Duration consideration with variable lines

Assume we have a textview with variable text inside. The text can change from 3 lines or up to 20 lines.
If we set the duration as let's say 300ms, the 3 line scenario will be too slow and 20 lines maybe too fast. 

Is there a way to have a method to set duration according to how many lines are in the TV?
setDurationPerLine(int)