I need to build an application which can render a pdf document. The application should allow the user to draw rectangles on the pdf to define regions such as Address region, Invoice Number region and so on. The application will need to capture these regions and save them.

I already have an application in which I can pass these region information with the pdf and it will get me the text back. My only problem at the moment is that I cannot get the region information from the user.

So can anybody please point me to any application which can do the above (allow the user to draw rectangles to capture the regions).