animateScale.dart

animateScale.dart

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

enum AnimationOptions { None, Transform }

void main() {
  var app = new Scaffold(
    body:new AnimationDemo()
  );

  runApp(new MaterialApp(home: app));  
}

class AnimationDemo extends StatefulWidget {
  @override
  _AnimationDemoState createState() => new _AnimationDemoState();
}

class _AnimationDemoState extends State<AnimationDemo> with TickerProviderStateMixin {
  AnimationController controller;
  @override
  void initState() {
    super.initState();

    controller = new AnimationController(
      duration: const Duration(milliseconds: 2000),
      vsync: this
    );
  }

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

  Widget build(BuildContext context) {
    return new Screen1(controller);
  }
}

class Screen1 extends StatelessWidget {
  Screen1(this.animationController);

  final AnimationController animationController;
  static AnimationOptions currentAnimation = AnimationOptions.None;
 
  Future<Null> playAnimation(animationOption) async {
    try {
      currentAnimation = animationOption;
      animationController.reset();
      await animationController.forward().orCancel;
      currentAnimation = AnimationOptions.None;
    } on TickerCanceled {
      // the animation got canceled, probably because we were disposed
    }   
  }  

  @override
  Widget build(BuildContext context) {
    return new Scaffold( // 1
      appBar: new AppBar(
        title: new Text("Animation Styles"), // screen title
      ),
      body: new Column(
          crossAxisAlignment: CrossAxisAlignment.center,
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: <Widget>[
            new FlatButton(
              child: new Text(" 1st Animate"),
              onPressed: () { 
                 this.playAnimation(AnimationOptions.Transform);
              },
            ),
            new AnimationWidget( controller: this.animationController.view),
          ]
        )
      //)
    );
  } 
}

class AnimationWidget extends StatelessWidget {
  AnimationWidget({ Key key, this.controller }) :
    super(key: key) {
      initializeAnimations();
  }
  
  initializeAnimations() {
    scale = new Tween<double>(
      begin: 1.0,
      end: 0.6,
    ).animate(
      new CurvedAnimation(
        parent: controller,
        curve: new Interval(
          0.0, 1.0,
          curve: Curves.ease,
        ),
      ),
    ); 
  }
  
  final Animation<double> controller;
  Animation<double> scale;

  _animateBuilder(BuildContext context, Widget child){
    switch (Screen1.currentAnimation) {
      case AnimationOptions.Transform:
       return  _animateTransform1(context, child);
      default:
        return  _noAnimation(context, child);
    }
  }

   Widget _animateTransform1(BuildContext context, Widget child) {
    var matrix = new Matrix4.identity()
                          ..scale(scale.value, scale.value, scale.value);

    return  new Transform(
      alignment: Alignment.center,
        transform: matrix,
        child: new Container(
        width: 200.0,
        height: 200.0,
        color: Colors.blue,
      ),
    );
  }

  Widget _noAnimation(BuildContext context, Widget child) {
    return new Container(
      child: new Container(
        width: 200.0,
        height: 200.0,
        color: Colors.blue,
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return new AnimatedBuilder(
      builder: _animateBuilder,
      animation: controller,
    );
  }
}