Flutter hooks tutorial (part 1) flutter animation using hooks (use effect and useanimationcontroller)

Flutter Hooks
Tutorial (Part
1): Flutter
Animation
using Hooks
(useEffect and
useAnimation
Controller)
www.bacancytechnology.com

Do you remember how we used to do
programming before Flutter hooks weren’t
part of Flutter? It was a bit difficult and
overwhelming, right? Here’s a Flutter
tutorial where we will explore pre-hooks
and post-hooks Flutter life. We will learn
how to use useEffect and
useAnimationController in our demo app.
Let’s get ready and build an application,
then!

Animation controller
Manage animation
Listen for updates
Manipulate animation
In this Flutter Hooks tutorial, we will learn
how to install and build an animation demo
using hooks in Flutter, and also, we will look
at how we used to code before hooks
weren’t introduced. Before moving on to
the Flutter hooks tutorial, let’s discuss the
basics of animation.

We need to do the below things for
animation,

The default part is the “Animation,” There
are two types of animation that Flutter
supports.

Tween Animation– It is the short form
of in-betweening. The animation must
define the start and endpoint. The
animation will have a start value and
then reaches the end value through
various intermediate values.
Physics-based Animation– It allows you
to interact with an app more
realistically and interactively.

In simple words, an Animation controller is
called whenever its value changes,

Ticker calls tick function every frame. After
each tick, it provides a callback function
after it is started. In our case, the ticker
listener is the controller.

useEffect hook fetches data from a
server and sets the fetch to the local
state
useState hook manages local states in
apps
useMemoized hook memoizes
complicated functions to achieve
optimal app performance
useRef hook creates an object that has
one mutable property.
Flutter hooks have not received much
visibility and acknowledgment, but that
won’t make them less awesome. With the
help of the flutter_hooks library, we can
provide a robust way for managing the
lifecycle of widgets by reducing code
duplication and increasing code-sharing.

Flutter provides in-built hooks as shown
below:

useCallback hook cache a function
instance.
useContext hook obtain the
BuildContext of the building
HookWidget
useValueChanged Hook watches a value
and calls a callback whenever the value
changes.

In this guide, we’ll use the useEffect hook
for redirection after some duration, and
useAnimationController hook to create an
instance of AnimationController. Flutter,
just like ReactJS, also gives you the
opportunity of creating your custom hooks.
We will discuss that later in the tutorial.
Without further ado, let’s get started with
the Flutter hooks tutorial.

Pre-Hooks
Life:
Animation
without
Flutter Hooks

First of all, let’s see the splash screen
animation demo without implementing
flutter hooks and using the stateful widget;
it needs to be mixed in with a
TickerProviderStateMixin.

And don’t forget to dispose of the animation
controller.

class SplashScreen extends StatefulWidget {
const SplashScreen();
@override
_SplashScreenState createState() =>
_SplashScreenState();
}
class _SplashScreenState extends State
with TickerProviderStateMixin {
late AnimationController
_animationController;
late AnimationController controller;
late Animation< Offset > offset

@override
void initState() {
super.initState();
startTime();
_animationController = new
AnimationController(vsync: this, duration:
Duration(seconds: 3));
_animationController.repeat(reverse:
false);
controller = AnimationController(vsync:
this, duration: Duration(seconds: 2));
offset = Tween< Offset >(begin: Offset(0.0,
1.0), end: Offset.zero).animate(controller);
controller.forward();
}

startTime() async {
var duration = Duration(seconds: 3);
return Timer(duration, navigatePage);
}
Future navigatePage() async {
Route route = MaterialPageRoute(builder:
(context) => HomePage());
Navigator.of(context).pushReplacement(ro
ute);
}
@override
void dispose() {
_animationController.dispose();
controller.dispose();
super.dispose();
}
...
}

All of the above code is set up for
animation. And then we will just apply
these instances to our widgets/design. That
is just easy to understand.

Post-Hooks
Life:
Installation
and Flutter
Hooks
Example

How to Install Flutter hooks?
Run the following command for installing
flutter hooks
flutter pub add flutter_hooks
The command will update pubspec.yaml file
of the dependencies section with
flutter_hooks: VERSION_NUMER_HERE.

OR you can directly update pubspec.yaml
with flutter_hooks as shown below

dependencies:
flutter:
sdk: flutter
flutter_hooks:

Save the file, and Flutter will install the
dependency. Now, import the flutter_hooks
library.

import
'package:flutter_hooks/flutter_hooks.dart';
How to Implement
Animation using Flutter
Hooks?
The first change to make is to replace the
Stateful Widget with Hook Widget. And
then, to initialize the animation controllers,
we will use the useAnimationController()
method, a default method provided by the
flutter_hook library. And we can remove all
boilerplate code from initState and dispose
method.

class SplashScreen extends HookWidget {
@override
Widget build(BuildContext context) {
AnimationController
_animationController =
useAnimationController(duration:
Duration(seconds: 4), initialValue: 1);
_animationController.repeat(reverse:
false);
AnimationController controller =
controller.repeat(reverse: false, period:
controller =
controller.repeat(reverse: false, period:

Animation< Offset > offset = Tween< Offset
>(begin: Offset(0.0, 1.0), end:
Offset.zero).animate(controller);
controller.forward();
useEffect(() {
Timer.periodic(Duration(seconds: 4), (time)
{
Route route = MaterialPageRoute(builder:
(context) => HomePage());
Navigator.of(context).pushReplacement(ro
ute);
});
});
return SafeArea(
child: Scaffold(
body: Container(
decoration: BoxDecoration(
gradient: LinearGradient(
colors: [Color(0xFFFFFFFF),

Color(0xffE3F3FF)],
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
),
),
child: Stack(
children: [
FadeTransition(
opacity: _animationController,
child: Center(
child: FlutterLogo(
size: 50,
)),
),
Align(
alignment: Alignment.bottomCenter,
child: SlideTransition(
position: offset,
child: Image.asset(
'assets/images/splash_bg.png',
width: MediaQuery.of(context).size.width,
fit: BoxFit.fill,

),
))
],
),
),
));
}
}
But the problem with the above code is
there is no way to dispose the animation
controller instances; we have a solution for
this, called custom hooks.

Flutter Hooks
Tutorial to
Create
Custom
Hooks

The custom AnimationController hooks in
Flutter will instantiate an
AnimationController and return the
ScrollController to use it from the UI. It will
help in holding all the code, practically,
which was previously stored in the State
object of a StatefulWidget.

The most basic hook can be just a simple
function. Let’s create one under
hooks/controller_for_animation.dart. And
also one for Animation< Offset >.

// hooks/controller_for_animation.dart.
AnimationController
useControllerForAnimation() {
return
use(_AnimControllerForAnimationHook());
}
class _AnimControllerForAnimationHook
extends Hook {

@override
_AnimControllerForAnimationHookState
createState() =>
_AnimControllerForAnimationHookState();
}
class
_AnimControllerForAnimationHookState
extends HookState {
late AnimationController _animController;
@override
void initHook() {
_animController =
_animController.repeat(reverse: false);
}
@override
AnimationController build(BuildContext
context) => _animController;

@override
void dispose() =>
_animController.dispose();
}
Animation< Offset > useOffsetHook() {
return
use(_AnimOffsetForAnimationHook());
}
class _AnimOffsetForAnimationHook
extends Hook> {
@override
_AnimOffsetForAnimationHookState
createState() =>
_AnimOffsetForAnimationHookState();
}
class _AnimOffsetForAnimationHookState
extends HookState,
_AnimOffsetForAnimationHook> {
late AnimationController _controller;
late Animation< Offset > offset;

@override
void initHook() {
_controller =
_controller.repeat(reverse: false, period:
offset = Tween(begin: Offset(0.0, 1.0), end:
Offset.zero).animate(_controller);
_controller.forward();
}
@override
Animation< Offset > build(BuildContext
context) => offset;
@override
void dispose() => _controller.dispose();
}

All we did was move logic to this new class;
also, there is one dispose method from
which we can also dispose that controller,
and now simply use that
useControllerForAnimation. The method
inside build method of the splash screen.

@override
AnimationController
useControllerForAnimation();
Animation< Offset > offset =
useOffsetHook();
…….
}

Also, create one hook widget inside
hook/timer_widget.dart to redirect to a
home screen after some duration.
// hook/timer_widget.dart
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import
'package:flutter_hooks/flutter_hooks.dart';
import
'package:flutter_hooks_demo/home_page.
dart';
bool useTimerToNavigate() {
return use(const _NavigateTimer());
}
class _NavigateTimer extends Hook {
const _NavigateTimer();

@override
___NavigateTimerState createState() =>
___NavigateTimerState();
}
class ___NavigateTimerState extends
HookState {
late Timer _timer;
bool isRedirect = false;
@override
void initHook() {
super.initHook();
_timer = Timer(Duration(seconds: 4), () {
Route route =
MaterialPageRoute(builder: (context) =>
HomePage());
Navigator.of(context).pushReplacement(
route);
});
}

@override
bool build(BuildContext context) {
return isRedirect;
}
@override
void dispose() {
_timer.cancel();
super.dispose();
}
}
And here is the final Splash Screen code!
// splash_screen.dart
@override
AnimationController

Animation< Offset > offset =
useOffsetHook();
useTimerToNavigate();
return SafeArea(
child: Scaffold(
body: Container(
decoration: BoxDecoration(
gradient: LinearGradient(
colors: [Color(0xFFFFFFFF),
Color(0xffE3F3FF)],
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
),
),
child: Stack(
children: [
FadeTransition(
opacity: _animationController,
child: Center(
child: FlutterLogo(
size: 50,
),

// child:
Image.asset('assets/images/splashlogo.png'),
)),
Align(
alignment: Alignment.bottomCenter,
child: SlideTransition(
position: offset,
child: Image.asset(
'assets/images/splash_bg.png',
width: MediaQuery.of(context).size.width,
fit: BoxFit.fill,
),
))
],
),
),
));
}
}
The entire source is available on the
github: flutter-hooks-demo.

We can conclude that with the help of flutter
hooks we can reuse that AnimationController
and Animation< Offset > just by adding one
line!

AnimationController _animationController =

So, this is how we can reduce the boilerplate
code and make a smaller size code for the
widget. And also make clean, easy and
maintainable code. I hope the Flutter hooks
tutorial was helpful to you. For more such
Flutter Tutorials, feel free to visit the Flutter
tutorials page and clone the github repository
to play around with the code.

If you are looking for Flutter experts who can
help you with your projects, contact us to hire
Flutter developer. Since our developers have
great problem-solving skills, we assure you of
the absolute code quality and optimum
application performance.

Thank You
www.bacancytechnology.com

Flutter hooks tutorial (part 1) flutter animation using hooks (use effect and useanimationcontroller)

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