snap PageView

class MyHomePage extends StatelessWidget {
  int _index = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Carousel in vertical scrollable'),
      ),
      body: Center(
        child: SizedBox(
          height: 200, // card height
          child: PageView.builder(
            itemCount: 10,
            controller: PageController(viewportFraction: 0.7),
            onPageChanged: (int index) => (() => _index = index),
            itemBuilder: (_, i) {
              return Transform.scale(
                scale: i == _index ? 1 : 0.9,
                child: Card(
                  elevation: 6,
                  shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(20)),
                  child: Center(
                    child: Text(
                      "Card ${i + 1}",
                      style: TextStyle(fontSize: 32),
                    ),
                  ),
                ),
              );
            },
          ),
        ),
      )
    );
  }

  Widget _buildCarousel(BuildContext context, int carouselIndex) {
    return Column(
      mainAxisSize: MainAxisSize.min,
      children: <Widget>[
        Text('Carousel $carouselIndex'),
        SizedBox(
          // you may want to use an aspect ratio here for tablet support
          height: 200.0,
          child: PageView.builder(
            // store this controller in a State to save the carousel scroll position
            itemCount: 3,
            controller: PageController(viewportFraction: 0.8),
            itemBuilder: (BuildContext context, int itemIndex) {
              return _buildCarouselItem(context, carouselIndex, itemIndex);
            },
          ),
        )
      ],
    );
  }

  Widget _buildCarouselItem(BuildContext context, int carouselIndex, int itemIndex) {
    return Padding(
      padding: EdgeInsets.symmetric(horizontal: 4.0),
      child: Container(
        child: Center(child: Text('${itemIndex}')),
        decoration: BoxDecoration(
          color: Colors.grey,
          borderRadius: BorderRadius.all(Radius.circular(4.0)),
        ),
      ),
    );
  }
}