scarab: Apply scaling factor in Wayland (#348427)

pkgs/tools/games/scarab/default.nix

@@ -1,13 +1,10 @@
 {
   lib,
+  bc,
   buildDotnetModule,
   fetchFromGitHub,
-  glibc,
-  zlib,
-  gtk3,
   copyDesktopItems,
   icoutils,
-  wrapGAppsHook3,
   makeDesktopItem,
 }:
 
@@ -34,19 +31,12 @@ buildDotnetModule rec {
   '';
 
   runtimeDeps = [
-    glibc
-    zlib
-    gtk3
-  ];
-
-  buildInputs = [
-    gtk3
+    bc
   ];
 
   nativeBuildInputs = [
     copyDesktopItems
     icoutils
-    wrapGAppsHook3
   ];
 
   doCheck = true;
@@ -60,6 +50,8 @@ buildDotnetModule rec {
       size=''${sizes[$i]}x''${sizes[$i]}
       install -D omegamaggotprime_''$((i+1))_''${size}x32.png $out/share/icons/hicolor/$size/apps/scarab.png
     done
+
+    wrapProgram "$out/bin/Scarab" --run '. ${./scaling-settings.bash}'
   '';
 
   desktopItems = [

pkgs/tools/games/scarab/scaling-settings.bash

@@ -0,0 +1,24 @@
+# Keep existing value if it is already non-empty
+if [[ -z "${AVALONIA_GLOBAL_SCALE_FACTOR-}" ]] && command -v gsettings >/dev/null; then
+    echo 'Attempting to get GNOME desktop interface scaling factor' >&2
+    AVALONIA_GLOBAL_SCALE_FACTOR="$(gsettings get org.gnome.desktop.interface scaling-factor)"
+    AVALONIA_GLOBAL_SCALE_FACTOR="${AVALONIA_GLOBAL_SCALE_FACTOR##* }"
+fi
+
+if [[ "${AVALONIA_GLOBAL_SCALE_FACTOR-}" == "0" ]]; then
+    echo 'Unset invalid scaling value' >&2
+    unset AVALONIA_GLOBAL_SCALE_FACTOR
+fi
+
+if [[ -z "${AVALONIA_GLOBAL_SCALE_FACTOR-}" ]] && command -v xrdb >/dev/null; then
+    echo 'Attempting to get scaling factor from X FreeType DPI setting' >&2
+    dpi="$(xrdb -get Xft.dpi)"
+    if [[ -n "${dpi}" ]]; then
+        AVALONIA_GLOBAL_SCALE_FACTOR=$(echo "scale=2; ${dpi}/96" | bc)
+    fi
+fi
+
+if [[ -n "${AVALONIA_GLOBAL_SCALE_FACTOR-}" ]]; then
+    echo "Applying scale factor: ${AVALONIA_GLOBAL_SCALE_FACTOR}" >&2
+    export AVALONIA_GLOBAL_SCALE_FACTOR
+fi