Re: [Tuxpaint-devel] Windows & Android (& others?) FontConfig `fonts.conf` parsing

[Bill K. <nb...@so...>]

On Sat, Feb 22, 2025 at 04:10:46PM +0900, Shin-ichi TOYAMA wrote:
> Hi!
> 
> I had made it to load fonts stored in user's font directory on Windows.
> 
> See commit 365ee3ea20af489996e045f97ae2d874e43f5591
> 
> Then I think there is no more thing to be added so far.

What I'm hoping for is a location (or locations) on Windows to read
FontConfig configuration file(s) -- "fonts.conf" -- which might contain
some <dir>...</dir> clauses that point to other places to find fonts.
(Tux Paint then proceeds to pass each path along to `loadfonts()`.)


For example, on my Linux system, Tux Paint will look for fonts
in three locations, based on two configuration files (user and system):

  $ grep "<dir>" ~/.config/fontconfig/fonts.conf /etc/fonts/fonts.conf
  /home/kendrick/.config/fontconfig/fonts.conf: <dir>~/.fonts</dir>
  /etc/fonts/fonts.conf:  <dir>/usr/share/fonts</dir>
  /etc/fonts/fonts.conf:  <dir>/usr/local/share/fonts</dir>
  /etc/fonts/fonts.conf:  <dir>~/.fonts</dir>

I actually just went in and updated `load_user_fonts()` to utilize
some environment variables, if set, in the 'default' block of code
that's used by Linux (and anything else not __APPLE__ or __HAIKU__).

Specifically,

 * Don't assume `/etc/fonts/fonts.conf`, but use $FONTCONFIG_PATH if set.
 * Don't assume `$HOME/.config/fonts.conf`, but use $XDG_CONFIG_HOME if set.


As a reminder, now that Tux Paint explicitly looks for and loads fonts
found in the "<dir>" paths that my `fonts.conf` files point to, I am now
able to use a lot more fonts in Tux Paint than I could before;
things I'm used to seeing in other apps (Gimp, Inkscape, LibreOffice).


So to summarize my question for you -- is there a location (or set of
locations) -- where one would expect to find FontConfig "fonts.conf" files
on Windows?


Interestingly, when I search Google for the question
"where is fontconfig fonts.conf on windows", it's AI Overview states:

  On Windows, there is no "fonts.conf" file in the traditional sense
  of Fontconfig, as Windows manages fonts through its own system, and
  does not utilize the Fontconfig framework; therefore, you won't find a
  "fonts.conf" file on a Windows system; all fonts are typically stored
  in the "C:\Windows\Fonts" directory.

HOWEVER, I cannot determine how it came to this conclusion, so I don't
trust this answer.  It may be a hallucination. >:-(


Tux Paint actually SHIPS with its own "fonts.conf" file for Windows [*],
which includes these <dir> paths:

  <dir prefix="cwd">data/fonts/locale</dir>
  <dir prefix="cwd">data/fonts</dir>
  <dir>WINDOWSFONTDIR</dir> <dir>WINDOWSUSERFONTDIR</dir>
  <dir prefix="xdg">fonts</dir>
  <dir>~/.fonts</dir>

Those "WINDOWSFONTDIR" and "WINDOWSUSERFONTDIR" values seem to be magic
strings used by FontConfig; see:

  https://gitlab.freedesktop.org/fontconfig/fontconfig/-/blob/main/src/fcxml.c#L1330


I think at the very least, one place the Windows version of Tux Paint
should look for "fonts.conf" is own one that ships with Tux Paint:
`etc/fonts/fonts.conf` (inside Tux Paint).

If we were to mimick the behavior of FontConfig itself when
those two "WINDOWS...FONTDIR" values are seen, I think that might
actually remove the need for your user font dir scanning code
(added in `365ee3ea20af489996e045f97ae2d874e43f5591`).  Wouldn't it?

I think I might drop some FIXME's in there, and I'd appreciate if
you could try implementing and testing. :)  Expect more commits
in a few minutes.

Then, as usual, I REALLY need to get to bed. :-D


-bill!

[*] We also ship a "fonts.conf" inside the macOS build.  Comments in
tuxpaint.c explain:

  /* Pango uses Fontconfig which requires fonts.conf.  By default, Fontconfig
   * searches for this file in a global path (e.g., /opt/local/etc/fonts if
   * using the MacPorts port of Fontconfig) which does not exist on a vanilla
   * macOS install.  As a workaround, the macOS port of Tux Paint provides its
   * own copy, and tells Fontconfig to look inside the Tux Paint app bundle for
   * this file by setting the FONTCONFIG_PATH environment variable here.


> 
> Thanks
> 
> On Sun, 16 Feb 2025 12:57:15 -0800, Bill Kendrick wrote:
> >
> >I've been quite busy lately, and was just trying to remind myself
> >what's up in the in-progress 0.9.35 version of Tux Paint.
> >
> >In CHANGES.txt I spotted this entry:
> >
> > + WIP Checking for fonts in any locations specified by "<dir>"
> >   entries found in system-wide and user-level FontConfig config files.
> >   This allows more fonts, and user-specific fonts, to be found & loaded.
> >   - TODO - Looks in $FONTCONFIG_PATH/fonts.conf on macOS/iOS,
> >     `/boot/system/settings/fonts/fonts.conf` on Haiku, otherwise
> >     the Un*x-specific `/etc/fonts/fonts.conf` and
> >     `~/.config/fontconfig/fonts.conf`.  Should look in the correct
> >     places on other platforms.
> >   - Note: This adds a build dependency on `libxml-2.0`.
> >
> >Pere and Shin-ichi, I'm sure I asked already, but can you let me know
> >what else, if anything, we should add so that Tux Paint can find a user's
> >`fonts.conf` (FontConfig XML configuration file) so the Android & Windows
> >builds of Tux Paint can also take advantage of this new capability...?
> >
> >And of course if anyone else out here has suggestions for more OS-specific
> >paths that we should look at, please speak up!
> >
> >Thanks in advance!
> >
> >-bill!
> >
> >PS - As a reminder, the _other_ things coming in 0.9.35 (so far) are:
> >
> > * "emitter" (heart, stars, sparkles) magic tools
> > * text pasting (copy/paste buffer) in Text & Label tools
> > * UX improvement to HSV color picker
> > * minor doc improvements
> > * some build improvements (NetBSD, Slackware)
> > * less noise to STDOUT
> >
> >
> >
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> 
> 
> -- 
> Shin-ichi TOYAMA <dol...@wm...>
>