为什么这个双击检测代码不可靠? [英] Why is this double-click detection code unreliable?

问题描述

我正在尝试通过一些简单的挑战来学习 Rx，首先是通过仅观看 MouseUp 事件来检测双击.我想出了以下解决方案(此代码可通过创建 WPF 项目并添加 Reactive Extensions NuGet 包进行编译):

I'm trying to learn Rx through some simple challenges, first by detecting double-clicks by watching only MouseUp events. I came up with the following solution (this code is compilable by creating a WPF project and adding the Reactive Extensions NuGet package):

using System;
using System.Reactive.Linq;
using System.Windows.Input;

namespace WpfApplication1 {
    public partial class MainWindow {
        public MainWindow() {
            InitializeComponent();
            var clickEvents = Observable
                .FromEventPattern<MouseButtonEventArgs>(this, "MouseLeftButtonUp");

            var intraClickInterval = TimeSpan.FromMilliseconds(500);
            var interClickInterval = TimeSpan.FromMilliseconds(1000);

            var doubleClicks = clickEvents
                .TimeInterval()
                .SkipWhile(t => t.Interval < interClickInterval)
                .FirstAsync(t => t.Interval < intraClickInterval)
                .Repeat();

            var doubleClickReady = doubleClicks
                .Delay(interClickInterval)
                .Subscribe(e => Console.WriteLine("Now accepting double click!"));

            doubleClicks.Subscribe(e => Console.WriteLine(e.Interval));
        }
    }
}

我见过的大多数解决方案都没有处理多次点击，所以这个想法是在每次双击之间总是等待一定的时间间隔(interClickInterval)，然后双击是下一个鼠标向上事件间隔小于intraClickInterval.我还添加了一条消息，该消息在每次双击后的 interClickInterval 过去后打印，以便我知道何时应该注册双击.

Most solutions I've seen don't deal with multiple clicks, so the idea is to always wait for a certain interval (interClickInterval) between each double-click, and then a double-click is the next mouse up event that has an interval smaller than the intraClickInterval. I've also added a message that gets printed after the interClickInterval elapses following each double-click so that I know when double-clicks are supposed to register.

这似乎总体上运行良好，但似乎有时即使我看到现在接受双击！"他们也不会注册.信息.如果我在消息出现之前单击，这似乎尤其会发生.什么可能导致这种情况?

This seems to work well in general, but it seems that sometimes they do not register even though I see the "Now accepting double-click!" message. This seems to happen particularly if I click just before the message appears. What could be causing this?

我认为双击检测实际上是正确的，它的消息不是.基本上，它会忽略双击后的任何后续单击.我需要做类似的事情

I think the double-click detection is actually correct, it's the message that isn't. Basically, it ignores any subsequent click after a double-click. I'd need to do something like

• 对于每个双击事件
• 等待interClickInterval
• 如果此后未注册任何点击，则显示现在接受双重点击！"

但我不确定如何实现...

But I'm not sure how to achieve that...

推荐答案

所以我怀疑，检测代码是正确的，是消息时间错误.它没有考虑双击后的任何后续点击；它总是在每次双击后 1000 毫秒打印其消息.这是就绪消息的一个版本，它在每次双击后正确等待 1000 毫秒自上次单击以来已经过去:

So as I suspected, the detection code is correct, it's the message that was timed incorrectly. It didn't take into account any subsequent clicks after a double-click; it just always printed its message 1000ms after each double-click. Here's a version of the ready message that correctly waits for 1000ms to have elapsed since the last click after each double-click:

        var doubleClickReady = doubleClicks
            .SelectMany(clickEvents
                .Buffer(interClickInterval)
                .FirstAsync(b => b.Count == 0));

        doubleClickReady
            .Subscribe(e => Console.WriteLine("Now accepting double click!"));

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