Rotate icon 180 degree with animation in flutter

Question

I have a IconButton, Normally, It's icon is Icons.expand_more but When I press that its icon should be Icons.expand_less. I want to animated this so that if I press that button, it will rotate and point the downwords from upwords. and same when I press the expand_less then it should become expand_more with rotating animation. How can I acheive this ? below is my code :

    IconButton(
      icon:  _expanded ? Icon(Icons.expand_less) : Icon(Icons.expand_more),
      onPressed: () {
        setState(() {
           _expanded = !_expanded;
        });
      },
   )

I tried to use animatedContainer but it didn't work as I am using two different icons and that rotation effect I cannot acheive with this. I also tried to rotate the icon with below approach but it cannot show the animation when it is rotating from 0 to 180 degree.

IconButton(
              icon: AnimatedContainer(
                  duration: Duration(seconds: 3),
                  child: Transform.rotate(
                      angle: _expanded ? 0 : 180 * math.pi / 180,
                      child: Icon(Icons.expand_less))),
              // icon:
              //     _expanded ? Icon(Icons.expand_less) : Icon(Icons.expand_more),
              onPressed: () {
                setState(() {
                  _expanded = !_expanded;
                });
              },
            )

This is before expansion :

This is after expansion :

I want the rotation animation on button click.

Answer 1

Check out this test sample I have made for what you need.

This also applies a curve which is a good Flutter suggestion.

import 'package:flutter/material.dart';

class RotateIcon extends StatefulWidget {
  const RotateIcon({Key? key}) : super(key: key);

  @override
  _RotateIconState createState() => _RotateIconState();
}

class _RotateIconState extends State<RotateIcon>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
        duration: const Duration(milliseconds: 500), vsync: this);
    _animation =
        Tween(begin: 0.0, end: .5).animate(CurvedAnimation(
        parent: _controller, curve: Curves.easeOut));
    }

  @override
  void dispose() {
    super.dispose();
    _controller.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
          child: Column(
            children: [
              RotationTransition(
                turns: _animation,
                child: const Icon(Icons.expand_more),
              ),
              ElevatedButton(
                  onPressed: () {
                    if (_controller.isDismissed) {
                      _controller.forward();
                    } else {
                      _controller.reverse();
                    }
                  },
                  child: const Text("Animate"))
            ],
          )),
    );
  }
}

Answer 2

Thanks to @krumpli.

1. Define AnimationController _controller.

2. Define init method as :

  @override
  void initState() {
    super.initState();

    _controller = AnimationController(
      vsync: this,
      duration: Duration(milliseconds: 300),
      upperBound: 0.5,
    );
  }

3. Define dispose method as :

@override
  void dispose() {
    super.dispose();
    _controller.dispose();
  }

4. With the use of the widget RotationTransition :

RotationTransition(
              turns: Tween(begin: 0.0, end: 1.0).animate(_controller),
              child: IconButton(
                icon: Icon(Icons.expand_less),
                onPressed: () {
                  setState(() {
                    if (_expanded) {
                      _controller..reverse(from: 0.5);
                    } else {
                      _controller..forward(from: 0.0);
                    }
                    _expanded = !_expanded;
                  });
                },
              ),
            )

Don't forget to add with SingleTickerProviderStateMixin in the class defintion.

Answer 3

Try this: Add an animation controller: AnimationController _animationController:

initState() {
    _animationController = new AnimationController(
        vsync: this, duration: Duration(milliseconds: 300));
    }

wrap your icon in this:

RotationTransition(
         turns: Tween(begin: 0.0, end: 1.0)
                .animate(_animationController),
         child: IconButton(icon: //YOUR ICON),
         onPressed: () {
             setState(() {
        _animationController1.forward(from: 0.0);
      });
     },
   ),
 )

Finally:

  @override
  void dispose() {
    super.dispose();
    _animationController?.dispose();
  }