anchor.diff:      librsvg
       lensfun
       libspiro
  +    maxflow
       netsurf.libnsgif
       pango
       poly2tri-c
  
positive.code: 
  stdenv.mkDerivation rec {
    pname = "gegl";
    version = "0.4.26";
  
    outputs = [ "out" "dev" "devdoc" ];
    outputBin = "dev";
  
    src = fetchurl {
      url = "https://download.gimp.org/pub/gegl/${lib.versions.majorMinor version}/${pname}-${version}.tar.xz";
      sha256 = "sha256-DzceLtK5IWL+/T3edD5kjKCKahsrBQBIZ/vdx+IR5CQ=";
    };
  
    patches = [
      # fix build with darwin: https://github.com/NixOS/nixpkgs/issues/99108
      # https://gitlab.gnome.org/GNOME/gegl/-/merge_requests/83
      (fetchpatch {
        url = "https://gitlab.gnome.org/GNOME/gegl/-/merge_requests/83.patch";
        sha256 = "sha256-CSBYbJ2xnEN23xrla1qqr244jxOR5vNK8ljBSXdg4yE=";
      })
    ];
  
    nativeBuildInputs = [
      pkg-config
  
negative.code:     vala
      gobject-introspection
      gtk-doc
      docbook-xsl-nons
      docbook_xml_dtd_43
    ];
  
  