sourceRectAtTime() does not work in expressions, only in scripts. For versions CS6 and below there is no property of text with that name that can be accessed through expressions. Look at nab's expression here http://www.aenhancers.com/viewtopic.php?f=6&t=931 Though if you want a workaround then ...

Seems like you need to know the size of text layer to resize the elements associated with it. nab was working on an expression using sampleImage() which determines the size of your text layer (after which you can resize your elements). You can find the discussion here http://www.aenhancers.com/viewt...

There is a little modification that is required to use the expression effectively. When you create the source layer, you need to add another return line (press enter).
If that is not done, the last and the second last word get a bit jumbled up.

Attached is the file that shows working of this code

I had been looking for some expression that would allow me to change multiple text layers while I (or any other user) would need to change only 1 layer. To explain my point, I had a composition in which there were 5 words in 5 different layers with different animations. In order to change a word, I ...