pdfbooklet.rb

require 'rubygems'
require 'rmagick'
include Magick

class Array
  def odd_values
    self.values_at(* self.each_index.select {|i| i.odd?})
  end
  def even_values
    self.values_at(* self.each_index.select {|i| i.even?})
  end
end

# Burst pdf into single pages, split pages, and reorder into single pdf
def make_booklet(inputpdf)
  original_dir = Dir.pwd
  Dir.mkdir("temp")
  Dir.mkdir("booklets") unless File.exists?("booklets")

  # split into individual pdfs
  `pdftk '#{inputpdf}' burst output temp/page_%02d.pdf`

  Dir.chdir("temp")

  # Create array of individual pdfs
  pages = Dir["*.pdf"]
  pages.each do |page|
    pagenum = page.to_s.scan(/\d+/)
    pdf = ImageList.new("#{page}") { 
      self.density = "300"}
    width = pdf[0].columns
    height = pdf[0].rows
  
    # crop and output as jpgs then pdfs for 1st page  
    pageone = pdf.crop(0, 0, width/2, height)
    pageone.write("page_#{pagenum}A.jpg")
    jpg = ImageList.new("page_#{pagenum}A.jpg")
    jpg.write("page_#{pagenum}A.pdf")
  
    # crop and output as jpgs then pdfs for 2nd page
    pagetwo = pdf.crop(width/2, 0, width/2, height)
    pagetwo.write("page_#{pagenum}B.jpg")
    jpg = ImageList.new("page_#{pagenum}B.jpg")
    jpg.write("page_#{pagenum}B.pdf")
  
  end

  a_pages = Dir["*A.pdf"]
  b_pages = Dir["*B.pdf"]

  a_pages_odd = a_pages.odd_values
  a_pages_even = a_pages.even_values.reverse
  b_pages_odd = b_pages.odd_values.reverse
  b_pages_even = b_pages.even_values

  combined_pages = b_pages_even.zip(a_pages_odd).flatten + b_pages_odd.zip(a_pages_even).flatten

  # combine all pdfs to single pdf with original name in folder /booklets
  `pdftk #{combined_pages.join(' ')} output '#{File.join(File::SEPARATOR , original_dir, 'booklets', inputpdf)}'`

  # delete contents of /temp
  Dir["*"].each {|f| File.delete(f) }
  Dir.chdir(original_dir)
  Dir.delete("temp")
end

# For each input pdf
ARGV.each do |input|
  make_booklet(input)
end