如何在 flutter 应用程序中使用 ProgressHUD show() 和 Dismiss() 作为小部件？

Question

在下面的 Home 和 Invoices 代码中，我实现了 ProgressHUD show() 和 dismiss() 来显示加载器。现在我必须在返回中心的末尾实现这个 ProgressHUD show() 和 dismiss() 加载器，带有圆形进度指示器小部件。我怎样才能实现它。我试过这样实现它：

return ProgressHUD(
                        child: Builder(builder: (context) {
                          final progress = ProgressHUD.of(context);
progress!.show();
                         
                        }),
                      );

但是没有用。有没有另一种方法来实现它。

import 'package:flutter/material.dart';
import 'package:flutter_progress_hud/flutter_progress_hud.dart';
import 'package:flutter_svg/flutter_svg.dart';
import 'package:provider/provider.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:xuriti/logic/view_models/company_details_manager.dart';
import 'package:xuriti/models/core/credit_limit_model.dart';
import 'package:xuriti/models/core/invoice_model.dart';
import 'package:xuriti/ui/screens/bhome_screens/bhome_screen.dart';
import 'package:xuriti/ui/screens/invoices_screens/invoices_screen.dart';
import 'package:xuriti/ui/theme/constants.dart';
import 'package:fluttertoast/fluttertoast.dart';

import '../../../logic/view_models/transaction_manager.dart';
import '../../../models/helper/service_locator.dart';
import '../../widgets/drawer_widget.dart';

class LandingScreen extends StatefulWidget {
  const LandingScreen({Key? key}) : super(key: key);

  @override
  State<LandingScreen> createState() => _LandingScreenState();
}

class _LandingScreenState extends State<LandingScreen> {
  @override
  void initState() {
    getIt<CompanyDetailsManager>().resetSellerInfo();

    super.initState();
  }

  void refreshFutureToGetInvoicesList() {
    setState(() {});
  }

  @override
  // void didChangeDependencies() {
  //   print("dependency called");
  //
  //   // getIt<TransactionManager>().getOutStandingAmt();
  //   super.didChangeDependencies();
  // }
  GlobalKey<ScaffoldState> sk = GlobalKey();
  int currentIndex = 0;

  DateTime? currentBackPressTime;
  @override
  Widget build(BuildContext context) {
    DateTime _lastExitTime = DateTime.now();
    onWillPop() async {
      if (DateTime.now().difference(_lastExitTime) >= Duration(seconds: 2)) {
        //showing message to user
        final snack = SnackBar(
          content: Text("Press the back button again to exist the app"),
          duration: Duration(seconds: 2),
        );
        ScaffoldMessenger.of(context).showSnackBar(snack);
        _lastExitTime = DateTime.now();
        return false; // disable back press
      } else {
        return true; //  exit the app
      }
    }

    String? id = getIt<SharedPreferences>().getString('companyId');

    List<Widget> screens = [
      const BhomeScreen(),
      InvoicesScreen(refreshingFunction: refreshFutureToGetInvoicesList),
    ];
    return ProgressHUD(
      child: LayoutBuilder(builder: (context, constraints) {
        final progress = ProgressHUD.of(context);

        double maxHeight = constraints.maxHeight;
        double maxWidth = constraints.maxWidth;
        double h1p = maxHeight * 0.01;
        double h10p = maxHeight * 0.1;
        double w10p = maxWidth * 0.1;
        return WillPopScope(
          onWillPop: onWillPop,
          child: SafeArea(
              child: FutureBuilder(
                  future: getIt<TransactionManager>().getInvoices(id),
                  builder: (context, snapshot) {
                    if (snapshot.connectionState == ConnectionState.done) {
                      if (snapshot.hasError) {
                        return Center(
                          child: Text(
                            '${snapshot.error} occurred',
                            style: TextStyle(fontSize: 18),
                          ),
                        );
                      } else if (snapshot.hasData) {
                        Invoices data = snapshot.data as Invoices;

                        return Scaffold(
                          key: sk,
                          endDrawer: DrawerWidget(
                            maxHeight: maxHeight,
                            maxWidth: maxWidth,
                          ),
                          backgroundColor: Colours.black,
                          appBar: AppBar(
                            backgroundColor: Colours.black,
                            leading: Padding(
                              padding: const EdgeInsets.only(left: 15),
                              child: Image.asset("assets/images/xuriti1.png"),
                            ),
                            actions: [
                              InkWell(
                                onTap: () {
                                  sk.currentState!.openEndDrawer();
                                },
                                child: Padding(
                                    padding: const EdgeInsets.all(18),
                                    child: SvgPicture.asset(
                                        "assets/images/menubutton.svg")),
                              ),
                            ],
                          ),
                          body: screens[currentIndex],
                          bottomNavigationBar: Container(
                            color: Colors.black,
                            child: Padding(
                              padding: const EdgeInsets.all(8.0),
                              child: Row(
                                mainAxisAlignment:
                                    MainAxisAlignment.spaceAround,
                                children: [
                                  GestureDetector(
                                    onTap: () async {
                                      progress!.show();
                                      await Future.delayed(
                                          const Duration(seconds: 1));

                                      setState(() {
                                        currentIndex = 0;
                                      });
                                      progress.dismiss();
                                    },
                                    child: Container(
                                      height: h10p * 0.5,
                                      width: w10p * 4.5,
                                      decoration: BoxDecoration(
                                          borderRadius:
                                              BorderRadius.circular(15),
                                          color: currentIndex == 0
                                              ? Colours.tangerine
                                              : Colours.black),
                                      child: const Center(
                                        child: Text(
                                          "Home",
                                          style: TextStyles.textStyle,
                                        ),
                                      ),
                                    ),
                                  ),
                                  GestureDetector(
                                    onTap: () async {
                                      progress!.show();
                                      await Future.delayed(
                                          const Duration(seconds: 1));
                                      setState(() {
                                        currentIndex = 1;
                                      });
                                      progress.dismiss();
                                    },
                                    child: Container(
                                      height: h10p * 0.5,
                                      width: w10p * 4.5,
                                      decoration: BoxDecoration(
                                          borderRadius:
                                              BorderRadius.circular(15),
                                          color: currentIndex == 1
                                              ? Colours.tangerine
                                              : Colours.black),
                                      child: const Center(
                                        child: Text(
                                          "Invoices",
                                          style: TextStyles.textStyle,
                                        ),
                                      ),
                                    ),
                                  )
                                ],
                              ),
                            ),
                          ),
                        );
                      } else {
                        return Center(
                          child: Text(""),
                        );
                      }
                    } else {
                      return Center(child: CircularProgressIndicator());
                    }
                  })),
        );
      }),
    );
  }
}