Flutter:在窗体验证完成之前禁用选项卡导航

import 'package:flutter/material.dart';

class MyFormPage extends StatefulWidget {
  @override
  _MyFormPageState createState() => _MyFormPageState();
}

class _MyFormPageState extends State<MyFormPage> {
  bool isFormValid = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Form Page'),
      ),
      body: Form(
        onChanged: () {
          setState(() {
            isFormValid = Form.of(context).validate();
          });
        },
        child: Column(
          children: [
            // Add form fields here
          ],
        ),
      ),
      bottomNavigationBar: TabBar(
        tabs: [
          Tab(
            text: 'Tab 1',
          ),
          Tab(
            text: 'Tab 2',
          ),
        ],
        isScrollable: true,
        indicatorColor: Colors.white,
        indicatorWeight: 2.0,
        labelColor: Colors.white,
        unselectedLabelColor: Colors.grey,
        indicatorPadding: EdgeInsets.symmetric(horizontal: 16.0),
        onTap: (index) {
          if (!isFormValid) {
            // Show a message or perform any action when form is not valid
            return;
          }
          // Handle tab navigation
        },
      ),
    );
  }
}