Flutter有一的动画引擎很强大, 可以为应用添加任何的效果个动画,但是有些时候,有些效果和动画并不需要那么炫酷,比如淡入淡出.
Flutter同样也提供了很多转场可以加入应用中,比如FadeTransition,FadeTransition可以对Widget进行淡入淡出效果,它只需要一个子项和一个动画.

fadetranstion.gif

import 'package:flutter/material.dart';

class GoogleFadeTransition extends StatefulWidget {
  @override
  GoogleFadeTransitionState createState() => new GoogleFadeTransitionState();
}

class GoogleFadeTransitionState extends State<GoogleFadeTransition> with SingleTickerProviderStateMixin{
  AnimationController _controller;
  Animation _animation;
  @override
  Widget build(BuildContext context) {
    _controller.forward();
    return FadeTransition(
      child: Container(
        color: Colors.red,
        width: 200.0,
        height: 200.0,
      ),
      opacity: _animation,
    );
  }

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 2),
    );
    _animation = Tween(
      begin: 0.0,
      end: 1.0,
    ).animate(_controller);
  }

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

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代码github