dataLabelSurfaceColor method 
    
      
  
Color
dataLabelSurfaceColor(
 - CartesianChartDataLabelPositioned label
)override
     
    
    
  Implementation
  @override
Color dataLabelSurfaceColor(CartesianChartDataLabelPositioned label) {
  final ChartDataLabelAlignment alignment = label.labelAlignment;
  final ChartSegment segment = segments[label.dataPointIndex];
  switch (alignment) {
    case ChartDataLabelAlignment.auto:
    case ChartDataLabelAlignment.outer:
    case ChartDataLabelAlignment.top:
    case ChartDataLabelAlignment.bottom:
      return super.dataLabelSurfaceColor(label);
    case ChartDataLabelAlignment.middle:
      return segment.getFillPaint().color;
  }
}