picom: remove refreshRate option

Removed by upstream since commit:

    bcbc410c92

This commit is included since v9 release:

    https://github.com/yshui/picom/releases/tag/v9
    https://github.com/yshui/picom/releases/tag/v9-rc1 (the actual changelog)

While this doesn't break the config per see, it results in the
following warning in the logs:

    [ DD/MM/YYYY HH:MM:SS.mmm parse_config_libconfig WARN ] The
      refresh-rate option has been deprecated. Please remove it from
      your configuration file. If you encounter any problems without
      this feature, please feel free to open a bug report

Beside the above change we also remove an old workaround and also
write the configuration file to a well-known location in the user's
home directory.

modules/services/picom.nix

@@ -1,13 +1,14 @@
 { config, lib, pkgs, ... }:
 
-with lib;
-with builtins;
-
 let
+  inherit (builtins) toJSON toString;
+  inherit (lib)
+    concatStringsSep elemAt literalExpression mkEnableOption mkIf mkOption
+    mkRemovedOptionModule optional optionalAttrs optionalString types;
 
   cfg = config.services.picom;
 
-  configFile = pkgs.writeText "picom.conf" (optionalString cfg.fade ''
+  configFile = optionalString cfg.fade ''
     # fading
     fading = true;
     fade-delta    = ${toString cfg.fadeDelta};
@@ -46,8 +47,7 @@ let
     # other options
     backend = ${toJSON cfg.backend};
     vsync = ${toJSON cfg.vSync};
-    refresh-rate = ${toString cfg.refreshRate};
-  '' + cfg.extraOptions);
+  '' + cfg.extraOptions;
 
 in {
 
@@ -250,15 +250,6 @@ in {
       '';
     };
 
-    refreshRate = mkOption {
-      type = types.int;
-      default = 0;
-      example = 60;
-      description = ''
-        Screen refresh rate (0 = automatically detect).
-      '';
-    };
-
     package = mkOption {
       type = types.package;
       default = pkgs.picom;
@@ -282,6 +273,11 @@ in {
     };
   };
 
+  imports = [
+    (mkRemovedOptionModule [ "services" "picom" "refreshRate" ]
+      "The option `refresh-rate` has been deprecated by upstream.")
+  ];
+
   config = mkIf cfg.enable {
     assertions = [
       (lib.hm.assertions.assertPlatform "services.picom" pkgs
@@ -290,6 +286,8 @@ in {
 
     home.packages = [ cfg.package ];
 
+    xdg.configFile."picom/picom.conf".text = configFile;
+
     systemd.user.services.picom = {
       Unit = {
         Description = "Picom X11 compositor";
@@ -299,17 +297,13 @@ in {
 
       Install = { WantedBy = [ "graphical-session.target" ]; };
 
-      Service = let
-        experimentalBackendsFlag =
-          if cfg.experimentalBackends then " --experimental-backends" else "";
-      in {
-        ExecStart = "${cfg.package}/bin/picom --config ${configFile}"
-          + experimentalBackendsFlag;
+      Service = {
+        ExecStart = concatStringsSep " " ([
+          "${cfg.package}/bin/picom"
+          "--config ${config.xdg.configFile."picom/picom.conf".source}"
+        ] ++ optional cfg.experimentalBackends "--experimental-backends");
         Restart = "always";
         RestartSec = 3;
-      } // optionalAttrs (cfg.backend == "glx") {
-        # Temporarily fixes corrupt colours with Mesa 18.
-        Environment = [ "allow_rgb10_configs=false" ];
       };
     };
   };

tests/default.nix

@@ -155,6 +155,7 @@ import nmt {
     ./modules/services/mpd
     ./modules/services/pantalaimon
     ./modules/services/pbgopy
+    ./modules/services/picom
     ./modules/services/playerctld
     ./modules/services/polybar
     ./modules/services/redshift-gammastep

tests/modules/services/picom/default.nix

@@ -0,0 +1 @@
+{ picom-basic-configuration = ./picom-basic-configuration.nix; }

tests/modules/services/picom/picom-basic-configuration-expected.conf

@@ -0,0 +1,33 @@
+# fading
+fading = true;
+fade-delta    = 5;
+fade-in-step  = 0.04;
+fade-out-step = 0.04;
+fade-exclude  = ["window_type *= 'menu'","name ~= 'Firefox$'","focused = 1"];
+
+# shadows
+shadow = true;
+shadow-offset-x = -10;
+shadow-offset-y = -15;
+shadow-opacity  = 0.8;
+shadow-exclude  = ["window_type *= 'menu'","name ~= 'Firefox$'","focused = 1"];
+
+# opacity
+active-opacity   = 1.0;
+inactive-opacity = 1.0;
+inactive-dim     = 0.0;
+opacity-rule     = [];
+
+wintypes:
+{
+  dock          = { shadow = false; };
+  dnd           = { shadow = false; };
+  popup_menu    = { opacity = 1.0; };
+  dropdown_menu = { opacity = 1.0; };
+};
+
+# other options
+backend = "xrender";
+vsync = true;
+unredir-if-possible = true;
+dbe = true;

tests/modules/services/picom/picom-basic-configuration-expected.service

@@ -0,0 +1,12 @@
+[Install]
+WantedBy=graphical-session.target
+
+[Service]
+ExecStart=@picom@/bin/picom --config /nix/store/00000000000000000000000000000000-hm_picompicom.conf --experimental-backends
+Restart=always
+RestartSec=3
+
+[Unit]
+After=graphical-session-pre.target
+Description=Picom X11 compositor
+PartOf=graphical-session.target

tests/modules/services/picom/picom-basic-configuration.nix

@@ -0,0 +1,37 @@
+{ config, pkgs, ... }:
+
+{
+  services.picom = {
+    enable = true;
+    fade = true;
+    fadeDelta = 5;
+    fadeSteps = [ "0.04" "0.04" ];
+    fadeExclude =
+      [ "window_type *= 'menu'" "name ~= 'Firefox$'" "focused = 1" ];
+    shadow = true;
+    shadowOffsets = [ (-10) (-15) ];
+    shadowOpacity = "0.8";
+    shadowExclude =
+      [ "window_type *= 'menu'" "name ~= 'Firefox$'" "focused = 1" ];
+    backend = "xrender";
+    vSync = true;
+    extraOptions = ''
+      unredir-if-possible = true;
+      dbe = true;
+    '';
+    experimentalBackends = true;
+  };
+
+  test.stubs.picom = { };
+
+  nmt.script = ''
+    assertFileContent \
+        home-files/.config/picom/picom.conf \
+        ${./picom-basic-configuration-expected.conf}
+
+    serviceFile=$(normalizeStorePaths home-files/.config/systemd/user/picom.service)
+    assertFileContent \
+        "$serviceFile" \
+        ${./picom-basic-configuration-expected.service}
+  '';
+}