libjxl: build gdk-pixbuf loader and thumbnailer

pkgs/development/libraries/libjxl/default.nix

@@ -1,4 +1,6 @@
-{ stdenv, lib, fetchFromGitHub
+{ stdenv
+, lib
+, fetchFromGitHub
 , fetchpatch
 , brotli
 , cmake
@@ -9,8 +11,10 @@
 , libjpeg
 , libpng
 , libwebp
-, openexr
+, gdk-pixbuf
+, openexr_3
 , pkg-config
+, makeWrapper
 , zlib
 , buildDocs ? true
 , asciidoc
@@ -19,6 +23,11 @@
 , python3
 }:
 
+let
+  inherit (gdk-pixbuf) moduleDir;
+  loadersPath = "${gdk-pixbuf.binaryDir}/jxl-loaders.cache";
+in
+
 stdenv.mkDerivation rec {
   pname = "libjxl";
   version = "0.8.2";
@@ -47,6 +56,8 @@ stdenv.mkDerivation rec {
     cmake
     gtest
     pkg-config
+    gdk-pixbuf
+    makeWrapper
   ] ++ lib.optionals buildDocs [
     asciidoc
     doxygen
@@ -79,7 +90,8 @@ stdenv.mkDerivation rec {
     libjpeg
     libpng
     libwebp
-    openexr
+    gdk-pixbuf
+    openexr_3
     zlib
   ];
 
@@ -106,17 +118,30 @@ stdenv.mkDerivation rec {
     # Viewer tools for evaluation.
     # "-DJPEGXL_ENABLE_VIEWERS=ON"
 
-    # TODO: Update this package to enable this (overridably via an option):
     # Enable plugins, such as:
     # * the `gdk-pixbuf` one, which allows applications like `eog` to load jpeg-xl files
     # * the `gimp` one, which allows GIMP to load jpeg-xl files
-    # "-DJPEGXL_ENABLE_PLUGINS=ON"
+    "-DJPEGXL_ENABLE_PLUGINS=ON"
   ] ++ lib.optionals stdenv.hostPlatform.isStatic [
     "-DJPEGXL_STATIC=ON"
   ] ++ lib.optionals stdenv.hostPlatform.isAarch32 [
     "-DJPEGXL_FORCE_NEON=ON"
   ];
 
+  postPatch = ''
+    substituteInPlace plugins/gdk-pixbuf/jxl.thumbnailer \
+      --replace '/usr/bin/gdk-pixbuf-thumbnailer' "$out/libexec/gdk-pixbuf-thumbnailer-jxl"
+  '';
+
+  postInstall = ''
+    GDK_PIXBUF_MODULEDIR="$out/${moduleDir}" \
+    GDK_PIXBUF_MODULE_FILE="$out/${loadersPath}" \
+    gdk-pixbuf-query-loaders --update-cache
+    mkdir -p "$out/bin"
+    makeWrapper ${gdk-pixbuf}/bin/gdk-pixbuf-thumbnailer "$out/libexec/gdk-pixbuf-thumbnailer-jxl" \
+      --set GDK_PIXBUF_MODULE_FILE "$out/${loadersPath}" \
+  '';
+
   LDFLAGS = lib.optionalString stdenv.hostPlatform.isRiscV "-latomic";
   CXXFLAGS = lib.optionalString stdenv.hostPlatform.isAarch32 "-mfp16-format=ieee";