[Notion-devel] XRandR-based multihead support

[Arnout E. <no...@bz...>]

Hi,

With mod_xinerama, you can have a dual-head setup with 1 WScreen on each 
monitor.

This is very nice, but has a couple of disadvantages:
- xinerama is marked deprecated and generally out-of-fashion
- changes in layout (adding/removing monitors, changing order) require notion
  to be restarted. Not as bad as it sounds because the client windows stay 
  alive, but still.

I took a stab at porting mod_xinerama to XRandR. 

The first very rough prototype is at https://github.com/raboof/mod_xrandr-3. 
It already supports the current mod_xinerama functionality, but I'm running
into trouble when dynamically changing the screen order.

Suppose you have 2 monitors with different resolutions, one left of the other.
Notion starts up and shows 2 correctly-sized WScreens. Now you run
'xrandr --output one --right-of other', and the 2 monitors switch places.
Because the positions of the 2 WScreens relative to the abstract Screen have
not changed, the bigger WScreen is now shown on the smaller monitor and 
vice-versa.

I tried to reposition the WScreens like this (existingscreen is the WScreen, 
fp.g is the new desired geometry):

    REGION_GEOM(existingscreen)=fp.g;
    mplex_managed_geom((WMPlex*)existingscreen, &(fp.g));
    mplex_do_fit_managed((WMPlex*)existingscreen, &fp);

This however does not appear to have any effect. Does anyone have any idea 
how to approach this?


Kind regards,

Arnout