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onPressed: () {
  final _cart = Provider.of<CartProvider>(context);
  _cart.addProduct(this.product);
},

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final _cart = Provider.of<CartProvider>(context);

...

FlatButton(
  child: Text(
    "${_cart.products.length}",
    style: TextStyle(color: Colors.white, fontSize: 20),
  ),
  onPressed: () {

slamdon

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: ChangeNotifierProvider.value(
        value: CartProvider(),

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class CartProvider with ChangeNotifier {
  List<Product> products = [];
  
  addProduct(Product product) {
    products.add(product);
    notifyListeners();
  }
  
}

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Widget _buildInformationMiddleContainer(BuildContext context) {
  return Padding(
    padding: EdgeInsets.fromLTRB(0, 4, 0, 4),
    child: Text(
      this.product.description,
      maxLines: 2,
      overflow: TextOverflow.ellipsis,
      style: TextStyle(color: Colors.grey, fontSize: 12),
    ),
  );

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Widget _buildInformationTopContainer(BuildContext context) {
  return Container(
    child: Row(
      children: <Widget>[
        Expanded(
          child: Text(this.product.title),
          flex: 1,
        ),
        Expanded(
          child: ListView.builder(

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Column(
  children: <Widget>[
    _buildInformationTopContainer(context),
    _buildInformationMiddleContainer(context),
    _buildInformationBottomContainer(context),
  ],
),

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Widget _buildImageContainer(BuildContext context) {
  return ClipRRect(
    child: SizedBox(
      child: Image.asset(
        this.product.imagePath,
        fit: BoxFit.cover,
      ),
    ),
    borderRadius: BorderRadius.circular(10),
  );

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@override
Widget build(BuildContext context) {
  return Center(
    child: SizedBox.fromSize(
      size: Size.fromHeight(550),
      child: TripPageTransformer(
        pageViewBuilder: (context, visibilityResolver) {
          return PageView.builder(
            controller: PageController(viewportFraction: 0.85),
            itemCount: trips.length,

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  @override
  Widget build(BuildContext context) {
    final pageView = this.widget.pageViewBuilder(
          context,
          _visibilityResolver ?? TripPageVisibilityResolver(),
        );

    return NotificationListener<ScrollNotification>(
      child: pageView,
      onNotification: (ScrollNotification notification) {