How do I measure the size of a TextBlock in WPF before it is rendered?

Question

I have a WPF DataTemplate with two TextBlock controls (stacked) and then some other elements underneath. Due to some complicated layout code, I need to know the height of the two TextBlock elements so that I can draw some fancy connector lines, and line up other controls, etc.

If I know the text that's going into the TextBlocks, and I know the font, etc., is there some way I can compute or measure the height of these TextBlocks without actually rendering them?

Answer 1

I think it should be sufficient to call the UIElement.Measure(Size) method and subsequently check the UIElement.DesiredSize property. For more information, check the provided MSDN links.

Answer 2

The call to UIElement.Measure(Size), takes as a parameter Size. The second call UIElement.DesiredSize returns whatever Size you passed into the Measure method.

I think this is the case because UIElement (TextBlock in this case) is NOT a child of any control (yet) and therefore DesiredSize has no reason to be anything different.