Re: multiple monitor detection

[Óscar Fuentes]

Psionic K <psionik@positron.solutions> writes:

> I was going to add multiple monitor support to the dslide package.  I
> have to physical monitors active now.
>
> However `display-monitor-attributes-list` returns the following:
>
>     (((name . "combined screen") (geometry 0 0 6400 2160) (workarea
> 6400 2080 0 80)
>       (mm-size 1693 572) (frames #<frame Emacs 0x3cca5d50>) (source .
> "fallback")))
>
> When running `xrandr`, xrandr is installed, so I'm not sure why the
> source is fallback.  I restarted Emacs.  (30.0.91).
>
> Xrandr's output more distinctly shows the two physical monitors:
>
>     $ xrandr
>     Screen 0: minimum 320 x 200, current 6400 x 2160, maximum 16384 x 16384
>     eDP connected 2560x1440+3840+0 (normal left inverted right x axis
> y axis) 309mm x 174mm
>        2560x1440     60.01*+  48.01
>        <snip>
>     HDMI-A-0 connected primary 3840x2160+0+0 (normal left inverted
> right x axis y axis) 600mm x 340mm
>        3840x2160     60.00*+  50.00    59.94    30.00    30.00
> 25.00    24.00    29.97    23.98
>        <snip>
>
> I'm not sure why the fallback is being used by
> `display-monitor-attribute-list'.  Xrandr is available to
> `executible-find`.
>
> My goal is to detect the physical monitor and allow the user to
> display dslide presentations on the other physical monitor and switch
> between them.  I'm presently unable to decide how to recognize the two
> physical monitors without rolling my own solution on top of xrandr.

Which is your O.S.? What is the output of xrandr -v ?

Here (display-monitor-attribute-list) shows

(((name . "HDMI-2") (geometry 0 0 1920 1080) (workarea 44 0 1876 1080)
(mm-size 480 270) (frames #<frame Emacs: *Minibuf-1* ** @ sky
0x557560867c50>) (source . "XRandR 1.5")) ((name . "HDMI-3") (geometry
1920 0 1680 1050) (workarea 1920 0 1680 1050) (mm-size 474 296) (frames
#<frame pdf 0x5575618a4550>) (source . "XRandR 1.5")) ((name . "DP-1")
(geometry 3600 0 3840 2160) (workarea 3600 0 3840 2160) (mm-size 600
340) (frames) (source . "XRandR 1.5")))

This is GNU/Linux, X window system, KDE, xrandr 1.5.2

Anyways, depending on xrandr is a bit too specific, isn't it? With
Wayland becoming more and more used, but maybe the GTK Wayland port does
the right thing already on this regard.