如何在 Flutter 中使用 PageView 创建轮播（滑动动画）？

Question

我想用图像创建滑块动画，还想允许用户使用滑动手势来回移动。另一个要求是页面指示器。为此，我使用了

page_indicator: ^0.1.3

目前我可以使用带有页面指示器的滑动手势在图像之间滑动，现在我想以 x 的持续时间重复设置幻灯片动画。我的代码如下。

final PageController controller = new PageController();

@override
Widget build(BuildContext context) {
List<Widget> list = new List<Widget>();
list.add(new SliderBox(image: 'assets/shirt.png'));
list.add(new SliderBox(image: 'assets/laptops.png'));
list.add(new SliderBox(image: 'assets/bags.png'));

PageIndicatorContainer container = new PageIndicatorContainer(
  pageView: new PageView(
    children: list,
    controller: controller,
  ),
  length: 3,
  padding: EdgeInsets.fromLTRB(10, 40, 10, 10),
  indicatorSpace: 10,
  indicatorColor: Colors.grey[350],
  indicatorSelectorColor: Colors.grey,
);

return Stack(children: <Widget>[
  Container(color: Colors.grey[100], height: double.infinity),
  Container(
      color: Colors.white,
      child: container,
      margin: EdgeInsets.only(bottom: 50)),Text('$moveToPage')
]);


class SliderBox extends StatelessWidget {
final image;

const SliderBox({Key key, this.image}) : super(key: key);

@override
Widget build(BuildContext context) {
// TODO: implement build
return Container(
    padding: EdgeInsets.all(10),
    child: Image.asset(
      image,
      height: 300,
      fit: BoxFit.fill,
    ));
}
}

Answer 1

我对您的小部件进行了一些修改，以便为您提供一个完整的示例。您可以通过多种方式执行此操作，使用 AnimationController by itself or even combined with a custom Animation 或者，您可以采用最快的方式来实现您想要实现的目标：使用递归方法等待 x 持续时间（单页时间）然后为新页面设置一些新的持续时间。为此，您可以例如：

使您的 List 在 state 本身内可用，以便检索其长度。
创建将处理动画本身的递归方法。
确保在屏幕上呈现第一帧后调用它，以防止 PageController 在 PageView 呈现在屏幕上之前被访问，这你可能不想要。为此，您可以利用 WidgetsBinding.instance.addPostFrameCallback.

class Carousel extends StatefulWidget {
  _CarouselState createState() => _CarouselState();
}

class _CarouselState extends State<Carousel> with SingleTickerProviderStateMixin {
  final PageController _controller = PageController();

  List<Widget> _list = [
    SliderBox(
        child: FlutterLogo(
      colors: Colors.red,
    )),
    SliderBox(
        child: FlutterLogo(
      colors: Colors.green,
    )),
    SliderBox(
        child: FlutterLogo(
      colors: Colors.blue,
    ))
  ];

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) => _animateSlider());
  }

  void _animateSlider() {
    Future.delayed(Duration(seconds: 2)).then((_) {
      int nextPage = _controller.page.round() + 1;

      if (nextPage == _list.length) {
        nextPage = 0;
      }

      _controller
          .animateToPage(nextPage, duration: Duration(seconds: 1), curve: Curves.linear)
          .then((_) => _animateSlider());
    });
  }

  @override
  Widget build(BuildContext context) {
    PageIndicatorContainer container = new PageIndicatorContainer(
      pageView: new PageView(
        children: _list,
        controller: _controller,
      ),
      length: _list.length,
      padding: EdgeInsets.fromLTRB(10, 40, 10, 10),
      indicatorSpace: 10,
      indicatorColor: Colors.grey[350],
      indicatorSelectorColor: Colors.grey,
    );

    return Stack(
      children: <Widget>[
        Container(color: Colors.grey[100], height: double.infinity),
        Container(color: Colors.white, child: container, margin: EdgeInsets.only(bottom: 50)),
      ],
    );
  }
}

class SliderBox extends StatelessWidget {
  final Widget child;
  const SliderBox({Key key, this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(padding: EdgeInsets.all(10), child: child);
  }
}

Answer 2

将 Worm Indicator 与 PageView 一起使用以显示滚动进度

在你的flutter项目中添加lib依赖

dependencies:
  worm_indicator: 0.1.1

使用

WormIndicator(
  length: PAGE_VIEW_SIZE,
  controller: PAGE_VIEW_CONTROLLER,
  size: DOT_SIZE_IN_PT,
  spacing: DOT_SPACING_IN_PT,
),

Circle 和方形 DotShape 需要尺寸。 Rectangle DotShape 需要宽度和高度。

WormIndicator(
  length: 3,
  controller: _controller,
  shape: Shape(
    size: 16,
    spacing: 8,
    shape: DotShape.Circle  // Similar for Square
  ),
),
WormIndicator(
  length: 3,
  controller: _controller,
  shape: Shape(
    width: 16,
    height: 24,
    spacing: 8,
    shape: DotShape.Rectangle
  ),
),

如何在 Flutter 中使用 PageView 创建轮播（滑动动画）？

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