Script to reverse the tiling an image goes through when processed by Zoomify

unzoomify

#!/usr/bin/env ruby

require 'rubygems'
require 'fileutils'
require 'open-uri'
require 'rexml/document'
require 'tempfile'
require 'shellwords'

module Shell
  # Exceptions
  class CommandFailed < RuntimeError; end

  def run(command, args="")
    full_command = "#{command} #{escape_args(args)}"
    puts "Running command: #{full_command}"
    begin
      result = `#{full_command}`
    rescue Errno::ENOENT
      raise_shell_command_failed(full_command)
    end
    if $?.exitstatus == 1
      throw :unable_to_handle
    elsif !$?.success?
      raise_shell_command_failed(full_command)
    end
  end

  def raise_shell_command_failed(command)
    raise CommandFailed, "Command failed (#{command}) with exit status #{$?.exitstatus}"
  end

  def escape_args(args)
    args.shellsplit.map do |arg|
      quote arg.gsub(/\\?'/, %q('\\\\''))
    end.join(' ')
  end

  def quote(s)
    "'#{s}'"
  end
end

class Zoomify
  TILESIZE = 256
  include Shell

  def unzoomify(url, level=5)
    @url = url
    @level = level
    @output_filename = "tmp/#{File.basename(@url)}.png"

    # Read properties file
    doc = nil
    begin
      open("#{@url}/ImageProperties.xml") do |f|
        doc = REXML::Document.new(f)
      end
    rescue OpenURI::HTTPError
      puts "ERROR: Failed to open ImageProperties.xml"
      return nil
    end

    # Sanity check
    attrs = doc.root.attributes
    unless attrs['TILESIZE'] == TILESIZE.to_s && attrs['VERSION'] == '1.8'
      puts "ERROR: unexpected tile size"
      return nil
    end

    # Get properties
    width = attrs['WIDTH'].to_i
    height = attrs['HEIGHT'].to_i
    num_tiles = attrs['NUMTILES'].to_i
    num_tiles_x = width / TILESIZE
    num_tiles_y = height / TILESIZE

    @tile_groups = (0..num_tiles/TILESIZE).to_a

    image = transparent(width, height)
    (0..num_tiles_x).each do |column|
      (0..num_tiles_y).each do |row|
        # Get tile
        filename = "#{@level}-#{column}-#{row}.jpg"
        puts "Getting #{filename}..."
        tile_image = get_tile(filename)

        # Merge it into master image
        composite!(tile_image, column*TILESIZE, row*TILESIZE) if tile_image
      end
    end

    return @output_filename
  end

  def get_tile(filename)
    @tile_groups.each do |group|
      begin
        tile_url = "#{@url}/TileGroup#{group}/#{filename}"
        file_ext = ".#{File.extname(filename).split('.').last}"
        tempfile = ::Tempfile.new ['unzoomify', file_ext]
        tempfile.binmode

        puts "Getting #{tile_url}..."
        open(tile_url) do |f|
          tempfile.write(f.read)
        end

        tempfile.close
        return tempfile
      rescue OpenURI::HTTPError, Errno::ENOENT
        puts "Not found."
      end
    end
    puts "WARNING: (#{@url}, #{filename}) appears to be missing or invalid"
    nil
  end

  def transparent(width, height)
    run :convert, %(-size #{width}x#{height} canvas:none #{@output_filename})
  end

  def composite!(tile, x, y)
    run :composite, %(-compose src-over -geometry '#{TILESIZE}x#{TILESIZE}+#{x}+#{y}' #{tile.path} #{@output_filename} #{@output_filename})
  end
end

z = Zoomify.new
full_image_path = z.unzoomify 'directory_or_url'
puts full_image_path ? "Full size image written to #{full_image_path}." : "ERROR"