使用拖动手势或PageView ()检查页面是否更改

Question

在Scaffold页面中，其结构如下所示

@override
Widget build(BuildContext context){
  body: PageView(
          controller: _controller;
          children: <Widget>[Page1(), Page2(), Page3()];
        );
  bottomNavigationBar: BottomNavBar(
                         onItemSelected: (index) => _controller.animateToPage()
                       )
}

从Page2()到Page1()有两种方法

_controller.animateToPage(0)

• 从左到右滑动屏幕，

• 点击bottomNavigationBar上的Page1()图标，从而调用Page1()

问题是，如何通过滑动手势或animateToPage()函数来判断页面是否被更改？

谢谢。

Answer 1

如果animateToPage是否正在进行，也许您可以添加一个设置标志。

示例：

import 'package:flutter/material.dart';

void main() => runApp(Root());

class Root extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final PageController controller = PageController();
    bool isAnimateToPage = false;

    controller.addListener(() {
      print('LISTENER isAnimateToPage = $isAnimateToPage');
    });

    return MaterialApp(
      home: Scaffold(
        body: Column(
          children: <Widget>[
            Expanded(
              child: PageView(
                controller: controller,
                onPageChanged: (int page) {
                  print(
                      'ONPAGECHANGED isAnimateToPage = $isAnimateToPage ; page = $page');
                },
                children: <Widget>[
                  const Center(child: Text('page 1')),
                  const Center(child: Text('page 2')),
                  const Center(child: Text('page 3')),
                ],
              ),
            ),
            FlatButton(
              onPressed: () async {
                isAnimateToPage = true;
                await controller.animateToPage(
                  controller.page.toInt() + 1,
                  duration: const Duration(seconds: 1),
                  curve: Curves.easeIn,
                );
                isAnimateToPage = false;
              },
              child: const Text('Next'),
            ),
          ],
        ),
      ),
    );
  }
}