Android 颤振不'；如果有动画小部件，则无法重建

我在颤振中遇到了一个奇怪的问题。在我的应用程序中，我在初始化模型和其他东西之前显示一个启动屏幕，然后在应用程序期间显示一个不同的小部件

一切正常-除非第一个小部件包含任何动画（例如，

CircularProgressIndicator

）！在这种情况下，当我调用

setState

时，将不再调用

build

方法，即使我在几秒钟后从

计时器调用
setState

如果我在IDE中点击“热重启”或“热重新加载”，应用程序将按预期重建。如果第一个小部件不包含
循环进程指示器
，或任何其他动画小部件，它也可以工作

最简单的例子：

import 'dart:async';
import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

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

  @override
  _MyAppState createState() => _MyAppState();
}


class _MyAppState extends State<MyApp> {
  bool splash = true;

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

    Timer(Duration(milliseconds: 3000), (){
      if( mounted ) setState((){
        print('Enough splashing!');
        splash = false;
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    print('build   splash: $splash');

    return MaterialApp(
      title: 'FlutterTest',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: Text('FlutterTest'),
        ),
        body: Center(
          child: splash
            ? Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                CircularProgressIndicator(strokeWidth: 1, valueColor: AlwaysStoppedAnimation<Color>(Colors.red)),
                Text('Splash...', style: TextStyle(color: Colors.red))
              ],
            )
            : Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                Text('FlutterTest', style: TextStyle(color: Colors.blue)),
              ],
            ),
        ),
      )
    );
  }
}

无循环压缩器指示器的结果，或“热重新加载”/“热刷新”后的结果：

这是怎么回事

我在调试模式下的Android模拟器上看到了这一点

flutter doctor -v

[✓] Flutter (Channel stable, 1.20.3, on Mac OS X 10.15.1 19B88, locale en-SE)
    • Flutter version 1.20.3 at /Users/username/dev/flutter
    • Framework revision 216dee60c0 (5 weeks ago), 2020-09-01 12:24:47 -0700
    • Engine revision d1bc06f032
    • Dart version 2.9.2

 
[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
    • Android SDK at /Users/username/Library/Android/sdk
    • Platform android-30, build-tools 30.0.2
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1136-b06)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 11.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 11.1, Build version 11A1027
    • CocoaPods version 1.8.4

[!] Android Studio (version 3.2)
    • Android Studio at /Applications/Android Studio.app/Contents
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1136-b06)

[✓] IntelliJ IDEA Community Edition (version 2018.3)
    • IntelliJ at /Applications/IntelliJ IDEA CE.app
    • Flutter plugin version 32.0.2
    • Dart plugin version 183.4733

[✓] Connected device (1 available)
    • sdk gphone x86 (mobile) • emulator-5554 • android-x86 • Android 11 (API 30) (emulator)

更新

在另一台电脑上试过，效果很好。那台计算机有颤振版本1.12.13+修补程序。8，所以我尝试在计算机上更新颤振到1.22，但它不起作用。还是一样的结果。我检查了模拟器——它们在两台计算机上运行完全相同的API、系统映像、模拟器版本和相同的HAXM版本

在那台失败的电脑上，我尝试了一个较低的安卓API——它奏效了。因此，我尝试更新API 30的系统映像版本-新AVD仍然存在同样的问题。最后，我将emulator和HAXM更新为最新版本。现在它在API 30上工作。因此，问题似乎出在emulator/HAXM的某个地方，即使完全相同的版本在另一台计算机上工作。
使用future delayed with duration，或者在init状态下设置postframecallback以调用setState@Yadu没用。（您是否注意到我正在从
计时器
调用
setState
？）是的，这很奇怪，setState应该重建小部件，这就是正确的点！我在dartpad上尝试了上面的代码，它在两个应用程序中都能正常工作cases@MagnusW您可能应该发布该更新作为答案。你可能不会在这里得到关于这个问题的更多信息。如果您认为应该继续关注Github问题，最好发布它。请使用future delayed with duration，或者在init状态下设置postframecallback以调用setState@Yadu没用。（您是否注意到我正在从
计时器
调用
setState
？）是的，这很奇怪，setState应该重建小部件，这就是正确的点！我在dartpad上尝试了上面的代码，它在两个应用程序中都能正常工作cases@MagnusW您可能应该发布该更新作为答案。你可能不会在这里得到关于这个问题的更多信息。如果您认为应该继续关注Github问题，那么最好发布它。
I/flutter (19436): build   splash: true
I/flutter (19436): Enough splashing!
I/flutter (19436): build   splash: false    

flutter doctor -v

[✓] Flutter (Channel stable, 1.20.3, on Mac OS X 10.15.1 19B88, locale en-SE)
    • Flutter version 1.20.3 at /Users/username/dev/flutter
    • Framework revision 216dee60c0 (5 weeks ago), 2020-09-01 12:24:47 -0700
    • Engine revision d1bc06f032
    • Dart version 2.9.2

 
[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
    • Android SDK at /Users/username/Library/Android/sdk
    • Platform android-30, build-tools 30.0.2
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1136-b06)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 11.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 11.1, Build version 11A1027
    • CocoaPods version 1.8.4

[!] Android Studio (version 3.2)
    • Android Studio at /Applications/Android Studio.app/Contents
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1136-b06)

[✓] IntelliJ IDEA Community Edition (version 2018.3)
    • IntelliJ at /Applications/IntelliJ IDEA CE.app
    • Flutter plugin version 32.0.2
    • Dart plugin version 183.4733

[✓] Connected device (1 available)
    • sdk gphone x86 (mobile) • emulator-5554 • android-x86 • Android 11 (API 30) (emulator)