Class: Array

Inherits:
Object
  • Object
show all
Defined in:
lib/dicom/ruby_extensions.rb

Overview

Extensions to the Array class. These mainly deal with encoding integer arrays as well as conversion between signed and unsigned integers.

Instance Method Summary collapse

Instance Method Details

#__original_pack__ ⇒ Object

Renames the original pack method.



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# File 'lib/dicom/ruby_extensions.rb', line 168

alias __original_pack__ pack

#pack(format) ⇒ String

Redefines the old pack method, adding the ability to encode signed integers in big endian (which surprisingly has not been supported out of the box in Ruby until version 1.9.3).

Parameters:

  • format (String) —

    a format string which decides the encoding scheme to use

Returns:

  • (String) —

    the encoded binary string



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# File 'lib/dicom/ruby_extensions.rb', line 176

def pack(format)
  # FIXME: At some time in the future, when Ruby 1.9.3 can be set as required ruby version,
  # this custom pack (as well as unpack) method can be discarded, and the desired endian
  # encodings can probably be achieved with the new template strings introduced in 1.9.3.
  #
  # Check for some custom pack strings that we've invented:
  case format
    when 'k*' # SS
      # Pack LE SS, re-unpack as LE US, then finally pack BE US:
      wrongly_packed = self.__original_pack__('s*')
      reunpacked = wrongly_packed.__original_unpack__('S*')
      correct = reunpacked.__original_pack__('n*')
    when 'r*' # SL
      # Pack LE SL, re-unpack as LE UL, then finally pack BE UL:
      wrongly_packed = self.__original_pack__('l*')
      reunpacked = wrongly_packed.__original_unpack__('I*')
      correct = reunpacked.__original_pack__('N*')
    else
      # Call the original method for all other (normal) cases:
      self.__original_pack__(format)
  end
end

#to_blob(depth) ⇒ String

Packs an array of (unsigned) integers to a binary string (blob).

Parameters:

  • depth (Integer) —

    the bit depth to be used when encoding the unsigned integers

Returns:

  • (String) —

    an encoded binary string

Raises:

  • (ArgumentError) 


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# File 'lib/dicom/ruby_extensions.rb', line 204

def to_blob(depth)
  raise ArgumentError, "Expected Integer, got #{depth.class}" unless depth.is_a?(Integer)
  raise ArgumentError, "Unsupported bit depth #{depth}." unless [8,16].include?(depth)
  case depth
  when 8
    return self.pack('C*') # Unsigned char
  when 16
    return self.pack('S*') # Unsigned short, native byte order
  end
end

#to_signed(depth) ⇒ Array<Integer>

Shifts the integer values of the array to make a signed data set. The size of the shift is determined by the given bit depth.

Parameters:

  • depth (Integer) —

    the bit depth of the integers

Returns:

  • (Array<Integer>) —

    an array of signed integers

Raises:

  • (ArgumentError) 


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# File 'lib/dicom/ruby_extensions.rb', line 221

def to_signed(depth)
  raise ArgumentError, "Expected Integer, got #{depth.class}" unless depth.is_a?(Integer)
  raise ArgumentError, "Unsupported bit depth #{depth}." unless [8,16].include?(depth)
  case depth
  when 8
    return self.collect {|i| i - 128}
  when 16
    return self.collect {|i| i - 32768}
  end
end

#to_unsigned(depth) ⇒ Array<Integer>

Shifts the integer values of the array to make an unsigned data set. The size of the shift is determined by the given bit depth.

Parameters:

  • depth (Integer) —

    the bit depth of the integers

Returns:

  • (Array<Integer>) —

    an array of unsigned integers

Raises:

  • (ArgumentError) 


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# File 'lib/dicom/ruby_extensions.rb', line 238

def to_unsigned(depth)
  raise ArgumentError, "Expected Integer, got #{depth.class}" unless depth.is_a?(Integer)
  raise ArgumentError, "Unsupported bit depth #{depth}." unless [8,16].include?(depth)
  case depth
  when 8
    return self.collect {|i| i + 128}
  when 16
    return self.collect {|i| i + 32768}
  end
end