totalSumPredicate property
A boolean value, based on which the data point will be considered as total sum or not.
If this has true value, then that point will be considered as a total sum. Else if it has false, then it will be considered as a normal data point in chart.
This callback will be called for all the data points to check if the data is total sum.
Note: This is applicable only for waterfall chart.
Defaults to null.
Widget build(BuildContext context) {
  return SfCartesianChart(
    series: <WaterfallSeries<SalesData, num>>[
      WaterfallSeries<SalesData, num>(
        dataSource: <SalesData>[
          SalesData(2, 24, true),
          SalesData(3, 22, true),
          SalesData(4, 31, false),
        ],
        xValueMapper: (SalesData sales, _) => sales.x,
        yValueMapper: (SalesData sales, _) => sales.y,
        totalSumPredicate: (SalesData data, _) => data.isTotalSum,
      ),
    ],
  );
}
class SalesData {
  SalesData(this.x, this.y, this.isTotalSum);
    final num x;
    final num y;
    final bool isTotalSum;
}
Implementation
final ChartValueMapper<T, bool>? totalSumPredicate;