libsixel: make linking against gd a choosable option.

  gdk-pixbuf,

  gd,

  pkg-config,

  # Enable linking against image loading libraries as part of the

  # implementation of the sixel_helper_{load,write}_image_file() functions.

  # These helper functions are not needed for the main functionality of the

  # library to encode image buffers to sixels.

  #

  # libsixel already uses vendored stb image loading to provide basic

  # implementations, but also allows for the "gd" library to be linked for

  # a wider set of image formats.

  # This pulls in a large amount of deps bloating the resulting library.

  #

  # Default off, but configurable in case you really need it.

  withGd ? false,

}:

stdenv.mkDerivation rec {

stdenv.mkDerivation (finalAttrs: {

  pname = "libsixel";

  version = "1.10.5";

  src = fetchFromGitHub {

    owner = "libsixel";

    repo = "libsixel";

    rev = "v${version}";

    rev = "v${finalAttrs.version}";

    hash = "sha256-obzBZAknN3N7+Bvtd0+JHuXcemVb7wRv+Pt4VjS6Bck=";

  };

  buildInputs = [

  buildInputs = lib.optionals withGd [

    gdk-pixbuf

    gd

  ];

  mesonFlags = [

    "-Dtests=enabled"

    # build system seems to be broken here, it still seems to handle jpeg

    # through some other ways.

    "-Dimg2sixel=enabled"

    "-Dsixel2png=enabled"

    (lib.mesonEnable "gd" withGd)

    # build system seems to be broken here; error message indicates pkconfig

    # issue.

    # Not to worry: jpeg and png are handled by the built-in stb and/or gd lib.

    "-Djpeg=disabled"

    "-Dpng=disabled"

  ];

    license = licenses.mit;

    platforms = platforms.unix;

  };

}

})