# File lib/bio/graphics/ruler.rb, line 27
  def initialize(panel, colour = [0,0,0])
    @panel = panel
    @name = 'ruler'
    @colour = colour
    
    # Number of pixels between each tick, used to calculate tick spacing
    @min_pixels_per_tick = 5
    # The base height of minor ticks in pixels
    @tick_height = 5
    # The height of the text in pixels
    @tick_text_height = 10

    @minor_tick_distance = @min_pixels_per_tick ** self.scaling_factor
    @major_tick_distance = @minor_tick_distance * 10       
  end