flutter timeline item不固定高

这大概是flutter最简单的时间线了吧 maybe ，利用stack的特性 摒弃传统的计算逻辑

import 'package:flutter/material.dart';

typedef IndexedTimeItemBuilder = InfoItem Function(
    BuildContext context, int index);

class TimeLineWidget extends StatelessWidget {
  const TimeLineWidget(
      {Key? key,
      required this.iconItem,
      required this.lineItem,
      required this.itemBuilder,
      required this.itemCount,
      this.lineItemSpace})
      : super(key: key);

  final IconItem iconItem;
  final LineItem lineItem;
  final IndexedTimeItemBuilder itemBuilder;
  final double? lineItemSpace;
  final int itemCount;

  @override
  Widget build(BuildContext context) {
    return  ListView.builder(
      shrinkWrap: true,
      itemBuilder: (context, index) {
        InfoItem timeItem = itemBuilder(context, index);
        return Stack(
          children: [
            if (index != itemCount - 1)
              Positioned(
                child: Container(
                  width: lineItem.width,
                  color:
                  timeItem.isActive ? lineItem.activeColor : lineItem.color,
                ),
                left: (iconItem.width-lineItem.width )/ 2,
                bottom: 0,
                top: 0,
              ),
            Positioned(
              child:
              timeItem.isActive ? iconItem.activeWidget : iconItem.widget,
              top: 0,
            ),
            Padding(
              padding: EdgeInsets.only(
                  left: lineItemSpace! + iconItem.width, bottom: 5),
              child:
              timeItem.isActive ? timeItem.activeWidget : timeItem.widget,
            ),
          ],
        );
      },
      itemCount: itemCount,
    );
  }

}

class LineItem {
  final Color color;
  final Color activeColor;
  final double width;

  LineItem(
      {required this.color, required this.width, required this.activeColor});
}

class IconItem {
  final double width;
  final Widget widget;
  final Widget activeWidget;

  IconItem(
      {required this.width, required this.widget, required this.activeWidget});
}

class InfoItem {
  final bool isActive;
  final Widget widget;
  late final Widget? activeWidget;

  InfoItem({required this.isActive, required this.widget, this.activeWidget});
}

调用示范：

import 'package:flitter_okgo/time_line.dart';
import 'package:flutter/material.dart';

void main() => runApp(StartPage());

class StartPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: TestPage(),
    );
  }
}

class TestPage extends StatefulWidget {
  @override
  _TestPageState createState() => _TestPageState();
}

class _TestPageState extends State
    with SingleTickerProviderStateMixin {

  @override
  void initState() {
    super.initState();
  }

  final int len = 10;
  final double iconWidth = 10;
  final double lineItemSpace = 20;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('时间线'),
      ),
      body: Padding(
        padding: EdgeInsets.all(15),
        child: TimeLineWidget(
          itemCount: len,
          lineItem: LineItem(
            width: 2,
            color: Colors.grey,
            activeColor: Colors.red,
          ),
          lineItemSpace: lineItemSpace,
          iconItem: IconItem(
            widget: ClipRRect(
              borderRadius: BorderRadius.circular(10),
              child: Container(
                color: Colors.grey,
                width: iconWidth,
                height: iconWidth,
              ),
            ),
            activeWidget: ClipRRect(
              borderRadius: BorderRadius.circular(10),
              child: Container(
                color: Colors.red,
                width: iconWidth,
                height: iconWidth,
              ),
            ),
            width: iconWidth,
          ),
          itemBuilder: (context, index) {
            return InfoItem(
              isActive: index != 0,
              widget: Container(
                height: (index + 1) * 30,
                child: Text(
                  '第$index个',
                  style: TextStyle(color: Colors.grey),
                ),
              ),
              activeWidget: Container(
                height: (index + 1) * 30,
                child: Text('第$index个'),
              ),
            );
          },
        ),
      ),
    );
  }
}