Flutter - Expand bottomNavigationBar by swiping or pressing the floatingActionButton - dart

I have a main widget called DashboardWidget. Inside it, I have a Scaffold with BottomNavigationBar and a FloatingActionButton:
Now, I want to make a widget that would be dragged from the bottom by:
Swiping up with the finger.
Pressing on FloatingActionButton.
In other words, I want to expand the BottomNavigationBar.
Here's a design concept in case I was unclear.
The problem is, I'm not sure where to start to implement that. I've thought about removing the BottomNavigationBar and create a custom widget that can be expanded, but I'm not sure if it's possible either.

Output:
I used a different approach and did it without AnimationController, GlobalKey etc, the logic code is very short (_handleClick).
I only used 4 variables, simple and short!
void main() => runApp(MaterialApp(home: HomePage()));
class HomePage extends StatefulWidget {
#override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
static double _minHeight = 80, _maxHeight = 600;
Offset _offset = Offset(0, _minHeight);
bool _isOpen = false;
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Color(0xFFF6F6F6),
appBar: AppBar(backgroundColor: Color(0xFFF6F6F6), elevation: 0),
body: Stack(
alignment: Alignment.bottomCenter,
children: <Widget>[
Align(
alignment: Alignment.topLeft,
child: FlatButton(
onPressed: _handleClick,
splashColor: Colors.transparent,
textColor: Colors.grey,
child: Text(_isOpen ? "Back" : ""),
),
),
Align(child: FlutterLogo(size: 300)),
GestureDetector(
onPanUpdate: (details) {
_offset = Offset(0, _offset.dy - details.delta.dy);
if (_offset.dy < _HomePageState._minHeight) {
_offset = Offset(0, _HomePageState._minHeight);
_isOpen = false;
} else if (_offset.dy > _HomePageState._maxHeight) {
_offset = Offset(0, _HomePageState._maxHeight);
_isOpen = true;
}
setState(() {});
},
child: AnimatedContainer(
duration: Duration.zero,
curve: Curves.easeOut,
height: _offset.dy,
alignment: Alignment.center,
decoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.only(
topLeft: Radius.circular(30),
topRight: Radius.circular(30),
),
boxShadow: [BoxShadow(color: Colors.grey.withOpacity(0.5), spreadRadius: 5, blurRadius: 10)]),
child: Text("This is my Bottom sheet"),
),
),
Positioned(
bottom: 2 * _HomePageState._minHeight - _offset.dy - 28, // 56 is the height of FAB so we use here half of it.
child: FloatingActionButton(
child: Icon(_isOpen ? Icons.keyboard_arrow_down : Icons.add),
onPressed: _handleClick,
),
),
],
),
);
}
// first it opens the sheet and when called again it closes.
void _handleClick() {
_isOpen = !_isOpen;
Timer.periodic(Duration(milliseconds: 5), (timer) {
if (_isOpen) {
double value = _offset.dy + 10; // we increment the height of the Container by 10 every 5ms
_offset = Offset(0, value);
if (_offset.dy > _maxHeight) {
_offset = Offset(0, _maxHeight); // makes sure it does't go above maxHeight
timer.cancel();
}
} else {
double value = _offset.dy - 10; // we decrement the height by 10 here
_offset = Offset(0, value);
if (_offset.dy < _minHeight) {
_offset = Offset(0, _minHeight); // makes sure it doesn't go beyond minHeight
timer.cancel();
}
}
setState(() {});
});
}
}

You can use the BottomSheet class.
Here is a Medium-tutorial for using that, here is a youtube-tutorial using it and here is the documentation for the class.
The only difference from the tutorials is that you have to add an extra call method for showBottomSheet from your FloatingActionButton when it is touched.
Bonus: here is the Material Design page on how to use it.

You can check this code, it is a complete example of how to start implementing this kind of UI, take it with a grain of salt.
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
import 'package:rxdart/rxdart.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Orination Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> with TickerProviderStateMixin {
bool _isOpen;
double _dragStart;
double _hieght;
double _maxHight;
double _currentPosition;
GlobalKey _cardKey;
AnimationController _controller;
Animation<double> _cardAnimation;
#override
void initState() {
_isOpen = false;
_hieght = 50.0;
_cardKey = GlobalKey();
_controller =
AnimationController(vsync: this, duration: Duration(milliseconds: 700));
_cardAnimation = Tween(begin: _hieght, end: _maxHight).animate(
CurvedAnimation(parent: _controller, curve: Curves.easeInOut)
);
_controller.addListener(() {
setState(() {
_hieght = _cardAnimation.value;
});
});
super.initState();
}
#override
void dispose() {
_controller.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
elevation: 0.0,
backgroundColor: Colors.transparent,
titleSpacing: 0.0,
title: _isOpen
? MaterialButton(
child: Text(
"Back",
style: TextStyle(color: Colors.red),
),
onPressed: () {
_isOpen = false;
_cardAnimation = Tween(begin: _hieght, end: 50.0).animate(
CurvedAnimation(parent: _controller, curve: Curves.easeInOut)
);
_controller.forward(from: 0.0);
},
)
: Text(""),
),
floatingActionButton: FloatingActionButton(
child: Icon(Icons.keyboard_arrow_up),
onPressed: () {
final RenderBox renderBoxCard = _cardKey.currentContext
.findRenderObject();
_maxHight = renderBoxCard.size.height;
_cardAnimation = Tween(begin: _hieght, end: _maxHight).animate(
CurvedAnimation(parent: _controller, curve: Curves.easeInOut)
);
_controller.forward(from: 0.0);
_isOpen = true;
}),
body: Stack(
key: _cardKey,
alignment: Alignment.bottomCenter,
children: <Widget>[
Container(
width: double.infinity,
height: double.infinity,
color: Colors.black12,
),
GestureDetector(
onPanStart: _onPanStart,
onPanUpdate: _onPanUpdate,
onPanEnd: _onPanEnd,
child:Material(
borderRadius: BorderRadius.only(
topRight: Radius.circular(16.0),
topLeft: Radius.circular(16.0),
),
elevation: 60.0,
color: Colors.white,
// shadowColor: Colors.,
child: Container(
height: _hieght,
child: Center(
child: Text("Hello, You can drag up"),
),
),
),
),
],
),
);
}
void _onPanStart(DragStartDetails details) {
_dragStart = details.globalPosition.dy;
_currentPosition = _hieght;
}
void _onPanUpdate(DragUpdateDetails details) {
final RenderBox renderBoxCard = _cardKey.currentContext.findRenderObject();
_maxHight = renderBoxCard.size.height;
final hieght = _currentPosition - details.globalPosition.dy + _dragStart;
print(
"_currentPosition = $_currentPosition _hieght = $_hieght hieght = $hieght");
if (hieght <= _maxHight && hieght >= 50.0) {
setState(() {
_hieght = _currentPosition - details.globalPosition.dy + _dragStart;
});
}
}
void _onPanEnd(DragEndDetails details) {
_currentPosition = _hieght;
if (_hieght <= 60.0) {
setState(() {
_isOpen = false;
});
} else {
setState(() {
_isOpen = true;
});
}
}
}
Edit: I modified the code by using Material Widget instead of A container with shadow for better performance,If you have any issue, please let me know .

Related

Flutter Web Unexpectedly null value after call Hot Reload

We are developing a large project with flutter web. But when we run the application in debug mode, it works fine at first, but when we make a change and hot reload/hot restart, we get an Unexpected null value error. When we build our web application again, it continues to work without any problems.
Error Message:
The following TypeErrorImpl was thrown building AnimatedBuilder(animation:
AnimationController#6e18e(⏮ 0.000; paused), dirty, dependencies: [MediaQuery], state:
_AnimatedState#b099a):
Unexpected null value.
The relevant error-causing widget was:
AnimatedBuilder
AnimatedBuilder:file:///Users/taner/Documents/GitHub/kinderbox_web/lib/view/admin/page_controller/web/page_controller_web.dart:51:15
page_controller_web.dart file:
import 'package:flutter/material.dart';
import 'package:get/get.dart';
import 'package:kinderbox_web/core/constant/color_constant.dart';
import 'package:kinderbox_web/core/providers/page_controller_provider.dart';
import 'package:kinderbox_web/core/providers/user_provider.dart';
import 'package:kinderbox_web/widgets/admin/drawer/web/drawer_bar.dart';
import 'package:kinderbox_web/widgets/admin/header/web/header_web.dart';
class PageControllerWeb extends StatefulWidget {
final List<Widget> pages;
const PageControllerWeb({
Key? key,
required this.pages,
}) : super(key: key);
#override
State<PageControllerWeb> createState() => _PageControllerWebState();
}
class _PageControllerWebState extends State<PageControllerWeb>
with SingleTickerProviderStateMixin {
double maxWidth = 300;
double minWidth = 70;
bool isCollapsed = false;
late AnimationController _animationController;
late Animation<double> widthAnimation;
int currentIndex = 0;
#override
void dispose() {
_animationController.dispose();
super.dispose();
}
#override
void initState() {
_animationController =
AnimationController(vsync: this, duration: Duration(milliseconds: 300));
widthAnimation = Tween<double>(begin: maxWidth, end: minWidth)
.animate(_animationController);
super.initState();
}
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: ColorConstants.background,
body: AnimatedBuilder(
animation: _animationController,
builder: (BuildContext context, Widget? animatedWidget) {
return SizedBox(
height: context.height,
width: context.width,
child: Stack(
children: [
DrawerBarView(
onTapItem: (index) {
setState(() {
currentIndex = index;
});
},
animationController: _animationController,
isColapsed: isCollapsed,
menuCloseTapped: () {
setState(() {
isCollapsed = !isCollapsed;
isCollapsed
? _animationController.forward()
: _animationController.reverse();
});
},
widthAnimation: widthAnimation,
selectedIndex: currentIndex,
userModel: Get.put(UserProvider()).userData!,
),
Positioned(
left: widthAnimation.value,
child: Container(
decoration: BoxDecoration(
boxShadow: const [
BoxShadow(
color: Colors.black12,
blurRadius: 20,
spreadRadius: 5,
)
],
color: ColorConstants.white,
borderRadius: const BorderRadius.only(
topLeft: Radius.circular(40),
)),
height: context.height,
width: context.width,
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
HeaderView(
userModel: Get.put(UserProvider()).userData!,
),
Expanded(
child: widget.pages[currentIndex])
],
),
),
),
],
),
);
}));
}
}
Also i am using GetX package in my project. Could this cause such a problem?

Can you use Flutter's transform class to animate scale?

I'm trying to animate two square containers so that when they are tapped they are animated to scale. I see all these transform class examples online that show animation of a widget however when I use the transform class the scale just jumps from its initial value to its final value.
My end goal is to animate a container to 'bounce' every time it is tapped like what you can do with bounce.js in web development. To understand what I mean you can go to http://bouncejs.com, click 'select preset' in the upper left corner, select jelly from the drop down menu and click 'play animation'.
Can this be done with the transform class?
Here is my code:
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
_MyHomePageState createState() => _MyHomePageState();
}
var squareScaleA = 0.5;
var squareScaleB = 0.5;
class _MyHomePageState extends State<MyHomePage> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Bounce Example"),
),
body: Stack(
children: <Widget>[
Container(
width: 300.0,
height: 150.0,
color: Colors.yellowAccent,
),
Column(
children: <Widget>[
Row(
children: <Widget>[
GestureDetector(
onTap: () {
setState(() {
squareScaleA = 1.0;
});
},
child: Transform.scale(
scale: squareScaleA,
child: Container(
width: 150.0,
height: 150.0,
color: Colors.green,
),
),
),
GestureDetector(
onTap: () {
setState(() {
squareScaleB = 1.0;
});
},
child: Transform.scale(
scale: squareScaleB,
child: Container(
width: 150.0,
height: 150.0,
color: Colors.blue,
),
),
),
],
),
],
),
],
),
);
}
}
Thanks in advance for any help!
You need to use Animations, you can start using AnimationController it's very simple , I fixed your sample :
class _MyHomePageState extends State<TestingNewWidget>
with TickerProviderStateMixin {
var squareScaleA = 0.5;
var squareScaleB = 0.5;
AnimationController _controllerA;
AnimationController _controllerB;
#override
void initState() {
_controllerA = AnimationController(
vsync: this,
lowerBound: 0.5,
upperBound: 1.0,
duration: Duration(seconds: 1));
_controllerA.addListener(() {
setState(() {
squareScaleA = _controllerA.value;
});
});
_controllerB = AnimationController(
vsync: this,
lowerBound: 0.5,
upperBound: 1.0,
duration: Duration(seconds: 1));
_controllerB.addListener(() {
setState(() {
squareScaleB = _controllerB.value;
});
});
super.initState();
}
#override
void dispose() {
_controllerA.dispose();
_controllerB.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Bounce Example"),
),
body: Stack(
children: <Widget>[
Container(
width: 300.0,
height: 150.0,
color: Colors.yellowAccent,
),
Column(
children: <Widget>[
Row(
children: <Widget>[
GestureDetector(
onTap: () {
if (_controllerA.isCompleted) {
_controllerA.reverse();
} else {
_controllerA.forward(from: 0.0);
}
},
child: Transform.scale(
scale: squareScaleA,
child: Container(
width: 150.0,
height: 150.0,
color: Colors.green,
),
),
),
GestureDetector(
onTap: () {
if (_controllerB.isCompleted) {
_controllerB.reverse();
} else {
_controllerB.forward(from: 0.0);
}
},
child: Transform.scale(
scale: squareScaleB,
child: Container(
width: 150.0,
height: 150.0,
color: Colors.blue,
),
),
),
],
),
],
),
],
),
);
}
}
Also you can read more about animation here: https://flutter.dev/docs/development/ui/animations

Flutter GestureDetector: How to pinch in/out or zoom in/out Text using two fingers?

I'm creating a text field like Text or RichText. And after that, I want to zoom in/out the size of text using pinching. For now, I tried implementing GestureDetector but it zooms in/out with one finger too. And it is really hard to aim pinching detection. Sometimes is freezing. I added a video that shows when after pinching it freezes and suddenly get bigger. The second video is with the case that image zoom in only when I tap on the text with one finger and move to up left corner. The ideal implementation is to detect pinch and zoom in/out all text area. And disable zooming when I use only one finger. Could you send me some hints, link or code how to solve or where to find the solution?
body: GestureDetector(
onScaleUpdate: (details) {
setState(() {
_textSize =
_initTextSize + (_initTextSize * (details.scale * .35));
});
},
onScaleEnd: (ScaleEndDetails details) {
setState(() {
_initTextSize = _textSize;
});
},
child: Center(
child: SizedBox(
height: _textSize,
child: FittedBox(
child: Text("Test"),
),
))),
In Stateful widget with these configuration
double _scaleFactor = 1.0;
double _baseScaleFactor = 1.0;
And use setState only on update, using the scaleFactor on textScaleFactor property of RichText.
Only one setState to rebuild widget and store the initial factor when scale starts
GestureDetector(
onScaleStart: (details) {
_baseScaleFactor = _scaleFactor;
},
onScaleUpdate: (details) {
setState(() {
_scaleFactor = _baseScaleFactor * details.scale;
});
},
child: Container(
height: MediaQuery.of(context).size.height,
width: MediaQuery.of(context).size.width,
color: Colors.red,
child: Center(
child: Text(
'Test',
textScaleFactor: _scaleFactor,
),
),
),
);
The height and width I put just to expand and simulate area of gesture detector.
Google software engineers Gary Qian and Chris Yang demonstrated this in their Google Developer Days talk. The video is viewable here:
Text in Flutter: Building a fancy chat bubble at GDD China
There code is similar to some of the other answers here, but they notably add a clamp so that it doesn't get too big or small.
Here is a summary of their scalable text bubble:
Because scaling still gets called even for a single finger touch, I added a check for scaleUpdateDetails.scale == 1.0. That means the UI won't be updated if there was no change in scale.
class Bubble extends StatefulWidget {
#override
_BubbleState createState() => _BubbleState();
}
class _BubbleState extends State<Bubble> {
double _fontSize = 20;
final double _baseFontSize = 20;
double _fontScale = 1;
double _baseFontScale = 1;
#override
Widget build(BuildContext context) {
return GestureDetector(
onScaleStart: (ScaleStartDetails scaleStartDetails) {
_baseFontScale = _fontScale;
},
onScaleUpdate: (ScaleUpdateDetails scaleUpdateDetails) {
// don't update the UI if the scale didn't change
if (scaleUpdateDetails.scale == 1.0) {
return;
}
setState(() {
_fontScale = (_baseFontScale * scaleUpdateDetails.scale).clamp(0.5, 5.0);
_fontSize = _fontScale * _baseFontSize;
});
},
child: ...
// descendant with a Text widget that uses the _fontSize
);
}
}
Notes:
Use a StatefulWidget so that you can store the current font size and scale at all times
Use two additional variables to remember the original font size and also the scale at the start of the pinch
Wrap the Text widget in a GestureDetector
Save the original scale in onScaleStart
Calculate the new font size onScaleUpdate
Use setState to rebuild the widget with the new size
Solution: Two finger zoom-in and zoom-out.
import 'package:flutter/material.dart';
import 'package:matrix_gesture_detector/matrix_gesture_detector.dart';
class TransformText extends StatefulWidget {
TransformText({Key key}) : super(key: key); // changed
#override
_TransformTextState createState() => _TransformTextState();
}
class _TransformTextState extends State<TransformText> {
double scale = 0.0;
#override
Widget build(BuildContext context) {
final ValueNotifier<Matrix4> notifier = ValueNotifier(Matrix4.identity());
return Scaffold(
appBar: AppBar(
title: Text('Single finger Rotate text'), // changed
),
body: Center(
child: MatrixGestureDetector(
onMatrixUpdate: (m, tm, sm, rm) {
notifier.value = m;
},
child: AnimatedBuilder(
animation: notifier,
builder: (ctx, child) {
return Transform(
transform: notifier.value,
child: Center(
child: Stack(
children: <Widget>[
Container(
color: Colors.red,
padding: EdgeInsets.all(10),
margin: EdgeInsets.only(top: 50),
child: Transform.scale(
scale:
1, // make this dynamic to change the scaling as in the basic demo
origin: Offset(0.0, 0.0),
child: Container(
height: 100,
child: Text(
"Two finger to zoom!!",
style:
TextStyle(fontSize: 26, color: Colors.white),
),
),
),
),
],
),
),
);
},
),
),
),
);
}
}
Full code. Hope it helps.
import 'package:flutter/material.dart';
import 'package:flutter/foundation.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
final appTitle = 'Demo';
return MaterialApp(
title: appTitle,
home: MyHomePage(title: appTitle),
);
}
}
class MyHomePage extends StatelessWidget {
final String title;
MyHomePage({Key key, this.title}) : super(key: key);
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(title),
),
body: TransformText());
}
}
class TransformText extends StatefulWidget {
TransformText({Key key}) : super(key: key); // changed
#override
_TransformTextState createState() => _TransformTextState();
}
class _TransformTextState extends State<TransformText> {
double scale = 0.0;
double _scaleFactor = 1.0;
double _baseScaleFactor = 1.0;
double _savedVal = 1.0;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('GestureDetector Test'), // changed
),
body: Column(
children: <Widget>[
RaisedButton(
child: Text('get'),
onPressed: () {
_savedVal = _scaleFactor;
}),
RaisedButton(
child: Text('set'),
onPressed: () {
setState(() {
_scaleFactor = _savedVal;
});
}),
Expanded(
child: Center(
child: GestureDetector(
behavior: HitTestBehavior.translucent,
onScaleStart: (details) {
_baseScaleFactor = _scaleFactor;
},
onScaleUpdate: (details) {
setState(() {
_scaleFactor = _baseScaleFactor * details.scale;
});
},
child: Container(
height: MediaQuery.of(context).size.height,
width: MediaQuery.of(context).size.width,
child: Center(
child: Text(
'Test',
textScaleFactor: _scaleFactor,
),
),
),
)),
),
],
),
);
}
}

Flutter - Animate change on height when child of container renders

I'm trying to recreate something like ExpansionTile but in a Card. When I click the card, its child renders and the card changes its height, so I want to animate that change.
I tried using AnimatedContainer and GlobalKey to know the final size of the card with its child rendered and then set the new height to AnimatedContainer but that didn't work.
In the end I just had to use AnimatedSize. It replicates exactly the animation that I want.
AnimatedSize(
vsync: this,
duration: Duration(milliseconds: 150),
curve: Curves.fastOutSlowIn,
child: Container(
child: Container(
child: !_isExpanded
? null
: FadeTransition(opacity: animationFade, child: widget.child),
),
),
);
You can use the AnimatedContainer for animations
class Animate extends StatefulWidget {
#override
_AnimateState createState() => _AnimateState();
}
class _AnimateState extends State<Animate> {
var height = 200.0;
#override
Widget build(BuildContext context) {
var size = MediaQuery.of(context).size;
return Scaffold(
body: Center(
child: AnimatedContainer(
color: Colors.amber,
duration: new Duration(milliseconds: 500),
height: height,
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
setState(() {
if (height == 200.0) {
height = 400.0;
} else {
height = 200.0;
}
});
},
child: Icon(Icons.settings),
),
);
}
}
I tweaked the ExpansionTile, this has proper animation. Hope this helps
class _FixedExpansionTileState extends State<FixedExpansionTile> with SingleTickerProviderStateMixin {
AnimationController _controller;
CurvedAnimation _easeOutAnimation;
CurvedAnimation _easeInAnimation;
ColorTween _borderColor;
ColorTween _headerColor;
ColorTween _iconColor;
ColorTween _backgroundColor;
Animation<double> _iconTurns;
bool _isExpanded = false;
#override
void initState() {
super.initState();
_controller = new AnimationController(duration: _kExpand, vsync: this);
_easeOutAnimation = new CurvedAnimation(parent: _controller, curve: Curves.easeOut);
_easeInAnimation = new CurvedAnimation(parent: _controller, curve: Curves.easeIn);
_borderColor = new ColorTween();
_headerColor = new ColorTween();
_iconColor = new ColorTween();
_iconTurns = new Tween<double>(begin: 0.0, end: 0.5).animate(_easeInAnimation);
_backgroundColor = new ColorTween();
_isExpanded = PageStorage.of(context)?.readState(context) ?? widget.initiallyExpanded;
if (_isExpanded)
_controller.value = 1.0;
}
#override
void dispose() {
_controller.dispose();
super.dispose();
}
void _handleTap() {
setState(() {
_isExpanded = !_isExpanded;
if (_isExpanded)
_controller.forward();
else
_controller.reverse().then<void>((value) {
setState(() {
// Rebuild without widget.children.
});
});
PageStorage.of(context)?.writeState(context, _isExpanded);
});
if (widget.onExpansionChanged != null)
widget.onExpansionChanged(_isExpanded);
}
Widget _buildChildren(BuildContext context, Widget child) {
final Color borderSideColor = Colors.transparent;
// final Color titleColor = _headerColor.evaluate(_easeInAnimation);
return new Container(
decoration: new BoxDecoration(
color: _backgroundColor.evaluate(_easeOutAnimation) ?? Colors.transparent,
border: new Border(
top: new BorderSide(color: borderSideColor),
bottom: new BorderSide(color: borderSideColor),
)
),
child: new Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
IconTheme.merge(
data: new IconThemeData(color: _iconColor.evaluate(_easeInAnimation)),
child: new ListTile(
onTap: _handleTap,
leading: widget.leading,
title: new DefaultTextStyle(
style: Theme.of(context).textTheme.subhead.copyWith(color: Colors.transparent),
child: widget.title,
),
trailing: widget.trailing ?? new RotationTransition(
turns: _iconTurns,
child: const Icon(Icons.expand_more),
),
),
),
new ClipRect(
child: new Align(
heightFactor: _easeInAnimation.value,
child: child,
),
),
],
),
);
}
#override
Widget build(BuildContext context) {
final ThemeData theme = Theme.of(context);
_borderColor.end = theme.dividerColor;
_headerColor
..begin = theme.textTheme.subhead.color
..end = theme.accentColor;
_iconColor
..begin = theme.unselectedWidgetColor
..end = theme.accentColor;
_backgroundColor.end = widget.backgroundColor;
final bool closed = !_isExpanded && _controller.isDismissed;
return new AnimatedBuilder(
animation: _controller.view,
builder: _buildChildren,
child: closed ? null : new Column(children: widget.children),
);
}
}
It works better for me
AnimatedCrossFade(
duration: _controller.duration!,
firstCurve: Curves.easeInOut,
secondCurve: Curves.easeInOut,
firstChild: Container(),
secondChild: widget.content,
crossFadeState: isExpanded ? CrossFadeState.showSecond : CrossFadeState.showFirst,
)

Flutter - Effect of flip card

I'm trying to make a flip card, what would be the best way to get the effect
I would use an AnimatedBuilder or AnimatedWidget to animate the values of a Transform widget. ScaleTransition almost does this for you, but it scales both directions, and you only want one.
import 'package:flutter/material.dart';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return new MaterialApp(
home: new MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePageState createState() => new MyHomePageState();
}
class MyCustomCard extends StatelessWidget {
MyCustomCard({ this.colors });
final MaterialColor colors;
Widget build(BuildContext context) {
return new Container(
alignment: FractionalOffset.center,
height: 144.0,
width: 360.0,
decoration: new BoxDecoration(
color: colors.shade50,
border: new Border.all(color: new Color(0xFF9E9E9E)),
),
child: new FlutterLogo(size: 100.0, colors: colors),
);
}
}
class MyHomePageState extends State<MyHomePage> with TickerProviderStateMixin {
AnimationController _controller;
Animation<double> _frontScale;
Animation<double> _backScale;
#override
void initState() {
super.initState();
_controller = new AnimationController(
vsync: this,
duration: const Duration(seconds: 1),
);
_frontScale = new Tween(
begin: 1.0,
end: 0.0,
).animate(new CurvedAnimation(
parent: _controller,
curve: new Interval(0.0, 0.5, curve: Curves.easeIn),
));
_backScale = new CurvedAnimation(
parent: _controller,
curve: new Interval(0.5, 1.0, curve: Curves.easeOut),
);
}
#override
void dispose() {
_controller.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
ThemeData theme = Theme.of(context);
return new Scaffold(
appBar: new AppBar(),
floatingActionButton: new FloatingActionButton(
child: new Icon(Icons.flip_to_back),
onPressed: () {
setState(() {
if (_controller.isCompleted || _controller.velocity > 0)
_controller.reverse();
else
_controller.forward();
});
},
),
body: new Center(
child: new Stack(
children: <Widget>[
new AnimatedBuilder(
child: new MyCustomCard(colors: Colors.orange),
animation: _backScale,
builder: (BuildContext context, Widget child) {
final Matrix4 transform = new Matrix4.identity()
..scale(1.0, _backScale.value, 1.0);
return new Transform(
transform: transform,
alignment: FractionalOffset.center,
child: child,
);
},
),
new AnimatedBuilder(
child: new MyCustomCard(colors: Colors.blue),
animation: _frontScale,
builder: (BuildContext context, Widget child) {
final Matrix4 transform = new Matrix4.identity()
..scale(1.0, _frontScale.value, 1.0);
return new Transform(
transform: transform,
alignment: FractionalOffset.center,
child: child,
);
},
),
],
),
),
);
}
}
I used simple approach, rotated it on X axis. Here is the full code.
void main() => runApp(MaterialApp(home: HomePage()));
class HomePage extends StatefulWidget {
#override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> with SingleTickerProviderStateMixin {
AnimationController _controller;
bool _flag = true;
Color _color = Colors.blue;
#override
void initState() {
super.initState();
_controller = AnimationController(vsync: this, duration: Duration(seconds: 1), value: 1);
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
floatingActionButton: FloatingActionButton(
child: Icon(Icons.crop_rotate),
onPressed: () async {
if (_flag) {
await _controller.reverse();
setState(() {
_color = Colors.orange;
});
await _controller.forward();
} else {
await _controller.reverse();
setState(() {
_color = Colors.blue;
});
await _controller.forward();
}
_flag = !_flag;
},
),
body: Center(
child: AnimatedBuilder(
animation: _controller,
builder: (context, child) {
return Transform(
transform: Matrix4.rotationX((1 - _controller.value) * math.pi / 2),
alignment: Alignment.center,
child: Container(
height: 100,
margin: EdgeInsets.symmetric(horizontal: 20),
padding: EdgeInsets.symmetric(vertical: 12),
alignment: Alignment.center,
decoration: BoxDecoration(color: _color.withOpacity(0.2), border: Border.all(color: Colors.grey)),
child: FlutterLogo(colors: _color, size: double.maxFinite),
),
);
},
),
),
);
}
}
You can use the flip_card Flutter package. It lets you define a front and back widget and can be flipped horizontally or vertically.

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