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flutter: WidgetsBindingObserver

flutter: WidgetsBindingObserver

作者: ChaosHeart | 来源:发表于2020-08-24 17:01 被阅读0次

    WidgetsBindingObserver : 检测页面生命周期
    代码:

    class FlutterLifeCycleState extends State<FlutterLifeCycle>
        with WidgetsBindingObserver {
      @override
      void initState() {
        super.initState();
        WidgetsBinding.instance.addObserver(this); //添加观察者
      }
    
      ///生命周期变化时回调
    //  resumed:应用可见并可响应用户操作
    //  inactive:用户可见,但不可响应用户操作
    //  paused:已经暂停了,用户不可见、不可操作
    //  suspending:应用被挂起,此状态IOS永远不会回调
      @override
      void didChangeAppLifecycleState(AppLifecycleState state) {
        super.didChangeAppLifecycleState(state);
        print("@@@@@@@@@  didChangeAppLifecycleState: $state");
      }
    
      ///当前系统改变了一些访问性活动的回调
      @override
      void didChangeAccessibilityFeatures() {
        super.didChangeAccessibilityFeatures();
        print("@@@@@@@@@ didChangeAccessibilityFeatures");
      }
    
      /// Called when the system is running low on memory.
      ///低内存回调
      @override
      void didHaveMemoryPressure() {
        super.didHaveMemoryPressure();
        print("@@@@@@@@@ didHaveMemoryPressure");
      }
    
      /// Called when the system tells the app that the user's locale has
      /// changed. For example, if the user changes the system language
      /// settings.
      ///用户本地设置变化时调用,如系统语言改变
      @override
      void didChangeLocales(List<Locale> locale) {
        super.didChangeLocales(locale);
        print("@@@@@@@@@ didChangeLocales");
      }
    
      /// Called when the application's dimensions change. For example,
      /// when a phone is rotated.
      ///应用尺寸改变时回调,例如旋转
      @override
      void didChangeMetrics() {
        super.didChangeMetrics();
        Size size = WidgetsBinding.instance.window.physicalSize;
        print("@@@@@@@@@ didChangeMetrics  :宽:${size.width} 高:${size.height}");
      }
    
      /// {@macro on_platform_brightness_change}
      @override
      void didChangePlatformBrightness() {
        super.didChangePlatformBrightness();
        print("@@@@@@@@@ didChangePlatformBrightness");
      }
    
      ///文字系数变化
      @override
      void didChangeTextScaleFactor() {
        super.didChangeTextScaleFactor();
        print(
            "@@@@@@@@@ didChangeTextScaleFactor  :${WidgetsBinding.instance.window.textScaleFactor}");
      }
    
      @override
      Widget build(BuildContext context) {
        return Container(
          child: Center(
            child: Text("flutter"),
          ),
        );
      }
    
      @override
      void dispose() {
        super.dispose();
        WidgetsBinding.instance.removeObserver(this); //销毁观察者
      }
    }
    
    

    控制台:

    //屏幕旋转
    //竖屏切横屏
    //2019-05-22 09:04:58.350 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeLocales
    //2019-05-22 09:04:58.353 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeTextScaleFactor  :1.0
    //2019-05-22 09:04:58.354 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangePlatformBrightness
    //2019-05-22 09:04:58.401 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeLocales
    //2019-05-22 09:04:58.402 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeTextScaleFactor  :1.0
    //2019-05-22 09:04:58.402 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangePlatformBrightness
    //2019-05-22 09:04:58.404 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeMetrics  :宽:1080.0 高:2280.0
    //2019-05-22 09:04:58.405 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeMetrics  :宽:2198.0 高:1080.0
    //横屏切竖屏
    //2019-05-22 09:05:05.714 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeLocales
    //2019-05-22 09:05:05.715 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeTextScaleFactor  :1.0
    //2019-05-22 09:05:05.715 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangePlatformBrightness
    //2019-05-22 09:05:05.766 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeLocales
    //2019-05-22 09:05:05.767 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeTextScaleFactor  :1.0
    //2019-05-22 09:05:05.767 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangePlatformBrightness
    //2019-05-22 09:05:05.768 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeMetrics  :宽:2198.0 高:1080.0
    //2019-05-22 09:05:05.769 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeMetrics  :宽:1080.0 高:2280.0
    
    //改变系统语言,回到应用才调用以下方法
    //2019-05-22 09:08:04.428 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeLocales
    //2019-05-22 09:08:04.429 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangeTextScaleFactor  :1.0
    //2019-05-22 09:08:04.429 27881-27901/com.yourcompany.test1 I/flutter: @@@@@@@@@ didChangePlatformBrightness
    
    
    //  inactive:用户可见,但不可响应用户操作
    //  resumed:应用可见并可响应用户操作
    //  paused:已经暂停了,用户不可见、不可操作
    //  suspending:应用被挂起,此状态IOS永远不会回调
    
    //  Home键退出,锁屏
    //  2019-05-22 08:29:26.321 27526-27546/com.yourcompany.test1 I/flutter:  AppLifecycleState.inactive
    //  2019-05-22 08:29:26.378 27526-27546/com.yourcompany.test1 I/flutter: AppLifecycleState.paused
    //  Home键退出后再点击应用图标启动,解锁屏幕
    //  2019-05-22 08:30:37.533 27526-27546/com.yourcompany.test1 I/flutter: AppLifecycleState.inactive
    //  2019-05-22 08:30:37.535 27526-27546/com.yourcompany.test1 I/flutter: AppLifecycleState.resumed
    //  进入该页面或者back键退出该页面,没有调用didChangeAppLifecycleState方法
    

    参考:
    https://www.jianshu.com/p/2fd5562c1c9b

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