Linux PNGOUT script generator

make-compress-script.rb

#!/usr/bin/env ruby
require 'open3'
require 'tempfile'

ThreadCount = 2

Infinity  = 1.0/0.0
Filenames = Dir['**/favicon.ico', '**/*.png'].map! { |filename| File.expand_path filename }
BestSizes = Hash.new { |h, filename| h[filename] = [Infinity, nil] }

def pngout args
  args_old = args
  args = args.dup
  filename = args[1]
  if File.extname(filename) == '.png'
    temp_file = nil
  else
    temp_file = Tempfile.new(['pngout-needs-png-extension-', '.png'])
    temp_file.close
    FileUtils.cp filename, temp_file.path
    args[1] = temp_file.path
  end

  exit_code = 1
  while exit_code == 1
    output, status = Open3.capture2e *args
    exit_code = (output =~ /unsupported format/) ? 3 : status.exitstatus
  end

  unless temp_file.nil?
    FileUtils.cp temp_file.path, filename if exit_code == 0
    temp_file.unlink
  end

  if exit_code == 3
    nil
  else
    Integer(output.scan(/Out:\s*(\d+)/m).last.first)
  end
end

def process_file filename
  puts "[#{ Time.now }] Starting to process #{ filename }"
  args = ['pngout', filename, '-v', '-y', '-kt', '-k0']
  [0, 2, 3, 4, 6].each do |c|
    args << "-c#{ c }"
    # Only continue trying this color type if it can work
    unless pngout(args + ['-f0', '-s4', '-n1']).nil?
      (((c == 0) or (c == 3)) ? [1, 2, 4, 8] : [nil]).each do |d|
        args << "-d#{ d }" unless d.nil?
        # Only continue trying this bit depth if it can work
        if d.nil? or not pngout(args + ['-f0', '-s4', '-n1']).nil?
          [0, 1, 2, 3, 4, 5].each do |f|
            args << "-f#{ f }"
            (f == 0 ? [0, 4] : [0]).each do |s|
              args << "-s#{ s }"
              # Try uncompressed once: some really small files do better.
              if s == 4
                args << '-n1'
                pngout args
                args.pop
              else
                best_size = Infinity
                best_n = 1
                n = 1
                while n <= best_n + 3
                  args << "-n#{ n }"
                  size = pngout args
                  unless size.nil?
                    if size <= best_size
                      best_size = size
                      best_n = n
                    end
                    BestSizes[filename] = [size, args.dup] if size < BestSizes[filename].first
                  end
                  n += 1
                  args.pop
                end
              end
              args.pop
            end
            args.pop
          end
        end
        args.pop unless d.nil?
      end
    end
    args.pop
  end
  size, args = BestSizes[filename]
  if size == Infinity
    puts "[#{ Time.now }] Cannot handle #{ filename }"
  else
    puts "[#{ Time.now }] Best: #{ size } bytes with #{ args.first } \"#{ filename }\" #{ args[2..-1].join(' ') }"

    # Try the other -s settings once just in case they are smaller
    (1..3).each { |temp_s| pngout(args[0..-3] + ["-s#{ temp_s }", args.last]) }
  end
end

Array.new(ThreadCount) do
  Thread.new do
    filename = Filenames.shift
    until filename.nil?
      process_file filename
      filename = Filenames.shift
    end
  end
end.each { |thr| thr.join }

File.open('compress-all', 'wb') do |script|
  script.chmod(0755)
  script.puts <<"END"
#!/usr/bin/env ruby
require 'open3'
require 'tempfile'

ThreadCount = #{ ThreadCount }

Args = [
END
  BestSizes.keys.sort.each do |filename|
    size, args = BestSizes[filename]
    script.puts "  #{ (args + ['-r']).inspect }," unless size == Infinity
  end
  script.puts <<'END'
]
FileCount = Args.length
FileSizes = Hash.new { |h, filename| h[filename] = File.size filename }

def pngout args
  args = args.dup
  filename = args[1]
  if File.extname(filename) == '.png'
    temp_file = nil
  else
    temp_file = Tempfile.new(['pngout-needs-png-extension-', '.png'])
    temp_file.close
    FileUtils.cp filename, temp_file.path
    args[1] = temp_file.path
  end

  exit_code = 1
  while exit_code == 1
    output, status = Open3.capture2e *args
    exit_code = (output =~ /unsupported format/) ? 3 : status.exitstatus
  end

  unless temp_file.nil?
    FileUtils.cp temp_file.path, filename if exit_code == 0
    temp_file.unlink
  end

  if exit_code == 3
    nil
  else
    Integer(output.scan(/Out:\s*(\d+)/m).last.first)
  end
end

Array.new(ThreadCount) do
  Thread.new do
    loop do
      Args.shuffle.each do |args|
        filename = args[1]

        old_size = FileSizes[filename]
        new_size = pngout args
        if old_size > new_size
          puts "[#{ Time.now }] #{ old_size } => #{ new_size } (#{ filename })"
          FileSizes[filename] = new_size
        end
      end
    end
  end
end.each { |thr| thr.join }
END
end

puts "[#{ Time.now }] ./compress-all generated!"