如何在颤动中制作滚动计数器

Question

我想创建一个滚动计数器，我想知道如何在 flutter 中实现它。

Answer 1

我将补间动画与动画生成器一起使用

IntTween(begin: 0, end: starredCount).animate(
      CurvedAnimation(parent: animationController, curve: Curves.easeOut)

Answer 2

您应该通过以下方式实施

class ValueChangeAnimationWidget extends StatefulWidget {
  @override
  ValueChangeAnimationWidgetState createState() =>
      ValueChangeAnimationWidgetState();
}

class ValueChangeAnimationWidgetState
    extends State<ValueChangeAnimationWidget> with TickerProviderStateMixin {
  AnimationController controller;
  Animation animation;

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

    controller = AnimationController(
        duration: const Duration(milliseconds: 1000), vsync: this);
    final Animation curve =
    CurvedAnimation(parent: controller, curve: Curves.easeOut);
    animation = IntTween(begin: 0, end: 10).animate(curve)
      ..addStatusListener((status) {
        if (status == AnimationStatus.completed) {
          controller.reverse();
        }
        if (status == AnimationStatus.dismissed) {
          Navigator.pop(context);
        }
      });
  }

  @override
  Widget build(BuildContext context) {
    controller.forward();
    return AnimatedBuilder(
        animation: controller,
        builder: (BuildContext context, Widget child) {
          return Scaffold(
              body: new Center(
                child: Text(animation.value.toString(), style: TextStyle(fontSize: 48.0)),
              ));
        });
  }

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

Answer 3

我想在一个项目中这样做，所以我创建了一个名为 AnimatedFlipCounter 的隐式动画小部件，它实现了类似的效果。

我已经打包发布了：https://pub.dev/packages/animated_flip_counter

用法：

AnimatedFlipCounter(
   duration: Duration(milliseconds: 500),
   value: _value, /* pass in a number like 2014 */
)

小数：

AnimatedFlipCounter(
  value: _value,
  fractionDigits: 2, // decimal precision
  suffix: "%",
  textStyle: TextStyle(
      fontSize: 40,
      color: _value >= 0 ? Colors.green : Colors.red,
  ),
)

如何在颤动中制作滚动计数器

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