def self.directed(args)
args = {
:height => 10,
:fill_color => 'red',
:stroke => "black",
:stroke_width => 1,
:style => "fill-opacity:0.4;"}.merge!(args)
if args[:strand] == '-'
args[:points] = "#{args[:x]},#{args[:y]} #{args[:x] + args[:width]},#{args[:y]} #{args[:x] + args[:width]},#{args[:y] + args[:height] } #{args[:x]},#{args[:y] + (args[:height])} #{args[:x] - (args[:height] * 0.2)},#{args[:y] + (args[:height]/2)}"
else
args[:points] = "#{args[:x]},#{args[:y]} #{args[:x] + args[:width] - (args[:height] * 0.2)},#{args[:y]} #{args[:x] + args[:width]},#{args[:y] + (args[:height]/2) } #{args[:x] + args[:width] - (args[:height] * 0.2)},#{args[:y] + args[:height]} #{args[:x]},#{args[:y] + args[:height]}"
end
[Bio::Graphics::Primitive.new(:polygon, args)]
end