autorandr: Set wallpaper on display change

Author: splintersuidman

configuration/home/autorandr.nix

@@ -10,8 +10,7 @@ in {
   programs.autorandr = {
     enable = true;
     profiles = {
-      # Default single-screen setup, with builtin laptop screen as
-      # primary.
+      # Default single-display setup, with builtin laptop display as primary.
       default = {
         fingerprint = { inherit (fingerprints) eDP-1; };
         config = {
@@ -23,8 +22,8 @@ in {
           };
         };
       };
-      # Double-screen setup with HDMI screen as primary and builtin
-      # laptop screen as secondary.
+      # Double-display setup with HDMI display as primary and builtin laptop
+      # display as secondary.
       doublescreen = {
         fingerprint = { inherit (fingerprints) HDMI-1 eDP-1; };
         config = {
@@ -46,6 +45,8 @@ in {
       postswitch = lib.optionalAttrs config.services.polybar.enable {
         "polybar-restart" =
           "${config.services.polybar.package}/bin/polybar-msg cmd restart";
+      } // lib.optionalAttrs (config.wallpaper.command != null) {
+        "wallpaper" = config.wallpaper.command;
       };
     };
   };

configuration/home/xsession.nix

@@ -16,14 +16,18 @@ let
     '';
   };
 in {
+  imports = [ ../../modules/home/wallpaper.nix ];
+
   home.packages = [ xmonad ];
 
   xsession = {
     enable = true;
-    initExtra = ''
-      ${pkgs.feh}/bin/feh --no-fehbg --bg-fill --geometry +0+0 ${wallpaper}
-    '';
-
     windowManager.command = "${xmonad}/bin/xmonad-${targetSystem}";
   };
+
+  wallpaper = {
+    enableXSession = true;
+    command =
+      "${pkgs.feh}/bin/feh --no-fehbg --bg-fill --geometry +0+0 ${wallpaper}";
+  };
 }

modules/home/wallpaper.nix

@@ -0,0 +1,28 @@
+{ config, lib, ... }:
+with lib;
+let cfg = config.wallpaper;
+in {
+  options.wallpaper = {
+    enableXSession = mkOption {
+      type = types.bool;
+      default = false;
+      description = ''
+        Whether to enable setting the wallpaper using X Session.
+      '';
+    };
+
+    command = mkOption {
+      type = types.str;
+      default = null;
+      description = ''
+        Command to set wallpaper.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enableXSession {
+    xsession.initExtra = ''
+      ${cfg.command}
+    '';
+  };
+}