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#-*- coding: utf-8 -*-

require 'benchmark'

# When you convert a jpg image using ImageMagick,
# convert command options combination make a big difference in performance.
# so i try to do a benchmark test about parameter combination.
# 
# Fastest combination   : when given define option with width and height.
# Secondary combination : when given define with either width or height, debug option make faster.
# Thirdly combination   : when given define with either width or height.
# Slowest               : no given define and debug.
def resize(options)
  # ImageMagick's option parameter combination
  size = options[:size] || '180x120'
  command = ['convert']
  command << '-debug Coder -log %e' if options[:debug]
  command << '-define jpeg:size='+size if options[:define]
  command << '-resize'
  command << size
  command << options[:filename]
  command << 'after_' + options[:filename].downcase

  system(*command)
end

# 50 image file were prepared.
list = Dir::glob('./*.JPG').map {|item|
  File.basename(item)
}

# test it.
Benchmark.bm(30) {|x|
  x.report("no debug & define:") {
    list.each {|item| resize(:filename => item )}
  }
  x.report("with debug:") {
    list.each {|item| resize(:filename => item, :debug => true, :define => true)}
  }
  x.report("with define:") {
    list.each {|item| resize(:filename => item, :define => true)}
  }
  x.report("no define size=x600:") {
    list.each {|item| resize(:filename => item, :size=> "x600")}
  }
  x.report("with define size=x600:") {
    list.each {|item| resize(:filename => item, :size=> "x600", :define => true)}
  }
  x.report("with define size=x120:") {
    list.each {|item| resize(:filename => item, :size => "x120", :define => true)}
  }
  x.report("with define size=800x600:") {
    list.each {|item| resize(:filename => item, :size => "800x600", :define => true)}
  }
  x.report("with define & debug size=x120:") {
    list.each {|item| resize(:filename => item, :size => "x120", :define => true, :debug => true)}
  }
  x.report("with define & debug size=x600:") {
    list.each {|item| resize(:filename => item, :size => "x600", :define => true, :debug => true)}
  }
}


=begin
Result:
-------------------------------------------------------------------------------
                                        user     system      total        real
no debug & define :                 0.070000   0.780000 243.620000 (137.978237)
with debug & define :               0.000000   0.260000  30.860000 ( 24.966679)
no define size=x600 :               0.020000   0.940000 289.010000 (156.380973)
with define size=x600 :             0.040000   0.890000 282.290000 (153.480008)
with define size=x120 :             0.060000   0.940000 252.440000 (144.542583)
with define size=800x600 :          0.040000   0.480000  96.330000 ( 59.767320)
with define & debug size=x120 :     0.030000   0.260000  36.170000 ( 27.981825)
with define & debug size=x600 :     0.080000   0.410000 106.170000 ( 62.490479)
=end