Flutter Animating listview elements is not working - flutter

Question

I am trying to do a glow effect on the container. I am using streambuilder to build list items and when item price changes I want to show container glow effect. So far I have done this but the widget doesn't show the effect at all. didUpdateWidget doesn't show any update and when it does, all of the listview items animates themselves for infinite amount of time. Is there something I am missing?
AnimationController _animationController;
#override
void initState() {
super.initState();
_animationController = new AnimationController(
vsync: this, duration: new Duration(milliseconds: 500));
}
#override
void didUpdateWidget(CustomContainer oldWidget) {
super.didUpdateWidget(oldWidget);
if (oldWidget.price != widget.price) {
print("changed");
_animationController.repeat(
reverse: true, period: Duration(milliseconds: 1000));
}
}
#override
void dispose() {
_animationController.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return AnimatedBuilder(
animation: _animationController,
builder: (context, _) {
return Container(
height:100,
width:double.infinity,
decoration: BoxDecoration(
color: Theme.of(context).canvasColor,
borderRadius: BorderRadius.circular(10),
boxShadow: [
BoxShadow(
blurRadius: 4 * _animationController.value,
color: primaryColor.withOpacity(0.7),
),
],
),
);
});

Answer 1

AnimationController.repeat() will start running the animation and repeat it an infinite amount of times. This is why the items are animating themselves for infinitely. You would have to use .forward method instead:
_animationController = AnimationController(
duration: Duration(milliseconds: 500),
vsync: this);
_animationController.forward(); //tell the animation to start without repeating
From Flutter Docs:
AnimationController is a special Animation object that generates a new
value whenever the hardware is ready for a new frame. By default, an
AnimationController linearly produces the numbers from 0.0 to 1.0
during a given duration.
AnimationController derives from Animation, so it can be used
wherever an Animation object is needed. However, the
AnimationController has additional methods to control the animation.
For example, you start an animation with the .forward() method. The
generation of numbers is tied to the screen refresh, so typically 60
numbers are generated per second. After each number is generated, each
Animation object calls the attached Listener objects. To create a
custom display list for each child, see RepaintBoundary.
Here is the docs for AnimationController.forward(): https://api.flutter.dev/flutter/animation/AnimationController/forward.html