问题
Using iTextSharp or some other library, is it possible to determine if a given part of the text is visible?
Using other word, is it possible to extract (to simple text) only the visible parts?
For example, if a given text segment has its font color white, then that text segment would be invisible when printing or displaying on screen.
My goal is to find a way to extract only the text that would be visible when printing that document!
来源：https://stackoverflow.com/questions/18302431/programmatically-determine-text-visibility-in-pdf-document