asisi.rb

#!/usr/bin/env ruby                                                                                               

require "rubygems"
require "RMagick"

#
# draw the sequence in the background                                                                           
def draw_sequence( image )
  sequence = Magick::Draw.new

  start  = 0
  stop   = image.columns
  height = image.rows / 2

  sequence.stroke( "black" )
  # sequence.stroke_width(2.5)
  sequence.line( start, height, stop, height )
  sequence.draw( image )

  return image
end

#
# draw an arrow at a point
def draw_arrow( image, point )
  arrow    = Magick::Draw.new

  arrow.stroke( "black" )
  # arrow.stroke_width(1.5)
  arrow.line( 100,45,point.first, point.last ).draw( image )
  arrow.line(  98,48,point.first, point.last ).draw( image )
  arrow.line( 102,48,point.first, point.last ).draw( image )

  return arrow
end

#                                                                                                                 
# prototyping rendering AsiSI                                                                                     
def draw_asisi( image, position )
  asisi    = Magick::Draw.new

  # draw the AsiSI on the sequence                                                                                
  asisi.annotate( image, 50, 20, position, 25, "AsiSI" ) do
    self.gravity     = Magick::CenterGravity
    self.stroke      = "black"
    self.pointsize   = 14
    self.font_family = "arial"
  end

  draw_arrow( image, [100, 50] )

  return image
end

#
# Main script
image_file = "./asisi.png"
image      = Magick::Image.new( 200, 100 )

draw_sequence( image )
draw_asisi( image, 75 )

# write image to file
image.write( image_file )