Add NixOS module for fontconfig-ultimate

Details:
* The option `fonts.fontconfig.ultimate.enable` can be used to disable
  the fontconfig-ultimate configuration.
* The user-configurable options provided by fontconfig-ultimate are
  exposed in the NixOS module: `allowBitmaps` (default: true),
  `allowType1` (default: false), `useEmbeddedBitmaps` (default: false),
  `forceAutohint` (default: false), `renderMonoTTFAsBitmap` (default:
  false).
* Upstream provides three substitution modes for substituting TrueType
  fonts for Type 1 fonts (which do not render well). The default,
  "free", substitutes free fonts for Type 1 fonts. The option "ms"
  substitutions Microsoft fonts for Type 1 fonts. The option "combi"
  uses a combination of Microsoft and free fonts. Substitutions can also
  be disabled.
* All 21 of the Infinality rendering modes supported by fontconfig-ultimate
  or by the original Infinality distribution can be selected through
  `fonts.fontconfig.ultimate.rendering`. The default is the medium style
  provided by fontconfig-ultimate. Any of the modes may be customized,
  or Infinality rendering can be disabled entirely.

1 files changed, 193 insertions, 0 deletions

diff --git a/nixos/modules/config/fonts/fontconfig-ultimate.nix b/nixos/modules/config/fonts/fontconfig-ultimate.nix
new file mode 100644
index 000000000000..408d49053dde
--- /dev/null
+++ b/nixos/modules/config/fonts/fontconfig-ultimate.nix
@@ -0,0 +1,193 @@
+{ config, pkgs, ... }:
+
+with pkgs.lib;
+
+let fcBool = x: if x then "<bool>true</bool>" else "<bool>false</bool>";
+in
+{
+
+  options = {
+
+    fonts = {
+
+      fontconfig = {
+
+        ultimate = {
+          enable = mkOption {
+            type = types.bool;
+            default = true;
+            description = ''
+              Enable fontconfig-ultimate settings (formerly known as
+              Infinality). Besides the customizable settings in this NixOS
+              module, fontconfig-ultimate also provides many font-specific
+              rendering tweaks.
+            '';
+          };
+
+          allowBitmaps = mkOption {
+            type = types.bool;
+            default = true;
+            description = ''
+              Allow bitmap fonts. Set to <literal>false</literal> to ban all
+              bitmap fonts.
+            '';
+          };
+
+          allowType1 = mkOption {
+            type = types.bool;
+            default = false;
+            description = ''
+              Allow Type-1 fonts. Default is <literal>false</literal> because of
+              poor rendering.
+            '';
+          };
+
+          useEmbeddedBitmaps = mkOption {
+            type = types.bool;
+            default = false;
+            description = ''Use embedded bitmaps in fonts like Calibri.'';
+          };
+
+          forceAutohint = mkOption {
+            type = types.bool;
+            default = false;
+            description = ''
+              Force use of the TrueType Autohinter. Useful for debugging or
+              free-software purists.
+            '';
+          };
+
+          renderMonoTTFAsBitmap = mkOption {
+            type = types.bool;
+            default = false;
+            description = ''Render some monospace TTF fonts as bitmaps.'';
+          };
+
+          substitutions = mkOption {
+            type = types.str // {
+              check = flip elem ["none" "free" "combi" "ms"];
+            };
+            default = "free";
+            description = ''
+              Font substitutions to replace common Type 1 fonts with nicer
+              TrueType fonts. <literal>free</literal> uses free fonts,
+              <literal>ms</literal> uses Microsoft fonts,
+              <literal>combi</literal> uses a combination, and
+              <literal>none</literal> disables the substitutions.
+            '';
+          };
+
+          rendering = mkOption {
+            type = types.attrs;
+            default = pkgs.fontconfig-ultimate.rendering.ultimate;
+            description = ''
+              FreeType rendering settings presets. The default is
+              <literal>pkgs.fontconfig-ultimate.rendering.ultimate</literal>.
+              The other available styles are:
+              <literal>ultimate-lighter</literal>,
+              <literal>ultimate-darker</literal>,
+              <literal>ultimate-lightest</literal>,
+              <literal>ultimate-darkest</literal>,
+              <literal>default</literal> (the original Infinality default),
+              <literal>osx</literal>,
+              <literal>ipad</literal>,
+              <literal>ubuntu</literal>,
+              <literal>linux</literal>,
+              <literal>winxplight</literal>,
+              <literal>win7light</literal>,
+              <literal>winxp</literal>,
+              <literal>win7</literal>,
+              <literal>vanilla</literal>,
+              <literal>classic</literal>,
+              <literal>nudge</literal>,
+              <literal>push</literal>,
+              <literal>shove</literal>,
+              <literal>sharpened</literal>,
+              <literal>infinality</literal>. Any of the presets may be
+              customized by editing the attributes. To disable, set this option
+              to the empty attribute set <literal>{}</literal>.
+            '';
+          };
+        };
+      };
+    };
+
+  };
+
+
+  config =
+    let ultimate = config.fonts.fontconfig.ultimate;
+        fontconfigUltimateConf = ''
+          <?xml version="1.0"?>
+          <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
+          <fontconfig>
+
+            ${optionalString ultimate.allowBitmaps ''
+            <!-- Reject bitmap fonts -->
+            <selectfont>
+              <rejectfont>
+                <pattern>
+                  <patelt name="scalable"><bool>false</bool></patelt>
+                </pattern>
+              </rejectfont>
+            </selectfont>
+            ''}
+
+            ${optionalString ultimate.allowType1 ''
+            <!-- Reject Type 1 fonts -->
+            <selectfont>
+              <rejectfont>
+                <pattern>
+                  <patelt name="fontformat">
+                    <string>Type 1</string>
+                  </patelt>
+                </pattern>
+              </rejectfont>
+            </selectfont>
+            ''}
+
+            <!-- Use embedded bitmaps in fonts like Calibri? -->
+            <match target="font">
+              <edit name="embeddedbitmap" mode="assign">
+                ${fcBool ultimate.useEmbeddedBitmaps}
+              </edit>
+            </match>
+
+            <!-- Force autohint always -->
+            <match target="font">
+              <edit name="force_autohint" mode="assign">
+                ${fcBool ultimate.forceAutohint}
+              </edit>
+            </match>
+
+            <!-- Render some monospace TTF fonts as bitmaps -->
+            <match target="pattern">
+              <edit name="bitmap_monospace" mode="assign">
+                ${fcBool ultimate.renderMonoTTFAsBitmap}
+              </edit>
+            </match>
+
+            ${optionalString (ultimate.substitutions != "none") ''
+            <!-- Type 1 font substitutions -->
+            <include ignore_missing="yes">${pkgs.fontconfig-ultimate.confd}/etc/fonts/presets/${ultimate.substitutions}</include>
+            ''}
+
+            <include ignore_missing="yes">${pkgs.fontconfig-ultimate.confd}/etc/fonts/conf.d</include>
+
+          </fontconfig>
+        '';
+    in mkIf (config.fonts.fontconfig.enable && ultimate.enable) {
+
+      environment.etc."fonts/conf.d/52-fontconfig-ultimate.conf" = {
+        text = fontconfigUltimateConf;
+      };
+
+      environment.etc."fonts/${pkgs.fontconfig.configVersion}/conf.d/52-fontconfig-ultimate.conf" = {
+        text = fontconfigUltimateConf;
+      };
+
+      environment.variables = ultimate.rendering;
+
+    };
+
+}