class TTFunk::Table::Cmap::Subtable

Character to Glyph Index encoding record. This class can be extended with a format-specific

@see TTFunk::Table::Cmap::Format00 @see TTFunk::Table::Cmap::Format04 @see TTFunk::Table::Cmap::Format06 @see TTFunk::Table::Cmap::Format10 @see TTFunk::Table::Cmap::Format12

Constants

ENCODING_MAPPINGS

Most used encoding mappings.

Attributes

encoding_id[R]

Platform-specific encoding ID. @return [Integere]

format[R]

Record encoding format. @return [Integer]

platform_id[R]

Platform ID. @return [Integer]

Public Class Methods

encode(charmap, encoding) click to toggle source

Encode encoding record.

@param charmap [Hash{Integer => Integer}] keys are code points in the

used encoding, values are Unicode code points.

@param encoding [Symbol] - one of the encodign mapping in

{ENCODING_MAPPINGS}

@return [Hash]

* `:platform_id` (<tt>Integer</tt>) - Platform ID of this encoding record.
* `:encoding_id` (<tt>Integer</tt>) - Encodign ID of this encoding record.
* `:subtable` (<tt>String</tt>) - encoded encoding record.
* `:max_glyph_id` (<tt>Integer</tt>) - maximum glyph ID in this encoding
  record.
* `:charmap` (<tt>Hash{Integer => Hash}</tt>) - keys are codepoints in this
  encoding record, values are hashes:
  * `:new` - new glyph ID.
  * `:old` - glyph ID in the original font.
# File lib/ttfunk/table/cmap/subtable.rb, line 56
def self.encode(charmap, encoding)
  case encoding
  when :mac_roman
    result = Format00.encode(charmap)
  when :unicode
    result = Format04.encode(charmap)
  when :unicode_ucs4
    result = Format12.encode(charmap)
  else
    raise NotImplementedError,
      "encoding #{encoding.inspect} is not supported"
  end

  mapping = ENCODING_MAPPINGS[encoding]

  # platform-id, encoding-id, offset
  result.merge(
    platform_id: mapping[:platform_id],
    encoding_id: mapping[:encoding_id],
    subtable: [
      mapping[:platform_id],
      mapping[:encoding_id],
      12,
      result[:subtable],
    ].pack('nnNA*'),
  )
end
new(file, table_start) click to toggle source

@param file [TTFunk::File] @param table_start [Integer]

# File lib/ttfunk/table/cmap/subtable.rb, line 86
def initialize(file, table_start)
  @file = file
  @platform_id, @encoding_id, @offset = read(8, 'nnN')
  @offset += table_start

  parse_from(@offset) do
    @format = read(2, 'n').first

    case @format
    when 0 then extend(TTFunk::Table::Cmap::Format00)
    when 4 then extend(TTFunk::Table::Cmap::Format04)
    when 6 then extend(TTFunk::Table::Cmap::Format06)
    when 10 then extend(TTFunk::Table::Cmap::Format10)
    when 12 then extend(TTFunk::Table::Cmap::Format12)
    end

    parse_cmap!
  end
end

Public Instance Methods

[](_code) click to toggle source

Get glyph ID for character code.

@param _code [Integer] character code. @return [Integer] glyph ID.

# File lib/ttfunk/table/cmap/subtable.rb, line 125
def [](_code)
  raise NotImplementedError, "cmap format #{@format} is not supported"
end
supported?() click to toggle source

Is this encoding record format supported?

@return [Boolean]

# File lib/ttfunk/table/cmap/subtable.rb, line 117
def supported?
  false
end
unicode?() click to toggle source

Is this an encoding record for Unicode?

@return [Boolean]

# File lib/ttfunk/table/cmap/subtable.rb, line 109
def unicode?
  (platform_id == 3 && (encoding_id == 1 || encoding_id == 10) && format != 0) ||
    (platform_id.zero? && format != 0)
end

Private Instance Methods

parse_cmap!() click to toggle source
# File lib/ttfunk/table/cmap/subtable.rb, line 131
def parse_cmap!
  # do nothing...
end