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nixpkgs/nixos/modules/config/gtk/gtk-icon-cache.nix
pennae 2e751c0772 treewide: automatically md-convert option descriptions
the conversion procedure is simple:

 - find all things that look like options, ie calls to either `mkOption`
   or `lib.mkOption` that take an attrset. remember the attrset as the
   option
 - for all options, find a `description` attribute who's value is not a
   call to `mdDoc` or `lib.mdDoc`
 - textually convert the entire value of the attribute to MD with a few
   simple regexes (the set from mdize-module.sh)
 - if the change produced a change in the manual output, discard
 - if the change kept the manual unchanged, add some text to the
   description to make sure we've actually found an option. if the
   manual changes this time, keep the converted description

this procedure converts 80% of nixos options to markdown. around 2000
options remain to be inspected, but most of those fail the "does not
change the manual output check": currently the MD conversion process
does not faithfully convert docbook tags like <code> and <package>, so
any option using such tags will not be converted at all.
2022-07-30 15:16:34 +02:00

88 lines
3.3 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
{
options = {
gtk.iconCache.enable = mkOption {
type = types.bool;
default = config.services.xserver.enable;
defaultText = literalExpression "config.services.xserver.enable";
description = lib.mdDoc ''
Whether to build icon theme caches for GTK applications.
'';
};
};
config = mkIf config.gtk.iconCache.enable {
# (Re)build icon theme caches
# ---------------------------
# Each icon theme has its own cache. The difficult is that many
# packages may contribute with icons to the same theme by installing
# some icons.
#
# For instance, on my current NixOS system, the following packages
# (among many others) have icons installed into the hicolor icon
# theme: hicolor-icon-theme, psensor, wpa_gui, caja, etc.
#
# As another example, the mate icon theme has icons installed by the
# packages mate-icon-theme, mate-settings-daemon, and libmateweather.
#
# The HighContrast icon theme also has icons from different packages,
# like gnome-theme-extras and meld.
# When the cache is built all of its icons has to be known. How to
# implement this?
#
# I think that most themes have all icons installed by only one
# package. On my system there are 71 themes installed. Only 3 of them
# have icons installed from more than one package.
#
# If the main package of the theme provides a cache, presumably most
# of its icons will be available to applications without running this
# module. But additional icons offered by other packages will not be
# available. Therefore I think that it is good that the main theme
# package installs a cache (although it does not completely fixes the
# situation for packages installed with nix-env).
#
# The module solution presented here keeps the cache when there is
# only one package contributing with icons to the theme. Otherwise it
# rebuilds the cache taking into account the icons provided all
# packages.
environment.extraSetup = ''
# For each icon theme directory ...
find $out/share/icons -mindepth 1 -maxdepth 1 -print0 | while read -d $'\0' themedir
do
# In order to build the cache, the theme dir should be
# writable. When the theme dir is a symbolic link to somewhere
# in the nix store it is not writable and it means that only
# one package is contributing to the theme. If it already has
# a cache, no rebuild is needed. Otherwise a cache has to be
# built, and to be able to do that we first remove the
# symbolic link and make a directory, and then make symbolic
# links from the original directory into the new one.
if [ ! -w "$themedir" -a -L "$themedir" -a ! -r "$themedir"/icon-theme.cache ]; then
name=$(basename "$themedir")
path=$(readlink -f "$themedir")
rm "$themedir"
mkdir -p "$themedir"
ln -s "$path"/* "$themedir"/
fi
# (Re)build the cache if the theme dir is writable, replacing any
# existing cache for the theme
if [ -w "$themedir" ]; then
rm -f "$themedir"/icon-theme.cache
${pkgs.buildPackages.gtk3.out}/bin/gtk-update-icon-cache --ignore-theme-index "$themedir"
fi
done
'';
};
}