我如何实现实时 fl_chart 颤振？

Question

这是 fl_chart 我想实现实时图表，例如，心率随时间变化。

child: StreamBuilder<QuerySnapshot>(
                  stream: FirebaseFirestore.instance
                      .collection('#')
                      .orderBy("ad")
                      .limitToLast(5)
                      .snapshots(),
                  builder: (context, snapshot) {
                    if (snapshot.hasData) {
                      return LineChart(

                        mainData(snapshot.data),

                      );
                    }

这是实时数据 在哪里构建数据

LineChartData mainData(QuerySnapshot graphData) {
    var liveGraphData;
    liveGraphData = graphData.docs
        .map((documentSnapshot) => Gadget.fromMap(documentSnapshot.data()))
        .toList();

    List<FlSpot> gatherGraphData() {
      List<FlSpot> graphPoints = [];
      for (int i = 0; i < liveGraphData.length; i++) {
        graphPoints.add(
            FlSpot((liveGraphData[i].ts).toDouble(), liveGraphData[i].yadc));
      }
      print(graphPoints.length);
      return graphPoints;
    }