flutter tabbar设置indicator高度、宽度

import 'package:flutter/material.dart';

class MyCustomIndicator extends Decoration {

  final double indWidth;
  final double indHeight;
  final double radius;

  MyCustomIndicator({this.indWidth = 70.0, this.indHeight = 12.0, this.radius = 5});

  @override
  BoxPainter createBoxPainter([VoidCallback onChanged]) {
    return _CustomBoxPainter(this, onChanged, indWidth, indHeight, radius);
  }
}

class _CustomBoxPainter extends BoxPainter {
  final MyCustomIndicator decoration;
  final double indWidth;
  final double indHeight;
  final double radius;

  _CustomBoxPainter(this.decoration, VoidCallback onChanged, this.indWidth, this.indHeight, this.radius)
      : super(onChanged);

  @override
  void paint(Canvas canvas, Offset offset, ImageConfiguration configuration) {
    final size = configuration.size;
    final newOffset = Offset(offset.dx + (size.width - indWidth) / 2, size.height - indHeight);
    final Rect rect = newOffset & Size(indWidth, indHeight);
    final Paint paint = Paint();
    paint.color = Colors.yellow;
    paint.style = PaintingStyle.fill;
    canvas.drawRRect(
      RRect.fromRectAndRadius(rect, Radius.circular(radius)), // 圆角半径
      paint,
    );
  }
}
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使用

TabBar(
      isScrollable: false,
      labelPadding: EdgeInsets.symmetric(horizontal: 0),
      indicator: MyCustomIndicator(),
      labelColor: Color(0xff333333),
      labelStyle: TextStyle(
        fontSize: 30.sp,
        fontWeight: FontWeight.w600,
      ),
      unselectedLabelColor: JadeColors.grey,
      unselectedLabelStyle: TextStyle(
        fontSize: 30.sp,
      ),
      indicatorSize: TabBarIndicatorSize.label,
      controller: _tabController,
      tabs: _tabs
          .map((value) => Container(padding: EdgeInsets.symmetric(horizontal: 20.w),child: Text(value))).toList(),
      onTap: (index) {},
    )
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