libjxl: build gdk-pixbuf loader and thumbnailer

pkgs/development/libraries/libjxl/default.nix

@@ -8,15 +8,22 @@
 , libjpeg
 , libpng
 , libwebp
+, gdk-pixbuf
 , openexr_3
 , pkg-config
+, makeWrapper
 , zlib
 , asciidoc
 , graphviz
 , doxygen
 , python3
+, lcms2
 }:
 
+let
+  loadersPath = "${gdk-pixbuf.binaryDir}/jxl-loaders.cache";
+in
+
 stdenv.mkDerivation rec {
   pname = "libjxl";
   version = "0.9.1";
@@ -37,6 +44,8 @@ stdenv.mkDerivation rec {
   nativeBuildInputs = [
     cmake
     pkg-config
+    gdk-pixbuf
+    makeWrapper
     asciidoc
     doxygen
     python3
@@ -63,12 +72,14 @@ stdenv.mkDerivation rec {
   # conclusively in its README or otherwise; they can best be determined
   # by checking the CMake output for "Could NOT find".
   buildInputs = [
+    lcms2
     giflib
     gperftools # provides `libtcmalloc`
     gtest
     libjpeg
     libpng
     libwebp
+    gdk-pixbuf
     openexr_3
     zlib
   ];
@@ -96,17 +107,30 @@ 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/${gdk-pixbuf.moduleDir}" \
+    GDK_PIXBUF_MODULE_FILE="$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}"
+  '';
+
   CXXFLAGS = lib.optionalString stdenv.hostPlatform.isAarch32 "-mfp16-format=ieee";
 
   # FIXME x86_64-darwin: