通过CustomPainter自定义雷达图

效果如下

 主要代码

import 'package:flutter/material.dart';
import 'dart:math';
import 'dash_painter.dart';
import 'model/charts_model.dart';class RadarChart extends StatelessWidget {final List<ChartModel> list;final double maxValue;final Color radarColor;final Color dataColor;const RadarChart({super.key,required this.list,this.maxValue = 100,this.radarColor = Colors.grey,this.dataColor = Colors.green,});@overrideWidget build(BuildContext context) {return CustomPaint(painter: RadarChartPainter(list: list,maxValue: maxValue,radarColor: radarColor,dataColor: dataColor,numLayers: 4,),);}
}class RadarChartPainter extends CustomPainter {final int numLayers;final List<ChartModel> list;final double maxValue;final Color radarColor;final Color dataColor;List<Offset> startList = []; //存放第一层的点List<Offset> endList = []; //存放最外层的点List<Offset> textOffsetList = [];final int _offsetDy = 20;final int _offsetDx = 5;RadarChartPainter({required this.numLayers,required this.list,required this.maxValue,required this.radarColor,required this.dataColor,});@overridevoid paint(Canvas canvas, Size size) {final center = Offset(size.width / 2, size.height / 2);final radius = size.width / 2;final dataPoints = <Offset>[];final radarPaint = Paint()..color = radarColor..style = PaintingStyle.stroke;final bgPaint = Paint()..color = const Color(0xFFCAD0E8).withOpacity(.4)..style = PaintingStyle.fill;//画背景颜色for (var layer = 1; layer <= numLayers; layer++) {if (layer == 3) {final layerRadius = radius * (layer / numLayers);final radarPath = Path();for (var i = 0; i < 6; i++) {//每一层的6个点final angle = (2 * pi / 6) * i - (pi / 2);final x = center.dx + layerRadius * cos(angle);final y = center.dy + layerRadius * sin(angle);final point = Offset(x, y);if (i == 0) {radarPath.moveTo(point.dx, point.dy);} else {radarPath.lineTo(point.dx, point.dy);}}radarPath.close();canvas.drawPath(radarPath, bgPaint);}}//连接每一层的6个点和文字for (var layer = 1; layer <= numLayers; layer++) {final layerRadius = radius * (layer / numLayers);final radarPath = Path();for (var i = 0; i < 6; i++) {final angle = (2 * pi / 6) * i - (pi / 2);final x = center.dx + layerRadius * cos(angle);final y = center.dy + layerRadius * sin(angle);final point = Offset(x, y);if (i == 0) {radarPath.moveTo(point.dx, point.dy);} else {radarPath.lineTo(point.dx, point.dy);}//保存第一层的点if (layer == 1) {startList.add(point);}//保存最外层的点，用于后面画第一层的最外层点的连线if (layer == 4) {endList.add(point);//画label文字const textStyle = TextStyle(fontSize: 12, fontWeight: FontWeight.bold, color: Color(0XFF999999));final textSpan = TextSpan(text: list[i].label, style: textStyle);final textPainter = TextPainter(text: textSpan,textDirection: TextDirection.ltr,);textPainter.layout();double w = textPainter.width;Offset off = const Offset(0, 0);if (i == 0) {off = Offset(point.dx - w * 0.5, point.dy - _offsetDy);} else if (i == 1 || i == 2) {off = Offset(point.dx + _offsetDx, point.dy);} else if (i == 4 || i == 5) {off = Offset(point.dx - _offsetDx - w, point.dy);} else if (i == 3) {off = Offset(point.dx - w * 0.5, point.dy);}textPainter.paint(canvas, off);}}radarPath.close();const DashPainter(span: 3, step: 3).paint(canvas, radarPath, radarPaint);}//画第一层的点到最外层的点的连线for (var i = 0; i < 6; i++) {final path = Path();path.moveTo(startList[i].dx, startList[i].dy);path.lineTo(endList[i].dx, endList[i].dy);const DashPainter(span: 4, step: 9).paint(canvas, path, radarPaint);}//画数据区域final dataPaint = Paint()..color = dataColor..style = PaintingStyle.stroke..strokeWidth = 2.0;final dataFillPaint = Paint()..color = dataColor.withOpacity(.3)..style = PaintingStyle.fill..strokeWidth = 2.0;final dataPath = Path();for (var i = 0; i < 6; i++) {final angle = (2 * pi / 6) * i - (pi / 2);final value = list[i].y;final normalizedValue = value / maxValue;final dataRadius = radius * 0.75 * normalizedValue + radius * 0.25;final x = center.dx + dataRadius * cos(angle);final y = center.dy + dataRadius * sin(angle);final point = Offset(x, y);if (i == 0) {dataPath.moveTo(point.dx, point.dy);} else {dataPath.lineTo(point.dx, point.dy);}dataPoints.add(point);}dataPath.close();canvas.drawPath(dataPath, dataFillPaint);canvas.drawPath(dataPath, dataPaint);final dataPointPaint = Paint()..color = dataColor;for (var point in dataPoints) {canvas.drawCircle(point, 4.0, dataPointPaint);}}@overridebool shouldRepaint(covariant CustomPainter oldDelegate) {return true;}
}

项目地址 ： flutter_radar: flutter 雷达图