emacs-config/test.org

• Changing the transparency of specific windows

Changing the transparency of specific windows

  ;; Stack Trace
  ;; - https://www.google.com/search?client=firefox-b-1-d&q=change+window+transparency+compton
  ;; - https://github.com/chjj/compton/issues/219
  ;; - _NET_WM_WINDOW_OPACITY
  ;; - https://github.com/i3/i3/issues/2840
  ;; - Failure

  ;; - https://www.google.com/search?client=firefox-b-1-d&ei=Qn4OXarOFNG4tQX1yKrwAg&q=dynamically+set+window+transparency+compton&oq=dynamically+set+window+transparency+compton&gs_l=psy-ab.3...1302.1926..2080...0.0..0.121.655.6j1......0....1..gws-wiz.......0i71j33i22i29i30j35i304i39j33i160.w6gx35dRUJc
  ;; - https://www.reddit.com/r/unixporn/comments/3osw03/toggling_transparency_on_windows_in_compton_and/
  ;; - https://github.com/freedesktop/transset
  ;; - XChangeProperty
  ;; - https://gitlab.peach-bun.com/pinion/SFML/commit/135c1716e877464db720265f37316cbb54ef13f2?expanded=1&view=parallel
  ;; - xcb_change_property
  ;; - https://www.x.org/releases/current/doc/man/man3/xcb_change_property.3.xhtml

  ;; Also found this: https://xcb.freedesktop.org/XmlXcb/
  ;; C-h f xcb change property
  ;; Found xcb:ChangeProperty
  ;; Let the hacking begin

  ;; Found xcb:ewmh:-atoms
  ;; added opacity to list
  ;; called init function xcb:ewmh:init
  ;; found opacity is cardinal atom through xprop

  ;; example c call: https://github.com/ehntoo/unagi/blob/master/plugins/opacity.c#L71
  ;; True example: https://github.com/polybar/polybar/blob/ca4426a9620f4db05a0117282fbed3a32a14ec92/src/x11/ewmh.cpp#L168

  ;; reading from transset
  ;; So in C with Xlib, NWWO (my new abbreviation) is essentially an unsigned int.
  ;; max value is completely opaque, min is the opposite.
  ;; However, it's converted to a char array when passed to xlib xchangeproperty

  ;; xcb_change_property(conn->connection, XCB_PROP_MODE_REPLACE, win, _NET_WM_WINDOW_OPACITY, XCB_ATOM_CARDINAL, 32, 1, &values);

  (defun my/int-to-char-array (int)
    (cl-labels ((thunk (int depth)
                       (if (= depth 4)
                           nil
                         (cons (% int 256)
                               (thunk (/ int 256)
                                      (1+ depth))))))
      (thunk int 0)))

  (defun my/char-array-to-int (arr)
    (let ((iter (1- (length arr)))
          (sum 0))
      (while (>= iter 0)
        (setf sum (+ (* 256 sum) (aref arr iter)))
        (decf iter))
      sum))

  (let ((window-id 46137347))
    (my/set-transparency window-id 0.5)
    (my/char-array-to-int (slot-value (my/get-transparency window-id) 'value)))

  (defun my/set-transparency (window-id value)
    "`value` should be an float between 0 and and 1,"
    (xcb:+request exwm--connection
        (make-instance
         xcb:ChangeProperty
         :mode xcb:PropMode:Replace :window window-id
         :property xcb:Atom:_NET_WM_WINDOW_OPACITY :type xcb:Atom:CARDINAL
         :format 32 :data-len 1 :data (my/int-to-char-array (round (* 4294967295 value)))))
    (xcb:flush exwm--connection))

  (defun my/get-transparency (window-id)
    (xcb:+request-unchecked+reply exwm--connection
        (make-instance
         xcb:GetProperty
         :delete 0 :window window-id
         :property xcb:Atom:_NET_WM_WINDOW_OPACITY :type xcb:Atom:CARDINAL
         :long-offset 0 :long-length 1)))

  (defun my/increase-transparency (window-id))

  (defun my/decrease-transparency (window-id))

  (defun my/reset-transparency (window-id))

  (let ((window-id 79691779))
    (xcb:-+request exwm--connection
                   (make-instance xcb:ChangeProperty :mode xcb:PropMode:Replace :window window-id :property xcb:Atom:_NET_WM_WINDOW_OPACITY :type xcb:Atom:CARDINAL :format 32 :data-len 1 :data 10))
    (xcb:flush exwm--connection))

  (let ((name (symbol-name '_NET_WM_WINDOW_TYPE)))
    (slot-value
     (xcb:+request-unchecked+reply exwm--connection
         (make-instance 'xcb:InternAtom
                        :only-if-exists 0
                        :name-len (length name)
                        :name name))
     'atom))