如何在使用自定义画家制作绘图板时为 onPanEnd 赋予空值

how to give a null value to onPanEnd while making a drawpad using custom painter

onPanEnd: (details) {
          pointsList.add(null);
          
          pointsStream.add(pointsList);
           },

class DrawModel {
  final Offset offset;
  final Paint paint;
  

      DrawModel({required this.offset, required this.paint});

}

错误：无法将参数类型 'Null' 分配给参数类型 'DrawModel

这是您要找的吗？

List<DrawModel?> pointList = [];