.dcx file format: Ruby parsing library

DCX is a simple extension of PCX image format allowing to bundle many PCX images (typically, pages of a document) in one file. It saw some limited use in DOS-era fax software, but was largely superseded with multi-page TIFFs and PDFs since then.

File extension

dcx

KS implementation details

License: CC0-1.0

References

This page hosts a formal specification of .dcx file format using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime library

All parsing code for Ruby generated by Kaitai Struct depends on the Ruby runtime library. You have to install it before you can parse data.

The Ruby runtime library can be installed from RubyGems:

gem install kaitai-struct

Code

Parse a local file and get structure in memory:

data = PcxDcx.from_file("path/to/local/file.dcx")

Or parse structure from a string of bytes:

bytes = "\x00\x01\x02..."
data = PcxDcx.new(Kaitai::Struct::Stream.new(bytes))

After that, one can get various attributes from the structure by invoking getter methods like:

data.magic # => get magic

Ruby source code to parse .dcx file format

pcx_dcx.rb

# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

require 'kaitai/struct/struct'

unless Gem::Version.new(Kaitai::Struct::VERSION) >= Gem::Version.new('0.9')
  raise "Incompatible Kaitai Struct Ruby API: 0.9 or later is required, but you have #{Kaitai::Struct::VERSION}"
end


##
# DCX is a simple extension of PCX image format allowing to bundle
# many PCX images (typically, pages of a document) in one file. It saw
# some limited use in DOS-era fax software, but was largely
# superseded with multi-page TIFFs and PDFs since then.
class PcxDcx < Kaitai::Struct::Struct
  def initialize(_io, _parent = nil, _root = self)
    super(_io, _parent, _root)
    _read
  end

  def _read
    @magic = @_io.read_bytes(4)
    raise Kaitai::Struct::ValidationNotEqualError.new([177, 104, 222, 58].pack('C*'), magic, _io, "/seq/0") if not magic == [177, 104, 222, 58].pack('C*')
    @files = []
    i = 0
    begin
      _ = PcxOffset.new(@_io, self, @_root)
      @files << _
      i += 1
    end until _.ofs_body == 0
    self
  end
  class PcxOffset < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @ofs_body = @_io.read_u4le
      self
    end
    def body
      return @body unless @body.nil?
      if ofs_body != 0
        _pos = @_io.pos
        @_io.seek(ofs_body)
        @body = Pcx.new(@_io)
        @_io.seek(_pos)
      end
      @body
    end
    attr_reader :ofs_body
  end
  attr_reader :magic
  attr_reader :files
end