玩转字体内嵌

#!/usr/bin/env ruby
# vim:ts=2 sw=2 et
# ttfemb.rb : check if TTF can be embedded.
# Edward G.J. Lee

# check if this file is a TTF or OTF.
def ifTTF(file)
  f = File.new(file)
  tag = f.read(4)
  head = tag[0].to_s + tag[1].to_s + tag[2].to_s + tag[3].to_s
  if (head == '0100') || (tag == 'OTTO')
    return true
  else
    return false
  end
  f.close
end

# where the tname table data area start?
def dataOffset(file, tname)
  open(file, 'rb') do |f|
    f.seek(4, 1)
    tnum = f.read(2).unpack('n')
    f.seek(12, 0)

    0.upto(tnum[0] - 1) do |i|
      if f.read(4) == tname
        break
      end
    f.seek(12, 1)
    end

    f.seek(4, 1)
    offset = f.read(4).unpack('N')

    return offset[0]
  end
end

# check OS/2 table's fsType value.
def scanOS2(file)
  start = dataOffset(file, 'OS/2')
  f = File.new(file, 'rb')
  f.seek(start, 0)

  f.seek(8, 1)
  fsType = f.read(2).unpack('n')

  return fsType[0]
  f.close
end

if ARGV.length != 1
  puts "ttfemb.rb your.ttf"
  exit
elsif !test(?e, ARGV[0])
  puts 'File not exist!'
  exit
elsif File.extname(ARGV[0]).downcase == '.ttc'
  puts 'Not support yet!'
  exit
elsif !ifTTF(ARGV[0])
  puts 'Not a TrueType or OpenType font.'
  exit
else
  ft = scanOS2(ARGV[0])
  puts "fsType(dec) = " + ft.to_s
  print "fsType(bin) = "
  printf("%16.16b\n", ft)

  if ft == 2
    puts 'Warning: you cannot embed this TTF!'
  else
    puts "You may embed this TTF."
  end
end