flutter - 在flutter中syncfusion_flutter_charts动画期间更改PieChart的颜色

Question

我正在尝试更改syncfusion_flutter_charts包中的圆形条系列的颜色，以在加载动画期间从 0 更改为 20 而

0=>5(color = red) then 
6=>10(color = yellow) then 
11=>15(color = green) then 
16=>20(color = blue).

有人能帮帮我吗？ 带有单色动画的图表

    SfCircularChart(
        annotations: [
            CircularChartAnnotation(
                widget: const PhysicalModel(
                    child: SizedBox(width: 170, height: 170),
                    shape: BoxShape.circle,
                    elevation: 4,
                    shadowColor: Colors.black,
                    color: Color.fromRGBO(230, 230, 230, 1)),
            ),
        ],
        legend: Legend(
            overflowMode: LegendItemOverflowMode.wrap),
        palette: [colorData(today)],
        series: [
            RadialBarSeries(
            dataSource: _chartData,
            xValueMapper: (GDPData data, _) =>
                data.continent,
            yValueMapper: (GDPData data, _) => data.gdp,
            trackColor: Colors.grey.shade200,
            radius: '50',
            animationDuration: 2000,
            animationDelay: 800,
            innerRadius: '85',
            maximumValue: 20)
        ],
    ),