Class: Fontisan::Tables::Post

Inherits:
Binary::BaseRecord show all
Defined in:
lib/fontisan/tables/post.rb

Overview

Parser for the ‘post’ (PostScript) table

The post table contains PostScript information, primarily glyph names. Different versions exist (1.0, 2.0, 2.5, 3.0, 4.0) with varying glyph name storage strategies.

Reference: OpenType specification, post table

Constant Summary collapse

STANDARD_NAMES =

Standard Mac glyph names for version 1.0 (258 glyphs) rubocop:disable Metrics/CollectionLiteralLength

%w[
  .notdef .null nonmarkingreturn space exclam quotedbl numbersign
  dollar percent ampersand quotesingle parenleft parenright asterisk
  plus comma hyphen period slash zero one two three four five six
  seven eight nine colon semicolon less equal greater question at
  A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
  bracketleft backslash bracketright asciicircum underscore grave
  a b c d e f g h i j k l m n o p q r s t u v w x y z
  braceleft bar braceright asciitilde Adieresis Aring Ccedilla
  Eacute Ntilde Odieresis Udieresis aacute agrave acircumflex
  adieresis atilde aring ccedilla eacute egrave ecircumflex
  edieresis iacute igrave icircumflex idieresis ntilde oacute
  ograve ocircumflex odieresis otilde uacute ugrave ucircumflex
  udieresis dagger degree cent sterling section bullet paragraph
  germandbls registered copyright trademark acute dieresis notequal
  AE Oslash infinity plusminus lessequal greaterequal yen mu
  partialdiff summation product pi integral ordfeminine ordmasculine
  Omega ae oslash questiondown exclamdown logicalnot radical florin
  approxequal Delta guillemotleft guillemotright ellipsis
  nonbreakingspace Agrave Atilde Otilde OE oe endash emdash
  quotedblleft quotedblright quoteleft quoteright divide lozenge
  ydieresis Ydieresis fraction currency guilsinglleft guilsinglright
  fi fl daggerdbl periodcentered quotesinglbase quotedblbase
  perthousand Acircumflex Ecircumflex Aacute Edieresis Egrave
  Iacute Icircumflex Idieresis Igrave Oacute Ocircumflex apple
  Ograve Uacute Ucircumflex Ugrave dotlessi circumflex tilde
  macron breve dotaccent ring cedilla hungarumlaut ogonek caron
  Lslash lslash Scaron scaron Zcaron zcaron brokenbar Eth
  eth Yacute yacute Thorn thorn minus multiply onesuperior
  twosuperior threesuperior onehalf onequarter threequarters franc
  Gbreve gbreve Idotaccent Scedilla scedilla Cacute cacute Ccaron
  ccaron dcroat
].freeze
VERSION_2_0_RAW =

Version 2.0 as Fixed 16.16 constant

131_072

Instance Method Summary collapse

Methods inherited from Binary::BaseRecord

#raw_data, read, #valid?

Instance Method Details

#complete_version_2_data? ⇒ Boolean

Validation helper: Check if version 2.0 data is complete

For version 2.0, we should have glyph count and name data

Returns:

  • (Boolean) —

    True if version 2.0 data is present and complete



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# File 'lib/fontisan/tables/post.rb', line 198

def complete_version_2_data?
  return true unless version == 2.0

  !num_glyphs_v2.nil? && num_glyphs_v2.positive? && !remaining_data.empty?
end

#glyph_names ⇒ Array<String>

Get glyph names based on version

Returns:

  • (Array<String>) —

    array of glyph names



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# File 'lib/fontisan/tables/post.rb', line 82

def glyph_names
  @glyph_names ||= case version
                   when 1.0
                     STANDARD_NAMES.dup
                   when 2.0
                     parse_version_2_names
                   else
                     []
                   end
end

#has_glyph_names? ⇒ Boolean

Validation helper: Check if glyph names are available

For versions 1.0 and 2.0, glyph names should be accessible

Returns:

  • (Boolean) —

    True if glyph names can be retrieved



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# File 'lib/fontisan/tables/post.rb', line 188

def has_glyph_names?
  names = glyph_names
  !names.nil? && !names.empty?
end

#has_underline_metrics? ⇒ Boolean

Validation helper: Check if underline values are present

Both position and thickness should be non-zero for valid underline

Returns:

  • (Boolean) —

    True if underline metrics exist



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# File 'lib/fontisan/tables/post.rb', line 172

def has_underline_metrics?
  underline_position != 0 && underline_thickness != 0
end

#italic_angle ⇒ Object

Get italic angle as float (Fixed 16.16 format)



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# File 'lib/fontisan/tables/post.rb', line 75

def italic_angle
  fixed_to_float(italic_angle_raw)
end

#valid_fixed_pitch_flag? ⇒ Boolean

Validation helper: Check if fixed pitch flag is consistent

Returns:

  • (Boolean) —

    True if is_fixed_pitch is 0 or 1



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# File 'lib/fontisan/tables/post.rb', line 179

def valid_fixed_pitch_flag?
  [0, 1].include?(is_fixed_pitch)
end

#valid_italic_angle? ⇒ Boolean

Validation helper: Check if italic angle is reasonable

Italic angle should be between -60 and 60 degrees

Returns:

  • (Boolean) —

    True if italic angle is within reasonable bounds



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# File 'lib/fontisan/tables/post.rb', line 163

def valid_italic_angle?
  italic_angle.abs <= 60.0
end

#valid_version? ⇒ Boolean

Validation helper: Check if version is valid

Common versions: 1.0, 2.0, 2.5, 3.0, 4.0

Returns:

  • (Boolean) —

    True if version is recognized



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# File 'lib/fontisan/tables/post.rb', line 154

def valid_version?
  [1.0, 2.0, 2.5, 3.0, 4.0].include?(version)
end

#version ⇒ Object

Get version as float (Fixed 16.16 format)



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# File 'lib/fontisan/tables/post.rb', line 70

def version
  fixed_to_float(version_raw)
end