flutter画廊效果 ViewPage

最新推荐文章于 2024-10-31 18:07:31 发布

原创最新推荐文章于 2024-10-31 18:07:31 发布 · 1.9k 阅读

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#flutter #android #css

本文介绍了一个使用Flutter实现的画廊视图效果，通过自定义`PageView`的缩放和平移，使得当前页面、左右相邻页面以及其它页面呈现出不同的缩放比例，实现了平滑的画廊过渡效果。

/*
* 画廊效果
*缩放ViewPage
* */
class GalleryViewPage extends StatefulWidget {
  double viewPageHeight;
  GalleryViewPage({
    this.viewPageHeight
  });
  @override
  State<StatefulWidget> createState() => _GalleryViewPageState();
}

class _GalleryViewPageState extends BaseState<GalleryViewPage> {
  var imgList = [ ];
  PageController _pageController;

  var _currPageValue = 0.0;

  //缩放系数
  double _scaleFactor = .8;

  @override
  void initState() {
    super.initState();
    _pageController = PageController(viewportFraction: 0.85);
    _pageController.addListener(() {
      setState(() {
        _currPageValue = _pageController.page;
      });
    });
  }

  @override
  void dispose() {
    super.dispose();
    _pageController.dispose();
  }
  @override
  Widget build(BuildContext context) {
    return onActivityCreate(context);
  }

  @override
  onActivityCreate(BuildContext context) {
    // TODO: implement onActivityCreate
    return Container(
        //height: _height,
        child: PageView.builder(
          itemBuilder: (context, index) => _buildPageItem(index),
          itemCount: 2,
          controller: _pageController,
        ));
  }

  _buildPageItem(int index) {
    Matrix4 matrix4 = Matrix4.identity();
    if (index == _currPageValue.floor()) {
      //当前的item
      var currScale = 1 - (_currPageValue - index) * (1 - _scaleFactor);
      var currTrans = widget.viewPageHeight * (1 - currScale) / 2;

      matrix4 = Matrix4.diagonal3Values(1.0, currScale, 1.0)
        ..setTranslationRaw(0.0, currTrans, 0.0);
    } else if (index == _currPageValue.floor() + 1) {
      //右边的item
      var currScale =
          _scaleFactor + (_currPageValue - index + 1) * (1 - _scaleFactor);
      var currTrans = widget.viewPageHeight * (1 - currScale) / 2;

      matrix4 = Matrix4.diagonal3Values(1.0, currScale, 1.0)
        ..setTranslationRaw(0.0, currTrans, 0.0);
    } else if (index == _currPageValue.floor() - 1) {
      //左边
      var currScale = 1 - (_currPageValue - index) * (1 - _scaleFactor);
      var currTrans = widget.viewPageHeight * (1 - currScale) / 2;

      matrix4 = Matrix4.diagonal3Values(1.0, currScale, 1.0)
        ..setTranslationRaw(0.0, currTrans, 0.0);
    } else {
      //其他，不在屏幕显示的item
      matrix4 = Matrix4.diagonal3Values(1.0, _scaleFactor, 1.0)
        ..setTranslationRaw(0.0, widget.viewPageHeight * (1 - _scaleFactor) / 2, 0.0);
    }
    return Transform(
      transform: matrix4,
      child: Padding(
        padding: EdgeInsets.symmetric(horizontal: ScreenUtil().setWidth(20)),
        child: GuaranteeRemindDetailCardView(),
      ),
    );
  }