How can I make a "show up" text animation in Flutter? - flutter

Question

I want to achieve the kind of behavior shown in the material.io page:
The text does a nice transition when is being shown for the first time.
How can I do that in Flutter?

Answer 1

You can compose widgets like this:
import 'dart:async';
import 'package:flutter/material.dart';
class ShowUp extends StatefulWidget {
final Widget child;
final int delay;
ShowUp({#required this.child, this.delay});
#override
_ShowUpState createState() => _ShowUpState();
}
class _ShowUpState extends State<ShowUp> with TickerProviderStateMixin {
AnimationController _animController;
Animation<Offset> _animOffset;
#override
void initState() {
super.initState();
_animController =
AnimationController(vsync: this, duration: Duration(milliseconds: 500));
final curve =
CurvedAnimation(curve: Curves.decelerate, parent: _animController);
_animOffset =
Tween<Offset>(begin: const Offset(0.0, 0.35), end: Offset.zero)
.animate(curve);
if (widget.delay == null) {
_animController.forward();
} else {
Timer(Duration(milliseconds: widget.delay), () {
_animController.forward();
});
}
}
#override
void dispose() {
super.dispose();
_animController.dispose();
}
#override
Widget build(BuildContext context) {
return FadeTransition(
child: SlideTransition(
position: _animOffset,
child: widget.child,
),
opacity: _animController,
);
}
}
Then you can use it like this:
int delayAmount = 500;
...........
...........
...........
Column(
children: <Widget>[
ShowUp(
child: Text("The first texto to be shown"),
delay: delayAmount,
),
ShowUp(
child: Text("The text below the first"),
delay: delayAmount + 200,
),
ShowUp(
child: Column(
children: <Widget>[
Text("Texts together 1"),
Text("Texts together 2"),
Text("Texts together 3"),
],
),
delay: delayAmount + 400,
),
],
),
Note that this "ShowUp" widgets can animate anything, not just texts.

Answer 2

There's an existing package called show_up_animation for it which is based on the implementation below.
This is a generalized widget to provide this animation. All you have to do is to wrap your widget(yes, any widget) inside SlideFadeTransition widget and voila!
It gives a lot of control. For example, you can control the amount, speed, direction, delay and even the curve of the animation.
///Wrapper class to implement slide and fade animations at the same time to
///a given element. Wrap the widget that you wish to appear with slide-fade
///transition in this class.
import 'dart:async';
import 'package:flutter/material.dart';
enum Direction { vertical, horizontal }
class SlideFadeTransition extends StatefulWidget {
///The child on which to apply the given [SlideFadeTransition]
final Widget child;
///The offset by which to slide and [child] into view from [Direction].
///Defaults to 0.2
final double offset;
///The curve used to animate the [child] into view.
///Defaults to [Curves.easeIn]
final Curve curve;
///The direction from which to animate the [child] into view. [Direction.horizontal]
///will make the child slide on x-axis by [offset] and [Direction.vertical] on y-axis.
///Defaults to [Direction.vertical]
final Direction direction;
///The delay with which to animate the [child]. Takes in a [Duration] and
/// defaults to 0.0 seconds
final Duration delayStart;
///The total duration in which the animation completes. Defaults to 800 milliseconds
final Duration animationDuration;
SlideFadeTransition({
#required this.child,
this.offset = 0.2,
this.curve = Curves.easeIn,
this.direction = Direction.vertical,
this.delayStart = const Duration(seconds: 0),
this.animationDuration = const Duration(milliseconds: 800),
});
#override
_SlideFadeTransitionState createState() => _SlideFadeTransitionState();
}
class _SlideFadeTransitionState extends State<SlideFadeTransition>
with SingleTickerProviderStateMixin {
Animation<Offset> _animationSlide;
AnimationController _animationController;
Animation<double> _animationFade;
#override
void initState() {
super.initState();
_animationController = AnimationController(
vsync: this,
duration: widget.animationDuration,
);
//configure the animation controller as per the direction
if (widget.direction == Direction.vertical) {
_animationSlide =
Tween<Offset>(begin: Offset(0, widget.offset), end: Offset(0, 0))
.animate(CurvedAnimation(
curve: widget.curve,
parent: _animationController,
));
} else {
_animationSlide =
Tween<Offset>(begin: Offset(widget.offset, 0), end: Offset(0, 0))
.animate(CurvedAnimation(
curve: widget.curve,
parent: _animationController,
));
}
_animationFade =
Tween<double>(begin: -1.0, end: 1.0).animate(CurvedAnimation(
curve: widget.curve,
parent: _animationController,
));
Timer(widget.delayStart, () {
_animationController.forward();
});
}
#override
Widget build(BuildContext context) {
return FadeTransition(
opacity: _animationFade,
child: SlideTransition(
position: _animationSlide,
child: widget.child,
),
);
}
}
To use it, you just have to wrap your text widget or any widget for that matter with SlideFadeTransition widget. Below is a complete working example.
import 'dart:async';
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Show up Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Show up Demo'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
SlideFadeTransition(
child: Text(
'You have pushed the button this many times:',
),
),
SlideFadeTransition(
delayStart: Duration(milliseconds: 800),
child: Text(
'0',
style: Theme.of(context).textTheme.display1,
),
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
setState(() {});
},
tooltip: 'Animate',
child: Icon(Icons.add),
),
);
}
}
///Wrapper class to implement slide and fade animations at the same time to
///a given element. Wrap the widget that you wish to appear with slide-fade
///transition in this class.
enum Direction { vertical, horizontal }
class SlideFadeTransition extends StatefulWidget {
///The child on which to apply the given [SlideFadeTransition]
final Widget child;
///The offset by which to slide and [child] into view from [Direction].
///Defaults to 1.0
final double offset;
///The curve used to animate the [child] into view.
///Defaults to [Curves.easeIn]
final Curve curve;
///The direction from which to animate the [child] into view. [Direction.horizontal]
///will make the child slide on x-axis by [offset] and [Direction.vertical] on y-axis.
///Defaults to [Direction.vertical]
final Direction direction;
///The delay with which to animate the [child]. Takes in a [Duration] and
/// defaults to 0.0 seconds
final Duration delayStart;
///The total duration in which the animation completes. Defaults to 800 milliseconds
final Duration animationDuration;
SlideFadeTransition({
#required this.child,
this.offset = 1.0,
this.curve = Curves.easeIn,
this.direction = Direction.vertical,
this.delayStart = const Duration(seconds: 0),
this.animationDuration = const Duration(milliseconds: 800),
});
#override
_SlideFadeTransitionState createState() => _SlideFadeTransitionState();
}
class _SlideFadeTransitionState extends State<SlideFadeTransition>
with SingleTickerProviderStateMixin {
Animation<Offset> _animationSlide;
AnimationController _animationController;
Animation<double> _animationFade;
#override
void initState() {
super.initState();
_animationController = AnimationController(
vsync: this,
duration: widget.animationDuration,
);
//configure the animation controller as per the direction
if (widget.direction == Direction.vertical) {
_animationSlide =
Tween<Offset>(begin: Offset(0, widget.offset), end: Offset(0, 0))
.animate(CurvedAnimation(
curve: widget.curve,
parent: _animationController,
));
} else {
_animationSlide =
Tween<Offset>(begin: Offset(widget.offset, 0), end: Offset(0, 0))
.animate(CurvedAnimation(
curve: widget.curve,
parent: _animationController,
));
}
_animationFade =
Tween<double>(begin: -1.0, end: 1.0).animate(CurvedAnimation(
curve: widget.curve,
parent: _animationController,
));
Timer(widget.delayStart, () {
_animationController.forward();
});
}
#override
void dispose() {
_animationController.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return FadeTransition(
opacity: _animationFade,
child: SlideTransition(
position: _animationSlide,
child: widget.child,
),
);
}
}

Answer 3

I built a package to do this simply.
delayed_widget
Example:
DelayedWidget(
delayDuration: Duration(milliseconds: 200),// Not required
animationDuration: Duration(seconds: 1),// Not required
animation: DelayedAnimations.SLIDE_FROM_BOTTOM,// Not required
child: Container(
width: 200,
height: 200,
color: Colors.red,
))