How to add a legend on pie chart from flutter (charts_flutter)?

Solution 1:

I implement a dirty solution. By adding new widget near pie chart as a legend.

    Widget pieChart3()=>new Container(
      color:Colors.white,
      height: 220.0,
      width: 220.0,
      child:Stack(
          children: <Widget>[
            Positioned(
              top: 50.0,
              right: 10.0,
              child:   new Container(
                    height: 180,
                    width: 280,
                    color:Colors.white,
                    child:new charts.PieChart(seriesList,
                        animate: animate,
                        defaultRenderer: new charts.ArcRendererConfig(
                          arcRendererDecorators: [
                            new charts.ArcLabelDecorator(
                              //labelPadding:-25,
                                labelPosition: charts.ArcLabelPosition.outside),
                          ],
                          arcWidth: 30,
                        )
                    )
                )
            ),
            Positioned(
              bottom: 20.0,
              left: 10.0,
              child: new Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children:listWidgets(slices)
              ),
            ),
          ]
      )
  );

and this lists legend items.

      List<Widget> listWidgets(List<Slice> sliceList) {
    List<Widget> list = sliceList == null ? new List() : sliceList.map((value) {
      return new Row(
          crossAxisAlignment:  CrossAxisAlignment.start,
          mainAxisSize: MainAxisSize.min,
          children: <Widget>[
            Container(width: 10.0),
            Container(
                color: Color.fromARGB(value.color.a, value.color.r, value.color.g,value.color.b),
                width: 10.0,
                height: 15.0,
            ),
            Container(width: 5.0),
            new Text(value.name),
          ]
      );
    }).toList();
    return list;
  }

and Slice class

    class Slice {
  final String name;
  final int percent;
  final Color color;

  Slice(this.color,this.name, this.percent);
}

Defining slices

  HashMap<int,int> sliceValues= new HashMap();
  slices=new List();
  sliceValues[1]=0;
  sliceValues[2]=0;
  sliceValues[3]=0;
  sliceValues[4]=0;
  sliceValues[5]=0;
  for(Result r in items)
    if(r.point<45)
      if(sliceValues[1]==null)sliceValues[1]=1;
      else sliceValues[1]=sliceValues[1]+1;
    else if(r.point<55)
      if(sliceValues[2]==null)sliceValues[2]=1;
      else sliceValues[2]=sliceValues[2]+1;
    else if(r.point<70)
      if(sliceValues[3]==null)sliceValues[3]=1;
      else sliceValues[3]=sliceValues[3]+1;
    else if(r.point<85)
      if(sliceValues[4]==null)sliceValues[4]=1;
      else sliceValues[4]=sliceValues[4]+1;
    else
      if(sliceValues[5]==null)sliceValues[5]=1;
      else sliceValues[5]=sliceValues[5]+1;


  for(int key in sliceValues.keys)
    slices.add(new Slice(
        key==1?charts.MaterialPalette.red.shadeDefault.darker:
        key==2?charts.MaterialPalette.deepOrange.shadeDefault.darker:
        key==3?charts.MaterialPalette.yellow.shadeDefault.darker:
        key==4?charts.MaterialPalette.blue.shadeDefault.darker:
        key==5?charts.MaterialPalette.green.shadeDefault.darker:
    charts.MaterialPalette.black,
        key==1?"0-44":
        key==2?"45-54":
        key==3?"55-69":
        key==4?"70-84":
        key==5?"85+":
        "",
        items.length>0?100*sliceValues[key]~/items.length:0));