I am trying to animate an image that shifts slowly by 10px when you click a button, using AnimatedBuilder. I'm using AnimatedBuilder because I plan to animate multiple properties later on - not just position. Animation looks ok if my widget is a plain colour container with text, but it vibrates slightly if it's an image. It's most noticeable on the left and right edges of the image.
I tested in debug, profile and release mode without seeing any difference.
Why is the image vibrating and how can I prevent this?
Here is the video showing the issue: Link to video on Google Drive
Here is the code:
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatefulWidget {
const MyApp({super.key});
#override
State<MyApp> createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> with SingleTickerProviderStateMixin {
late AnimationController _controller;
late Animation _offsetAnimation;
#override
void initState() {
super.initState();
_controller =
AnimationController(duration: const Duration(seconds: 1), vsync: this);
_offsetAnimation =
Tween<Offset>(begin: const Offset(-10, 0), end: const Offset(0, 0))
.animate(_controller);
}
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: Container(
width: 1920,
height: 1080,
color: Colors.grey.shade100,
child: Stack(alignment: Alignment.center, children: [
Image.asset('assets/Map.jpg'),
Positioned(
left: 100,
child: AnimatedBuilder(
animation: _controller,
builder: ((context, child) {
return Transform.translate(
offset: _offsetAnimation.value, child: child);
}),
child: Image.asset("assets/Istanbul.png"),
)),
Positioned(
top: 50,
left: 0,
child: ElevatedButton(
onPressed: () => _controller.forward(),
child: const Text("Animate Offset")),
),
Positioned(
top: 100,
left: 0,
child: ElevatedButton(
onPressed: () => _controller.reset(),
child: const Text("Reset Position")),
)
]),
)),
);
}
}
Related
I'm building a Flutter app, mainly for iOS.
One of my views has a text field, and iOS keyboard appears when you tap on it. The problem is - layout does not change smoothly like it does in native iOS apps. Instead, it instantly jumps to the final available screen height even before keyboard opening animation finishes.
I tried wrapping my SafeArea element in AnimatedSize and AnimatedContainer - it didn't help.
My layout code:
SafeArea(child:
Column(children:[
TextField(...)
])
)
How can I make the layout resize smoothly when the keyboard appears?
Expected:
Actual
I use something like that:
AnimatedPadding(
padding: MediaQuery.of(context).viewInsets,
duration: const Duration(milliseconds: 100),
curve: Curves.decelerate,
child: ....
)
This animates the padding based on the viewInsets(software keyboard height).
The desired output can be achieved using AnimatedPadding Widget, though this is not perfect, but better than nothing :d
Open issue as of 15/03/21, for reference
import 'dart:math';
import 'package:flutter/material.dart';
final Color darkBlue = Color.fromARGB(255, 18, 32, 47);
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
debugShowCheckedModeBanner: false,
home: Scaffold(
body: Center(
child: MyWidget(),
),
),
);
}
}
class MyWidget extends StatelessWidget {
#override
Widget build(BuildContext context) {
return SafeArea(
bottom: false,
child: Scaffold(
// !!! Important part > to disable default scaffold insets
resizeToAvoidBottomInset: false,
appBar: AppBar(
title: Text("Appbar Title"),
),
body: Stack(
children: [
Scrollbar(
child: ListView.builder(
padding: EdgeInsets.all(0.0),
itemCount: 30,
itemBuilder: (context, i) {
return Container(
height: 100,
width: double.infinity,
color: Colors
.primaries[Random().nextInt(Colors.primaries.length)],
);
},
),
),
Align(
alignment: Alignment.bottomLeft,
child: AnimatedPadding(
padding: MediaQuery.of(context).viewInsets,
// You can change the duration and curve as per your requirement:
duration: const Duration(milliseconds: 200),
curve: Curves.decelerate,
child: InputField()),
)
],
)),
);
}
}
class InputField extends StatefulWidget {
InputField({Key key}) : super(key: key);
#override
_InputFieldState createState() => _InputFieldState();
}
class _InputFieldState extends State<InputField> {
#override
Widget build(BuildContext context) {
return Container(
color: Colors.grey[100],
padding: const EdgeInsets.symmetric(vertical: 6),
child: Row(
children: [
SizedBox(
width: 60,
child: Icon(Icons.add_a_photo),
),
Flexible(
child: TextField(
style: Theme.of(context).textTheme.bodyText1,
decoration: InputDecoration(
border: InputBorder.none,
hintText: 'Enter text...',
),
),
),
SizedBox(
width: 60,
child: Icon(Icons.send),
),
],
),
);
}
}
Output ->
You can use this package keyboard_visibility and listen to keyboard visibility. Then you can give your logic to implement your feature like you can shorten the home container height. That's not perfect . But I think it's the only way right now.
You need to use keyboard_visibility package and use it to trigger your AnimatedContainer or AnimatedPadding
bool _isKeyboardActive = false;
#override
void initState() {
super.initState();
//add keyboard visibility Listener
KeyboardVisibility.onChange.listen((event) {
setState(() {
_isKeyboardActive = event;
});
});
}
Widget build(BuildContext context){
return AnimatedContainer(
width: _isKeyboardActive ? 200 : MediaQuery.of(context).size.width,
height: 60,
color: Colors.red,
duration: Duration(milliseconds: 600)
)
}
use this as a basis.
You should try setting resizeToAvoidBottomPadding: false like so:
return Scaffold(
key: _scaffoldKey,
resizeToAvoidBottomPadding: false,
I am trying to move the container on the screen by giving begin and end offset like from Offset(0.0,0.0) to Offset(400.0,300.0). I am using Slide Transition to animate the container I am using Tween<Offset>(begin: const Offset(3.0, 4.0), end: Offset(0.0, 0.0)) to move it on the screen I want to pass these Offset(400.0,300.0) and animate it.
Here is my code
class MoveContainer extends StatefulWidget {
MoveContainer({Key key, }) : super(key: key);
#override
State<StatefulWidget> createState() {
return new _MyMoveContainer();
}
}
class _MyMoveContainer extends State<MoveContainer>
with TickerProviderStateMixin {
GlobalKey _globalKey = new GlobalKey();
AnimationController _controller;
Animation<Offset> _offset;
Offset local;
#override
void initState() {
super.initState();
_controller = AnimationController(
vsync: this,
duration: const Duration(seconds: 3),
);
_offset =
Tween<Offset>(begin: const Offset(3.0, 4.0), end: Offset(0.0, 0.0))
.animate(_controller);
_offset.addListener(() {
setState(() {});
});
_controller.forward();
}
#override
void dispose() {
_controller.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return SlideTransition(
position: _offset,
child: GestureDetector(
onPanStart: (start) {
RenderBox getBox = context.findRenderObject();
local = getBox.localToGlobal(start.globalPosition);
print('point are $local');
},
child: Container(
color: Colors.cyan,
height: 200.0,
width: 200.0,
child: Text("hello ")),
),
);
}
}
Probably this question is not actual for the author. (Asked 7 months ago).
But maybe my answer will help someone else.
Usually Slide Transition is used for transitions between pages. That is why, one unit of position value here is the size of one page. When you put there Offset(400.0,300.0) it's equal 400 screen right, and 300 pages down.
For your case it better to use AnimatedPositioned Widget.
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Scaffold(
backgroundColor: Colors.blue,
body: MoveContainer(),
),
);
}
}
class MoveContainer extends StatefulWidget {
#override
_MoveContainerState createState() => _MoveContainerState();
}
class _MoveContainerState extends State<MoveContainer> {
Offset offset = Offset.zero;
final double height = 200;
final double width = 200;
#override
Widget build(BuildContext context) {
return GestureDetector(
onPanStart: (details) {
RenderBox getBox = context.findRenderObject();
setState(() {
offset = getBox.localToGlobal(details.globalPosition);
});
},
child: Stack(
children: <Widget>[
AnimatedPositioned(
duration: Duration(milliseconds: 300),
top: offset.dy - (height / 2),
left: offset.dx - (width / 2),
child: Container(
color: Colors.cyan,
height: height,
width: width,
child: Text("hello "),
),
),
],
),
);
}
}
In Flutter, I can rotate a Widget using the Transform Widget. However, the rotation is around origin specified in the Transform widget properties rather than around the current focal point.
I tried modifying the Matrix by translating to the focal point, rotating, and then translating back.
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: new TransformContainer(),
),
);
}
}
class TransformContainer extends StatefulWidget {
const TransformContainer({
Key key,
}) : super(key: key);
#override
TransformContainerState createState() {
return new TransformContainerState();
}
}
class TransformContainerState extends State<TransformContainer> {
Matrix4 matrix = Matrix4.identity();
#override
Widget build(BuildContext context) {
return Stack(
children: <Widget>[
GestureDetector(
onTapDown: (details) {
matrix.translate(-details.globalPosition.dx, -details.globalPosition.dy);
matrix.rotateZ(0.174533);
matrix.translate(details.globalPosition.dx, details.globalPosition.dy);
setState(() {});
},
onDoubleTap: () {
setState(() {
matrix = Matrix4.identity();
});
},
child: Transform(
transform: matrix,
alignment: FractionalOffset.topLeft,
child: Container(
color: Colors.black54,
child: Center(
child: Container(
width: 320,
height: 320,
color: Colors.redAccent,
),
),
),
),
),
Positioned(
top: 64.0,
right: 64.0,
child: Container(
color: Colors.pinkAccent,
child: IconButton(
icon: Icon(Icons.refresh),
iconSize: 72.0,
color: Colors.white,
onPressed: () {
setState(() {
matrix = Matrix4.identity();
});
},
),
),
),
],
);
}
}
When you run the code and tap on the screen, the Widget is rotated around the origin. How can I make it rotate around the tap position?
Set the transform origin as center before applying rotation on the widget;
alignment: FractionalOffset.center
I'm attempting to create a draggable slider-like widget (like a confirm slider). My question is if there is a way to constrain the draggable area?
import 'package:flutter/material.dart';
import 'confirmation_slider.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return new MaterialApp(
home: new Scaffold(
body: new ListView(
children: <Widget>[
new Container(
margin: EdgeInsets.only(
top: 50.0
),
),
new Container(
margin: EdgeInsets.only(
left: 50.0,
right: 50.0
),
child: new Draggable(
axis: Axis.horizontal,
child: new FlutterLogo(size: 50.0),
feedback: new FlutterLogo(size: 50.0),
),
height: 50.0,
color: Colors.green
),
],
),
),
);
}
}
I imagined that the container class would constrain the draggable area, but it doesn't appear to do that.
No. That's not the goal of Draggable widget. Instead, use a GestureDetector to detect drag. Then combine it with something like Align to move your content around
Here's a fully working slider based on your current code.
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: Center(
child: Slider(),
),
),
);
}
}
class Slider extends StatefulWidget {
final ValueChanged<double> valueChanged;
Slider({this.valueChanged});
#override
SliderState createState() {
return new SliderState();
}
}
class SliderState extends State<Slider> {
ValueNotifier<double> valueListener = ValueNotifier(.0);
#override
void initState() {
valueListener.addListener(notifyParent);
super.initState();
}
void notifyParent() {
if (widget.valueChanged != null) {
widget.valueChanged(valueListener.value);
}
}
#override
Widget build(BuildContext context) {
return Container(
color: Colors.green,
height: 50.0,
padding: EdgeInsets.symmetric(horizontal: 40.0),
child: Builder(
builder: (context) {
final handle = GestureDetector(
onHorizontalDragUpdate: (details) {
valueListener.value = (valueListener.value +
details.delta.dx / context.size.width)
.clamp(.0, 1.0);
},
child: FlutterLogo(size: 50.0),
);
return AnimatedBuilder(
animation: valueListener,
builder: (context, child) {
return Align(
alignment: Alignment(valueListener.value * 2 - 1, .5),
child: child,
);
},
child: handle,
);
},
),
);
}
}
As at 2022 here's a replica of #Remi's answer above, with minor tweaks to handle revisions to flutter/dart since 2018 (e.g. handling null-safety)
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return const MaterialApp(
home: Scaffold(
body: Center(
child: Slider(),
),
),
);
}
}
class Slider extends StatefulWidget {
final ValueChanged<double>? valueChanged;
const Slider({this.valueChanged});
#override
SliderState createState() {
return SliderState();
}
}
class SliderState extends State<Slider> {
ValueNotifier<double> valueListener = ValueNotifier(.0);
#override
void initState() {
valueListener.addListener(notifyParent);
super.initState();
}
void notifyParent() {
if (widget.valueChanged != null) {
widget.valueChanged!(valueListener.value);
}
}
#override
Widget build(BuildContext context) {
return Container(
color: Colors.green,
height: 50.0,
padding: const EdgeInsets.symmetric(horizontal: 40.0),
child: Builder(
builder: (context) {
final handle = GestureDetector(
onHorizontalDragUpdate: (details) {
valueListener.value = (valueListener.value + details.delta.dx / context.size!.width).clamp(.0, 1.0);
},
child: const FlutterLogo(size: 50.0),
);
return AnimatedBuilder(
animation: valueListener,
builder: (context, child) {
return Align(
alignment: Alignment(valueListener.value * 2 - 1, .5),
child: child,
);
},
child: handle,
);
},
),
);
}
}
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.