huixiang_app/lib/view_widget/my_appbar.dart

import 'package:flutter/material.dart';

class MyAppBar extends StatelessWidget implements PreferredSizeWidget {
  final Function onTap;
  final Widget action;
  final String title;
  final double titleSize;
  final Color titleColor;
  final Color leadingColor;
  final Color background;
  final Size preferredSize;
  final double toolbarHeight;
  MyAppBar({
    Key key,
    this.onTap,
    this.action,
    this.title,
    this.toolbarHeight,
    this.background = const Color(0xFFF7F7F7),
    this.leadingColor = Colors.black,
    this.titleColor = Colors.black,
    this.titleSize = 18,
  })  : preferredSize = Size.fromHeight(toolbarHeight ?? kToolbarHeight),
        super(key: key);

  @override
  Widget build(BuildContext context) {
    return AppBar(
      backgroundColor: background,
      elevation: 0,
      leading: GestureDetector(
        onTap: () {
          Navigator.of(context).pop();
        },
        child: Container(
          alignment: Alignment.centerRight,
          margin: EdgeInsets.only(left: 10),
          padding: EdgeInsets.all(6),
          child: Icon(
            Icons.arrow_back_ios,
            color: leadingColor,
            size: 24,
          ),
        ),
      ),
      titleSpacing: 2,
      centerTitle: false,
      leadingWidth: 56,
      title: (title == null || title == "")
          ? null
          : Text(
              title,
              style: TextStyle(
                color: titleColor,
                fontSize: titleSize,
              ),
            ),
      actions: [
        if (action != null)
          Container(
            margin: EdgeInsets.only(right: 15),
            child: GestureDetector(
              onTap: onTap,
              child: action,
            ),
          )
      ],
    );
  }
}