Flutter - No BorderRadius assignment - flutter

Question

When I build the application, I encounter such an error.
lib/input_page/pacman_slider.dart:41:7: Error: A value of type 'Animation<BorderRadius?>' can't be assigned to a variable of type 'Animation' because 'BorderRadius?' is nullable and 'BorderRadius' isn't.
'Animation' is from 'package:flutter/src/animation/animation.dart' ('../../Dev/flutter/packages/flutter/lib/src/animation/animation.dart').
'BorderRadius' is from 'package:flutter/src/painting/border_radius.dart' ('../../Dev/flutter/packages/flutter/lib/src/painting/border_radius.dart').
).animate(CurvedAnimation(
^
Error Code:
void initState() {
super.initState();
pacmanMovementController =
AnimationController(vsync: this, duration: Duration(milliseconds: 400));
_bordersAnimation = BorderRadiusTween(
begin: BorderRadius.circular(8.0),
end: BorderRadius.circular(50.0),
).animate(CurvedAnimation(
parent: widget.submitAnimationController,
curve: Interval(0.0, 0.07),
));
}
Full Code:
const double _pacmanWidth = 21.0;
const double _sliderHorizontalMargin = 24.0;
const double _dotsLeftMargin = 8.0;
class PacmanSlider extends StatefulWidget {
final VoidCallback onSubmit;
final AnimationController submitAnimationController;
const PacmanSlider(
{Key? key,
required this.onSubmit,
required this.submitAnimationController})
: super(key: key);
#override
_PacmanSliderState createState() => _PacmanSliderState();
}
class _PacmanSliderState extends State<PacmanSlider>
with TickerProviderStateMixin {
double _pacmanPosition = 24.0;
late Animation<BorderRadius> _bordersAnimation;
late Animation<double> _submitWidthAnimation;
late AnimationController pacmanMovementController;
late Animation<double> pacmanAnimation;
#override
void initState() {
super.initState();
pacmanMovementController =
AnimationController(vsync: this, duration: Duration(milliseconds: 400));
_bordersAnimation = BorderRadiusTween(
begin: BorderRadius.circular(8.0),
end: BorderRadius.circular(50.0),
).animate(CurvedAnimation(
parent: widget.submitAnimationController,
curve: Interval(0.0, 0.07),
));
}
#override
void dispose() {
pacmanMovementController.dispose();
super.dispose();
}
// double get width => _submitWidthAnimation?.value ?? 0.0;
double get width => _submitWidthAnimation.value;
#override
Widget build(BuildContext context) {
return LayoutBuilder(
builder: (context, constraints) {
_submitWidthAnimation = Tween<double>(
begin: constraints.maxWidth,
end: screenAwareSize(52.0, context),
).animate(CurvedAnimation(
parent: widget.submitAnimationController,
curve: Interval(0.05, 0.15),
));
return AnimatedBuilder(
animation: widget.submitAnimationController,
builder: (context, child) {
Decoration decoration = BoxDecoration(
borderRadius: _bordersAnimation.value,
color: Theme.of(context).primaryColor,
);
return Center(
child: Container(
height: screenAwareSize(52.0, context),
width: width,
decoration: decoration,
child: _submitWidthAnimation.isDismissed
? GestureDetector(
behavior: HitTestBehavior.translucent,
onTap: () => _animatePacmanToEnd(),
child: Stack(
alignment: Alignment.centerRight,
children: <Widget>[
AnimatedDots(),
_drawDotCurtain(decoration),
_drawPacman(),
],
),
)
: Container(),
),
);
},
);
},
);
}
Widget _drawDotCurtain(Decoration decoration) {
if (width == 0.0) {
return Container();
}
double marginRight =
width - _pacmanPosition - screenAwareSize(_pacmanWidth / 2, context);
return Positioned.fill(
right: marginRight,
child: Container(decoration: decoration),
);
}
Widget _drawPacman() {
pacmanAnimation = _initPacmanAnimation();
return Positioned(
left: _pacmanPosition,
child: GestureDetector(
onHorizontalDragUpdate: (details) => _onPacmanDrag(width, details),
onHorizontalDragEnd: (details) => _onPacmanEnd(width, details),
child: PacmanIcon(),
),
);
}
Animation<double> _initPacmanAnimation() {
Animation<double> animation = Tween(
begin: _pacmanMinPosition(),
end: _pacmanMaxPosition(width),
).animate(pacmanMovementController);
animation.addListener(() {
setState(() {
_pacmanPosition = animation.value;
});
if (animation.status == AnimationStatus.completed) {
_onPacmanSubmit();
}
});
return animation;
}
_onPacmanSubmit() {
widget.onSubmit();
Future.delayed(Duration(seconds: 1), () => _resetPacman());
}
_onPacmanDrag(double width, DragUpdateDetails details) {
setState(() {
_pacmanPosition += details.delta.dx;
_pacmanPosition = math.max(_pacmanMinPosition(),
math.min(_pacmanMaxPosition(width), _pacmanPosition));
});
}
_onPacmanEnd(double width, DragEndDetails details) {
bool isOverHalf =
_pacmanPosition + screenAwareSize(_pacmanWidth / 2, context) >
0.5 * width;
if (isOverHalf) {
_animatePacmanToEnd();
} else {
_resetPacman();
}
}
_animatePacmanToEnd() {
pacmanMovementController.forward(
from: _pacmanPosition / _pacmanMaxPosition(width));
}
_resetPacman() {
if (this.mounted) {
setState(() => _pacmanPosition = _pacmanMinPosition());
}
}
double _pacmanMinPosition() =>
screenAwareSize(_sliderHorizontalMargin, context);
double _pacmanMaxPosition(double sliderWidth) =>
sliderWidth -
screenAwareSize(_sliderHorizontalMargin / 2 + _pacmanWidth, context);
}
class AnimatedDots extends StatefulWidget {
#override
_AnimatedDotsState createState() => _AnimatedDotsState();
}
class _AnimatedDotsState extends State<AnimatedDots>
with TickerProviderStateMixin {
final int numberOfDots = 10;
final double minOpacity = 0.1;
final double maxOpacity = 0.5;
late AnimationController hintAnimationController;
#override
void initState() {
super.initState();
_initHintAnimationController();
hintAnimationController.forward();
}
#override
void dispose() {
hintAnimationController.dispose();
super.dispose();
}
void _initHintAnimationController() {
hintAnimationController = AnimationController(
vsync: this,
duration: Duration(milliseconds: 800),
);
hintAnimationController.addStatusListener((status) {
if (status == AnimationStatus.completed) {
Future.delayed(Duration(milliseconds: 800), () {
if (this.mounted) {
hintAnimationController.forward(from: 0.0);
}
});
}
});
}
#override
Widget build(BuildContext context) {
return Padding(
padding: EdgeInsets.only(
left: screenAwareSize(
_sliderHorizontalMargin + _pacmanWidth + _dotsLeftMargin,
context),
right: screenAwareSize(_sliderHorizontalMargin, context)),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: List.generate(numberOfDots, _generateDot)
..add(Opacity(
opacity: maxOpacity,
child: Dot(size: 14.0),
)),
),
);
}
Widget _generateDot(int dotNumber) {
Animation animation = _initDotAnimation(dotNumber);
return AnimatedBuilder(
animation: animation,
builder: (context, child) => Opacity(
opacity: animation.value,
child: child,
),
child: Dot(size: 9.0),
);
}
Animation<double> _initDotAnimation(int dotNumber) {
double lastDotStartTime = 0.4;
double dotAnimationDuration = 0.5;
double begin = lastDotStartTime * dotNumber / numberOfDots;
double end = begin + dotAnimationDuration;
return SinusoidalAnimation(min: minOpacity, max: maxOpacity).animate(
CurvedAnimation(
parent: hintAnimationController,
curve: Interval(begin, end),
),
);
}
}
class SinusoidalAnimation extends Animatable<double> {
SinusoidalAnimation({required this.min, required this.max});
final double min;
final double max;
#override
double transform(double t) {
return min + (max - min) * math.sin(math.pi * t);
}
}
class Dot extends StatelessWidget {
final double size;
const Dot({Key? key, required this.size}) : super(key: key);
#override
Widget build(BuildContext context) {
return Container(
height: screenAwareSize(size, context),
width: screenAwareSize(size, context),
decoration: BoxDecoration(
shape: BoxShape.circle,
color: Colors.white,
),
);
}
}
class PacmanIcon extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Padding(
padding: EdgeInsets.only(
right: screenAwareSize(16.0, context),
),
child: SvgPicture.asset(
'images/pacman.svg',
height: screenAwareSize(25.0, context),
width: screenAwareSize(21.0, context),
),
);
}
}

Answer 1

As you see in the attached capture, BorderRadiusTween has a nullable value of type BorderRadius?
I'd suggest to either declare _bordersAnimation as Animation<BorderRadius?>or just using an Animation<double> instead