Module: Fontisan::Converters::GlyfTableBuilder

Included in:
OutlineConverter
Defined in:
lib/fontisan/converters/glyf_table_builder.rb

Overview

Builds glyf and loca tables from glyph outlines

This module handles the construction of TrueType glyph tables:

  • glyf table: Contains actual glyph outline data

  • loca table: Contains offsets to glyph data in glyf table

The loca table format depends on the maximum offset:

  • Short format (offsets/2) if max offset <= 0x1FFFE

  • Long format (raw offsets) if max offset > 0x1FFFE

Instance Method Summary collapse

Instance Method Details

#build_glyf_loca_tables(outlines) ⇒ Array<String, String, Integer>

Build glyf and loca tables from outlines

Parameters:

  • outlines (Array<Outline>) —

    Glyph outlines

Returns:

  • (Array<String, String, Integer>) —
    glyf_data, loca_data, loca_format


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# File 'lib/fontisan/converters/glyf_table_builder.rb', line 21

def build_glyf_loca_tables(outlines)
  glyf_data = "".b
  offsets = []

  # Build each glyph
  outlines.each do |outline|
    offsets << glyf_data.bytesize

    if outline.empty?
      # Empty glyph - no data
      next
    end

    # Build glyph data using GlyphBuilder class method
    glyph_data = Fontisan::Tables::GlyphBuilder.build_simple_glyph(outline)
    glyf_data << glyph_data

    # Add padding to 4-byte boundary
    padding = (4 - (glyf_data.bytesize % 4)) % 4
    glyf_data << ("\x00" * padding) if padding.positive?
  end

  # Add final offset
  offsets << glyf_data.bytesize

  # Build loca table
  # Determine format based on max offset
  max_offset = offsets.max
  if max_offset <= 0x1FFFE
    # Short format (offsets / 2)
    loca_format = 0
    loca_data = offsets.map { |off| off / 2 }.pack("n*")
  else
    # Long format
    loca_format = 1
    loca_data = offsets.pack("N*")
  end

  [glyf_data, loca_data, loca_format]
end