Class: Fontisan::Woff2::CollectionEncoder

Inherits:
Object
  • Object
show all
Defined in:
lib/fontisan/woff2/collection_encoder.rb

Overview

Encodes a TTC/OTC font collection into WOFF2 collection format per spec section 4.2.

Output layout:

[WOFF2Header (48 bytes, flavor = 'ttcf')]
[TableDirectory]              # one entry per unique table
[CollectionDirectory]         # CollectionHeader + N CollectionFontEntry
[CompressedFontData]          # single brotli stream of all tables

Each font references tables via indices in its CollectionFontEntry. Identical tables across fonts share a single directory entry.

Per spec section 5.5, glyf/loca pairs from the same font MUST be adjacent (loca immediately follows glyf) in the directory.

Constant Summary collapse

TTC_FLAVOR =

'ttcf'

0x74746366

Instance Method Summary collapse

Constructor Details

#initialize(brotli_quality: 11) ⇒ CollectionEncoder

Returns a new instance of CollectionEncoder.

Parameters:

  • brotli_quality (Integer) (defaults to: 11) —

    0-11



26
27
28
 
# File 'lib/fontisan/woff2/collection_encoder.rb', line 26

def initialize(brotli_quality: 11)
  @brotli_quality = brotli_quality
end

Instance Method Details

#encode_fonts(fonts) ⇒ String

Encode an array of fonts as a WOFF2 collection.

Parameters:

Returns:

  • (String) —

    WOFF2 collection binary

Raises:

  • (ArgumentError) 


34
35
36
37
38
39
40
41
42
 
# File 'lib/fontisan/woff2/collection_encoder.rb', line 34

def encode_fonts(fonts)
  raise ArgumentError, "fonts cannot be empty" if fonts.nil? || fonts.empty?

  prepared = fonts.map.with_index { |font, i| prepare_font(font, i) }
  _, font_to_ckeys = deduplicate(prepared)
  layout = build_layout(prepared, font_to_ckeys)
  compressed = compress_stream(layout)
  assemble(fonts:, layout:, font_to_ckeys:, compressed:)
end