Flutter Animation AnimatedBuilder

创建动画的widget

Key key,

@required Listenable animation,

@required this.builder,

this.child,

animation：Animationcontroller //动画

child 动画作用的view

builder：每次controller值改变都会回到builder 重新生成view

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      initialRoute: '/buildAnimation',
      routes: {
        '/':(context)=>AnimationDemo(),
        '/test':(context)=>TestAnimation(),
        '/buildAnimation':(context)=>BuildAnimation(),
      },
    );
  }
}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

class BuildAnimation extends StatefulWidget{
  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return BuildAnimationState();
  }
}

class BuildAnimationState extends State<BuildAnimation> with TickerProviderStateMixin{
  AnimationController animationController;
  var animation;

  @override
  void initState() {
    super.initState();
    animationController = AnimationController(
        duration: Duration(seconds: 2),
        vsync: this);
    animation = Tween(begin: 20, end: 200).animate(animationController);
    animationController.forward();   //放到某个其他地方去启动, 会唤起Builder
  }


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('builder'),),
      body: Container(
         double.infinity,
        height: double.infinity,
        child: Stack(
          children: <Widget>[
            AnimatedBuilder(
              animation: animation,
              builder: (context, Widget child){  //child 可以定义要动的东西....这里先暂时省略了.
                return Positioned(
                  left: animation.value/1.0,
                  top: animation.value/1.0,
                  child: Container(child: RaisedButton(
                  child: Text('abc'),onPressed: (){
                    print(animation.value);
                  }),),
                );
              },
            ),
          ],
        ),
      ),
    );
  }
}



///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
class TestAnimation extends StatefulWidget{
  @override
  State<StatefulWidget> createState() {
    return TestAnimationState();
  }
}

class TestAnimationState extends State<TestAnimation> with TickerProviderStateMixin{
  AnimationController animationController;
  Tween positionTween = Tween(begin: 20, end: 200);
  var animation;

  @override
  void initState() {
    super.initState();
    animationController = AnimationController(
        vsync: this,
        duration: Duration(seconds: 1),
    );
     animation = positionTween.animate(animationController);

     animationController.addListener((){
       print(animationController.value);
     });
     animationController.addStatusListener((value){
       print('status: $value');
     });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('test'),),
      body: Container(
         double.infinity,
        height: double.infinity,
        color: Colors.black12,
        child: TestAnimationDemo(animationController: animationController,animation:animation),
      ),
    );
  }
}

class TestAnimationDemo extends AnimatedWidget {
  AnimationController animationController;
  Animation animation;
  TestAnimationDemo({this.animationController, this.animation}):super(listenable:animationController);

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: <Widget>[
        Positioned(
          left: animation.value/1.0,
          top: animation.value/1.0,
          child: Container(
            child: IconButton(icon: Icon(Icons.forward), onPressed: (){
              animationController.forward();
            }),
          ),
        ),
      ],
    );
  }
}



/////////////////////////////////////////////////////////////////////////////////////////////////////////
class AnimationDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text('AnimationDemo'),
          elevation: 0.0,
        ),
        body: AnimationDemoHome());
  }
}
/////////////////////////////////////////////////////////////////////////////////////////////////////////
class AnimationDemoHome extends StatefulWidget {
  @override
  _AnimationDemoHomeState createState() => _AnimationDemoHomeState();
}

class _AnimationDemoHomeState extends State<AnimationDemoHome>
    with TickerProviderStateMixin {
  AnimationController animationDemoController;
  Animation animation;
  Animation animationColor;
  CurvedAnimation curve;

  @override
  void initState() {
    super.initState();
    animationDemoController = AnimationController(
      // value: 32.0,
      // lowerBound: 32.0,
      // upperBound: 100.0,
      duration: Duration(milliseconds: 1000),
      vsync: this,
    );

    curve = CurvedAnimation(
        parent: animationDemoController, curve: Curves.bounceOut);

    animation = Tween(begin: 32.0, end: 100.0).animate(curve);
    animationColor =
        ColorTween(begin: Colors.red, end: Colors.red[900]).animate(curve);
    // animationDemoController.addListener(() {
    //   // print('${animationDemoController.value}');
    //   setState(() {});
    // });
    animationDemoController.addStatusListener((AnimationStatus status) {
      print(status);
    });
    // animationDemoController.forward();
  }

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

  @override
  Widget build(BuildContext context) {
    return Center(
      child: AnimatedHeart(
        animations: [
          animation,
          animationColor,
        ],
        controller: animationDemoController,
      ),
    );
  }
}


class AnimatedHeart extends AnimatedWidget {
  final List animations;
  final AnimationController controller;

  AnimatedHeart({
    this.animations,
    this.controller,
  }) : super(listenable: controller);

  @override
  Widget build(BuildContext context) {
    return IconButton(
      icon: Icon(Icons.favorite),
      iconSize: animations[0].value,
      color: animations[1].value,
      onPressed: () {
        switch (controller.status) {
          case AnimationStatus.completed:
            controller.reverse();
            break;
          default:
            controller.forward();
        }
      },
    );
  }
}