我试着在屏幕的左上角和右上角用flutter绘制形状，但我不能做完全相同的事情

class MyPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    // 在左上角绘制形状
    Paint paint = Paint()..color = Colors.blue;
    canvas.drawRect(Rect.fromLTWH(0, 0, size.width / 2, size.height / 2), paint);

    // 在右上角绘制形状
    paint.color = Colors.red;
    canvas.drawRect(
        Rect.fromLTWH(size.width / 2, 0, size.width / 2, size.height / 2),
        paint);
  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) {
    return false;
  }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return CustomPaint(
      painter: MyPainter(),
      child: Container(), // 可以在这里添加其他小部件
    );
  }
}