How to apply linear gradient in flutter charts?

Question

How to apply linear gradient in the flutter charts?

I have tried with colors class but i am able to apply only a solid color and unable to find a way for using gradient in the graph bars.

chart.Series<Person,String>(
    id:"Person3",
    colorFn:(_,__)=>chart.MaterialPalette.red.shadeDefault,
    domainFn: (Person dataPoint, _)=>dataPoint.name,
    measureFn: (Person dataPoint, _)=>dataPoint.no,
    data:data2,
  )

Provide me some way to apply linear gradient

Answer 1

Apparently there is no such functionality yet. I managed to get it working with the following code:

Widget _buildChart() {
  return Container(
    height: 300,
    child: ShaderMask(
      child: charts.BarChart(
        _createRandomData(),
        animate: true,
        primaryMeasureAxis: new charts.NumericAxisSpec(
            renderSpec: new charts.NoneRenderSpec(), showAxisLine: false),
        domainAxis: new charts.OrdinalAxisSpec(
            showAxisLine: false, renderSpec: new charts.NoneRenderSpec()),
        layoutConfig: new charts.LayoutConfig(
            leftMarginSpec: new charts.MarginSpec.fixedPixel(0),
            topMarginSpec: new charts.MarginSpec.fixedPixel(0),
            rightMarginSpec: new charts.MarginSpec.fixedPixel(0),
            bottomMarginSpec: new charts.MarginSpec.fixedPixel(0)),
        defaultRenderer: new charts.BarRendererConfig(
            cornerStrategy: const charts.ConstCornerStrategy(30)),
      ),
      shaderCallback: (Rect bounds) {
        return LinearGradient(
          begin: Alignment.bottomCenter,
          end: Alignment.topCenter,
          colors: [Color(0xFF51DE93), Color(0xFFFFB540), Color(0xFFFA4169)],
          stops: [
            0.0,
            0.5,
            1.0,
          ],
        ).createShader(bounds);
      },
      blendMode: BlendMode.srcATop,
    )
  );
}

Result:

Answer 2

An Example of AreaSeries chart

@override
      Widget build(BuildContext context) {
    final List<Color> color = <Color>[];
        color.add(Colors.blue[50]);
        color.add(Colors.blue[100]);
        color.add(Colors.blue);

    final List<double> stops = <double>[];
    stops.add(0.0);
    stops.add(0.5);
    stops.add(1.0);

    final LinearGradient gradientColors =
        LinearGradient(colors: color, stops: stops);
 return   Container(
                      width: double.infinity,
                      height: 250,
                      child: SfCartesianChart(
                        primaryXAxis: CategoryAxis(),
                        series: <AreaSeries<SalesData, String>>[
                          AreaSeries<SalesData, String>(
                            dataSource: <SalesData>[
                              SalesData('Jan', 85),
                              SalesData('Feb', 58),
                              SalesData('Mar', 64),
                              SalesData('Apr', 62),
                              SalesData('May', 78),
                              SalesData('Jun', 92),
                              SalesData('Jul', 90),

                            ],
                            xValueMapper: (SalesData sales, _) => sales.year,
                            yValueMapper: (SalesData sales, _) => sales.sales,
                            gradient: gradientColors,
                          ),
                        ],
                      ),
                    );

}

Answer 3

Use the property BoxDecoration of Container can implement it , like this :

  @override
  Widget build(BuildContext context) {
    return Container(
      width: double.infinity,
      height: 370,
      decoration: BoxDecoration(
          boxShadow: [
            BoxShadow(
                color: Colors(0XFFA573FF),
                blurRadius: 10,
                offset: Offset(2, 3)),
          ],
          borderRadius: BorderRadius.all(Radius.circular(18)),
          gradient: LinearGradient(colors: [
            color: Colors(0XFFA573FF),
            color: Colors(0XFF645AFF),
          ], stops: [
            0.35,
            1
          ], begin: Alignment.topLeft, end: Alignment.bottomRight)),
          child: 
              SizedBox(
                  height: 280,
                  width: double.infinity,
                  child: StackedAreaCustomColorLineChart(
                      StackedAreaCustomColorLineChart._createSampleData())
                      // replace child with your chart here
                      ),
    );
  }