def get_fields
      # vips_image_get_fields() was added in libvips 8.5
      return [] unless Vips.respond_to? :vips_image_get_fields

      array = Vips::vips_image_get_fields self

      names = []
      p = array
      until (q = p.read_pointer).null?
        names << q.read_string
        GLib::g_free q
        p += FFI::Type::POINTER.size
      end
      GLib::g_free array

      names
    end
def get_fields
      # vips_image_get_fields() was added in libvips 8.5
      return [] unless Vips.respond_to? :vips_image_get_fields

      array = Vips::vips_image_get_fields self

      names = []
      p = array
      until (q = p.read_pointer).null?
        names << q.read_string
        GLib::g_free q
        p += FFI::Type::POINTER.size
      end
      GLib::g_free array

      names
    end
Get the names of all fields on an image. Use this to loop over all
 image metadata.

 @return [[String]] array of field names