如何使用Flutter AnimationController和Transform旋转图像？

Question

我有星星png图像，我需要使用Flutter AnimationController和Transformer旋转星星。我找不到图像旋转动画的任何文档或示例。

任何想法如何使用Flutter AnimationController和Transform旋转图像？

更新：

class _MyHomePageState extends State<MyHomePage>  with TickerProviderStateMixin {

  AnimationController animationController;

  @override
  void initState() {
    super.initState();
    animationController = new AnimationController(
      vsync: this,
      duration: new Duration(milliseconds: 5000),
    );
    animationController.forward();
    animationController.addListener(() {
      setState(() {
        if (animationController.status == AnimationStatus.completed) {
          animationController.repeat();
        }
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return new Container(
      alignment: Alignment.center,
      color: Colors.white,
      child: new AnimatedBuilder(
        animation: animationController,
        child: new Container(
          height: 80.0,
          width: 80.0,
          child: new Image.asset('images/StarLogo.png'),
        ),
        builder: (BuildContext context, Widget _widget) {
          return new Transform.rotate(
            angle: animationController.value,
            child: _widget,
          );
        },
      ),
    );
  }
}

Answer 1

屏幕截图（空安全）

完整代码：

import 'dart:math' as math;

class _FooPageState extends State<FooPage> with SingleTickerProviderStateMixin{
  late final AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(vsync: this, duration: Duration(seconds: 2))..repeat();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: AnimatedBuilder(
          animation: _controller,
          builder: (_, child) {
            return Transform.rotate(
              angle: _controller.value * 2 * math.pi,
              child: child,
            );
          },
          child: FlutterLogo(size: 200),
        ),
      ),
    );
  }
}

Answer 2

这是我旋转图像的示例。我不知道-但也许适合您

AnimationController rotationController;

@override
void initState() {
  rotationController = AnimationController(duration: const Duration(milliseconds: 500), vsync: this);
  super.initState();
}
//...
RotationTransition(
  turns: Tween(begin: 0.0, end: 1.0).animate(rotationController),
  child: ImgButton(...)
//...
rotationController.forward(from: 0.0); // it starts the animation

UPD-如何解决问题 Transform.rotate

在您的情况下，所有功能均与您编写的完全一样-将图片从0.0旋转到1.0（这是的默认参数AnimationController）。对于完整的圆，您必须将上参数设置为2 * pi（来自math程序包）

import 'dart:math';
//...
animationController = AnimationController(vsync: this, duration: Duration(seconds: 5), upperBound: pi * 2);

Answer 3

完整示例：

按“执行”使星形图标旋转，直到按“停止”。

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> with TickerProviderStateMixin {
  AnimationController _controller;

  @override
  void initState() {
    _controller = AnimationController(
      duration: const Duration(milliseconds: 5000),
      vsync: this,
    );
    super.initState();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          children: <Widget>[
            RotationTransition(
              turns: Tween(begin: 0.0, end: 1.0).animate(_controller),
              child: Icon(Icons.stars),
            ),
            RaisedButton(
              child: Text("go"),
              onPressed: () => _controller.forward(),
            ),
            RaisedButton(
              child: Text("stop"),
              onPressed: () => _controller.reset(),
            ),
          ],
        ),
      ),
    );
  }
}

分步指南：

首先，让您的窗口小部件状态类实现TickerProviderStateMixin。

其次，定义一个AnimationController并且不要忘记处理它。

AnimationController _controller;

@override
void initState() {
  _controller = AnimationController(
    duration: const Duration(milliseconds: 5000),
    vsync: this,
  );
  super.initState();
}

@override
void dispose() {
  _controller.dispose();
  super.dispose();
}

然后Widget用RotationTransition。

RotationTransition(
  turns: Tween(begin: 0.0, end: 1.0).animate(_controller),
  child: Icon(Icons.stars),
),

最后，调用上的方法AnimationController以开始/停止动画。

• 运行动画一次，使用 ::forward
• 无限重复，使用 ::repeat
• 立即停止使用 ::stop
• 停止并重新设置为原始旋转，使用 ::reset
• 停止并为旋转设置动画，使用 ::animateTo

Answer 4

在这里，我将动画生成器放在 Stack 中。然后你可以动画图像右旋转（顺时针）和左旋转（逆时针）。

import 'package:flutter/material.dart';
import 'package:fynd/services/auth.dart';
import 'dart:async';
import 'package:fynd/services/cons.dart';

class SplashScreen extends StatefulWidget {
  _SplashScreen createState() => new _SplashScreen();
}

class _SplashScreen extends State<StatefulWidget>
    with SingleTickerProviderStateMixin {
  AnimationController animationController;

  @override
  void initState() {
    super.initState();
    animationController = new AnimationController(
      vsync: this,
      duration: new Duration(seconds: 5),
    );

    animationController.repeat();

  }

  @override
  Widget build(BuildContext context)

    return new Container(
      alignment: Alignment.center,
      color: Colors.white,

      child: new Stack(children: <Widget>[

        new AnimatedBuilder(
          animation: animationController,
          child :Container(
            decoration: BoxDecoration(
                image: DecorationImage(image: AssetImage('assets/images/splash_circle3.png'),fit: BoxFit.cover)),

          ),
          builder: (BuildContext context, Widget _widget) {
            return new Transform.rotate(
              angle: animationController.value * 10,
              child: _widget,
            );
          },
        ),

       new AnimatedBuilder(
        animation: animationController,
        child: Container(
          decoration: BoxDecoration(
              image: DecorationImage(image: AssetImage('assets/images/splash_circle2.png'),fit: BoxFit.cover)),

        ),
        builder: (BuildContext context, Widget _widget) {
          return new Transform.rotate(
            angle: -animationController.value * 10,
            child: _widget,
          );
        },
       ),

        new AnimatedBuilder(
            animation: animationController,
           child: Container(
              decoration: BoxDecoration(
                  image: DecorationImage(image: AssetImage('assets/images/splash_circle1.png'), fit: BoxFit.cover)),
            ),
            builder: (BuildContext context, Widget _widget) {
              return new Transform.rotate(
                angle: animationController.value * 10,
                child: _widget,
              );
            }),

      ],),
    );
  }
}