Module: Fontisan::Ufo::Compile::MathTable

Defined in:
lib/fontisan/ufo/compile/math.rb

Overview

Builds the OpenType MATH table for mathematical formula layout.

The MATH table provides constants and glyph info for rendering equations in math-aware environments (Word, LibreOffice, TeX).

Layout:

Header (10 bytes):
uint16 version (= 1)
Offset32 mathConstantsOffset
Offset32 mathGlyphInfoOffset
Offset32 mathVariantsOffset

MathConstants: 57 layout constants (int16 + bool each)
MathGlyphInfo: italic correction, top accent, extension
MathVariants: glyph assembly for stretched delimiters

See Also:

Constant Summary collapse

VERSION = 
1
HEADER_SIZE = 
10

Class Method Summary collapse

Class Method Details

.build(constants: nil, glyph_info: nil, variants: nil) ⇒ String?

Returns MATH table bytes, or nil if no data.

Parameters:

  • constants (Hash, nil) (defaults to: nil) —

    math layout constants

  • glyph_info (Hash, nil) (defaults to: nil) —

    per-glyph math data

  • variants (Hash, nil) (defaults to: nil) —

    stretched delimiter data

Returns:

  • (String, nil) —

    MATH table bytes, or nil if no data



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# File 'lib/fontisan/ufo/compile/math.rb', line 31

def self.build(constants: nil, glyph_info: nil, variants: nil)
  return nil unless constants || glyph_info || variants

  constants_bytes = constants ? build_constants(constants) : nil
  glyph_info_bytes = glyph_info ? build_glyph_info(glyph_info) : nil
  variants_bytes = variants ? build_variants(variants) : nil

  constants_off = constants_bytes ? HEADER_SIZE : 0
  gi_off = glyph_info_bytes ? constants_off + (constants_bytes&.bytesize || 0) : 0
  if gi_off.zero? && glyph_info_bytes
    gi_off = HEADER_SIZE + (constants_bytes&.bytesize || 0)
  end
  variants_off = variants_bytes ? gi_off + (glyph_info_bytes&.bytesize || 0) : 0
  if variants_off.zero? && variants_bytes
    variants_off = HEADER_SIZE + (constants_bytes&.bytesize || 0) + (glyph_info_bytes&.bytesize || 0)
  end

  io = +""
  io << [0x00010000, constants_off, gi_off, variants_off].pack("Nnnn")
  io << constants_bytes if constants_bytes
  io << glyph_info_bytes if glyph_info_bytes
  io << variants_bytes if variants_bytes
  io
end