Class: TTFunk::Table::OS2

Inherits:
TTFunk::Table show all
Defined in:
lib/ttfunk/table/os2.rb

Overview

OS/2 and Windows Metrics (OS/2) table

Constant Summary collapse

CODE_PAGE_BITS =

Code page bits.

{
  1252 => 0,
  1250 => 1,
  1251 => 2,
  1253 => 3,
  1254 => 4,
  1255 => 5,
  1256 => 6,
  1257 => 7,
  1258 => 8,
  874 => 16,
  932 => 17,
  936 => 18,
  949 => 19,
  950 => 20,
  1361 => 21,
  10_000 => 29,
  869 => 48,
  866 => 49,
  865 => 50,
  864 => 51,
  863 => 52,
  862 => 53,
  861 => 54,
  860 => 55,
  857 => 56,
  855 => 57,
  852 => 58,
  775 => 59,
  737 => 60,
  708 => 61,
  850 => 62,
  437 => 63,
}.freeze
UNICODE_BLOCKS =

Unicode blocks.

{
  (0x0000..0x007F) => 0,
  (0x0080..0x00FF) => 1,
  (0x0100..0x017F) => 2,
  (0x0180..0x024F) => 3,
  (0x0250..0x02AF) => 4,
  (0x1D00..0x1D7F) => 4,
  (0x1D80..0x1DBF) => 4,
  (0x02B0..0x02FF) => 5,
  (0xA700..0xA71F) => 5,
  (0x0300..0x036F) => 6,
  (0x1DC0..0x1DFF) => 6,
  (0x0370..0x03FF) => 7,
  (0x2C80..0x2CFF) => 8,
  (0x0400..0x04FF) => 9,
  (0x0500..0x052F) => 9,
  (0x2DE0..0x2DFF) => 9,
  (0xA640..0xA69F) => 9,
  (0x0530..0x058F) => 10,
  (0x0590..0x05FF) => 11,
  (0xA500..0xA63F) => 12,
  (0x0600..0x06FF) => 13,
  (0x0750..0x077F) => 13,
  (0x07C0..0x07FF) => 14,
  (0x0900..0x097F) => 15,
  (0x0980..0x09FF) => 16,
  (0x0A00..0x0A7F) => 17,
  (0x0A80..0x0AFF) => 18,
  (0x0B00..0x0B7F) => 19,
  (0x0B80..0x0BFF) => 20,
  (0x0C00..0x0C7F) => 21,
  (0x0C80..0x0CFF) => 22,
  (0x0D00..0x0D7F) => 23,
  (0x0E00..0x0E7F) => 24,
  (0x0E80..0x0EFF) => 25,
  (0x10A0..0x10FF) => 26,
  (0x2D00..0x2D2F) => 26,
  (0x1B00..0x1B7F) => 27,
  (0x1100..0x11FF) => 28,
  (0x1E00..0x1EFF) => 29,
  (0x2C60..0x2C7F) => 29,
  (0xA720..0xA7FF) => 29,
  (0x1F00..0x1FFF) => 30,
  (0x2000..0x206F) => 31,
  (0x2E00..0x2E7F) => 31,
  (0x2070..0x209F) => 32,
  (0x20A0..0x20CF) => 33,
  (0x20D0..0x20FF) => 34,
  (0x2100..0x214F) => 35,
  (0x2150..0x218F) => 36,
  (0x2190..0x21FF) => 37,
  (0x27F0..0x27FF) => 37,
  (0x2900..0x297F) => 37,
  (0x2B00..0x2BFF) => 37,
  (0x2200..0x22FF) => 38,
  (0x2A00..0x2AFF) => 38,
  (0x27C0..0x27EF) => 38,
  (0x2980..0x29FF) => 38,
  (0x2300..0x23FF) => 39,
  (0x2400..0x243F) => 40,
  (0x2440..0x245F) => 41,
  (0x2460..0x24FF) => 42,
  (0x2500..0x257F) => 43,
  (0x2580..0x259F) => 44,
  (0x25A0..0x25FF) => 45,
  (0x2600..0x26FF) => 46,
  (0x2700..0x27BF) => 47,
  (0x3000..0x303F) => 48,
  (0x3040..0x309F) => 49,
  (0x30A0..0x30FF) => 50,
  (0x31F0..0x31FF) => 50,
  (0x3100..0x312F) => 51,
  (0x31A0..0x31BF) => 51,
  (0x3130..0x318F) => 52,
  (0xA840..0xA87F) => 53,
  (0x3200..0x32FF) => 54,
  (0x3300..0x33FF) => 55,
  (0xAC00..0xD7AF) => 56,
  (0xD800..0xDFFF) => 57,
  (0x10900..0x1091F) => 58,
  (0x4E00..0x9FFF) => 59,
  (0x2E80..0x2EFF) => 59,
  (0x2F00..0x2FDF) => 59,
  (0x2FF0..0x2FFF) => 59,
  (0x3400..0x4DBF) => 59,
  (0x20000..0x2A6DF) => 59,
  (0x3190..0x319F) => 59,
  (0xE000..0xF8FF) => 60,
  (0x31C0..0x31EF) => 61,
  (0xF900..0xFAFF) => 61,
  (0x2F800..0x2FA1F) => 61,
  (0xFB00..0xFB4F) => 62,
  (0xFB50..0xFDFF) => 63,
  (0xFE20..0xFE2F) => 64,
  (0xFE10..0xFE1F) => 65,
  (0xFE30..0xFE4F) => 65,
  (0xFE50..0xFE6F) => 66,
  (0xFE70..0xFEFF) => 67,
  (0xFF00..0xFFEF) => 68,
  (0xFFF0..0xFFFF) => 69,
  (0x0F00..0x0FFF) => 70,
  (0x0700..0x074F) => 71,
  (0x0780..0x07BF) => 72,
  (0x0D80..0x0DFF) => 73,
  (0x1000..0x109F) => 74,
  (0x1200..0x137F) => 75,
  (0x1380..0x139F) => 75,
  (0x2D80..0x2DDF) => 75,
  (0x13A0..0x13FF) => 76,
  (0x1400..0x167F) => 77,
  (0x1680..0x169F) => 78,
  (0x16A0..0x16FF) => 79,
  (0x1780..0x17FF) => 80,
  (0x19E0..0x19FF) => 80,
  (0x1800..0x18AF) => 81,
  (0x2800..0x28FF) => 82,
  (0xA000..0xA48F) => 83,
  (0xA490..0xA4CF) => 83,
  (0x1700..0x171F) => 84,
  (0x1720..0x173F) => 84,
  (0x1740..0x175F) => 84,
  (0x1760..0x177F) => 84,
  (0x10300..0x1032F) => 85,
  (0x10330..0x1034F) => 86,
  (0x10400..0x1044F) => 87,
  (0x1D000..0x1D0FF) => 88,
  (0x1D100..0x1D1FF) => 88,
  (0x1D200..0x1D24F) => 88,
  (0x1D400..0x1D7FF) => 89,
  (0xF0000..0xFFFFD) => 90,
  (0x100000..0x10FFFD) => 90,
  (0xFE00..0xFE0F) => 91,
  (0xE0100..0xE01EF) => 91,
  (0xE0000..0xE007F) => 92,
  (0x1900..0x194F) => 93,
  (0x1950..0x197F) => 94,
  (0x1980..0x19DF) => 95,
  (0x1A00..0x1A1F) => 96,
  (0x2C00..0x2C5F) => 97,
  (0x2D30..0x2D7F) => 98,
  (0x4DC0..0x4DFF) => 99,
  (0xA800..0xA82F) => 100,
  (0x10000..0x1007F) => 101,
  (0x10080..0x100FF) => 101,
  (0x10100..0x1013F) => 101,
  (0x10140..0x1018F) => 102,
  (0x10380..0x1039F) => 103,
  (0x103A0..0x103DF) => 104,
  (0x10450..0x1047F) => 105,
  (0x10480..0x104AF) => 106,
  (0x10800..0x1083F) => 107,
  (0x10A00..0x10A5F) => 108,
  (0x1D300..0x1D35F) => 109,
  (0x12000..0x123FF) => 110,
  (0x12400..0x1247F) => 110,
  (0x1D360..0x1D37F) => 111,
  (0x1B80..0x1BBF) => 112,
  (0x1C00..0x1C4F) => 113,
  (0x1C50..0x1C7F) => 114,
  (0xA880..0xA8DF) => 115,
  (0xA900..0xA92F) => 116,
  (0xA930..0xA95F) => 117,
  (0xAA00..0xAA5F) => 118,
  (0x10190..0x101CF) => 119,
  (0x101D0..0x101FF) => 120,
  (0x102A0..0x102DF) => 121,
  (0x10280..0x1029F) => 121,
  (0x10920..0x1093F) => 121,
  (0x1F030..0x1F09F) => 122,
  (0x1F000..0x1F02F) => 122,
}.freeze
UNICODE_MAX =

Indicates that font supports supplementary characters.

0xFFFF
UNICODE_RANGES =

Unicode block ranges.

UNICODE_BLOCKS.keys.sort_by(&:max).freeze
LOWERCASE_START =

Start chracter for average character width calculation.

'a'.ord
LOWERCASE_END =

End chracter for average character width calculation.

'z'.ord
LOWERCASE_COUNT =

Number of chracters for average character width calculation.

(LOWERCASE_END - LOWERCASE_START) + 1
CODEPOINT_SPACE =

Space character code point.

32
SPACE_GLYPH_MISSING_ERROR =

Error message for missing space character.

"Space glyph (0x#{CODEPOINT_SPACE.to_s(16)}) must be included in the font"
WEIGHT_SPACE =

Used to calculate the xAvgCharWidth field. From https://docs.microsoft.com/en-us/typography/opentype/spec/os2:

“When first defined, the specification was biased toward Basic Latin characters, and it was thought that the xAvgCharWidth value could be used to estimate the average length of lines of text. A formula for calculating xAvgCharWidth was provided using frequency-of-use weighting factors for lowercase letters a - z.”

The array below contains 26 weight values which correspond to the 26 letters in the Latin alphabet. Each weight is the relative frequency of that letter in the English language.

166
WEIGHT_LOWERCASE =

chracter weights for average character width calculation.

[
  64, 14, 27, 35, 100, 20, 14, 42, 63, 3, 6, 35, 20,
  56, 56, 17, 4, 49, 56, 71, 31, 10, 18, 3, 18, 2,
].freeze

Instance Attribute Summary collapse

Attributes inherited from TTFunk::Table

#file, #length, #offset

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from TTFunk::Table

#exists?, #initialize, #raw

Constructor Details

This class inherits a constructor from TTFunk::Table

Instance Attribute Details

#ascent ⇒ Integer (readonly)

The typographic ascender for this font.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 100
100
def ascent

101
  @ascent

102
end

#ave_char_width ⇒ Integer (readonly)

Average weighted escapement.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 16
16
def ave_char_width

17
  @ave_char_width

18
end

#break_char ⇒ Integer (readonly)

The Unicode code point, in UTF-16 encoding, of a character that can be used as a default break character.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 141
141
def break_char

142
  @break_char

143
end

#cap_height ⇒ Integer (readonly)

The distance between the baseline and the approximate height of uppercase letters.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 130
130
def cap_height

131
  @cap_height

132
end

#char_range ⇒ Integer (readonly)

Unicode Character Range.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 80
80
def char_range

81
  @char_range

82
end

#code_page_range ⇒ Integer (readonly)

Code Page Character Range.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 120
120
def code_page_range

121
  @code_page_range

122
end

#default_char ⇒ Integer (readonly)

The Unicode code point, in UTF-16 encoding, of a character that can be used for a default glyph if a requested character is not supported in the font.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 136
136
def default_char

137
  @default_char

138
end

#descent ⇒ Integer (readonly)

The typographic descender for this font.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 104
104
def descent

105
  @descent

106
end

#family_class ⇒ Integer (readonly)

Font-family class and subclass.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 72
72
def family_class

73
  @family_class

74
end

#first_char_index ⇒ Integer (readonly)

The minimum Unicode index (character code) in this font.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 92
92
def first_char_index

93
  @first_char_index

94
end

#last_char_index ⇒ Integer (readonly)

The maximum Unicode index (character code) in this font.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 96
96
def last_char_index

97
  @last_char_index

98
end

#line_gap ⇒ Integer (readonly)

The typographic line gap for this font.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 108
108
def line_gap

109
  @line_gap

110
end

#max_context ⇒ Integer (readonly)

The maximum length of a target glyph context for any feature in this font.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 146
146
def max_context

147
  @max_context

148
end

#panose ⇒ Integer (readonly)

PANOSE classification number.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 76
76
def panose

77
  @panose

78
end

#selection ⇒ Integer (readonly)

Font selection flags.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 88
88
def selection

89
  @selection

90
end

#type ⇒ Integer (readonly)

Type flags.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 28
28
def type

29
  @type

30
end

#vendor_id ⇒ String (readonly)

Font Vendor Identification.

Returns:

  • (String)
Source Code
lib/ttfunk/table/os2.rb, line 84
84
def vendor_id

85
  @vendor_id

86
end

#version ⇒ Integer (readonly)

Table version.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 12
12
def version

13
  @version

14
end

#weight_class ⇒ Integer (readonly)

Weight class.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 20
20
def weight_class

21
  @weight_class

22
end

#width_class ⇒ Integer (readonly)

Width class.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 24
24
def width_class

25
  @width_class

26
end

#win_ascent ⇒ Integer (readonly)

The “Windows ascender” metric.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 112
112
def win_ascent

113
  @win_ascent

114
end

#win_descent ⇒ Integer (readonly)

The “Windows descender” metric.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 116
116
def win_descent

117
  @win_descent

118
end

#x_height ⇒ Integer (readonly)

The distance between the baseline and the approximate height of non-ascending lowercase letters.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 125
125
def x_height

126
  @x_height

127
end

#y_strikeout_position ⇒ Integer (readonly)

Strikeout position.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 68
68
def y_strikeout_position

69
  @y_strikeout_position

70
end

#y_strikeout_size ⇒ Integer (readonly)

Strikeout size.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 64
64
def y_strikeout_size

65
  @y_strikeout_size

66
end

#y_subscript_x_offset ⇒ Integer (readonly)

Subscript x offset.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 40
40
def y_subscript_x_offset

41
  @y_subscript_x_offset

42
end

#y_subscript_x_size ⇒ Integer (readonly)

Subscript horizontal font size.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 32
32
def y_subscript_x_size

33
  @y_subscript_x_size

34
end

#y_subscript_y_offset ⇒ Integer (readonly)

Subscript y offset.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 44
44
def y_subscript_y_offset

45
  @y_subscript_y_offset

46
end

#y_subscript_y_size ⇒ Integer (readonly)

Subscript vertical font size.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 36
36
def y_subscript_y_size

37
  @y_subscript_y_size

38
end

#y_superscript_x_offset ⇒ Integer (readonly)

Superscript x offset.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 56
56
def y_superscript_x_offset

57
  @y_superscript_x_offset

58
end

#y_superscript_x_size ⇒ Integer (readonly)

Superscript horizontal font size.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 48
48
def y_superscript_x_size

49
  @y_superscript_x_size

50
end

#y_superscript_y_offset ⇒ Integer (readonly)

Superscript y offset.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 60
60
def y_superscript_y_offset

61
  @y_superscript_y_offset

62
end

#y_superscript_y_size ⇒ Integer (readonly)

Superscript vertical font size.

Returns:

  • (Integer)
Source Code
lib/ttfunk/table/os2.rb, line 52
52
def y_superscript_y_size

53
  @y_superscript_y_size

54
end

Class Method Details

.encode(os2, subset) ⇒ String

Encode table.

Parameters:

Returns:

  • (String)
Source Code
lib/ttfunk/table/os2.rb, line 411
411
def encode(os2, subset)

412
  result = ''.b

413
  result << [

414
    os2.version, avg_char_width_for(os2, subset), os2.weight_class,

415
    os2.width_class, os2.type, os2.y_subscript_x_size,

416
    os2.y_subscript_y_size, os2.y_subscript_x_offset,

417
    os2.y_subscript_y_offset, os2.y_superscript_x_size,

418
    os2.y_superscript_y_size, os2.y_superscript_x_offset,

419
    os2.y_superscript_y_offset, os2.y_strikeout_size,

420
    os2.y_strikeout_position, os2.family_class,

421
  ].pack('n*')

422
423
  result << os2.panose

424
425
  new_char_range = unicode_blocks_for(os2, os2.char_range, subset)

426
  result << BinUtils

427
    .slice_int(

428
      new_char_range.value,

429
      bit_width: 32,

430
      slice_count: 4,

431
    )

432
    .pack('N*')

433
434
  result << os2.vendor_id

435
436
  new_cmap_table = subset.new_cmap_table[:charmap]

437
  code_points = new_cmap_table

438
    .keys

439
    .select { |k| (new_cmap_table[k][:new]).positive? }

440
    .sort

441
442
  # "This value depends on which character sets the font supports.

443
  # This field cannot represent supplementary character values

444
  # (codepoints greater than 0xFFFF). Fonts that support

445
  # supplementary characters should set the value in this field

446
  # to 0xFFFF."

447
  first_char_index = [code_points.first || 0, UNICODE_MAX].min

448
  last_char_index = [code_points.last || 0, UNICODE_MAX].min

449
450
  result << [

451
    os2.selection, first_char_index, last_char_index,

452
  ].pack('n*')

453
454
  if os2.version.positive?

455
    result << [

456
      os2.ascent, os2.descent, os2.line_gap,

457
      os2.win_ascent, os2.win_descent,

458
    ].pack('n*')

459
460
    result << BinUtils

461
      .slice_int(

462
        code_pages_for(subset).value,

463
        bit_width: 32,

464
        slice_count: 2,

465
      )

466
      .pack('N*')

467
468
    if os2.version > 1

469
      result << [

470
        os2.x_height, os2.cap_height, os2.default_char,

471
        os2.break_char, os2.max_context,

472
      ].pack('n*')

473
    end

474
  end

475
476
  result

477
end







    
  


  

    
Instance Method Details


    
      

  

  
    #tag  ⇒ String 
  

  

  


  

    
Table tag.



  





  


Returns:


    
  
    
  • 
      
      
        (String)
      
      
      
    
    • 
  







  Source Code
  
lib/ttfunk/table/os2.rb, line 400

  
400
def tag

401
  'OS/2'

402
end