VIM GTK-UI font - vim

Question

The vim manual states:
On systems where 'guifontset' is supported (X11) and 'guifontset' is
not empty, then 'guifont' is not used.
Spaces after a comma are ignored. To include a comma in a font name
precede it with a backslash. Setting an option requires an extra
backslash before a space and a backslash. See also
|option-backslash|. For example: >
:set guifont=Screen15,\ 7x13,font\\,with\\,commas
will make Vim try to use the font "Screen15" first, and if it fails it
will try to use "7x13" and then "font,with,commas" instead.
So, I would like to do the following:
if has("gui_running")
if has("gui_gtk2")
set guifont=Droid\ Sans\ Mono,Inconsolata,Monospace
elseif has("gui_win32")
set guifont=Droid\ Sans\ Mono:h10,Consolas:h11:cANSI
endif
endif
Trouble is that it does not work for me... I have been trying for a couple of hours on CentOS6.3 and Debian Wheey, but when ever I write this command like this, VIM will just start with Sans font.
Am I doing something wrong? How do you smartly detect which fonts are on the system ?

Answer 1

OK, I know this is probably not the right way, but it works. So, here is how I set a fallback font for VIM-GTK:
if has("gui_running")
if has("gui_gtk2")
let dsm=system('fc-list | grep -c Droid\ Sans\ Mono')
let cons=system('fc-list | grep -c Inconsola')
if ( dsm > 0)
set gfn=Droid\ Sans\ Mono\ 10
elseif ( cons > 0)
set gfn=Inconsolata\ 12
else
set gfn=Monospace\ 10
endif
elseif has("gui_win32")
set guifont=Droid\ Sans\ Mono:h10,Consolas:h11:cANSI
endif
endif
This snippet will check if Droid Sans Mono is installed, and also if Inconsolata is installed.
If the first one is install, the UI font will be Droid Sans Mono, if not it will be set to Inconsolata, and finally, it will be set to Monospace.
On Windows 7 the comma separated list just works.

Answer 2

I ran into the same issue. The problem here is that when Vim calls gui_init_font (code) it expects if gui_mch_get_font (code) fails it can move on to the next font in the comma-separated list. But in GTK gui_mch_get_font calls pango_font_description_from_string (code) which will never fail, it'll just return a default.
But pango_font_description_from_string itself takes a comma-separated list of families followed by style options, size and variations and has its own fallback logic (doc) withe the following format: [FAMILY-LIST] [STYLE-OPTIONS] [SIZE] [VARIATIONS]. Thus escape your list as follows:
if has("gui_running")
if has("gui_gtk2") || has("gui_gtk3")
set guifont=Droid\ Sans\ Mono\\,Inconsolata\\,Monospace 10
elseif has("gui_win32")
set guifont=Droid\ Sans\ Mono:h10,Consolas:h11:cANSI
endif
endif
Then Pango will do the fallback work and pick the right font for you. On GTK it seems to be best to fully escape your string and let GTK do the logic.

Answer 3

I either failed to get Oz123's answer properly abstracted into a function or else otherwise couldn't get this working on my system. I had additional issues due to actually using two users (a sandboxed web user and my main account); there was some problem executing fc-list).
My workaround was to reassign the alias for the Monospace font, which affects all of my apps (don't employ this technique if you only want this to work in gvim).
This change goes into ~/.config/fontconfig/fonts.conf:
<?xml version='1.0'?>
<!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
<fontconfig>
<alias>
<family>monospace</family>
<prefer><family>Panic Sans</family></prefer>
</alias>
</fontconfig>
I chose Panic Sans (unofficially hosted here), a variant of the highly popular free DejaVu Sans Mono font, because it is particularly good at rendering code (it additionally solves the underscore and dash problem in DejaVu). The font's files themselves live in my ~/.fonts/Panic_Sans directory.
Installing it in this manner allows me to share my ~/.vimrc between systems and not have to worry about whether Panic Sans is installed on them.
This means that my ~/.vimrc now merely contains:
if has("gui_running")
if has("gui_gtk2")
set guifont=Monospace\ 7
endif
" …
And this works because the fontconfig alias properly matches Monospace to Panic Sans:
$ fc-match Monospace
PanicSans.ttf: "Panic Sans" "Regular"