键盘事件：订单是否有保证？-Keyboardevents:Istheorderguaranteed?

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They should happen in that order when they happen, in most apps. But your window might not receive every event for every character entered.

在大多数应用中,它们应该按顺序发生。但是,您输入的每个字符的窗口可能都不会收到任何事件。

For example, in Windows, if you hold down a key you'll see a KeyDown and/or KeyPressed repeatedly as the key repeats, and a single KeyUp once the key is released.

例如,在Windows中,如果按住某个键,您将在键重复时重复看到KeyDown和/或KeyPressed,并在键释放后重复显示单个KeyUp。

Edit:

Now that i think about it, though...Windows starts out only posting WM_KEYDOWN and WM_KEYUP messages to your window (and only if you have focus). WM_CHAR messages (the Win32 analogue to KeyPressed) are posted based on those when the message loop calls TranslateMessage. This means two things:

现在我考虑一下,但是...... Windows开始只向你的窗口发布WM_KEYDOWN和WM_KEYUP消息(只有你有焦点)。 WM_CHAR消息(Win32模拟到KeyPressed)基于消息循环调用TranslateMessage时发布的消息。这意味着两件事:

• If the window has a backlog of messages, the API might just add the message to the end of the queue (IDK); this makes more sense to me (the message queue being a queue, after all, and not a stack), but it does mean that if there is already a WM_KEYUP for that key in the queue (for example, if the user hit and released a key while another message was being processed), the corresponding WM_CHAR might appear after it.

如果窗口有积压的消息,API可能只是将消息添加到队列的末尾(IDK);这对我来说更有意义(消息队列毕竟是一个队列,而不是堆栈),但它确实意味着如果队列中已存在该键的WM_KEYUP(例如,如果用户命中并释放当正在处理另一条消息时,一个密钥),相应的WM_CHAR可能会出现在它之后。

• Languages like C and C++ have more flexibility (read: less built-in automation) in how they handle messages; in order for them to get WM_CHAR messages, they have to either call TranslateMessage explicitly or do the translation themselves (barring another app posting such messages to it). With the latter, there's no telling what order the messages will be posted in.

C和C ++等语言在处理消息方面具有更大的灵活性(读取:内置自动化程度更低);为了让他们获得WM_CHAR消息,他们必须明确地调用TranslateMessage或自己进行翻译(除非另一个应用程序向其发布此类消息)。对于后者,无法确定消息的发布顺序。

Also, as mentioned in the comments, if the focus switches while a key is down, you might only see a KeyUp or KeyDown. (The key state was already that way before the focus switch, and Windows probably won't tell you about it.) And dead keys (ones that don't generate a character on their own) won't trigger a KeyPressed at all (though they do typically trigger KeyUp and KeyDown). They typically just wait for the next real character and modify it.

此外,如评论中所述,如果焦点在按键关闭时切换,您可能只会看到KeyUp或KeyDown。 (关键状态在焦点切换之前已经是这样了,Windows可能不会告诉你它。)死键(不能自己生成一个字符的键)根本不会触发KeyPressed(虽然他们通常会触发KeyUp和KeyDown)。他们通常只是等待下一个真正的角色并进行修改。

Short version of all that: You can rely on the order in which KeyDown events appear in relation to each other. Same with KeyPressed, and even KeyUp. But, at least in Windows, the three message types are not really coordinated with each other. So don't assume that every KeyUp will match a KeyDown (or vice versa), or that KeyPressed appears before KeyUp.

所有这些的简短版本:您可以依赖KeyDown事件相对于彼此出现的顺序。与KeyPressed相同,甚至与KeyUp相同。但是,至少在Windows中,这三种消息类型并不真正相互协调。因此,不要假设每个KeyUp都与KeyDown匹配(反之亦然),或KeyPress出现在KeyUp之前。

You should probably also decide whether you want to process characters or keys. That's part of the confusion here, i think; the two are actually different concepts, and most of the time you only really care about one or the other. While Win32 would allegedly tell you the key code when you're handling a KeyPressed event, the real intent of that event is to tell you what character was entered. (There's a reason it's called WM_CHAR and not WM_KEYPRESS. :) And why .net's KeyPressEventArgs type only has a KeyChar and not a KeyCode.) The other two treat the keyboard as basically a bunch of buttons.

您可能还应该决定是否要处理字符或键。我认为这是混乱的一部分;这两者实际上是不同的概念,大多数时候你只关心其中一个。据称Win32会在您处理KeyPressed事件时告诉您关键代码,而该事件的真正意图是告诉您输入的字符。 (有一个原因,它被称为WM_CHAR而不是WM_KEYPRESS。:)为什么.net的KeyPressEventArgs类型只有KeyChar而不是KeyCode。)其他两个将键盘视为基本上是一堆按钮。

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If you are Windows user, the rule of thumb here is: check the order of events by logging or in debugger and then assume that this will be always so.

如果您是Windows用户,那么这里的经验法则是:通过记录或在调试器中检查事件的顺序,然后假设这将始终如此。

This is not perfect, but this works in 95% of cases. I many times heard stories that Windows team always pushes back to change anything because 100% sure this will break something.

这并不完美,但这在95%的情况下有效。我多次听过Windows团队总是推迟改变任何事情的故事,因为100%肯定会破坏某些东西。

This is direct result of poor documentation of the Windows 2.0 era.

这是Windows 2.0时代文档记录不佳的直接结果。