WPF DataTemplate: how to create a tooltip right on time?

Question

I am using DataTemplates to render items in an ItemsControl. I want to show a tooltip for each item. If I use a binding such as ToolTip = "{Binding MyToolTip, Mode = OneWay}", WPF receives the tooltip once at the beginning and does not update the tooltip when it opens.

My objects implement INotifyPropertyChanged, so basically I can generate change notifications for MyToolTip. The problem is that a tooltip is created based on many pieces of information in the base model. These pieces of information often change, and they can be cumbersome and inefficient to generate change notifications for the MyToolTip property. In addition, I do not need tooltips for ALL items that will be initially released. Instead, I would like to force a new tooltip to be generated when opening the tooltip. How can i do this?

Answer 1

, .

<object ToolTip="{Binding MyToolTip, Mode=OneWay}" ToolTipOpening="MyToolTip_Opening" />

private void MyToolTip_Opening(object sender, ToolTipEventArgs e)
{
    DependencyObject depObj = sender as DependencyObject;
    if (depObj == null) return;
    BindingExpression be = BindingOperations.GetBindingExpression(depObj, FrameworkElement.ToolTipProperty);
    if (be != null) be.UpdateTarget();
}