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Tag Cloud in Ruby

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  1.  
  2. def font_size_for_tag_cloud( total, lowest, highest, options={} )
  3.  return nil if total.nil? or highest.nil? or lowest.nil?
  4.  #
  5.  # options
  6.  maxf = options.delete( :max_font_size ) || 14
  7.  minf = options.delete( :min_font_size ) || 11
  8.  maxc = options.delete( :max_color ) || [ 0, 0, 0 ]
  9.  minc = options.delete( :min_color ) || [ 156, 156, 156 ]
  10.  hide_sizes = options.delete( :hide_sizes )
  11.  hide_colours = options.delete( :hide_colours )
  12.  #
  13.  # function to work out rgb values
  14.  def rgb_color( a, b, i, x)
  15.   return nil if i <= 1 or x <= 1
  16.   if a > b
  17.    a-(Math.log(i)*(a-b)/Math.log(x)).floor
  18.   else
  19.    (Math.log(i)*(b-a)/Math.log(x)+a).floor
  20.   end
  21.  end
  22.  #
  23.  # work out colours
  24.  c = []
  25.  (0..2).each { |i| c << rgb_color( minc[i], maxc[i], total, highest ) || nil }
  26.  colors = c.compact.empty? ? minc.join(',') : c.join(',')
  27.  #
  28.  # work out the font size
  29.  spread = highest.to_f - lowest.to_f
  30.  spread = 1.to_f if spread <= 0
  31.  fontspread = maxf.to_f - minf.to_f
  32.  fontstep = spread / fontspread
  33.  size = ( minf + ( total.to_f / fontstep ) ).to_i
  34.  size = maxf if size > maxf
  35.  #
  36.  # display the results
  37.  size_txt = "font-size:#{ size.to_s }px;" unless hide_sizes
  38.  color_txt = "color:rgb(#{ colors });" unless hide_colours
  39.  return [ size_txt, color_txt ].join
  40. end
  41.  

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