How does screenshot work in an OS running Xorg

[walter harms]

Am 11.03.2014 21:40, schrieb 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.
> 

A look at xwd may also be helpful.

re,
 wh