How does screenshot work in an OS running Xorg

[Thomas Lübking]

On Dienstag, 11. März 2014 21:06:20 CEST, Hongze Zhao wrote:
> Hi List,
>
> I am curious about how screenshot  in an OS running Xorg works? I guess
> Linux does not provide such a system call or interface. Is screenshot
> implemented by calling a special xorg interface?

Coding C(++):
XLib: http://tronche.com/gui/x/xlib/graphics/XGetImage.html
xcb: http://www.x.org/archive/current/doc/man/man3/xcb_get_image.3.xhtml

As user tool, xwd should be available everywhere (?), the DEs provide their own utils and there're plenty of other tools to provide this, but afaik no common call to trigger the desktop aware screenshot utility.

Cheers,
Thomas