ruby script to convert images inside keynote 4 bundles to PNG

keynotepng.rb

#!/usr/bin/env ruby -w

# Converts images inside keynote bundles to PNG
# We need RMagick with tiff support installed
# You may get libtiff from macports
# and RMagick from rubygems

# Licensed under GPLv3

require 'rubygems'
require 'optparse'
require 'zlib'
require 'rexml/document'
require 'RMagick'

# the extensions that will be compressed to PNG
EXTENSIONS = ['.tiff', '.pict', '.bmp']

quiet = false
clean = false

# deletes a directory and all files in it (non-recursive)
def deletedir(dir, quiet = false)
  if File.exists?(dir)
    Dir.foreach(dir) do |f|
      fn = dir + File::SEPARATOR + f
      unless File.directory?(fn)
        puts "Deleting #{fn}" unless quiet
        File.unlink(fn)
      end
    end
    puts "Deleting #{dir}" unless quiet
    Dir.unlink(dir)
  end
end

OptionParser.new do |o|
  o.banner = "Usage: #{$0} [options] filename"

  o.on('-c', '--[no-]clean', 'clean up temporary files (e.g. thumbnails)') do |v|
    clean = v
  end

  o.on('-q', '--[no-]quiet', 'No output') do |v|
    quiet = v
  end

  o.on_tail("-h", "--help", "Shows this message") do
    puts o
    exit
  end
end.parse!

if ARGV.length != 1
  puts 'Missing argument (try --help)'
  exit(1)
end

indir = ARGV.shift + File::SEPARATOR
index = indir + 'index.apxl.gz'

if clean
  deletedir(indir + 'thumbs', quiet) # thumbnails will be regenerated by keynote
  deletedir(indir + 'QuickLook', quiet) # quicklook thumbnail
end

# read index.apxl.gz
doc = nil
Zlib::GzipReader.open(index) { |f| doc = REXML::Document.new(f) }

# XPath is really slow in REXML :(
doc.elements.each('//key:page//sf:data') do |element|
  name = element.attributes['sf:path']
  newname = element.attributes['sf:path'] + '.png'

  if EXTENSIONS.include?(File.extname(name))
    if File.exists?(newname)
      puts "Won't compress #{name} because #{newname} already exists" unless quiet
    else
      # compress image
      image = Magick::ImageList.new(indir + name)
      image.write(indir + newname)

      # write new filename
      if element.attributes['sf:displayname'] == name # not sure if this is necessary
        element.attributes['sf:displayname'] = newname
      end
      element.attributes['sf:path'] = newname
      puts "Compressed #{name}" unless quiet
      File.unlink(indir + name) # delete old file
    end
  else
    puts "Won't compress #{name}" unless quiet
  end
end

# write changed xml back
Zlib::GzipWriter.open(index) { |f| doc.write(f) }