无限像素溢出的颤动底部答案

【问题标题】：Flutter bottom overflowed by infinity pixels无限像素溢出的颤动底部
【发布时间】：2019-10-14 17:35:15
【问题描述】：

当我将某个小部件添加到列的子项中时，我一直面临“底部被无限像素溢出”的问题。现在这是添加名为 countdown 的新小部件之前的样子：

以下是我添加countdown后发生的情况：

这是屏幕下半部分的代码，我在其中添加了countdown：

    final countdown = Countdown();

    final quizBottomContent = SingleChildScrollView(
      child: Container(
      width: MediaQuery.of(context).size.width,
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: <Widget>[quizBottomContentText, quizOptions, countdown],
        ),
      )
    );

这是倒计时小部件：

import 'package:flutter/material.dart';
import 'dart:math' as math;

class Countdown extends StatefulWidget {
  @override
  CountdownState createState() => CountdownState();
}

class CountdownState extends State<Countdown> with TickerProviderStateMixin {
  AnimationController controller;

  String get timerString {
    Duration duration = controller.duration * controller.value;
    return '${duration.inMinutes}:${(duration.inSeconds % 60).toString().padLeft(2, '0')}';
  }

  @override
  void initState() {
    super.initState();
    controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 10),
    );
  }

  @override
  Widget build(BuildContext context) {
    ThemeData themeData = Theme.of(context);
    return Scaffold(
      body: Padding(
        padding: EdgeInsets.all(8.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: <Widget>[
            Expanded(
              child: Align(
                alignment: FractionalOffset.center,
                child: AspectRatio(
                  aspectRatio: 1.0,
                  child: Stack(
                    children: <Widget>[
                      Positioned.fill(
                        child: AnimatedBuilder(
                          animation: controller,
                          builder: (BuildContext context, Widget child) {
                            return CustomPaint(
                                painter: TimerPainter(
                              animation: controller,
                              backgroundColor: Colors.white,
                              color: themeData.indicatorColor,
                            ));
                          },
                        ),
                      ),
                      Align(
                        alignment: FractionalOffset.center,
                        child: Column(
                          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                          crossAxisAlignment: CrossAxisAlignment.center,
                          children: <Widget>[
                            Text(
                              "Count Down",
                              style: themeData.textTheme.subhead,
                            ),
                            AnimatedBuilder(
                                animation: controller,
                                builder: (BuildContext context, Widget child) {
                                  return Text(
                                    timerString,
                                    style: themeData.textTheme.display4,
                                  );
                                }),
                          ],
                        ),
                      ),
                    ],
                  ),
                ),
              ),
            ),
            Container(
              margin: EdgeInsets.all(8.0),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: <Widget>[
                  FloatingActionButton(
                    child: AnimatedBuilder(
                      animation: controller,
                      builder: (BuildContext context, Widget child) {
                        return Icon(controller.isAnimating
                            ? Icons.pause
                            : Icons.play_arrow);
                      },
                    ),
                    onPressed: () {
                      if (controller.isAnimating)
                        controller.stop();
                      else {
                        controller.reverse(
                            from: controller.value == 0.0
                                ? 1.0
                                : controller.value);
                      }
                    },
                  )
                ],
              ),
            )
          ],
        ),
      ),
    );
  }
}

class TimerPainter extends CustomPainter {
  TimerPainter({
    this.animation,
    this.backgroundColor,
    this.color,
  }) : super(repaint: animation);

  final Animation<double> animation;
  final Color backgroundColor, color;

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = backgroundColor
      ..strokeWidth = 5.0
      ..strokeCap = StrokeCap.round
      ..style = PaintingStyle.stroke;

    canvas.drawCircle(size.center(Offset.zero), size.width / 2.0, paint);
    paint.color = color;
    double progress = (1.0 - animation.value) * 2 * math.pi;
    canvas.drawArc(Offset.zero & size, math.pi * 1.5, -progress, false, paint);
  }

  @override
  bool shouldRepaint(TimerPainter old) {
    return animation.value != old.animation.value ||
        color != old.color ||
        backgroundColor != old.backgroundColor;
  }
}

一些上下文： Countdown 基本上是一个带有动画的计时器，同时倒计时我从这个link 中提取。所以计时器就在按钮下方。

【问题讨论】：

尝试在 scrolllview 中添加内容

标签： flutter dart

【解决方案1】：

尝试设置列的主轴大小 mainAxisSize: MainAxisSize.min,

更新

好的，所以如果您尝试将倒计时小部件作为列中的小部件，您可以从倒计时小部件的构建方法中移除脚手架并将其包装在容器中并定义高度

 return Scaffold(
      body: Padding(
        padding: EdgeInsets.all(8.0),
        child: Column(

到

 return Container(
         height: 100,
         child: Padding(
              padding: EdgeInsets.all(8.0),
              child: Column(

【讨论】：

【解决方案2】：

只需用容器包装该小部件并指定高度就可以了

【讨论】：

【解决方案3】：

我有类似的问题，包装quizBottomContent 用Expanded 小部件为我解决了这个问题：

final quizBottomContent = Expanded(
  child: SingleChildScrollView(
    ...
  )
);

【讨论】：