xviewer: Support avif, heif, jxl, webp

Same as Nixpkgs PR 533230.

pkgs/by-name/xv/xviewer/package.nix

@@ -26,6 +26,11 @@
   yelp-tools,
   xapp,
   xapp-symbolic-icons,
+  gnome,
+  libavif,
+  libheif,
+  libjxl,
+  webp-pixbuf-loader,
 }:
 
 stdenv.mkDerivation (finalAttrs: {
@@ -75,6 +80,21 @@ stdenv.mkDerivation (finalAttrs: {
     xapp
   ];
 
+  postInstall = ''
+    # In postInstall to run before gappsWrapperArgsHook.
+    export GDK_PIXBUF_MODULE_FILE="${
+      gnome._gdkPixbufCacheBuilder_DO_NOT_USE {
+        extraLoaders = [
+          libavif
+          libheif.lib
+          libjxl
+          librsvg
+          webp-pixbuf-loader
+        ];
+      }
+    }"
+  '';
+
   preFixup = ''
     gappsWrapperArgs+=(
       --prefix XDG_DATA_DIRS : "${lib.makeSearchPath "share" [ xapp-symbolic-icons ]}"