fade slide animation flutter - flutter

Question

I saw many webs when scroll down they have slide fade animations on their widgetI am wondering how they work! Any example with fade slide animation will be appreciated
New to flutter wondering how to do where to start

Answer 1

Try this code
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
/// This Widget is the main application widget.
class MyApp extends StatelessWidget {
static const String _title = 'Flutter Code Sample';
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: _title,
home: FadeTransitionExample(),
);
}
}
class FadeTransitionExample extends StatefulWidget {
#override
State<StatefulWidget> createState() => _Fade();
}
class _Fade extends State<FadeTransitionExample> with TickerProviderStateMixin {
AnimationController? animationController;
Animation<double>? _animationValue;
#override
void initState() {
super.initState();
animationController = AnimationController(vsync: this, duration: const Duration(seconds: 2),);
_animationValue = Tween<double>(begin: 0.0, end: 0.5).animate(animationController!);
animationController!.addStatusListener((status){
if(status == AnimationStatus.completed){
animationController!.reverse();
}
else if(status == AnimationStatus.dismissed){
animationController!.forward();
}
});
animationController!.forward();
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
child: Center(
child: FadeTransition(
opacity: _animationValue!,
child: Container(
color: Colors.blue,
width: 150,
height: 150,
),
),
),
),
);
}
}