nixos/fonts: scale X11 core cursor

Most desktop environments manage the cursor using the Xcursor library
by default; this comes with scalable or multiple-sized cursor themes.
However, when running just a simple WM (twm, bspwm, ...) the cursor
handling is left to the X server, which uses a very simple fixed bitmap
font (this is called a "core" cursor). The font is uncomfortably small
on a high DPI display and must be replaced with a saner default.

Up until recently[1] it used to be possible to change the font on the
xserver command line, however the font name is now hardcoded. It's still
possible to change it, though: here I override the `fontcursormisc`
package and set an alias that points to a vector variant of the original
cursor font. The font size is set to match the standard cursor
dimensions on a 96dpi display. It's not perfect but it's a very simple
and effective solution.

[1]: 56ea4c769c
This commit is contained in:
rnhmjoj 2021-08-09 23:39:54 +02:00
parent 47787b24f4
commit dd38ae1f2c
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@ -2,6 +2,52 @@
with lib;
let
# A scalable variant of the X11 "core" cursor
#
# If not running a fancy desktop environment, the cursor is likely set to
# the default `cursor.pcf` bitmap font. This is 17px wide, so it's very
# small and almost invisible on 4K displays.
fontcursormisc_hidpi = pkgs.xorg.fontcursormisc.overrideAttrs (old:
let
# The scaling constant is 230/96: the scalable `left_ptr` glyph at
# about 23 points is rendered as 17px, on a 96dpi display.
# Note: the XLFD font size is in decipoints.
size = 2.39583 * config.services.xserver.dpi;
sizeString = builtins.head (builtins.split "\\." (toString size));
in
{
postInstall = ''
alias='cursor -xfree86-cursor-medium-r-normal--0-${sizeString}-0-0-p-0-adobe-fontspecific'
echo "$alias" > $out/lib/X11/fonts/Type1/fonts.alias
'';
});
hasHidpi =
config.hardware.video.hidpi.enable &&
config.services.xserver.dpi != null;
defaultFonts =
[ pkgs.dejavu_fonts
pkgs.freefont_ttf
pkgs.gyre-fonts # TrueType substitutes for standard PostScript fonts
pkgs.liberation_ttf
pkgs.unifont
pkgs.noto-fonts-emoji
];
defaultXFonts =
[ (if hasHidpi then fontcursormisc_hidpi else pkgs.xorg.fontcursormisc)
pkgs.xorg.fontmiscmisc
] ++ optionals (config.nixpkgs.config.allowUnfree or false)
[ # these are unfree, and will make usage with xserver fail
pkgs.xorg.fontbhlucidatypewriter100dpi
pkgs.xorg.fontbhlucidatypewriter75dpi
pkgs.xorg.fontbh100dpi
];
in
{
imports = [
(mkRemovedOptionModule [ "fonts" "enableCoreFonts" ] "Use fonts.fonts = [ pkgs.corefonts ]; instead.")
@ -32,25 +78,9 @@ with lib;
};
config = {
fonts.fonts = mkIf config.fonts.enableDefaultFonts
([
pkgs.dejavu_fonts
pkgs.freefont_ttf
pkgs.gyre-fonts # TrueType substitutes for standard PostScript fonts
pkgs.liberation_ttf
pkgs.xorg.fontmiscmisc
pkgs.xorg.fontcursormisc
pkgs.unifont
pkgs.noto-fonts-emoji
] ++ lib.optionals (config.nixpkgs.config.allowUnfree or false) [
# these are unfree, and will make usage with xserver fail
pkgs.xorg.fontbhlucidatypewriter100dpi
pkgs.xorg.fontbhlucidatypewriter75dpi
pkgs.xorg.fontbh100dpi
]);
};
config = mkMerge [
{ fonts.fonts = mkIf config.fonts.enableDefaultFonts defaultFonts; }
{ fonts.fonts = mkIf config.services.xserver.enable defaultXFonts; }
];
}