Class: Prawn::Fonts::TTF::FullFontSubsetsCollection

Inherits:
Object
  • Object
show all
Defined in:
lib/prawn/fonts/ttf.rb

Overview

An adapter for subset collection to represent a full font.

Constant Summary collapse

FULL_FONT = 
Object.new.tap do |obj|
  obj.singleton_class.define_method(:inspect) do
    super().insert(-2, ' FULL_FONT')
  end
end.freeze

Instance Method Summary collapse

Constructor Details

#initialize(original) ⇒ FullFontSubsetsCollection

Returns a new instance of FullFontSubsetsCollection.



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# File 'lib/prawn/fonts/ttf.rb', line 77

def initialize(original)
  @original = original

  (@cmap ||= original.cmap.unicode.first) || raise(NoUnicodeCMap.new(font: name))

  @code_space_size =
    case cmap.code_map.keys.max
    when 0..0xff then 1
    when 0x100..0xffff then 2
    when 0x10000..0xffffff then 3
    else
      4
    end

  # Codespaces are not sequentional, they're ranges in
  # a multi-dimentional space. Each byte is considered separately. So we
  # have to maximally extend the lower two bytes in order to allow for
  # continuos Unicode mapping.
  # We only keep the highest byte because Unicode only goes to 1FFFFF
  # and fonts usually cover even less of the space. We don't want to
  # list all those unmapped charac codes here.
  @code_space_max = cmap.code_map.keys.max | ('ff' * (code_space_size - 1)).to_i(16)
end

Instance Method Details

#encode(characters) ⇒ Array<Array(FULL_FONT, String)>

Encode characters.

Returns:



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# File 'lib/prawn/fonts/ttf.rb', line 104

def encode(characters)
  [
    [
      FULL_FONT,
      characters.map { |c|
        check_bounds!(c)
        [cmap[c]].pack('n')
      }.join(''),
    ],
  ]
end