Re: master fe7c015b20: Support XFCE in wallpaper.el

[Po Lu]

Stefan Kangas <stefankangas@gmail.com> writes:

> Po Lu <luangruo@yahoo.com> writes:
>
>> Stefan Kangas <stefankangas@gmail.com> writes:
>>
>>> +    ("xfconf-query" "-c" "xfce4-desktop" "-p"
>>> +     "/backdrop/screen0/monitoreDP/workspace0/last-image" "-s" "%f")
>>
>> Judging by the command, this assumes that:
>>
>>  - the screen number is 0
>>  - the monitor on which the backdrop will be changed is named "eDP"
>>  - the workspace is 0

> Is "eDP" the most common and/or default name?

No, it's the name used for the embedded DisplayPort internal panel on
laptops.  Some laptops use LVDS instead, and the name is thus "LVDS".

> Not sure what to do about the screen number or workspaces.  Is there any
> way to find out this information with a simple command?

The screen number should be the following part of the `display' frame
parameter:

  1.1.1.1:0.5
            ^ screen number is 5

if there is no period after the separator, then the screen number is 0.

The currently active workspace can be obtained like so:

  (x-window-property "_NET_CURRENT_DESKTOP" nil "CARDINAL" 0 nil t)

if it fails by returning NULL, then you should fall back to:

  (x-window-property "WIN_WORKSPACE" nil "CARDINAL" 0 nil t)

and failing that, 0.

The monitor name should also be easy to extract with
display-monitor-attributes-list, but if the source is anything other
than "XRandr", "XRandr 1.5" or "Gdk", you should fall back to using "0".