Tips and tricks

Adjusting the brightness and contrast of a background image

If you want to use a background image for your desktop but find it too bright or distracting, you can use the imagemagick package to dim the image, or adjust its brightness and contrast to suit your preference.

Here's an example Nix expression that takes an input image, applies a brightness/contrast adjustment to it, and saves the result as a new image file:

{ pkgs, ... }:

let
  inputImage = ./path/to/image.jpg;
  brightness = -30;
  contrast = 0;
  fillColor = "black"
in
{
  stylix.image = pkgs.runCommand "dimmed-background.png" { } ''
    ${pkgs.imagemagick}/bin/convert "${inputImage}" -brightness-contrast ${brightness},${contrast} -fill ${fillColor} $out
  '';
}

Dynamic wallpaper generation based on selected theme

With imagemagick, you can also dynamically generate wallpapers based on the selected theme. Similarly, you can use a template image and repaint it for the current theme.

{ pkgs, ... }:

let
  theme = "${pkgs.base16-schemes}/share/themes/catppuccin-latte.yaml";
  wallpaper = pkgs.runCommand "image.png" {} ''
        COLOR=$(${pkgs.yq}/bin/yq -r .base00 ${theme})
        COLOR="#"$COLOR
        ${pkgs.imagemagick}/bin/magick convert -size 1920x1080 xc:$COLOR $out
  '';
in {
  stylix = {
    image = wallpaper;
    base16Scheme = theme;
  };
}

Which is neatly implemented as a single function in lib.stylix.pixel:

{ pkgs, config, ... }:

{
  stylix = {
    image = config.lib.stylix.pixel "base0A";
    base16Scheme = "${pkgs.base16-schemes}/share/themes/catppuccin-latte.yaml";
  };
}