makeSfntTable function

dynamic makeSfntTable(dynamic tables)

Implementation

function makeSfntTable(tables) {
    const sfnt = new table.Table('sfnt', [
        {name: 'version', type: 'TAG', value: 'OTTO'},
        {name: 'numTables', type: 'USHORT', value: 0},
        {name: 'searchRange', type: 'USHORT', value: 0},
        {name: 'entrySelector', type: 'USHORT', value: 0},
        {name: 'rangeShift', type: 'USHORT', value: 0}
    ]);
    sfnt.tables = tables;
    sfnt.numTables = tables.length;
    const highestPowerOf2 = Math.pow(2, log2(sfnt.numTables));
    sfnt.searchRange = 16 * highestPowerOf2;
    sfnt.entrySelector = log2(highestPowerOf2);
    sfnt.rangeShift = sfnt.numTables * 16 - sfnt.searchRange;

    const recordFields = [];
    const tableFields = [];

    let offset = sfnt.sizeOf() + (makeTableRecord().sizeOf() * sfnt.numTables);
    while (offset % 4 !== 0) {
        offset += 1;
        tableFields.push({name: 'padding', type: 'BYTE', value: 0});
    }

    for (let i = 0; i < tables.length; i += 1) {
        const t = tables[i];
        check.argument(t.tableName.length === 4, 'Table name' + t.tableName + ' is invalid.');
        const tableLength = t.sizeOf();
        const tableRecord = makeTableRecord(t.tableName, computeCheckSum(t.encode()), offset, tableLength);
        recordFields.push({name: tableRecord.tag + ' Table Record', type: 'RECORD', value: tableRecord});
        tableFields.push({name: t.tableName + ' table', type: 'RECORD', value: t});
        offset += tableLength;
        check.argument(!isNaN(offset), 'Something went wrong calculating the offset.');
        while (offset % 4 !== 0) {
            offset += 1;
            tableFields.push({name: 'padding', type: 'BYTE', value: 0});
        }
    }

    // Table records need to be sorted alphabetically.
    recordFields.sort(function(r1, r2) {
        if (r1.value.tag > r2.value.tag) {
            return 1;
        } else {
            return -1;
        }
    });

    sfnt.fields = sfnt.fields.concat(recordFields);
    sfnt.fields = sfnt.fields.concat(tableFields);
    return sfnt;
}