blur swaylock background

home-manager/util/blur.nix

@@ -0,0 +1,26 @@
+{
+  stdenv,
+  imagemagick,
+  src,
+}:
+stdenv.mkDerivation {
+  pname = "blur-image";
+  version = "1.0";
+
+  inherit src;
+
+  buildInputs = [ imagemagick ];
+
+  # input is a file, not a directory, skip unpackPhase
+  unpackPhase = "true";
+
+  # command taken from: https://old.reddit.com/r/swaywm/comments/oz3t7v/setting_a_blurred_background_with_swaylock_and/
+  buildPhase = ''
+    magick ${src} -filter Gaussian -resize 20% -blur 0x2.5 -resize 500% output.png
+  '';
+
+  installPhase = ''
+    mkdir -p $out
+    mv output.png $out/
+  '';
+}