Exclusive Fullscreen Mode

[Peter Hutterer]

On Tue, Sep 07, 2010 at 03:33:48AM +0200, Roland Plüss wrote:
> 
> 
> On 09/07/2010 01:29 AM, Tomas Carnecky wrote:
> > On 9/6/10 8:51 PM, Roland Plüss wrote:
> >> On 09/06/2010 08:17 PM, Tomas Carnecky wrote:
> >>> On 9/6/10 5:53 PM, Roland Plüss wrote:
> >>>>  I tried searching on the Internet for informations on how to take over
> >>>> the screen using Xlib. I think here about fullscreen exclusive access
> >>>> like for example SDLMAME does it. I stumbled so far though only on one
> >>>> single mentioning of an Xlib call which should allow switching a window
> >>>> into a FullscreenExclusiveMode. I could though find nothing about such a
> >>>> call nor this FullscreenExclusiveMode. Has anybody an idea what this
> >>>> FullscreenExclusiveMode could be or in general how one can make a window
> >>>> take over the entire screen?
> >>> X11 doesn't have a 'fullscreen' mode like windows. What you have to do
> >>> is: resize and move the window so that it covers the whole screen.
> >>> However, some window managers won't let you place windows wherever you
> >>> want (because they also want to draw window decorations etc), so the
> >>> modern way to fullscreen your application is to tell the window manager.
> >>> The window manager will then resize your window and make sure it's on
> >>> top of all other windows. You can do that by setting _NET_WM_STATE to
> >>> _NET_WM_STATE_FULLSCREEN. See [1] and/or google 'ewmh fullscreen' or
> >>> variations thereof.
> >>>
> >>> tom
> >>>
> >>> [1]: http://standards.freedesktop.org/wm-spec/wm-spec-latest.html#id2551694
> >> That sounds like a plan. Thanks for the link there. I've got two
> >> questions left about the topic of fullscreen with X.
> >>
> >> 1) What about changing resolution?
> >> SDLMAME as far as I know changes the resolution while full screen and
> >> some games do this too (typically commercial ones like UT*, Quake* and
> >> company). I read somewhere that only root is allowed to change
> >> resolution on-the-fly. Another place states only resolutions in the
> >> xorg.conf are valid. What's the ground truth in this case? Can one
> >> change resolution dynamically from a client application?
> > Any user can change the resolution. The modern way is to use randr, on
> > older servers you need to use xf86vidmode. Proprietary nvidia drivers
> > don't use either, they have their own API for doing that.
> Sounds good. I checked out that Randr extension. I can't though wrap my
> head around how to use it. Under OpenGL you have a glGetProcAddress
> function to obtain function pointers once you know an extension exists.
> In X as far as I get it there is no such facility as you have to send
> the properly formated requests to the server which Xlib provided
> functions do behind the curtain. I somehow can not find in the scarce
> documentation how to send such requests bare handed using Xlib. Is there
> something liks XSendRequest? I assume you have to do it like that, right?

Xlib wraps the requests for a reason, I can't think of a reason for manually
writing the requests to the wire. Just use the Xrandr Xlib calls, they're
fairly low-level anyway. (AFAIK there's no way to manually write events to
the wire though if you want to get down to that level XCB may be an option.)

The xrandr source code should be a good start for what you want to do.

Cheers,
  Peter