Flutter：CustomAppBar 和automaticImplyLeading..如何做？

Question

我的自定义应用程序栏在向后导航方面与 flutter stock AppBar 的行为不同。

有没有一种简单的方法可以为我的自定义应用栏提供此功能？ ...涉及“自动暗示领先”吗？

仅供参考，如果你像我6岁一样向我解释，我不会生气；我对编码很陌生。 ..欢迎袜子木偶和代码片段。

我当前的代码（

gradient-app-bar.dart

＆

post_detail.dart

）：

// MY CUSTOM APPBAR (GRADIENT-APP-BAR.DART) //
import 'package:flutter/material.dart';

class GradientAppBar extends StatelessWidget implements PreferredSizeWidget {
    final double _preferredHeight = 200.0;
    final String bizName;
    final String streetAddress;
    final String cityStateZip;
    final String phoneNumber;
    // final String bizHours;
    final String masterList;
    final Color gradientBegin, gradientEnd;

    GradientAppBar({
            this.bizName,
            this.streetAddress,
            this.cityStateZip,
            this.phoneNumber,
            // this.bizHours,
            this.masterList,
            this.gradientBegin,
            this.gradientEnd,
            // List<Widget> actions,
        }):
        assert(bizName != null),
        assert(streetAddress != null),
        assert(cityStateZip != null),
        assert(phoneNumber != null),
        // assert(bizHours != null),
        assert(masterList != null),
        assert(gradientBegin != null),
        assert(gradientEnd != null);


    @override
    Widget build(BuildContext context) {
        return Container(
            height: _preferredHeight,
            alignment: Alignment.center,
            padding: EdgeInsets.only(top: 20.0),
            decoration: BoxDecoration(
                gradient: LinearGradient(
                    colors: < Color > [
                        gradientBegin,
                        gradientEnd
                    ]
                )
            ),

            child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                    Text(bizName,
                        style: TextStyle(
                            color: Colors.white,
                            letterSpacing: 5.0,
                            fontSize: 20.0,
                            fontWeight: FontWeight.w700
                        )
                    ),
                    Text(streetAddress,
                        style: TextStyle(
                            color: Colors.white,
                            letterSpacing: 2.0,
                            fontSize: 16.0,
                            fontWeight: FontWeight.w500
                        )
                    ),
                    Text(cityStateZip,
                        style: TextStyle(
                            color: Colors.white,
                            letterSpacing: 2.0,
                            fontSize: 16.0,
                            fontWeight: FontWeight.w500
                        )
                    ),
                    Text(phoneNumber,
                        style: TextStyle(
                            color: Colors.white,
                            letterSpacing: 2.0,
                            fontSize: 16.0,
                            fontWeight: FontWeight.w500
                        )
                    ),
                    // Text(bizHours,
                    //   style: TextStyle(
                    //     color:Colors.white,
                    //     letterSpacing: 5.0,
                    //     fontSize: 20.0,
                    //     fontWeight: FontWeight.w700
                    //   )
                    // ),
                    Text(masterList,
                        style: TextStyle(
                            color: Colors.white,
                            letterSpacing: 5.0,
                            fontSize: 20.0,
                            fontWeight: FontWeight.w700
                        )
                    ),
                ],
            ),
        );
    }

    @override
    Size get preferredSize => Size.fromHeight(_preferredHeight);
}


// MY CUSTOM APPBAR IMPLEMENTED (POST_DETAIL.DART) //

import 'package:appvervemenu/gradient-app-bar.dart';
import 'package:appvervemenu/post_model.dart';
import 'package:flutter/material.dart';

class PostDetail extends StatelessWidget {
    final Post post;

    PostDetail({
        @required this.post
    });

    @override
    Widget build(BuildContext context) {
        return Scaffold(
            appBar: GradientAppBar(
                bizName: "BIZNAME",
                streetAddress: "STREETADDRESS",
                cityStateZip: "CITYSTATEZIP",
                phoneNumber: "BIZPHONE",
                masterList: "\n\nMASTERLIST",
                gradientBegin: Color(0xFFB71C1C),
                gradientEnd: Color(0xFFB71C1C),
            ),

            body: SingleChildScrollView(
                child: Padding(
                    padding: const EdgeInsets.all(12.0),
                        child: Column(
                            children: < Widget > [
                                Card(
                                    child: Column(
                                        crossAxisAlignment: CrossAxisAlignment.center,
                                        children: < Widget > [
                                            ListTile(
                                                title: Text(post.title),
                                                // subtitle: Text(post.title),
                                            ),
                                            ListTile(
                                                title: Text("Featuring"),
                                                subtitle: Text(post.body),
                                            ),
                                            ListTile(
                                                // title: Text("ID"),
                                                subtitle: Text("${post.id}"),
                                            ),
                                        ],
                                    ),
                                ),
                            ],
                        ),
                ),
            )
        );
    }
}

Answer 1

您可以使用以下代码根据父路由显示后退按钮：

(ModalRoute.of(context)?.impliesAppBarDismissal ?? false) ? BackButton() : null