parseCmapTable function

dynamic parseCmapTable(dynamic data, dynamic start)

Implementation

parseCmapTable(data, start) {
    Map<String, dynamic> cmap = {};
    cmap["version"] = getUShort(data, start);
    argument(cmap["version"] == 0, 'cmap table version should be 0.');

    // The cmap table can contain many sub-tables, each with their own format.
    // We're only interested in a "platform 0" (Unicode format) and "platform 3" (Windows format) table.
    cmap["numTables"] = getUShort(data, start + 2);
    var offset = -1;
    for (var i = cmap["numTables"] - 1; i >= 0; i -= 1) {
        var platformId = getUShort(data, start + 4 + (i * 8));
        var encodingId = getUShort(data, start + 4 + (i * 8) + 2);
        if ((platformId == 3 && (encodingId == 0 || encodingId == 1 || encodingId == 10)) ||
            (platformId == 0 && (encodingId == 0 || encodingId == 1 || encodingId == 2 || encodingId == 3 || encodingId == 4))) {
            offset = getULong(data, start + 4 + (i * 8) + 4);
            break;
        }
    }

    if (offset == -1) {
        // There is no cmap table in the font that we support.
        throw('No valid cmap sub-tables found.');
    }

    var p = new Parser(data, start + offset);
    cmap["format"] = p.parseUShort();

    if (cmap["format"] == 12) {
        parseCmapTableFormat12(cmap, p);
    } else if (cmap["format"] == 4) {
        parseCmapTableFormat4(cmap, p, data, start, offset);
    } else {
        throw('Only format 4 and 12 cmap tables are supported (found format ' + cmap["format"] + ').');
    }

    return cmap;
}