Question

我正在构建一个从API获取数据的Flutter应用。

如何将快照数据从Flutter屏幕传递到小部件构建器上下文之外的浮动操作按钮？

然后，浮动按钮会将数据传递给PDF构建器函数。

这是我的代码。

@override 小部件build（BuildContext context）{ 返回脚手架（ appBar：AppBar（ backgroundColor：Colors.blue， automaticImplyLeading：否， centerTitle：是的，

                        title: Text(widget.bill.billNumber.toString(), 
                                    style: TextStyle(color: Colors.white)
                                    ),

                        leading: IconButton(icon:Icon(Icons.arrow_back),
                                  onPressed:() =>

                        Navigator.of(context).pushAndRemoveUntil(
                          MaterialPageRoute(
                             builder: (context) =>
                               BillsScreen(table: widget.table)), (Route<dynamic> route) => false)
                        )
              ),
              body: SafeArea(
                child: Container(
                       child: 
                          StreamBuilder<SalesResponse>(
                              stream: salesBloc.subject.stream,
                              builder: (context, AsyncSnapshot<SalesResponse> snapshot) {

                                     if (snapshot.hasData) {

            return  _buildSalesListWidget(snapshot.data);

                                     } 

                                     else if (snapshot.hasError) {

                                             return                   
                  _buildErrorWidget(snapshot.error);

                                     } 
                              },
                          )
              ),
        ),

              floatingActionButtonLocation:  FloatingActionButtonLocation.centerDocked,
                 floatingActionButton: Padding(
                    padding: const EdgeInsets.all(8.0),
                    child: Row(
                              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                              children: <Widget>[

                                 FloatingActionButton(
                                    heroTag: 1,
                                    backgroundColor: Colors.yellow,
                                    onPressed: () {
                                        Printing.layoutPdf(onLayout:(format)=> 
                                           buildReceipt(widget.table, 
                                                        widget.bill, 
                                                        data.sales));
                                    },
                                    child: Icon(FontAwesomeIcons.print),
                                 ),
                              ],
                    ),
                )    
    );    
  }

  Widget _buildSalesListWidget(SalesResponse data) {
          return ListView.builder(
                     itemCount: data.sales.length,
                     itemBuilder: (context, index) {
                         return ListTile(
                                  title: Text(
                                              data.sales[index].item,
                                              style: TextStyle(
                                                         fontWeight: FontWeight.w500,
                                                         fontSize: 20,
                                              ),
                                  ),
                                  subtitle: Text('qty' + ' ' + data.sales[index].qty.toString() + ', ' + 'price' + ' ' + data.sales[index].price.toStringAsFixed(2)),

                                  leading: Icon(
                                                FontAwesomeIcons.beer,
                                                color: Colors.blue[500],
                                  ),           
                                  onTap: () {},
                         );
                     },
        );

  }
}

Answer 1

class Screen extends StatefulWidget {
  @override
  _ScreenState createState() => _ScreenState();
}

class _ScreenState extends State<Screen> {

  String snapshotData = "";

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: FutureBuilder(
          future: Future.delayed(const Duration(seconds: 1), () => "data to pass"),
          builder: (context, AsyncSnapshot<String> snapshot) {
            if(!snapshot.hasData) {
             return Text("NO Data");
            } else {
              snapshotData = snapshot.data;
              return Text("Data loaded");
            }
          },
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => print(snapshotData),
      ),
    );
  }
}

如何将快照数据传递到Flutter浮动操作按钮？

1 个答案: