Question

当用户按下按钮时，我需要执行方法，换句话说，在按下操作期间，用户将按下按钮不明的时间段。在这段时间内，我需要执行方法，任何人都知道我如何在Flutter中做到了这一点，我尝试了GestureDetector，但是没有这样做的选项，而且onLongPress也没有此选项，因为在按下Operation之后触发的Long Press上，我将为我需要的内容编写psudo代码：

java.time

Answer 1

没有监听器的一种更简单的方法如下：

  GestureDetector(
      child: InkWell(
        child: Icon(Icons.skip_previous_rounded),
        onTap: widget.onPrevious,
      ),
      onLongPressStart: (_) async {
        isPressed = true;
        do {
          print('long pressing'); // for testing
          await Future.delayed(Duration(seconds: 1));
        } while (isPressed);
      },
      onLongPressEnd: (_) => setState(() => isPressed = false),
    );
  }

Answer 2

使用Listener和有状态的小部件。在每个循环之后，我还引入了一些延迟：

import 'dart:async';

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(brightness: Brightness.dark),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  bool _buttonPressed = false;
  bool _loopActive = false;

  void _increaseCounterWhilePressed() async {
    // make sure that only one loop is active
    if (_loopActive) return;

    _loopActive = true;

    while (_buttonPressed) {
      // do your thing
      setState(() {
        _counter++;
      });

      // wait a bit
      await Future.delayed(Duration(milliseconds: 200));
    }

    _loopActive = false;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Center(
        child: Listener(
          onPointerDown: (details) {
            _buttonPressed = true;
            _increaseCounterWhilePressed();
          },
          onPointerUp: (details) {
            _buttonPressed = false;
          },
          child: Container(
            decoration: BoxDecoration(color: Colors.orange, border: Border.all()),
            padding: EdgeInsets.all(16.0),
            child: Text('Value: $_counter'),
          ),
        ),
      ),
    );
  }
}

Flutter Execute方法，只要按下按钮

2 个答案: