Fastest method for screen capturing on Linux

Question

This question is similar to this one

Fastest method of screen capturing

but for linux/X11.

To be more specific, i need a method to capture the pixel

Answer 1

This is just a wild guess, but I presume you could use x11vnc with the -id [windowid] (http://www.karlrunge.com/x11vnc/x11vnc_opts.html#opt-id) option to stream that single window over VNC. This will show you the whole window, with the exact same positioning as in the main screen (you might lose some popup menus), even when it is covered. You can fetch the window coordinates from the true X11 screen.