flutter 绘制右上角圆角三角形标签

绘制：

import 'package:jade/utils/JadeColors.dart';
import 'package:flutter/material.dart';
import 'dart:math' as math;class LabelTopRightYellow extends StatefulWidget {final String labelTitle; // 只能两个字的（文字偏移量没有根据文字长度改变）const LabelTopRightYellow({@required this.labelTitle});@overrideState<StatefulWidget> createState() {return LabelViewState();}
}class LabelViewState extends State<LabelTopRightYellow> with SingleTickerProviderStateMixin {@overrideWidget build(BuildContext context) {return CustomPaint(painter: ArcPainter(labelTitle: widget.labelTitle),size: Size(35,35), // 调整大小以适应你的需求);}
}class ArcPainter extends CustomPainter {//标签文字String labelTitle;ArcPainter({this.labelTitle});@overridevoid paint(Canvas canvas, Size size) {double originX = 0.0 ;double originY = 0.0 ;double cx = size.width / 2;double cy = size.height / 2;Paint _paint = Paint()..color = Color(0xffFFE50F)..strokeWidth = 2//画笔是线段（默认是fill填充）/*..style = PaintingStyle.stroke*/;// canvas.drawCircle(Offset(cx,cy), 2, _paint);Path path = Path();// 绘制圆锥路径 权重越大路径越接近直角（不使用path.moveTo时，默认起点为左上角）path.conicTo(originX + size.width, originY, originX + size.width, originY+ size.height, 10);// 控制路径是否闭合，可不写path.close();canvas.drawPath(path, _paint);canvas.save();canvas.restore();TextPainter textPainterCenter = TextPainter(text: TextSpan(text: labelTitle, style: TextStyle(color: Color(0xff333333),fontSize: 10)),textDirection: TextDirection.ltr,);textPainterCenter.layout();canvas.rotate(math.pi / 4);canvas.translate(-math.pi , -((cy - math.pi)  * 2));textPainterCenter.paint(canvas, Offset(cx /*- textPainterCenter.size.width / 2*/,cy - textPainterCenter.size.height / 4));canvas.save();canvas.restore();}/// 度数转类似于π的那种角度double degToRad(double deg) => deg * (math.pi / 180.0);@overridebool shouldRepaint(covariant CustomPainter oldDelegate) {return true;}
}

引用：

Container(height: 180.wmargin: EdgeInsets.symmetric(horizontal: 20.w),padding: EdgeInsets.only(left: 20.w),decoration: BoxDecoration(color: Colors.white,borderRadius: BorderRadius.circular(8),boxShadow: [BoxShadow(color: JadeColors.grey_4,blurRadius: 2.0,offset: Offset(0.0, 0.0),)]),child: Column(children: [_userView(),SizedBox(height: 20.w),_productView(),_countdownView()],),)
_userView(){return Stack(alignment: Alignment.topRight,children: [Row(children: [Container(width: 70.w,height: 70.w,margin: EdgeInsets.only(right: 20.w),child: Utils().roundedImage(PathConfig.testImageUrl[3], 70),),Expanded(child: Column(crossAxisAlignment: CrossAxisAlignment.start,children: [Text('商户商户商户商户',style: TextStyle(fontSize: 30.sp,color: JadeColors.grey_2,fontWeight: FontWeight.w600),maxLines: 1,overflow: TextOverflow.ellipsis,),Text('10分钟前',style: TextStyle(fontSize: 22.sp,color: JadeColors.grey))],))],),LabelTopRightYellow(labelTitle: S.current.cuxiao,)],);}