Question

我目前正在使用carousel-slider库在Flutter中获取轮播。

该库基于PageView，在PageView中，元素居中。

这就是我得到的轮播：

First carousel

这就是我想要的：

Wanted carousel

以下是使用CarouselSlider的代码：

CarouselSlider(
    height: 150,
    viewportFraction: 0.5,
    initialPage: 0,
    enableInfiniteScroll: false,
    items: widget.user.lastGamesPlayed.map((game) {
      return Builder(
        builder: (BuildContext context) {
          return Padding(
              padding: EdgeInsets.symmetric(horizontal: 10),
              child: GestureDetector(
                  onTap: () {
                    game.presentGame(context, widget.user);
                  },
                  child: ClipRRect(
                      borderRadius: BorderRadius.all(Radius.circular(25)),
                      child: Container(
                        color: Theme.MyColors.lightBlue,
                        child: Center(
                          child: Padding(
                              padding: EdgeInsets.all(20),
                              child: AutoSizeText(game.name,
                                  style: TextStyle(fontSize: 70),
                                  maxLines: 1)),
                        ),
                      ))));
        },
      );
    }).toList(),
  )

这是CarouselSlider库中的代码：

@override
Widget build(BuildContext context) {
return getWrapper(PageView.builder(
  physics: widget.isScrollEnabled
      ? AlwaysScrollableScrollPhysics()
      : NeverScrollableScrollPhysics(),
  scrollDirection: widget.scrollDirection,
  controller: widget.pageController,
  reverse: widget.reverse,
  itemCount: widget.enableInfiniteScroll ? null : widget.items.length,
  onPageChanged: (int index) {
    int currentPage =
        _getRealIndex(index, widget.realPage, widget.items.length);
    if (widget.onPageChanged != null) {
      widget.onPageChanged(currentPage);
    }
  },
  itemBuilder: (BuildContext context, int i) {
    final int index = _getRealIndex(
        i + widget.initialPage, widget.realPage, widget.items.length);

    return AnimatedBuilder(
      animation: widget.pageController,
      child: widget.items[index],
      builder: (BuildContext context, child) {
        // on the first render, the pageController.page is null,
        // this is a dirty hack
        if (widget.pageController.position.minScrollExtent == null ||
            widget.pageController.position.maxScrollExtent == null) {
          Future.delayed(Duration(microseconds: 1), () {
            setState(() {});
          });
          return Container();
        }
        double value = widget.pageController.page - i;
        value = (1 - (value.abs() * 0.3)).clamp(0.0, 1.0);

        final double height = widget.height ??
            MediaQuery.of(context).size.width * (1 / widget.aspectRatio);
        final double distortionValue = widget.enlargeCenterPage
            ? Curves.easeOut.transform(value)
            : 1.0;

        if (widget.scrollDirection == Axis.horizontal) {
          return Center(
              child:
                  SizedBox(height: distortionValue * height, child: child));
        } else {
          return Center(
              child: SizedBox(
                  width:
                      distortionValue * MediaQuery.of(context).size.width,
                  child: child));
        }
      },
    );
  },
));

}

如何防止元素居中？

提前谢谢

Answer 1

如果您不希望通过滚动动画来调整页面大小，则无需使用此旋转木马滑块库。

此外，PageView并不是实现所需布局的最佳Widget，您应该将水平ListView与PageScrollPhysics一起使用。

import 'package:flutter/material.dart';

class Carousel extends StatelessWidget {
  Carousel({
    Key key,
    @required this.items,
    @required this.builderFunction,
    @required this.height,
    this.dividerIndent = 10,
  }) : super(key: key);

  final List<dynamic> items;
  final double dividerIndent;

  final Function(BuildContext context, dynamic item) builderFunction;

  final double height;

  @override
  Widget build(BuildContext context) {
    return Container(
      height: height,
      child: ListView.separated(
          physics: PageScrollPhysics(),
          separatorBuilder: (context, index) => Divider(
                indent: dividerIndent,
              ),
          scrollDirection: Axis.horizontal,
          itemCount: items.length,
          itemBuilder: (context, index) {
            Widget item = builderFunction(context, items[index]);
            if (index == 0) {
              return Padding(
                child: item,
                padding: EdgeInsets.only(left: dividerIndent),
              );
            } else if (index == items.length - 1) {
              return Padding(
                child: item,
                padding: EdgeInsets.only(right: dividerIndent),
              );
            }
            return item;
          }),
    );
  }
}

用法

           Carousel(
              height: 150,
              items: widget.user.lastGamesPlayed,
              builderFunction: (context, item) {
                return ClipRRect(
                  borderRadius: BorderRadius.all(Radius.circular(25)),
                  child: Container(
                    width: 200,
                    color: Theme.MyColors.lightBlue,
                    child: Center(
                      child: Padding(
                        padding: EdgeInsets.all(20),
                        child: AutoSizeText(
                          item.name,
                          style: TextStyle(fontSize: 70),
                          maxLines: 1,
                        ),
                      ),
                    ),
                  ),
                );
              },
            )

更新

@AdamK观察到，我的解决方案与PageView的滚动物理行为不同，它的行为更像是水平的ListView。

如果您正在寻找这种分页行为，则应考虑编写自定义ScrollPhysics并将其用于可滚动小部件。

This是一篇很好解释的文章，可以帮助我们达到预期的效果。

Answer 2

这是carouselSlider中的一个参数，名称为：expandCenterPage：设为true，这是我的代码，对我来说很好

 static List<String> imgList; //list of String link of pictures

 static List<T> map<T>(List list, Function handler) {
    List<T> result = [];
    for (var i = 0; i < list.length; i++) {
      result.add(handler(i, list[i]));
    }

    return result;
  }

 int _current = 0;

CarouselSlider(
                items: map<Widget>(
                  imgList,
                  (index, i) {
                    return Container(
                      margin: EdgeInsets.all(5.0),
                      child: ClipRRect(
                        borderRadius: BorderRadius.all(Radius.circular(5.0)),
                        child: Stack(children: <Widget>[
                          Image.network(i, fit: BoxFit.cover, width: 1000.0),
                          Positioned(
                            bottom: 0.0,
                            left: 0.0,
                            right: 0.0,
                            child: Container(
                              decoration: BoxDecoration(
                                gradient: LinearGradient(
                                  colors: [
                                    Color.fromARGB(200, 0, 0, 0),
                                    Color.fromARGB(0, 0, 0, 0)
                                  ],
                                  begin: Alignment.bottomCenter,
                                  end: Alignment.topCenter,
                                ),
                              ),
                              padding: EdgeInsets.symmetric(
                                  vertical: 10.0, horizontal: 20.0),
                              child: Text(
                                'No. $index image',
                                style: TextStyle(
                                  color: Colors.white,
                                  fontSize: 20.0,
                                  fontWeight: FontWeight.bold,
                                ),
                              ),
                            ),
                          ),
                        ]),
                      ),
                    );
                  },
                ).toList(),
                autoPlay: true,
                enlargeCenterPage: true,
                aspectRatio: 2.0,
                onPageChanged: (index) {
                  setState(() {
                    _current = index;
                  });
                },
              )

不要将PageView居中-Flutter

2 个答案: