Class: Origami::Stream

Inherits:
Object
  • Object
show all
Extended by:
TypeGuessing
Includes:
Enumerable, FieldAccessor, Object, StandardObject
Defined in:
lib/origami/stream.rb,
lib/origami/obfuscation.rb

Overview

Class representing a PDF Stream Object. Streams can be used to hold any kind of data, especially binary data.

Constant Summary collapse

TOKENS =

:nodoc:

["stream" + WHITECHARS_NORET + "(\\r\\n|\\r|\\n)", "endstream"]
DEFINED_FILTERS =

Actually only 5 first ones are implemented, other ones are mainly about image data processing (JPEG, JPEG2000 …)

%i[
  ASCIIHexDecode
  ASCII85Decode
  LZWDecode
  FlateDecode
  RunLengthDecode

  CCITTFaxDecode
  JBIG2Decode
  DCTDecode
  JPXDecode

  AHx
  A85
  LZW
  Fl
  RL
  CCF
  DCT
]
@@regexp_open = 
Regexp.new(WHITESPACES + TOKENS.first)
@@regexp_close = 
Regexp.new(TOKENS.last)

Constants included from StandardObject

Origami::StandardObject::DEFAULT_ATTRIBUTES

Instance Attribute Summary collapse

Attributes included from Object

#file_offset, #generation, #no, #objstm_offset, #parent

Class Method Summary collapse

Instance Method Summary collapse

Methods included from TypeGuessing

guess_type

Methods included from FieldAccessor

#method_missing, #respond_to_missing?

Methods included from StandardObject

included, #version_required

Methods included from Object

#copy, #document, #export, included, #indirect?, #indirect_parent, #logicalize, #logicalize!, #native_type, #numbered?, #reference, #set_document, #set_indirect, skip_until_next_obj, #solve, #to_o, #type, typeof, #version_required, #xrefs

Constructor Details

#initialize(data = "", dictionary = {}) ⇒ Stream

Creates a new PDF Stream.

data

The Stream uncompressed data.

dictionary

A hash representing the Stream attributes.



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# File 'lib/origami/stream.rb', line 86

def initialize(data = "", dictionary = {})
  super()

  set_indirect(true)

  @encoded_data = nil
  @dictionary, @data = Dictionary.new(dictionary), data
  @dictionary.parent = self
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class Origami::FieldAccessor

Instance Attribute Details

#dictionary ⇒ Object

Returns the value of attribute dictionary.



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# File 'lib/origami/stream.rb', line 71

def dictionary
  @dictionary
end

Class Method Details

.parse(stream, parser = nil) ⇒ Object

:nodoc:



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# File 'lib/origami/stream.rb', line 113

def self.parse(stream, parser = nil) # :nodoc:
  scanner = Parser.init_scanner(stream)
  dictionary = Dictionary.parse(scanner, parser)
  return dictionary if !scanner.skip(@@regexp_open)

  length = dictionary[:Length]
  if !length.is_a?(Integer)
    raw_data = scanner.scan_until(@@regexp_close)
    if raw_data.nil?
      raise InvalidStreamObjectError,
        "Stream shall end with a 'endstream' statement"
    end
  else
    length = length.value
    raw_data = scanner.peek(length)
    scanner.pos += length

    if !(unmatched = scanner.scan_until(@@regexp_close))
      raise InvalidStreamObjectError,
        "Stream shall end with a 'endstream' statement"
    end

    raw_data << unmatched
  end

  stm =
    if Origami::OPTIONS[:enable_type_guessing]
      guess_type(dictionary).new('', dictionary)
    else
      Stream.new('', dictionary)
    end

  raw_data.chomp!(TOKENS.last)

  if raw_data[-1, 1] == "\n"
    raw_data = if raw_data[-2, 1] == "\r"
      raw_data[0, raw_data.size - 2]
    else
      raw_data[0, raw_data.size - 1]
    end
  end
  # raw_data.chomp! if length.is_a?(Integer) and length < raw_data.length

  stm.encoded_data = raw_data
  stm.file_offset = dictionary.file_offset

  stm
end

Instance Method Details

#[](key) ⇒ Object

:nodoc:



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# File 'lib/origami/stream.rb', line 348

def [](key) # :nodoc:
  @dictionary[key]
end

#[]=(key, val) ⇒ Object

:nodoc:



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# File 'lib/origami/stream.rb', line 352

def []=(key, val) # :nodoc:
  @dictionary[key] = val
end

#cast_to(type, _parser = nil) ⇒ Object 



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# File 'lib/origami/stream.rb', line 220

def cast_to(type, _parser = nil)
  assert_cast_type(type)

  cast = type.new("", dictionary.copy)
  cast.encoded_data = encoded_data.dup
  cast.file_offset = file_offset

  transfer_attributes(cast)
end

#data ⇒ Object Also known as: decoded_data

Returns the uncompressed stream content.



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# File 'lib/origami/stream.rb', line 237

def data
  decode! unless decoded?

  @data
end

#data=(str) ⇒ Object Also known as: decoded_data=

Sets the uncompressed stream content.

str

The new uncompressed data.



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# File 'lib/origami/stream.rb', line 248

def data=(str)
  @encoded_data = nil
  @data = str
end

#decode! ⇒ Object

Uncompress the stream data.



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# File 'lib/origami/stream.rb', line 275

def decode!
  decrypt! if is_a?(Encryption::EncryptedStream)
  return if decoded?

  filters = self.filters
  dparams = decode_params

  @data = @encoded_data.dup
  @data.freeze

  filters.each_with_index do |filter, layer|
    params = dparams[layer].is_a?(Dictionary) ? dparams[layer] : {}

    # Handle Crypt filters.
    if filter == :Crypt
      raise Filter::Error, "Crypt filter must be the first filter" unless layer.zero?

      # Skip the Crypt filter.
      next
    end

    begin
      @data = decode_data(@data, filter, params)
    rescue Filter::Error => error
      @data = error.decoded_data
      raise
    end
  end

  self
end

#each_filter ⇒ Object

Iterates over each Filter in the Stream.



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# File 'lib/origami/stream.rb', line 165

def each_filter
  filters = self.Filter

  unless block_given?
    return enum_for(__method__) do
      case filters
      when NilClass then 0
      when Array then filters.length
      else
        1
      end
    end
  end

  return if filters.nil?

  if filters.is_a?(Array)
    filters.each do |filter| yield(filter) end
  else
    yield(filters)
  end

  self
end

#each_key(&b) ⇒ Object

:nodoc:



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# File 'lib/origami/stream.rb', line 356

def each_key(&b) # :nodoc:
  @dictionary.each_key(&b)
end

#each_pair(&b) ⇒ Object Also known as: each

:nodoc



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# File 'lib/origami/stream.rb', line 360

def each_pair(&b) # :nodoc
  @dictionary.each_pair(&b)
end

#encode! ⇒ Object

Compress the stream data.



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# File 'lib/origami/stream.rb', line 310

def encode!
  return if encoded?

  filters = self.filters
  dparams = decode_params

  @encoded_data = @data.dup
  (filters.length - 1).downto(0) do |layer|
    params = dparams[layer].is_a?(Dictionary) ? dparams[layer] : {}
    filter = filters[layer]

    # Handle Crypt filters.
    if filter == :Crypt
      raise Filter::Error, "Crypt filter must be the first filter" unless layer.zero?

      # Skip the Crypt filter.
      next
    end

    @encoded_data = encode_data(@encoded_data, filter, params)
  end

  self.Length = @encoded_data.length

  self
end

#encoded_data ⇒ Object

Returns the raw compressed stream content.



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# File 'lib/origami/stream.rb', line 257

def encoded_data
  encode! unless encoded?

  @encoded_data
end

#encoded_data=(str) ⇒ Object

Sets the raw compressed stream content.

str

the new raw data.



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# File 'lib/origami/stream.rb', line 267

def encoded_data=(str)
  @encoded_data = str
  @data = nil
end

#filters ⇒ Object

Returns an Array of Filters for this Stream.



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# File 'lib/origami/stream.rb', line 193

def filters
  each_filter.to_a
end

#key?(name) ⇒ Boolean Also known as: has_key?

Returns:



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# File 'lib/origami/stream.rb', line 365

def key?(name)
  @dictionary.key?(name)
end

#keys ⇒ Object 



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# File 'lib/origami/stream.rb', line 370

def keys
  @dictionary.keys
end

#post_build ⇒ Object 



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# File 'lib/origami/stream.rb', line 107

def post_build
  self.Length = @encoded_data.length

  super
end

#pre_build ⇒ Object 



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# File 'lib/origami/stream.rb', line 101

def pre_build
  encode!

  super
end

#set_predictor(predictor, colors: 1, bitspercomponent: 8, columns: 1) ⇒ Object

Set predictor type for the current Stream. Applies only for LZW and FlateDecode filters.



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# File 'lib/origami/stream.rb', line 201

def set_predictor(predictor, colors: 1, bitspercomponent: 8, columns: 1)
  filters = self.filters

  layer = filters.index(:FlateDecode) or filters.index(:LZWDecode)
  if layer.nil?
    raise InvalidStreamObjectError, 'Predictor functions can only be used with Flate or LZW filters'
  end

  params = Filter::LZW::DecodeParms.new
  params[:Predictor] = predictor
  params[:Colors] = colors if colors != 1
  params[:BitsPerComponent] = bitspercomponent if bitspercomponent != 8
  params[:Columns] = columns if columns != 1

  set_decode_params(layer, params)

  self
end

#to_obfuscated_str ⇒ Object 



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# File 'lib/origami/obfuscation.rb', line 219

def to_obfuscated_str
  content = ""

  content << @dictionary.to_obfuscated_str
  content << "stream" + $/
  content << encoded_data
  content << $/ << TOKENS.last

  super(content)
end

#to_s(indent: 1, tab: "\t", eol: $/) ⇒ Object

:nodoc:



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# File 'lib/origami/stream.rb', line 337

def to_s(indent: 1, tab: "\t", eol: $/) # :nodoc:
  content = +""

  content << @dictionary.to_s(indent: indent, tab: tab)
  content << "stream" + eol
  content << encoded_data
  content << eol << TOKENS.last

  super(content, eol: eol)
end

#value ⇒ Object

:nodoc:



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# File 'lib/origami/stream.rb', line 230

def value # :nodoc:
  self
end