CODEWITHSUNDEEP
animationflutterdart
Hasen
Hasen

Reputation: 12346

Flutter set start animation value

I want to pass in a value to set the starting animation value to 1.0 instead of starting from 0, but I don't know how this is achieved.

class AnimatedIconButton extends StatefulWidget {
  AnimatedIconButton(this.img, this.start);
  final String img;
  final double start;
  @override
  _AnimatedIconButtonState createState() => _AnimatedIconButtonState();
}

class _AnimatedIconButtonState extends State<AnimatedIconButton>
    with TickerProviderStateMixin {
  AnimationController _controller;
  Animation _animation;

  void animateButton() {
    if (_animation.value == 0)
      _controller.forward();
    else
      _controller.reverse();
  }

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: Duration(milliseconds: 300),
      vsync: this,
    );
    _animation =
        CurvedAnimation(parent: _controller, curve: Curves.easeOutQuad);
    _controller.addListener(() {
      setState(() {});
    });
    _animation.value = widget.start;// does not work
  }

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

  @override
  Widget build(BuildContext context) {
    return MaterialButton(
      splashColor: Colors.white,
      highlightColor: Colors.white,
      child: Image.asset("images/${widget.img}.png",
          width: 33 + (16 * _animation.value)),
      onPressed: () {
        animateButton();
      },
    );
  }
}

Upvotes: 1

Views: 10259

Answers (4)

Lukas Nevosad
Lukas Nevosad

Reputation: 304

If you want to use an animation where forward() will drive the value in reverse, i.e. 1.0 → 0.0, the simplest solution is to use ReverseAnimation:

  @override
  void initState() {
    super.initState();
    _animationController =
        AnimationController(vsync: this, duration: Duration(milliseconds: 500));
    _hideAnimation = ReverseAnimation(
      CurvedAnimation(
        parent: _animationController,
        curve: Curves.fastOutSlowIn,
      ),
    ),
  }

Upvotes: 2

Mohamed Gaber
Mohamed Gaber

Reputation: 1745

as i understand you want to make animation starts from 1.0 instead of starting from 0.0 so here we are ..

Make global variables like:- 

Animation<double> animation;
AnimationController controller;
Tween<double> tween = Tween(begin: 0, end: 100);

Override initState method:-

@override
void initState() {
super.initState();
controller=AnimationController(vsync: this, duration: Duration(seconds: 2));
animation = tween.animate(controller);
}

finally you can change start & end animation values by this :-

void accessToStartOfAnimation() {
print(tween.begin);
tween.begin = 1;
print(tween.begin);
}

Upvotes: 0

Andrii Turkovskyi
Andrii Turkovskyi

Reputation: 29468

You can use:

_controller.forward(from: 0.0);

or

_controller.reverse(from: 1.0);

And set value you need

Or for setting initial value you can use

_controller.value = widget.start;

Upvotes: 9

ibhavikmakwana
ibhavikmakwana

Reputation: 10161

Inside your code:

add _controller.forward(1.0);.

Here you can pass the value you want.

Like below:

void animateButton() {
  if (_animation.value == 0)
    _controller.forward(from: 1.0);
  else
    _controller.reverse(from: 1.0);
}

Upvotes: 1

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