which I didn't use anywhere else) to my TreeItem I extended TreeItem to create my own Widget. So I simply needed event.getTarget() to access it.

About FastTree:

For what I read people working with GWT usually go straight to using FastTree which, as Jason said, offers more possibilities and better performances. I had problem running FastTree in my configuration (even with the examples code) and little time to deal with it so that's why I sticked with the native Tree widget.