parseCmapTableFormat4 function

dynamic parseCmapTableFormat4(Map<String, dynamic> cmap, dynamic p, dynamic data, dynamic start, dynamic offset,)

Implementation

parseCmapTableFormat4(Map<String, dynamic> cmap, p, data, start, offset) {
    // Length in bytes of the sub-tables.
    cmap["length"] = p.parseUShort();
    cmap["language"] = p.parseUShort();

    // segCount is stored x 2.
    var segCount;
    cmap["segCount"] = segCount = p.parseUShort() >> 1;

    // Skip searchRange, entrySelector, rangeShift.
    p.skip('uShort', 3);

    // The "unrolled" mapping from character codes to glyph indices.
    cmap["glyphIndexMap"] = {};
    var endCountParser = new Parser(data, start + offset + 14);
    var startCountParser = new Parser(data, start + offset + 16 + segCount * 2);
    var idDeltaParser = new Parser(data, start + offset + 16 + segCount * 4);
    var idRangeOffsetParser = new Parser(data, start + offset + 16 + segCount * 6);
    var glyphIndexOffset = start + offset + 16 + segCount * 8;
    for (var i = 0; i < segCount - 1; i += 1) {
        var glyphIndex;
        var endCount = endCountParser.parseUShort();
        var startCount = startCountParser.parseUShort();
        var idDelta = idDeltaParser.parseShort();
        var idRangeOffset = idRangeOffsetParser.parseUShort();
        for (var c = startCount; c <= endCount; c += 1) {
            if (idRangeOffset != 0) {
                // The idRangeOffset is relative to the current position in the idRangeOffset array.
                // Take the current offset in the idRangeOffset array.
                glyphIndexOffset = (idRangeOffsetParser.offset + idRangeOffsetParser.relativeOffset - 2);

                // Add the value of the idRangeOffset, which will move us into the glyphIndex array.
                glyphIndexOffset += idRangeOffset;

                // Then add the character index of the current segment, multiplied by 2 for USHORTs.
                glyphIndexOffset += (c - startCount) * 2;
                glyphIndex = getUShort(data, glyphIndexOffset);
                if (glyphIndex != 0) {
                    glyphIndex = (glyphIndex + idDelta) & 0xFFFF;
                }
            } else {
                glyphIndex = (c + idDelta) & 0xFFFF;
            }

            cmap["glyphIndexMap"][c] = glyphIndex;
        }
    }
}