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Combined desktop resolution on multimonitor systems with Xin
David Gow
Guest
Post Posted: Tue Jun 25, 2013 2:07 pm
Using SDL_GetDisplayMode() on the display at (0,0) on Linux (X11) with
Xinerama enabled returns an extra mode covering the entire desktop. (For
instance, the mode 2880x900 would be returned for a system with two
1440x900 monitors arranged horizontally). The code causing this is here:
http://hg.libsdl.org/SDL/file/tip/src/video/x11/SDL_x11modes.c#l692

This is a bit of a pain, as the X11 backend (at least when XRandR is
enabled), does not support creating a fullscreen window of this size,
leaving users with a non-functional mode in the list. I concede that it
may be useful with the legacy fullscreen code, but that is broken anyhow.

Does anyone use this "feature" and should it be removed?

I've got a bug report (+ patch) at
http://bugzilla.libsdl.org/show_bug.cgi?id=1927 which I think has the
best of both worlds: the mode appears only when XVidMode is in use, and
the Xinerama backend otherwise will include the current modes for all
monitors.

Thoughts?

-- David


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Combined desktop resolution on multimonitor systems with Xin
gabomdq


Joined: 28 Jul 2011
Posts: 495
Location: Argentina
Post Posted: Tue Jun 25, 2013 2:11 pm
2013/6/25 David Gow
Quote:
Using SDL_GetDisplayMode() on the display at (0,0) on Linux (X11) with Xinerama enabled returns an extra mode covering the entire desktop. (For instance, the mode 2880x900 would be returned for a system with two 1440x900 monitors arranged horizontally). The code causing this is here: http://hg.libsdl.org/SDL/file/tip/src/video/x11/SDL_x11modes.c#l692

This is a bit of a pain, as the X11 backend (at least when XRandR is enabled), does not support creating a fullscreen window of this size, leaving users with a non-functional mode in the list. I concede that it may be useful with the legacy fullscreen code, but that is broken anyhow.

Does anyone use this "feature" and should it be removed?

I've got a bug report (+ patch) at http://bugzilla.libsdl.org/show_bug.cgi?id=1927 which I think has the best of both worlds: the mode appears only when XVidMode is in use, and the Xinerama backend otherwise will include the current modes for all monitors.

Thoughts?

-- David





I had made a patch ( http://bugzilla.libsdl.org/show_bug.cgi?id=1527 ) that enabled that mode properly, the problem is...I never got it to work, not sure why or if it's supposed to work at all or if it doesn't due to driver issues. I do think having a mode that spans both monitors (if it were to work), is useful.



--
Gabriel.
Combined desktop resolution on multimonitor systems with Xin
David Gow
Guest
Post Posted: Tue Jun 25, 2013 2:53 pm
On 25/06/13 22:11, Gabriel Jacobo wrote:

Quote:



2013/6/25 David Gow
Quote:
Using SDL_GetDisplayMode() on the display at (0,0) on Linux (X11) with Xinerama enabled returns an extra mode covering the entire desktop. (For instance, the mode 2880x900 would be returned for a system with two 1440x900 monitors arranged horizontally). The code causing this is here: http://hg.libsdl.org/SDL/file/tip/src/video/x11/SDL_x11modes.c#l692

This is a bit of a pain, as the X11 backend (at least when XRandR is enabled), does not support creating a fullscreen window of this size, leaving users with a non-functional mode in the list. I concede that it may be useful with the legacy fullscreen code, but that is broken anyhow.

Does anyone use this "feature" and should it be removed?

I've got a bug report (+ patch) at http://bugzilla.libsdl.org/show_bug.cgi?id=1927 which I think has the best of both worlds: the mode appears only when XVidMode is in use, and the Xinerama backend otherwise will include the current modes for all monitors.

Thoughts?

-- David





I had made a patch ( http://bugzilla.libsdl.org/show_bug.cgi?id=1527 ) that enabled that mode properly, the problem is...I never got it to work, not sure why or if it's supposed to work at all or if it doesn't due to driver issues. I do think having a mode that spans both monitors (if it were to work), is useful.



--
Gabriel.


Yeah: that's the problem even with this combined mode. It's because the NET_WM_STATE_FULLSCREEN hint doesn't support having fullscreen windows span monitors by default, and will resize them to fit a single monitor. There is an extension to this: NET_WM_FULLSCREEN_MONITORS, which takes (IIRC) the monitor IDs to span the window over, but I'm not sure if it's well supported by WMs.

I agree that it'd be nice to have a mode that spans both monitors, but it'd definitely need to be easily identified as such so that applications can choose to ignore it. Having the mode on a separate "metamodes" monitor is certainly an improvement, particularly if there were a simple way to identify this monitor so that it could be ignored or treated specially by an application.

Do you think it'd be okay to remove the combined mode for now, given it doesn't work, and add it back if we can implement NET_WM_FULLSCREEN_MONITORS and friends?

Cheers,
-- David
Combined desktop resolution on multimonitor systems with Xin
gabomdq


Joined: 28 Jul 2011
Posts: 495
Location: Argentina
Post Posted: Tue Jun 25, 2013 4:55 pm
2013/6/25 David Gow
Quote:
On 25/06/13 22:11, Gabriel Jacobo wrote:

Quote:



2013/6/25 David Gow
Quote:
Using SDL_GetDisplayMode() on the display at (0,0) on Linux (X11) with Xinerama enabled returns an extra mode covering the entire desktop. (For instance, the mode 2880x900 would be returned for a system with two 1440x900 monitors arranged horizontally). The code causing this is here: http://hg.libsdl.org/SDL/file/tip/src/video/x11/SDL_x11modes.c#l692

This is a bit of a pain, as the X11 backend (at least when XRandR is enabled), does not support creating a fullscreen window of this size, leaving users with a non-functional mode in the list. I concede that it may be useful with the legacy fullscreen code, but that is broken anyhow.

Does anyone use this "feature" and should it be removed?

I've got a bug report (+ patch) at http://bugzilla.libsdl.org/show_bug.cgi?id=1927 which I think has the best of both worlds: the mode appears only when XVidMode is in use, and the Xinerama backend otherwise will include the current modes for all monitors.

Thoughts?

-- David





I had made a patch ( http://bugzilla.libsdl.org/show_bug.cgi?id=1527 ) that enabled that mode properly, the problem is...I never got it to work, not sure why or if it's supposed to work at all or if it doesn't due to driver issues. I do think having a mode that spans both monitors (if it were to work), is useful.



--
Gabriel.


Yeah: that's the problem even with this combined mode. It's because the NET_WM_STATE_FULLSCREEN hint doesn't support having fullscreen windows span monitors by default, and will resize them to fit a single monitor. There is an extension to this: NET_WM_FULLSCREEN_MONITORS, which takes (IIRC) the monitor IDs to span the window over, but I'm not sure if it's well supported by WMs.

I agree that it'd be nice to have a mode that spans both monitors, but it'd definitely need to be easily identified as such so that applications can choose to ignore it. Having the mode on a separate "metamodes" monitor is certainly an improvement, particularly if there were a simple way to identify this monitor so that it could be ignored or treated specially by an application.

Do you think it'd be okay to remove the combined mode for now, given it doesn't work, and add it back if we can implement NET_WM_FULLSCREEN_MONITORS and friends?

Cheers,
-- David






Yes, it's probably best to remove it, specially if no one uses it specifically, because we are providing a mode as an option which really isn't so.

--
Gabriel.
Combined desktop resolution on multimonitor systems with Xin
Gabriele Greco
Guest
Post Posted: Wed Jun 26, 2013 7:42 am
Quote:

I agree that it'd be nice to have a mode that spans both monitors, but it'd definitely need to be easily identified as such so that applications can choose to ignore it. Having the mode on a separate "metamodes" monitor is certainly an improvement, particularly if there were a simple way to identify this monitor so that it could be ignored or treated specially by an application.

Do you think it'd be okay to remove the combined mode for now, given it doesn't work, and add it back if we can implement NET_WM_FULLSCREEN_MONITORS and friends?


 
I'm quite sure one of the latest GTK 3.x stable iterations added the support to that extension to handle a single fullscreen window that spawn over multiple monitors, so it should be fairly supported among window managers...


-- 
Bye,
 Gabry