Module: Fontisan::Ufo::Compile::SvgTable

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

Overview

Builds the OpenType SVG table for SVG-in-OpenType color glyphs.

Layout:

Header (10 bytes):
uint16 version (= 0)
Offset32 documentListOffset (= 10, immediately after header)
uint32 reserved (= 0)

Document List:
uint16 numEntries
DocumentRecord[numEntries]:
  uint16 startGlyphID
  uint16 endGlyphID
  Offset32 svgDocOffset (from start of SVG table)
  uint32 svgDocLength

SVG Documents (raw XML, optionally gzipped)

See Also:

Constant Summary collapse

VERSION = 
0
HEADER_SIZE = 
10
DOCUMENT_RECORD_SIZE = 
12

Class Method Summary collapse

Class Method Details

.build(entries:) ⇒ String?

Returns SVG table bytes, or nil if no entries.

Parameters:

  • entries (Array<Hash>) —

    each with :start_gid (Integer), :end_gid (Integer), :svg (String — raw SVG XML)

Returns:

  • (String, nil) —

    SVG table bytes, or nil if no entries



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# File 'lib/fontisan/ufo/compile/svg_table.rb', line 33

def self.build(entries:)
  return nil if entries.nil? || entries.empty?

  num_entries = entries.size
  doc_list_size = 2 + (num_entries * DOCUMENT_RECORD_SIZE)
  doc_data_offset = HEADER_SIZE + doc_list_size

  header = [VERSION, HEADER_SIZE, 0].pack("nNN")

  records = +""
  docs = +""
  offset = doc_data_offset
  entries.each do |entry|
    svg_bytes = entry[:svg].b
    records << [entry[:start_gid], entry[:end_gid],
                offset, svg_bytes.bytesize].pack("nnNN")
    docs << svg_bytes
    offset += svg_bytes.bytesize
  end

  doc_list = [num_entries].pack("n") + records

  header + doc_list + docs
end