Question

There has to be a better way then the following for getting "childItem"

    TaskItem task = (sender as Canvas).DataContext as TaskItem;
    TaskItem child = Tasks.CreateTask("New task", task);
    TreeViewItem item = treeView.ItemContainerGenerator.ContainerFromItem(task) as TreeViewItem;            

    item.UpdateLayout();
    TreeViewItem childItem = null;
    foreach (var i in item.GetDescendantContainers())
    {
        if (i.GetItem() == child)
            childItem = i;
    }

For some reason item.ItemGenerator.ContainerFromItem(child) does not work (must be due to the item having just been created)

Was it helpful?

Solution

Item container generation is asynchronous, so you cannot assume the container will exist as soon as the item was added. You will need to attach a handler to the ItemContainerGenerator.StatusChanged event so your code will be informed when container generation is complete.

Dr. WPF's blog entry "ItemsControl: 'G' is for Generator" has a good description of the problem and provides an example of using StatusChanged:

private void AddScooby()
{
    _scooby = new Character("Scooby Doo");
    Characters.Add(_scooby);
    CharacterListBox.ItemContainerGenerator.StatusChanged
        += OnStatusChanged;
}

private void OnStatusChanged(object sender, EventArgs e)
{
    if (CharacterListBox.ItemContainerGenerator.Status
        == GeneratorStatus.ContainersGenerated)
    {
        CharacterListBox.ItemContainerGenerator.StatusChanged
            -= OnStatusChanged;
        ListBoxItem lbi = CharacterListBox.ItemContainerGenerator
            .ContainerFromItem(_scooby) as ListBoxItem;
        if (lbi != null)
        {
            lbi.IsSelected = true;
        }
    }
}
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