i3wm window icon alternative using FontAwesome (or other icon based fonts)

i3wm title bar icons

# Title bar icons
for_window [class="(?i)firefox"] title_format "<tt></tt><span foreground='#FF6611'>  </span><tt> </tt>%title"
for_window [class="(.*)terminal(.*)"] title_format "<tt></tt><span foreground='#00FF00' background='#000000'>  </span><tt> </tt>%title"
for_window [class="(.*)Chromium-browser(.*)"] title_format "<tt></tt><span foreground='#367dd0' background='#d9e5f4'>  </span><tt> </tt>%title"
for_window [class="Evolution"] title_format "<tt></tt><span foreground='#FFFFFF' >  </span><tt> </tt>%title"
for_window [title=".* Evolution"] title_format "<tt></tt><span foreground='#FFFFFF' >  </span><tt> </tt>%title"
for_window [class="Slack"] title_format "<tt></tt><span foreground='#FFFFFF' >  </span><tt> </tt>%title"
for_window [class="Signal"] title_format "<tt></tt><span background='#2090ea' foreground='#FFFFFF' >  </span><tt> </tt>%title"
for_window [class="VirtualBox Machine"] title_format "<tt></tt><span  background='#073624' foreground='#AAAAFF' >  </span><tt> </tt>%title"
for_window [class="VirtualBox Manager"] title_format "<tt></tt><span  background='#073642' foreground='#AAAAFF' >  </span><tt> </tt>%title"
for_window [class="libreoffice-writer"] title_format "<tt></tt><span  background='#073642' foreground='#adc5e7' >  </span><tt> </tt>%title"
for_window [class="libreoffice-calc"] title_format "<tt></tt><span  background='#073642' foreground='#add58a' >  </span><tt> </tt>%title"
for_window [class="libreoffice-impress"] title_format "<tt></tt><span  background='#073642' foreground='#d07e7e' >  </span><tt> </tt>%title"

Example of what this can look like:

Colours need to be chosen to suit your theme - I'm running with a variation of dark Solarized.
The above snippet depends on FontAwesome, but is applicable to any icon font.

Nice solution... thanks!
I add that icons can be copy/pasted from https://fontawesome.com/cheatsheet

In case anyone doesn't get a solid variant of the envelope icon for email by default, you can set weight='bold' inside the span. Full documentation for the Pango markup here: https://developer.gnome.org/pygtk/stable/pango-markup-language.html

Nice solution. Thanks!

Great idea. You should also explain how to set this up. This is what I had to do:

1. Download Font Awesome, the "Free for Desktop" option, from its website

2. Unzip the zip file

3. Find the .otf (font) files

4. Double click each one to open it and click Install in the top right
   (from https://itsfoss.com/install-fonts-ubuntu/)

5. Add to the i3 config a line like this (from https://stackoverflow.com/questions/32596646/font-awesome-and-i3bar)
   font pango:DejaVu Sans Mono, Awesome 8

6. Add the for_window lines to the i3 config file.

Nice! Thank you!