#+TITLE: Desktop
#+AUTHOR: Christopher James Hayward
#+EMAIL: chris@chrishayward.xyz

#+PROPERTY: header-args:emacs-lisp :tangle desktop.el :comments org
#+PROPERTY: header-args            :results silent :eval no-export :comments org

#+OPTIONS: num:nil toc:nil todo:nil tasks:nil tags:nil
#+OPTIONS: skip:nil author:nil email:nil creator:nil timestamp:nil

I use Emacs as a Desktop Environment with the *EXWM*[fn:1] package. It allows Emacs to function as a complete tiling window manager for *X11*[fn:2]. 

* Initialization
:PROPERTIES:
:header-args: :tangle ../config/xinitrc :comments org
:END:

My workflow includes launching the window manager with *Xinit*[fn:3], without the use of a display manager, controlling *everything* within Emacs. In addition, compton is used as a display compositor, and slock for a screen lock.

#+begin_src conf
compton &
xss-lock -- slock &
exec dbus-launch --exit-with-session emacs -mm --debug-init
#+end_src

** Create a symbolic link(s)

*Xinit*[fn:3] reads its configuration from ~~/.xinitrc~. Override this location with a link to the custom configuration.

#+begin_src emacs-lisp
(dotfiles/symlink "~/.emacs.d/config/xinitrc"
                  "~/.xinitrc")
#+end_src

** Desktop environment

Use the *desktop-environment* package to automatically bind well-known programs for controlling the volume, brightness, media playback, and many other XF86 functionality bindings.

#+begin_src emacs-lisp
(use-package desktop-environment
  :after exwm
  :custom (desktop-environment-brightness-small-increment "2%+")
          (desktop-environment-brightness-small-decrement "2%-")
          (desktop-environment-brightness-normal-decrement "5%-")
          (desktop-environment-brightness-normal-decrement "5%-")
  :config (desktop-environment-mode))
#+end_src

** Keyboard tweaks
:PROPERTIES:
:header-args: conf :tangle ../config/xmodmap
:END:

Use *XModmap* to swap CapsLock and Ctrl to keep common bindings on the home row.

#+begin_src conf
clear lock
clear control

keycode 66 = Control_L

add control = Control_L
add Lock = Control_R
#+end_src

#+begin_src emacs-lisp
(dotfiles/symlink "~/.emacs.d/config/xmodmap"
                  "~/.Xmodmap")
#+end_src

#+RESULTS:

* Browser integration

Write out the ~$BROWSER~ variable so other applications can pick up the custom browser.

+ Place custom keybindings for browsing behind =SPC b=
  + URL with =u=
  + URL at point with =p=
  + URL at cursor with =c=

#+begin_src emacs-lisp
(setenv "BROWSER" dotfiles/browser)

(dotfiles/leader
  "u" '(:ignore t :which-key "Browse")
  "uu" '(browse-url :which-key "URL")
  "up" '(browse-url-at-point :which-key "Point")
  "uc" '(browse-url-at-cursor :which-key "Cursor"))
#+end_src

* Displays detection

When the window manager first launches the ~init-hook~ executes, allowing us to define some custom logic.

+ Display time and date
+ Display battery info (if available)

In my personal configuration, I do not want the battery or time displayed within Emacs when it's not running as desktop environment because that information is typically already available.

#+begin_src emacs-lisp
(defun dotfiles/init-hook ()
  (exwm-workspace-switch-create 1)
  (setq display-time-and-date t)
  (display-battery-mode 1)
  (display-time-mode 1))
#+end_src

Using =autorandr= with pre configured profiles, switching screens (AKA hot plugging) is also handled through a hook.

#+begin_src emacs-lisp
(defun dotfiles/update-display ()
  "Update the displays by forcing a change through autorandr."
  (dotfiles/run-in-background "autorandr --change --force"))
#+end_src

* Window manager

Connect our custom hooks and configure the input keys, a custom layer for key capture layers.

+ Enable =randr= support
+ Pass through to Emacs
  + =M-x= to Emacs
  + =C-g= to Emacs
  + =C-SPC= to Emacs
+ Bindings with =S= (Super / Win)
  + Reset =S-r=
  + Launch =S-&=
  + Workspace =S-[1..9]=
    
#+begin_src emacs-lisp
(use-package exwm
  :when (window-system)
  :custom (exwm-workspace-show-all-buffers t)
          (exwm-input-prefix-keys
            '(?\M-x
              ?\C-g
              ?\C-\ ))
          (exwm-input-global-keys
            `(([?\s-r] . exwm-reset)
              ,@(mapcar (lambda (i)
                          `(,(kbd (format "s-%d" i)) .
                          (lambda ()
                          (interactive)
                          (exwm-workspace-switch-create ,i))))
                          (number-sequence 1 9))))
  :config (require 'exwm-randr)
          (exwm-randr-enable)
          (add-hook 'exwm-init-hook #'dotfiles/init-hook)
          (add-hook 'exwm-randr-screen-change-hook #'dotfiles/update-display)
          (add-hook 'exwm-update-class-hook (lambda () (exwm-workspace-rename-buffer exwm-class-name)))
          (dotfiles/update-display)
          (exwm-enable))
#+end_src

* Footnotes

[fn:1] https://github.com/ch11ng/exwm

[fn:2] https://en.wikipedia.org/wiki/X_Window_System

[fn:3] https://en.wikipedia.org/wiki/Xinit

[fn:4] https://wiki.termux.com/wiki/Graphical_Environment