How to Display Google Calendar

Sat, Feb 4, 2023

Emacs is subsuming me! I have managed to get email up and running using mu4e and rss using elfeed and image viewing with image-dired

Next up is some form of calendar integration!

Although I use Google Calendar I don’t rely on any google apps directly; an android app called Simple Calendar is adequate for my needs and enables the thing I cherish most of all (except emacs of course!) and that is the ability to produce an offline copy. It can export to an ics file, and I have developed a habit of exporting to an offline file every time I update my calendar. This means that I have some exported calendar files lying around, including of course the most recent one.

Initially I attempted to use org-gcal which potentially enables a two way communication with Google Calendar through their API, but I got lost in the setup and of course this is Google, at some stage it is likely they will either change their API / remove it / or charge for it.

Anyway, do I really need to modify my calendar from within emacs?, I am quite comfortable using Simple Calendar on my phone and if I really need to add calendar entries from my laptop then I always have Thunderbird as a backup.

So I may just be in a very fortunate position regarding an adequate level of emacs calendar integration :

I only require read only
I have an up-to-date ics file available

I created the following function which opens up a nicely formatted calendar using the packages calfw and calfw-cal (and they didn’t require any additional setup).

(defun my/calendar ()
  (interactive)
  (setq tmp-file (concat home-dir "/DCIM/Backup/tmp.org"))
  (delete-file tmp-file)
  (when (get-buffer (file-name-nondirectory tmp-file))
    (kill-buffer (file-name-nondirectory tmp-file)))
  (setq last-ics
    (car (directory-files
           (concat home-dir "/DCIM/Backup")
           'full "\.ics$" #'file-newer-than-file-p)))
  (icalendar-import-file last-ics tmp-file)
  (cfw:open-diary-calendar)
  (when (get-buffer (file-name-nondirectory last-ics))
    (kill-buffer (file-name-nondirectory last-ics))))

and produces a calendar of the form:

I could import everything directly into my diary-file but I decided to be a little more flexible and potentially allow for multiple calendars by setting an include directive in my diary file as thus:

#include "~/DCIM/Backup/tmp.org"

The key to the my/calendar function is to pull in the most recent ics file and call the built in icalendar-import-file to convert / import the ics data into my diary file. The cfw packages will then take care of the rest. The other parts of the function are just tidying up various buffers and files to make things a little cleaner.

One little wrinkle I discovered and didn’t necessary solve to a satisfactory level was when I first call up cfw:open-diary-calendar the calendar didn’t resize correctly to fit the window, a second call however seemed to fix this and with no overhead.

One final addition was the following:

(add-to-list 'display-buffer-alist
  `(,(rx(or "Calendar"))
     display-buffer-in-direction
     (direction . right)
     (dedicated . t)
     (window . root)
     (window-width . 80)))

Which gives me greater control of where the calendar window is opened

How to Display Google Calendar

Comments