trackoffical_app/lib/widget/my_position_point.dart

import 'package:flutter/material.dart';
import 'package:trackoffical_app/screen.dart';
import 'dart:ui' as ui;
import 'package:common_pub/prelude.dart';

class MyPositionPoint extends StatelessWidget{
  const MyPositionPoint({
    super.key,
    required this.offset,
    required this.color,
    this.radius,
    this.direction
  });
  final Color color;
  final Offset offset;
  final double? radius;
  final double? direction;

  @override
  Widget build(BuildContext context) {

    final width = radius??6.62.wp;
    final height = width*3.3;
    final hasDirection = direction!= null;

    Widget child = CustomPaint(
      painter: _LayerMyPositionPointPainter(color, hasDirection, 255),
      size: Size(width, height),
    );
    if(hasDirection){
      child = Transform.rotate(
          angle: direction!,
          alignment: Alignment.center,
          child: child);
    }


    return Positioned(
        left: offset.dx-width/2,
        top: offset.dy-height/2,
        child: child);
  }
}
class _LayerMyPositionPointPainter extends CustomPainter {
  final Color color;
  final bool hasDirection;
  final int alpha;

  _LayerMyPositionPointPainter(
      this.color,
      this.hasDirection,
      this.alpha
      );

  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint();
    drawMyLocation(canvas, paint, size);
  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) => false;

  drawMyLocation(Canvas canvas, Paint paint, Size size) {

    final color = this.color.withAlpha(alpha);
    final color2 = this.color.withAlpha((alpha*0.8).toInt());
    final center = Offset(size.width/2, size.height/2);

    paint.color = color;
    var rect = Rect.fromLTRB(0 , 0, size.width, center.dy);
    paint.shader = ui.Gradient.linear(rect.topCenter, rect.bottomCenter, [
      const Color(0x00FFFFFF),
      color2
    ], [
      0,
      1,
    ]);

    final path = Path();

    path.moveTo(rect.topLeft.dx, rect.topLeft.dy);
    path.lineTo(rect.topRight.dx, rect.topRight.dy);
    path.lineTo(rect.bottomCenter.dx, rect.bottomCenter.dy);

    canvas.drawPath(path, paint);
    paint.shader = null;

    paint.color = Colors.white.withAlpha(alpha);
    canvas.drawCircle(center, center.dx* 0.8, paint);
    paint.color = color;
    canvas.drawCircle(center, center.dx * 0.5, paint);
  }
}

void main(){
  runPreview(Scaffold(
    backgroundColor: Colors.white,
    appBar: AppBar(title: const Text('data'),),
    body:const SizedBox(
      height: double.infinity,
      width: double.infinity,
      child: Stack(
        children: [
          MyPositionPoint(offset: Offset(200, 200), color: Colors.red, direction: 0,)
        ],
      ),
    )
  ));
}