如何在Flutter App中处理onPause/onResume? [英] How to handle onPause/onResume in Flutter App?

问题描述

我是Dart/Flutter的新手，并且想构建一个简单的应用，其中LinearProgressBar每秒更新一次.

I'm new to Dart/Flutter and would like to build a simple app where a LinearProgressBar gets updated every second.

在不花太多时间编写实际代码的情况下，我可以进行以下设置.

Without getting too much into the actual code, I have the following setup working.

• 基于经过时间计算进度的函数.
• 显示进度的LinearProgressBar.
• 一个定期的计时器，它重新计算进度并每秒更新进度栏.
• 我每次都调试打印"tick"，重新计算就完成了.

一切正常，但有一个例外.当我在Android设备上的后台移动应用程序时，滴答声"会一直打印.

Everything is working as expected with one exception. The 'tick' keeps getting printed when I move the app in the background on my Android device.

在本机Android上，当触发"onPause"事件时，我会取消定期计时器.

On native Android, I would cancel my periodic Timer when the 'onPause' event is triggered.

Flutter中有类似的东西吗?我所能找到的只是"initState"和"dispose".但是，将应用程序移至后台时，不会调用Dispose.

Is there something similar in Flutter? All I could find was 'initState' and 'dispose'. Dispose, however, does not get called when moving the app to background.

我不希望计时器一直在后台计时.

I don't want the timer to keep ticking in the background.

在研究中，我发现了这个堆栈溢出问题 onresume-and-pause -随风飘扬的小工具.答案是建议使用 TickerProviderStateMixin .

On my research, I found this Stack Overflow question onresume-and-onpause-for-widgets-on-flutter. It's answer suggests using TickerProviderStateMixin.

我以下列方式使用它.

class _BarItemState extends State<BarItem> with SingleTickerProviderStateMixin {
    Ticker ticker;
    num progress = 1.0;

    @override
    void initState() {
       super.initState();
       ticker = createTicker((duration) => setState(() {
          debugPrint('tick');
          progress = duration.inSeconds / 30;
       }))
      ..start();
    }

    // other stuff omitted

}

它正在工作，但我仍然不满意.

It is working, but I'm still not satisfied.

原因是，股票报价回调现在每隔几毫秒而不是每秒一次被调用.在我看来，这似乎是对资源的浪费(我不需要平滑的动画)，...我是否使事情过于复杂了?

The reason is, that the ticker callback is getting now called every few milliseconds instead of once a second. This seems to me like a waste of resources (I don't need a smooth animation), ... am I overcomplicating things?

即使我的用例似乎不需要它，我仍然想知道:

Even if it seems that I don't need it for my use case, I still would like to know:

如何自行处理onPause/onResume事件?

How to handle the onPause/onResume events on my own?

推荐答案

您可以覆盖WidgetBindingObserver界面的didChangeAppLifecycleState以接收有关 app生命周期更改的通知.

You can override the didChangeAppLifecycleState of the WidgetBindingObserver interface to receive notifications for app lifecycle changes.

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