Re: [RFC] _NET_WORKAREA and Xinerama

[Matthias Clasen <maclas gmx de>]

On Mon, 2003-03-03 at 22:48, Mark McLoughlin wrote:
> Hey,
> 
> On Tue, 2003-03-04 at 08:40, Peter Zijlstra wrote:
> > Dear all,
> > 
> > Implementing both xinerama and wm-spec support for windowmaker, I found
> > that _NET_WORKAREA is almost impossible to implement since it assumes
> > the desktop is rectangular. Mine is not. Xinerama allows for 2 or more
> > screens of different sizes to be used, I for example run one at
> > 2048x1536 and one at 1600x1200. _NET_WORKAREA is unable to communicate
> > this geometry.
> 
> 	Note that X itself is unable to communicate this screen geometry - the
> screen size in X is rectangular.
> 
> 	For this reason (and others) the new Xinerama spec being worked out
> disallows non-rectangular screen configurations. From XineramaDesign.txt
> available on their sourceforge project page:
> 
> "
>   Physical screen layout requirements.
>                                                                                                              
>     We did take note that screens can be configured in any layout
>     that a vendor allows.  You could make an L or an X or just a
>     straight line of screens.  However for the purposes of Xinerama,
>     this could get very confusing.  You could lose windows in the
>     gaps where there is no monitor.  The logic for warping a pointer
>     becomes awkward.  Neither does the protocol allow for a screen size
>     definition beyond width and height.  Therefore we determined that
>     for Xinerama purposes the configuration of screens much be
>     some sort of rectangle.
> "

The current spec has weakened this a bit. Non-rectangular layouts are no
longer disallowed, but merely unspecified (according to Draft Standard
Version 0.8.4, Last Modified 4 October 2002, found at 
http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/xinerama/xinerama/xc/doc/XineramaSpec.txt?rev=1.12&content-type=text/vnd.viewcvs-markup
):


It is undesirable to run Xinerama with dissimilar screen sizes; changes 
in screen size can confuse window managers. 

For the purpose of Xinerama, a screen is defined as a set of
framebuffers
joined logically as a single work surface.   Non-rectangular screen
configurations are beyond the scope of the Xinerama specification.


Matthias