Pdf Mouse cordinate

Hello exist a library or script to load a pdf and after with mouse to find the position of the pdf text. I need to load a Pdf and after when i select a part of pdf for example

Signature ______________

So i need a to select the line to take the cordinates and after to put the electronic signature

this is a web application not desktop so please if exist a library or script help me

is Not a problem Language (Php c# javascript Python )