(provide 'cce/display-test-functions)Calculating the display density is a pain in the ass because it's easier to parse xrandr output than it is to integrate with libXrandr. I guess I could write an elisp wrapper for it, but I would rather not right now. open threads
(defun cce/external-display-dpis ()
"Returns a list of integers, the DPI of the connected external Display Port displays. assumes square pixels, sorry."
(let (results (xrandr-buffer (get-buffer-create " *xrandr*")))
(with-current-buffer xrandr-buffer
(erase-buffer)
(call-process-shell-command "xrandr" nil xrandr-buffer)
(goto-char (point-min))
(setq-local results nil)
(while (re-search-forward "^\\([^e][a-zA-Z]+\\(-?[0-9]+\\)+\\)" nil t)
(when-let* ((eol (save-excursion (end-of-line) (point)))
(display-name (match-string 1))
(is-connected (re-search-forward "connected \\(primary \\)?\\([0-9]+\\)x\\([0-9]+\\)" eol t))
(pixels (string-to-number (match-string 3)))
(has-physical (re-search-forward "\\([0-9]+\\)mm x \\([0-9]+\\)mm" eol))
(physical (string-to-number (match-string 2)))
(dpi (if (equal 0 physical)
140
(floor (* 25.4 (/ (float pixels) physical))))))
(add-to-list 'results (cons display-name dpi))))
results)))
(defun cce/external-display-connected ()
"returns t if there are external displayport monitors connected."
(let ((dpis (cce/external-display-dpis)))
(> (length dpis) 0)))
(defun cce/connected-displays ()
"Returns a list of displays currently connceted"
(append (list "eDP-1")
(mapcar
(lambda (cons)
(car cons))
(cce/external-display-dpis))))
(defun cce/exwm-connected-displays ()
"Return a list of displays for [`exwm-randr-workspace-monitor-plist']"
(apply #'append
(seq-map-indexed (lambda (elt idx)
(list idx elt))
(cce/connected-displays))))