title: c++ fast screenshots in linux for use with opencv
body: <p>I'm trying to find a fast way to take screenshots (as in 30 fps or over) for use with opencv in c++</p>
  
  <p>All the information I've found online either involved windows.h or were too slow.</p>
  
  <p>Could someone provide me with some code that achieves this or at least point me in the right direction so I can solve this my self?</p>