How can I determine if my TextBlock text is being trimmed?

Question

The following textblock wraps and trims as expected. The elipsis \"...\" is displayed when the text is trimmed.

Answer 1

The solution above didn't work for me if the TextBlock is part of a ListBoxItem DataTemplate. I propose another solution:

public class MyTextBlock : System.Windows.Controls.TextBlock
{

    protected override void OnToolTipOpening(WinControls.ToolTipEventArgs e)
    {
        if (TextTrimming != TextTrimming.None)
        {
            e.Handled = !IsTextTrimmed(); 
        }
    }

    private bool IsTextTrimmed()
    {
        Measure(new Size(Double.PositiveInfinity, Double.PositiveInfinity));
        return ActualWidth < DesiredSize.Width;
    }
}

XAML: