Flutter 必备

1、图片控件
图片使用
2、动画

import 'package:flutter/material.dart';

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

class LogoApp extends StatefulWidget {
  @override
  _LogoAppState createState() => _LogoAppState();
}

/// SingleTickerProviderStateMixin 资源回收
class _LogoAppState extends State<LogoApp> with SingleTickerProviderStateMixin {

  Animation<double> animation;
  AnimationController controller;
  AnimationStatus animationStatus;
  double animationValue;
  @override
  void initState() {
    super.initState();
    controller = AnimationController(vsync: this, duration: Duration(seconds: 2));
    animation = Tween<double>(begin: 0, end: 300).animate(controller)
    ..addListener((){
      setState(() {
        animationValue = animation.value;
      });
    })
    ..addStatusListener((AnimationStatus status){
      setState(() {
        animationStatus = status;
      });
    });
  }

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

  @override
  Widget build(BuildContext context) {
    return Container(
      margin: EdgeInsets.only(top: 64),
      child: Column(
        children: <Widget>[
          GestureDetector(
            onTap: () {
              controller.reset();
              controller.forward();
            },
            child: Text('Start', textDirection: TextDirection.ltr,),
          ),
          Text('State' + animationStatus.toString(), textDirection: TextDirection.ltr,),
          Text('Value' + animationValue.toString(), textDirection: TextDirection.ltr,),
          Container(
            height: animation.value,
            width: animation.value,
            child: FlutterLogo(),
          ),
        ],
      ),
    );
  }
}

AnimatedWidget

import 'package:flutter/material.dart';

class AnimatedLogo extends AnimatedWidget {

  AnimatedLogo({Key key, Animation<double> animation}) : super(key: key, listenable: animation);

  @override
  Widget build(BuildContext context) {
    final Animation<double> animation = listenable;
    return Center(
      child: Container(
        margin: EdgeInsets.symmetric(vertical: 10),
        height: animation.value,
        width: animation.value,
        child: FlutterLogo(),
      ),
    );
  }
}

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

class LogoApp extends StatefulWidget {
  @override
  _LogoAppState createState() => _LogoAppState();
}

/// SingleTickerProviderStateMixin 资源回收
class _LogoAppState extends State<LogoApp> with SingleTickerProviderStateMixin {

  Animation<double> animation;
  AnimationController controller;
  AnimationStatus animationStatus;
  double animationValue;
  @override
  void initState() {
    super.initState();
    controller = AnimationController(vsync: this, duration: Duration(seconds: 2));
    animation = Tween<double>(begin: 0, end: 300).animate(controller);
    controller.forward();
  }

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

  @override
  Widget build(BuildContext context) {
    return AnimatedLogo(animation: animation,);
  }
}

AnimatedBuilder

import 'package:flutter/material.dart';

class LogoWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) => Container(
        margin: EdgeInsets.symmetric(vertical: 10),
        child: FlutterLogo(),
      );
}

class GrowTransition extends StatelessWidget {
  GrowTransition(this.child, this.animation);

  final Widget child;
  final Animation<double> animation;

  @override
  Widget build(BuildContext context) => Center(
        child: AnimatedBuilder(
          animation: animation,
          builder: (context, child) => Container(
            child: child,
            height: animation.value,
            width: animation.value,
          ),
          child: child,
        ),
      );
}

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

class LogoApp extends StatefulWidget {
  @override
  _LogoAppState createState() => _LogoAppState();
}

/// SingleTickerProviderStateMixin 资源回收
class _LogoAppState extends State<LogoApp> with SingleTickerProviderStateMixin {
  Animation<double> animation;
  AnimationController controller;
  AnimationStatus animationStatus;
  double animationValue;

  @override
  void initState() {
    super.initState();
    controller =
        AnimationController(vsync: this, duration: Duration(seconds: 2));
    animation = Tween<double>(begin: 0, end: 300).animate(controller);
    controller.forward();
  }

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

  @override
  Widget build(BuildContext context) => GrowTransition(LogoWidget(), animation);
}

Hero动画

import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart' show timeDilation;

void main() => runApp(MaterialApp(home: HeroAnimation(),));

class PhotoHero extends StatelessWidget {
  final String photo;
  final VoidCallback onTap;
  final double width;

  const PhotoHero({Key key, this.photo, this.onTap, this.width})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: width,
      child: Hero(
          tag: photo,
          child: Material(
            color: Colors.transparent,
            child: InkWell(
              onTap: onTap,
              child: Image.network(
                photo,
                fit: BoxFit.contain,
              ),
            ),
          )),
    );
  }
}

class HeroAnimation extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    timeDilation = 5.0;
    return Scaffold(
      appBar: AppBar(
        title: const Text('Basic hero animation'),
      ),
      body: Center(
        child: PhotoHero(
          photo: 'https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1576745823025&di=8067dd52c36dffd837f122247a609792&imgtype=0&src=http%3A%2F%2Fimg9.zol.com.cn%2Fdp_800%2F248%2F247227.jpg',
          width: 300,
          onTap: () {
            Navigator.of(context).push(
                MaterialPageRoute<void>(builder: (BuildContext context) {
                  return Scaffold(
                    appBar: AppBar(
                      title: const Text('Flipper page'),
                    ),
                    body: Container(
                      color: Colors.lightBlueAccent,
                      padding: const EdgeInsets.all(16),
                      alignment: Alignment.topLeft,
                      child: PhotoHero(
                        photo: 'https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1576745823025&di=8067dd52c36dffd837f122247a609792&imgtype=0&src=http%3A%2F%2Fimg9.zol.com.cn%2Fdp_800%2F248%2F247227.jpg',
                        width: 100,
                        onTap: () {
                          Navigator.of(context).pop();
                        },
                      ),
                    ),
                  );
                })
            );
          },
        ),
      ),
    );
  }
}

高阶待续…