Module: Fontisan::Converters::CffTableBuilder

Included in:
OutlineConverter, Type1Converter
Defined in:
lib/fontisan/converters/cff_table_builder.rb

Overview

Builds CFF table data from glyph outlines

This module handles the construction of complete CFF tables including all INDEX structures (name, Top DICT, String, GlobalSubr, CharStrings, LocalSubr) and the Private DICT.

The CFF table structure is:

  • Header (4 bytes)

  • Name INDEX

  • Top DICT INDEX

  • String INDEX

  • Global Subr INDEX

  • CharStrings INDEX

  • Private DICT (with offset in Top DICT)

  • Local Subr INDEX (with offset in Private DICT)

Instance Method Summary collapse

Instance Method Details

#build_cff_table(charstrings, local_subrs, font) ⇒ String

Build complete CFF table from pre-built charstrings

Parameters:

  • charstrings (Array<String>) —

    Pre-built CharString data (already optimized if needed)

  • local_subrs (Array<String>) —

    Local subroutines from optimization

  • font (TrueTypeFont) —

    Source font (for metadata)

Returns:

  • (String) —

    Complete CFF table binary data



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# File 'lib/fontisan/converters/cff_table_builder.rb', line 30

def build_cff_table(charstrings, local_subrs, font)
  # If we have local subrs from optimization, use them
  local_subrs = [] unless local_subrs.is_a?(Array)

  # Build font metadata
  font_name = extract_font_name(font)

  # Build all INDEXes
  header_size = 4
  name_index_data = Tables::Cff::IndexBuilder.build([font_name])
  string_index_data = Tables::Cff::IndexBuilder.build([]) # Empty strings
  global_subr_index_data = Tables::Cff::IndexBuilder.build([]) # Empty global subrs
  charstrings_index_data = Tables::Cff::IndexBuilder.build(charstrings)
  local_subrs_index_data = Tables::Cff::IndexBuilder.build(local_subrs)

  # Build Private DICT with Subrs offset if we have local subroutines
  private_dict_data, private_dict_size = build_private_dict(local_subrs)

  # Calculate offsets with iterative refinement
  top_dict_index_data, =
    calculate_cff_offsets(
      header_size,
      name_index_data,
      string_index_data,
      global_subr_index_data,
      charstrings_index_data,
      private_dict_size,
    )

  # Build CFF Header
  header = build_cff_header

  # Assemble complete CFF table
  header +
    name_index_data +
    top_dict_index_data +
    string_index_data +
    global_subr_index_data +
    charstrings_index_data +
    private_dict_data +
    local_subrs_index_data
end