英雄动画在Flutter中不起作用

问题内容：

因此，我正试图为一家杂乱无章的餐厅制作送货上门的应用程序，而我的英雄动画似乎无法正常工作。首先，我创建了一个初始屏幕，其中显示徽标，然后导航到该徽标应该进行英雄转换的主页。初始屏幕和主页位于两个独立的dart文件中。这是我的初始屏幕的代码：

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

class Splash extends StatefulWidget {
  @override
  _SplashState createState() => new _SplashState();
}

class _SplashState extends State<Splash> with SingleTickerProviderStateMixin 
{

  Animation<double> _mainLogoAnimation;
  AnimationController _mainLogoAnimationController;

  @override
  void initState() {
    super.initState();
    goToHomePage();
    _mainLogoAnimationController = new AnimationController(duration: new Duration(milliseconds: 2500) ,vsync: this);
    _mainLogoAnimation = new CurvedAnimation(parent: 
    _mainLogoAnimationController, curve: Curves.easeIn);
    _mainLogoAnimation.addListener(() => (this.setState(() {})));
    _mainLogoAnimationController.forward();
  }

  Future goToHomePage() async {
    await new Future.delayed(const Duration(milliseconds: 4000));
    Navigator.of(context).push(new MaterialPageRoute(builder: (BuildContext context) => new HomePage()));
  }

  @override
  Widget build(BuildContext context) {
    return new Material(
      color: Colors.black,
      child: new Center(
        child: new Opacity(
          opacity: 1.0 * _mainLogoAnimation.value,
          child: new Hero(
            tag: 'tbh_logo',
            child: new Image(
              image: new AssetImage('assets/images/tbh_main_logo.png'),
              width: 300.0
            )
          )
        )
      )
    );
  }
}

And here’s the code for the home page:

import 'package:flutter/material.dart';
import '../ui/drawer.dart';
import 'splash.dart';

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => new _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("The Barni House"),
        backgroundColor: Colors.black,
      ),
      drawer: new Drawer(child: MyDrawer()),
      body: new Center(
        child: Column(
          children: <Widget>[
            new Container(
              child: new Hero(
                tag: 'tbh_logo',
                child: new Image(
                  image: new AssetImage('assets/images/tbh_main_logo.png'),
                  width: 300.0
                )
              )
            )
          ],
        )
      ),
    );
  }
}

问题答案：

检查您的代码，使英雄动画正常工作，但是由于过渡持续时间仅为300毫秒，因此动画发生得很快。

要获得以下结果，您可以创建一个Custom MaterialPageRoute。

Before

@override
  Duration get transitionDuration => const Duration(milliseconds: 300);

After

@override
  Duration get transitionDuration => const Duration(milliseconds: 1000);

Also, you can play with the CurvedAnimation

new CurvedAnimation(
                parent: routeAnimation,
                curve: Curves.elasticIn,
              )

CustomRoute.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';

final Tween<Offset> _kBottomUpTween = new Tween<Offset>(
  begin: const Offset(0.0, 1.0),
  end: Offset.zero,
);

// Offset from offscreen to the right to fully on screen.
final Tween<Offset> _kRightMiddleTween = new Tween<Offset>(
  begin: const Offset(1.0, 0.0),
  end: Offset.zero,
);

// Offset from offscreen below to fully on screen.
class AppPageRoute extends MaterialPageRoute<String> {
  @override
  final bool maintainState;

  @override
  final WidgetBuilder builder;
  CupertinoPageRoute<String> _internalCupertinoPageRoute;

  AppPageRoute({
    @required this.builder,
    RouteSettings settings: const RouteSettings(),
    this.maintainState: true,
    bool fullscreenDialog: false,
  })  : assert(builder != null),
        assert(settings != null),
        assert(maintainState != null),
        assert(fullscreenDialog != null),
        super(
          settings: settings,
          fullscreenDialog: fullscreenDialog,
          builder: builder,
        ) {
    assert(opaque); // PageRoute makes it return true.
  }

  @override
  Color get barrierColor => null;

  @override
  Duration get transitionDuration => const Duration(milliseconds: 1000);

  CupertinoPageRoute<String> get _cupertinoPageRoute {
    assert(_useCupertinoTransitions);
    _internalCupertinoPageRoute ??= new CupertinoPageRoute<String>(
      builder: builder,
      fullscreenDialog: fullscreenDialog,
      hostRoute: this,
    );
    return _internalCupertinoPageRoute;
  }

  bool get _useCupertinoTransitions {
    return _internalCupertinoPageRoute?.popGestureInProgress == true ||
        Theme.of(navigator.context).platform == TargetPlatform.iOS;
  }

  @override
  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
    final Widget result = builder(context);
    assert(() {
      if (result == null) {
        throw new FlutterError('The builder for route "${settings.name}" returned null.\n'
            'Route builders must never return null.');
      }
      return true;
    }());
    return result;
  }

  @override
  Widget buildTransitions(
      BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation, Widget child) {
    if (_useCupertinoTransitions) {
      return _cupertinoPageRoute.buildTransitions(context, animation, secondaryAnimation, child);
    }

    return new _CustomPageTransition(routeAnimation: animation, child: child, fullscreenDialog: fullscreenDialog);
  }
}

class _CustomPageTransition extends StatelessWidget {
  final Animation<Offset> _positionAnimation;

  final Widget child;
  final bool fullscreenDialog;

  _CustomPageTransition({
    Key key,
    @required Animation<double> routeAnimation,
    @required this.child,
    @required this.fullscreenDialog,
  })  : _positionAnimation = !fullscreenDialog
            ? _kRightMiddleTween.animate(new CurvedAnimation(
                parent: routeAnimation,
                curve: Curves.elasticIn,
              ))
            : _kBottomUpTween.animate(new CurvedAnimation(
                parent: routeAnimation, // The route's linear 0.0 - 1.0 animation.
                curve: Curves.elasticIn,
              )),
        super(key: key);

  @override
  Widget build(BuildContext context) {
    return new SlideTransition(
      position: _positionAnimation,
      child: child,
    );
  }
}

Push new Route

 Future goToHomePage() async {
    await new Future.delayed(const Duration(milliseconds: 4000));
    Navigator.of(context).push(new AppPageRoute(builder: (BuildContext context) => new HomePage()));
  }

您可以将“自定义MaterialPageRoute”用于初始屏幕和其他路线MaterialPageRoute。

希望能帮助到你

英雄动画在Flutter中不起作用

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