Class: Cabriolet::LIT::Compressor

Inherits:
Object
  • Object
show all
Defined in:
lib/cabriolet/lit/compressor.rb

Overview

Compressor creates LIT eBook files

LIT files are Microsoft Reader eBook files that use LZX compression. The compressor allows adding multiple files to create a LIT archive.

NOTE: This implementation creates non-encrypted LIT files only. DES encryption (DRM protection) is not implemented.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io_system = nil) ⇒ Compressor

Initialize a new LIT compressor

Parameters:

  • io_system (System::IOSystem, nil) (defaults to: nil) —

    Custom I/O system or nil for default



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# File 'lib/cabriolet/lit/compressor.rb', line 20

def initialize(io_system = nil)
  @io_system = io_system || System::IOSystem.new
  @files = []
end

Instance Attribute Details

#files ⇒ Object

Returns the value of attribute files.



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# File 'lib/cabriolet/lit/compressor.rb', line 14

def files
  @files
end

#io_system ⇒ Object (readonly)

Returns the value of attribute io_system.



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# File 'lib/cabriolet/lit/compressor.rb', line 13

def io_system
  @io_system
end

Instance Method Details

#add_file(source_path, lit_path, **options) ⇒ void

This method returns an undefined value.

Add a file to the LIT archive

Parameters:

  • source_path (String) —

    Path to the source file

  • lit_path (String) —

    Path within the LIT archive

  • options (Hash) —

    Options for the file

Options Hash (**options):

  • :compress (Boolean) —

    Whether to compress the file (default: true)



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# File 'lib/cabriolet/lit/compressor.rb', line 33

def add_file(source_path, lit_path, **options)
  compress = options.fetch(:compress, true)

  @files << {
    source: source_path,
    lit_path: lit_path,
    compress: compress,
  }
end

#generate(output_file, **options) ⇒ Integer

Generate the LIT archive

Parameters:

  • output_file (String) —

    Path to output LIT file

  • options (Hash) —

    Generation options

Options Hash (**options):

  • :version (Integer) —

    LIT format version (default: 1)

  • :encrypt (Boolean) —

    Whether to encrypt (not supported, raises error)

Returns:

  • (Integer) —

    Bytes written to output file

Raises:

  • (Errors::CompressionError) —

    if generation fails

  • (NotImplementedError) —

    if encryption is requested



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# File 'lib/cabriolet/lit/compressor.rb', line 53

def generate(output_file, **options)
  version = options.fetch(:version, 1)
  encrypt = options.fetch(:encrypt, false)

  if encrypt
    raise NotImplementedError,
          "DES encryption is not implemented. " \
          "LIT files will be created without encryption."
  end

  raise ArgumentError, "No files added to archive" if @files.empty?

  output_handle = @io_system.open(output_file, Constants::MODE_WRITE)

  begin
    # Prepare file data
    file_data = prepare_files

    # Write header
    header_bytes = write_header(
      output_handle,
      version,
      file_data.size,
    )

    # Write file entries
    entries_bytes = write_file_entries(output_handle, file_data)

    # Write file contents
    content_bytes = write_file_contents(
      output_handle,
      file_data,
    )

    header_bytes + entries_bytes + content_bytes
  ensure
    @io_system.close(output_handle) if output_handle
  end
end