TextField... height problems

I have a textField with a lot of stuff in it, so I’m creating a scroller using a mask. To do the math to make the scroller work right, I need the height of the textField. But the stuff in it is retrieved from XML and the length of it varies when it is updated, which is quite often.

Is there a way I can find the height of just the text in the textField? Does that make any sense to anyone?