read method
Reads an OpenType font file and returns OpenTypeFont instance
Throws ChecksumException if calculated checksum is different than expected
Implementation
OpenTypeFont read() {
_tableMap.clear();
final entryMap = <String, TableRecordEntry>{};
_offsetTable = OffsetTable.fromByteData(_byteData);
_font = OpenTypeFont(_offsetTable, _tableMap);
_readTableRecordEntries(entryMap);
_readTables(entryMap);
_validateChecksums();
return _font;
}