niri: make focus ring the inverse of the average of the background color

home-manager/progs/niri.nix

@@ -5,6 +5,9 @@
   inputs,
   ...
 }:
+let
+  invert_image_avg = pkgs.callPackage ../util/inverse_color.nix;
+in
 {
   imports = [
     inputs.niri.homeModules.config
@@ -51,7 +54,9 @@
         focus-ring = {
           enable = true;
           active = {
-            color = "#bf7778";
+            color = builtins.readFile (invert_image_avg {
+              src = ../wallpaper.png;
+            });
           };
         };
       };
@@ -59,7 +64,7 @@
       spawn-at-startup = [
         {
           command = [
-            "${lib.getExe config.programs.eww.package}"
+            (lib.getExe config.programs.eww.package)
             "-c"
             "${config.programs.eww.configDir}"
             "open"
@@ -70,7 +75,7 @@
         # swaybg works on more than just sway (sets a wallpaper)
         {
           command = [
-            "${lib.getExe pkgs.swaybg}"
+            (lib.getExe pkgs.swaybg)
             "-i"
             "${../wallpaper.png}"
           ];
@@ -79,7 +84,7 @@
         # Xwayland on niri via xwayland-satellite
         {
           command = [
-            "${lib.getExe pkgs.xwayland-satellite}"
+            (lib.getExe pkgs.xwayland-satellite)
             config.programs.niri.settings.environment.DISPLAY
           ];
         }
@@ -125,14 +130,12 @@
 
       # https://github.com/sodiboo/niri-flake/issues/591
       switch-events = with config.lib.niri.actions; {
-        "lid-close".action = spawn "${pkgs.swaylock}/bin/swaylock";
+        "lid-close".action = spawn (lib.getExe pkgs.swaylock);
       };
 
       binds = with config.lib.niri.actions; {
         # Application launcher
-        "Mod+Space".action = spawn [
-          "${pkgs.fuzzel}/bin/fuzzel"
-        ];
+        "Mod+Space".action = spawn (lib.getExe pkgs.fuzzel);
 
         "Mod+O".action = toggle-overview;
 
@@ -140,7 +143,7 @@
         "Mod+T".action = spawn config.home.sessionVariables.TERMINAL;
 
         # lock the screen
-        "Mod+X".action = spawn "${pkgs.swaylock}/bin/swaylock";
+        "Mod+X".action = spawn (lib.getExe pkgs.swaylock);
 
         # screenshotting
         "Print".action = screenshot;
@@ -180,7 +183,7 @@
 
         # color picker and copies to clipboard
         "Mod+Ctrl+Alt+C".action = spawn [
-          "${pkgs.hyprpicker}/bin/hyprpicker"
+          (lib.getExe pkgs.hyprpicker)
           "-za"
         ];
 

home-manager/util/inverse_color.nix

@@ -0,0 +1,26 @@
+{
+  stdenv,
+  imagemagick,
+  gawk,
+  src,
+}:
+stdenv.mkDerivation {
+  pname = "invert-image-avg";
+  version = "1.0";
+
+  inherit src;
+
+  buildInputs = [
+    imagemagick
+    gawk
+  ];
+
+  # 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 = ''
+    rm -fr $out
+    magick ${src} -channel RGB -negate -resize 1x1 txt: | awk 'FNR == 2 {print $3}' > $out
+  '';
+}