Class: Prawn::SVG::TTF

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

Constant Summary collapse

SFNT_VERSION_STRINGS = 
["\x00\x01\x00\x00", 'true', 'typ1'].freeze
LANGUAGE_IDS =

English, US English

[0, 0x409].freeze
UTF_16BE_PLATFORM_IDS =

Unicode, Microsoft

[0, 3].freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(filename) ⇒ TTF

Returns a new instance of TTF.



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# File 'lib/prawn/svg/ttf.rb', line 8

def initialize(filename)
  load_data_from_file(filename)
end

Instance Attribute Details

#family ⇒ Object (readonly)

Returns the value of attribute family.



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# File 'lib/prawn/svg/ttf.rb', line 6

def family
  @family
end

#subfamily ⇒ Object (readonly)

Returns the value of attribute subfamily.



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# File 'lib/prawn/svg/ttf.rb', line 6

def subfamily
  @subfamily
end

#weight_class ⇒ Object (readonly)

Returns the value of attribute weight_class.



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# File 'lib/prawn/svg/ttf.rb', line 6

def weight_class
  @weight_class
end

Class Method Details

.read_name_table(io, font_offset) ⇒ Object 



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# File 'lib/prawn/svg/ttf.rb', line 34

def self.read_name_table(io, font_offset)
  io.seek(font_offset)
  offset_table = io.read(12)
  return unless offset_table && offset_table.length == 12 && SFNT_VERSION_STRINGS.include?(offset_table[0..3])

  table_count = (offset_table[4].ord * 256) + offset_table[5].ord
  tables = io.read(table_count * 16)
  return unless tables && tables.length == table_count * 16

  offset, length = table_count.times do |index|
    start = index * 16
    break tables[start + 8..start + 15].unpack('NNN') if tables[start..start + 3] == 'name'
  end

  return unless length

  io.seek(offset)
  data = io.read(length)
  return unless data && data.length == length

  _, name_count, string_offset = data[0..5].unpack('nnn')

  names = {}
  name_count.times do |index|
    start = 6 + (index * 12)
    platform_id, _, language_id, name_id, length, offset = data[start..start + 11].unpack('nnnnnn')
    next unless offset
    next unless LANGUAGE_IDS.include?(language_id)
    next unless [1, 2, 16, 17].include?(name_id)

    offset += string_offset
    field = data[offset..offset + length - 1]
    next unless field && field.length == length

    names[name_id] =
      if UTF_16BE_PLATFORM_IDS.include?(platform_id)
        begin
          field.force_encoding(Encoding::UTF_16BE).encode(Encoding::UTF_8)
        rescue StandardError
          field
        end
      else
        field
      end
  end

  family = names[16] || names[1]
  subfamily = names[17] || names[2]
  [family, subfamily]
end

.read_weight_class(io, font_offset) ⇒ Object 



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# File 'lib/prawn/svg/ttf.rb', line 12

def self.read_weight_class(io, font_offset)
  io.seek(font_offset)
  offset_table = io.read(12)
  return unless offset_table&.length == 12 && SFNT_VERSION_STRINGS.include?(offset_table[0..3])

  table_count = (offset_table[4].ord * 256) + offset_table[5].ord
  tables = io.read(table_count * 16)
  return unless tables&.length == table_count * 16

  table_count.times do |index|
    start = index * 16
    next unless tables[start..start + 3] == 'OS/2'

    offset, = tables[start + 8..start + 15].unpack('NN')
    io.seek(offset)
    data = io.read(6)
    return data[4..5].unpack1('n') if data&.length == 6
  end

  nil
end