anchor.diff:      final height = data[4] << 24 | data[5] << 16 | data[6] << 8 | data[7];
       final bits = data[8];
   
  -    int format;
  +    var format = -1;
       switch (data[9]) {
         case 0: // Greyscale
           format = _hasTrns ? gl.LUMINANCE_ALPHA : gl.LUMINANCE;
  
positive.code:   int _segmentIndex = 0;
    int _availableDataLength = 0;
  
    List<int> _sofBuffer;
  
    @override
    void add(List<int> data) {
  
negative.code:     }
    }
  
    void _parseSof() {
      subscription.cancel();
      final data = _sofBuffer;
      final bits = data[0];
      final height = data[1] << 8 | data[2];
      final width = data[3] << 8 | data[4];
  
      var format = -1;
      if (data[5] == 3) {
        format = gl.RGB;
      } else if (data[5] == 1) {
  