how to give a curve effect to a specific range from animation value - flutter - flutter

Question

I need to divide the range of animation value to a smaller ranges like this simple example:
class TextAnimation extends StatefulWidget {
const TextAnimation({Key? key}) : super(key: key);
#override
State<TextAnimation> createState() => _TextAnimationState();
}
class _TextAnimationState extends State<TextAnimation>
with SingleTickerProviderStateMixin {
late AnimationController anController;
#override
void initState() {
// TODO: implement initState
super.initState();
anController = AnimationController(
vsync: this,
duration: Duration(seconds: 5),
reverseDuration: Duration(seconds: 5));
}
#override
void dispose() {
// TODO: implement dispose
super.dispose();
anController.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: AnimatedBuilder(
animation: anController,
builder: (context, child) {
return Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
SizedBox(
width: double.infinity,
),
Container(
width: 300 *
Tween(begin: 0.0, end: 1.0)
.animate(CurvedAnimation(
parent: anController,
curve:
Curves.fastOutSlowIn))
.value,
height: 100,
color: Colors.red,
),
Container(
width: 300 *
(Tween(begin: 0.0, end: 1.0) .animate(CurvedAnimation(
parent: anController, curve: Curves.fastOutSlowIn))
.value.clamp(0.5, 1)),
height: 100,
color: Colors.blue),
InkWell(
onTap: () {
anController.forward();
},
child: Text(
'Start',
style: TextStyle(
color: Colors.black,
fontSize: 20,
),
))
],
);
}),
);
}
}
the second container need to start the animation from the half of the range to the end...
the problem is, the curve effect is lost in this range ,I need to give this range (0.5-1.0) its own curve ,
start fast in 0.5 and end with slow motion.
is there a way to do it without using another animation controller to drive this range?
note : without AnimatedContainer the code above is just a simple example for the problem.