Module: TTFunk::Table::Cmap::Format12

Defined in:
lib/ttfunk/table/cmap/format12.rb

Overview

Format 12: Segmented coverage.

This module conditionally extends Subtable.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#code_map ⇒ Hash{Integer => Integer} (readonly)

Code map.

Returns:

  • (Hash{Integer => Integer}) 


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# File 'lib/ttfunk/table/cmap/format12.rb', line 16

def code_map
  @code_map
end

#language ⇒ Integer (readonly)

Language.

Returns:

  • (Integer) 


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# File 'lib/ttfunk/table/cmap/format12.rb', line 12

def language
  @language
end

Class Method Details

.encode(charmap) ⇒ Hash

Encode the encoding record to format 12.

Parameters:

  • charmap (Hash{Integer => Integer}) —

    a hash mapping character codes to glyph IDs from the original font.

Returns:

  • (Hash) —

    • ‘:charmap` (Hash{Integer => Hash}) keys are the characrers in `charset`, values are hashes:

      • ‘:old` (Integer) - glyph ID in the original font.

      • ‘:new` (Integer) - glyph ID in the subset font.

      that maps the characters in charmap to a

    • ‘:subtable` (String) - serialized encoding record.

    • ‘:max_glyph_id` (Integer) - maximum glyph ID in the new font.



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# File 'lib/ttfunk/table/cmap/format12.rb', line 30

def self.encode(charmap)
  next_id = 0
  glyph_map = { 0 => 0 }
  range_firstglyphs = []
  range_firstcodes = []
  range_lengths = []
  last_glyph = last_code = -999

  new_map =
    charmap.keys.sort.each_with_object({}) do |code, map|
      glyph_map[charmap[code]] ||= next_id += 1
      map[code] = { old: charmap[code], new: glyph_map[charmap[code]] }

      if code > last_code + 1 || glyph_map[charmap[code]] > last_glyph + 1
        range_firstcodes << code
        range_firstglyphs << glyph_map[charmap[code]]
        range_lengths << 1
      else
        range_lengths.push(range_lengths.pop) + 1
      end
      last_code = code
      last_glyph = glyph_map[charmap[code]]
    end

  subtable = [
    12, 0, 16 + (12 * range_lengths.size), 0, range_lengths.size,
  ].pack('nnNNN')
  range_lengths.each_with_index do |length, i|
    firstglyph = range_firstglyphs[i]
    firstcode = range_firstcodes[i]
    subtable << [
      firstcode, firstcode + length - 1, firstglyph,
    ].pack('NNN')
  end

  { charmap: new_map, subtable: subtable, max_glyph_id: next_id + 1 }
end

Instance Method Details

#[](code) ⇒ Integer

Get glyph ID for character code.

Parameters:

  • code (Integer) —

    character code.

Returns:

  • (Integer) —

    glyph ID.



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# File 'lib/ttfunk/table/cmap/format12.rb', line 72

def [](code)
  @code_map[code] || 0
end

#supported? ⇒ true

Is this encoding record format supported?

Returns:

  • (true) 


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# File 'lib/ttfunk/table/cmap/format12.rb', line 79

def supported?
  true
end