"Hub Calculation Board" Generator. See also: http://jsfiddle.net/takehikom/MmXpJ/ http://jsfiddle.net/takehikom/NsCAL/

hubcalc.rb

#!/usr/bin/env ruby
# -*- coding: utf-8 -*-

# hubcalc.rb : "Hub Calculation Board" Generator
# by takehikom (http://d.hatena.ne.jp/takehikom/)

$svg_skel = DATA.read

module HubCalc
  class Generator
    def initialize(opt = Hash.new)
      @center = opt[:center] || "5"
      @outside = opt[:outside] || [0, 1, 2, 3, 4]
      @filename = opt[:filename] || "hubcalc.svg"
    end

    def start
      @code = ""

      # draw spokes
      n_spoke = @outside.length
      raise if n_spoke == 0
      n_spoke.times do |i|
        angle = 2.0 * Math::PI * i / n_spoke
        x = 200.0 + 150.0 * Math.sin(angle)
        y = 200.0 - 150.0 * Math.cos(angle)
        add_code('<line x1="200" y1="200" x2="%g" y2="%g"/>' % [x, y])
        add_code('<circle cx="%g" cy="%g" r="40"/>' % [x, y])
        add_code('<text x="%g" y="%g" class="smalltext">%s</text>' % [x, y + 17, @outside[i].to_s])
      end

      # draw center
      add_code('<circle cx="200" cy="200" r="60"/>')
      add_code('<text x="200" y="222" class="largetext">%s</text>' % @center.to_s)

      # save as svg
      svg = $svg_skel.dup
      svg["<!--content-->"] = @code
      open(@filename, "w") do |f_out|
        f_out.print svg
      end
    end

    private
    def add_code(line, indent_level = 1)
      @code += "  " * indent_level
      @code += line
      @code += "\n"
    end
  end
end

if __FILE__ == $0
  opt = { # [isbn:9784284202251], p.18
    :filename => "hubcalc.svg",
    :center => "5×",
    :outside => "94728563".split(//)
  }
  HubCalc::Generator.new(opt).start
  # HubCalc::Generator.new(:filename => "hubcalc2.svg").start
end

__END__
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg xmlns="http://www.w3.org/2000/svg" width="400" height="400" id="hubcalc">
  <style type="text/css" >
    <![CDATA[
      #bg { fill:#e0ffe0; stroke:none }
      circle { stroke:none; fill:#99ccff; }
      line { stroke:#99ccff; stroke-width:4; }
      text { font-family:sans-serif; font-style:normal; font-weight:normal; fill:#000000; stroke:none; text-anchor:middle; }
      .largetext { font-size:65px; }
      .smalltext { font-size:50px; }
    ]]>
  </style>
  <rect x="0" y="0" width="400" height="400" id="bg"/>
<!--content--></svg>