flutter_gauge 小部件不会更新 setState 上的索引值

Question

我遇到的问题是，虽然我通过 setState 成功地更新了我的仪表 (FlutterGauge) 小部件的值，但小部件本身并没有反映出这种变化。我知道重建正在进行，并且仪表小部件上的值确实正在更新。


void updateScore(bool isOnTopic) {
    //for the purposes of testing we won't use isOnTopic (its a hardcoded true anyway)
    setState(() {
      meterScore += 15;
    });
    print("Score Updated:");
    print("--------" + meterScore.toString() + "--------");
  }

  @override
  Widget build(BuildContext context) {
    print('+++++++We\'re building! Using this.meterScore value: ' +
        meterScore.toString() +
        '+++++++');

    //Replacing my FlutterGauge and return with the line below as a way to isolate the FlutterGauge widget as the problem
    //return Center(child: Text(this.meterScore.toString()));

    FlutterGauge meter = new FlutterGauge(
        circleColor: meterColor,
        secondsMarker: SecondsMarker.none,
        hand: Hand.short,
        number: Number.none,
        width: 200,
        index: meterScore,
        fontFamily: "Iran",
        counterStyle: TextStyle(color: Colors.black, fontSize: 35),
        counterAlign: CounterAlign.center,
        isDecimal: false);
    print("------------Accessing meter.index: " +
        meter.index.toString() +
        "----------------");
    return meter;
  }

我相当确定问题出在我如何使用 flutter_gauge 包中的 FlutterGauge 小部件，因为当我用一个简单的 Text 小部件替换它并向它提供我的值时，它会更新并按预期反映更新。

既然如此，这里有一个link到flutter_gauge供参考： https://pub.dev/packages/flutter_gauge#-readme-tab-

我是 flutter 的新手，这是我的第一个 Whosebug 问题，如果我犯了任何明显的错误，我深表歉意。提前致谢！

以防万一我遗漏了您可能需要查看的重要代码，这是整个文件：

import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_gauge/flutter_gauge.dart';

class Meter extends StatefulWidget {
  Meter({Key key}) : super(key: key);
  MeterState createState() => MeterState();
}

class MeterState extends State<Meter> {
  @override
  initState() {
    super.initState();
  }

  double meterScore = 75;
  Color meterColor = Colors.green;

  void updateMeterColor() {
    setState(() {
      meterColor = Colors.green;
    });
  }

  void updateScore(bool isOnTopic) {
    //for the purposes of testing we won't use isOnTopic (its a hardcoded true anyway)
    setState(() {
      meterScore += 15;
    });
    print("Score Updated:");
    print("--------" + meterScore.toString() + "--------");
  }

  @override
  Widget build(BuildContext context) {
    print('+++++++We\'re building! Using this.meterScore value: ' +
        meterScore.toString() +
        '+++++++');

    //Replacing my FlutterGauge and return with the line below as a way to isolate the FlutterGauge widget as the problem
    //return Center(child: Text(this.meterScore.toString()));

    FlutterGauge meter = new FlutterGauge(
        circleColor: meterColor,
        secondsMarker: SecondsMarker.none,
        hand: Hand.short,
        number: Number.none,
        width: 200,
        index: meterScore,
        fontFamily: "Iran",
        counterStyle: TextStyle(color: Colors.black, fontSize: 35),
        counterAlign: CounterAlign.center,
        isDecimal: false);
    print("------------Accessing meter.index: " +
        meter.index.toString() +
        "----------------");
    return meter;
  }

  @override
  void dispose() {
    print("---------We are disposing (as intended)------------");
    super.dispose();
  }
}

编辑：这是热重启和初次访问后我的终端：

I/flutter (11573): +++++++We're building! Using this.meterScore value: 75.0+++++++
I/flutter (11573): ------------Accessing meter.index: 75.0----------------
I/flutter (11573): 75.0

调用函数一次：

I/flutter (11573): Score Updated:
I/flutter (11573): --------90.0--------
I/flutter (11573): +++++++We're building! Using this.meterScore value: 90.0+++++++
I/flutter (11573): ------------Accessing meter.index: 90.0----------------

我更新了代码片段（从所有 meterScore 中删除了 this.，添加了解决函数未使用参数的注释）

我应该提一下，updateScore 函数是在文件外部调用的。正如我所说，函数本身似乎工作正常，如打印语句所示。

这是我使用小部件的地方（这是整个文件）：

class RecordingPage extends StatefulWidget {
  RecordingPage({Key key}) : super(key: key);

  _RecordingPageState createState() => _RecordingPageState();
}

class _RecordingPageState extends State<RecordingPage> {
  final GlobalKey<MeterState> meterState = GlobalKey<MeterState>();
  int yes = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        floatingActionButton: Container(
            width: this.yes * 10.0,
            child: FittedBox(
                child: FloatingActionButton(
              onPressed: null,
              backgroundColor: Colors.white,
            ))),
        floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
        backgroundColor: Colors.white,
        appBar: offTopTitle,
        body: Column(
          children: <Widget>[
            Row(children: [
              Expanded(
                child: FlatButton(
                  child: Text("Go To Websocket"),
                  color: Colors.blue,
                  onPressed: () {
                    Navigator.pushNamed(context, WebsocketRoute);
                  },
                ),
              ),
            ]),
            Container(
              height: MediaQuery.of(context).size.height / 4,
              child: Image.asset('assets/placeholderWave.gif'),
            ),
            Container(
              margin: EdgeInsets.only(top: 5),
              height: MediaQuery.of(context).size.height / 4,
              child: Meter(key: meterState),
            ),
            Recorder((isOnTopic) {
              meterState.currentState.updateScore(isOnTopic);
            }),
          ],
        ),
        bottomNavigationBar: AppBarBuilder());
  }
}

Answer 1

在一个新的 flutter 项目中玩弄了这个包之后，我一直无法在创建后使用许多不同的方式更新它，并且在此时查看了该包的所有可用文档之后，我不确定它旨在以这种方式使用。没有在构建后更改仪表的示例，因此它似乎是一个不可变的小部件。

我做了一些挖掘，syncfusion_flutter_gauges looks like a promising alternative and this 文章讨论了如何做我认为您在项目中尝试的事情。希望对你有帮助

Answer 2

我想我找到了解决办法。这对我有用。打开 flutter_gauge.dart 并删除所有评论部分。重新安装您的应用程序并刷新您的数据。这个步骤对我有用。

flutter_gauge 小部件不会更新 setState 上的索引值

flutter_gauge widget won't update index value on setState

flutter

dart

setstate

flutter-widget