显示键盘时如何拦截颤振后退按钮 [英] How to intercept flutter back-button when keyboard is shown

问题描述

我想颤抖地拦截软键盘的后退按钮.因此，当我想通过按后退按钮关闭键盘时，我想调用一个附加功能. 我该怎么办?

I want to intercept the back-button of the soft keyboard in flutter. So when I want to close the keyboard by pressing the back-button I want an additional function to be called. How can I do that?

键盘后退按钮

推荐答案

，您可以使用 keyboard_visibility 软件包即可实现.

you can use the keyboard_visibility package to achieve this.

工作示例

关闭键盘后，以下代码将显示SnackBar.

the following code displays a SnackBar once the keyboard is dismissed.

import 'package:flutter/material.dart';
import 'package:keyboard_visibility/keyboard_visibility.dart';

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

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  GlobalKey<ScaffoldState> _key;

  @override
  void initState() {
    super.initState();
    _key = GlobalKey<ScaffoldState>();
    KeyboardVisibilityNotification().addNewListener(
      onHide: () {
        _key.currentState.showSnackBar(
          SnackBar(
            content: Text("Keyboard closed"),
          ),
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        key: _key,
        body: Center(
          child: TextField(),
        ),
      ),
    );
  }
}

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