C++ 键盘输入和 Win32 消息循环

Keyboard Input & the Win32 message loop

提问by Tom J Nowell

How do I handle key presses and key up events in the windows message loop? I need to be able to call two functions OnKeyUp(char c);and OnKeyDown(char c);.

如何处理 Windows 消息循环中的按键和按键事件？我需要能够调用两个函数OnKeyUp(char c);和OnKeyDown(char c);.

Current literature I've found from googling has lead me to confusion over WM_CHAR or WM_KEYUP and WM_KEYDOWN, and is normally targeted at PDA or Managed code, whereas I'm using C++.

我从谷歌搜索中发现的当前文献使我对 WM_CHAR 或 WM_KEYUP 和 WM_KEYDOWN 感到困惑，并且通常针对 PDA 或托管代码，而我使用的是 C++。

回答by John Knoeller

A typical C++ message loop looks like this

典型的 C++ 消息循环如下所示

MSG msg;
while (GetMessage(&msg, null, 0, 0))
{
    TranslateMessage(&msg);
    DispatchMessage(&msg);
}

The function of TranslateMessage is to generate WM_CHAR messages from WM_KEYDOWN messages, so if you want to see WM_CHAR messages you need to be sure to pass WM_KEYDOWN messages to it. If you don't care about WM_CHAR messages, you can skip that, and do something like this.

TranslateMessage 的作用是从 WM_KEYDOWN 消息中生成 WM_CHAR 消息，所以如果你想看到 WM_CHAR 消息，你需要确保将 WM_KEYDOWN 消息传递给它。如果您不关心 WM_CHAR 消息，您可以跳过它，并执行类似的操作。

extern void OnKeyDown(WPARAM key);
extern void OnKeyUp(WPARAM key);

MSG msg;
while (GetMessage(&msg, null, 0, 0))
{
    if (msg.message == WM_KEYDOWN)
       OnKeyDown (msg.wParam);
    else if (msg.message == WM_KEYUP)
       OnKeyUp(msg.wParam);
    else
    {
       TranslateMessage(&msg);
       DispatchMessage(&msg);
    }
}

Notice that OnKeyDown and OnKeyUp messages are defined as taking a WPARAM rather than a char. That's because the values for WM_KEYDOWN and WM_KEYUP aren't limited to values that fit in a char. See WM_KEYDOWN

请注意， OnKeyDown 和 OnKeyUp 消息被定义为采用 WPARAM 而不是字符。这是因为 WM_KEYDOWN 和 WM_KEYUP 的值不限于适合字符的值。见WM_KEYDOWN

More:
Using Messages and Message Queues
https://docs.microsoft.com/en-us/windows/win32/winmsg/using-messages-and-message-queues

更多：
使用消息和消息队列
https://docs.microsoft.com/en-us/windows/win32/winmsg/using-messages-and-message-queues

回答by Tom J Nowell

Use char c = MapVirtualKey(param,MAPVK_VK_TO_CHAR);to convert virtual key codes to char, and process WM_KEYUP and WM_KEYDOWN and their wParams.

使用char c = MapVirtualKey(param,MAPVK_VK_TO_CHAR);虚拟键代码转换为字符，并处理WM_KEYUP和WM_KEYDOWN及其wParams。

if (PeekMessage (&mssg, hwnd, 0, 0, PM_REMOVE))
{
    switch (mssg.message)
    {
        case WM_QUIT:
            PostQuitMessage (0);
            notdone = false;
            quit = true;
            break;

        case WM_KEYDOWN:
            WPARAM param = mssg.wParam;
            char c = MapVirtualKey (param, MAPVK_VK_TO_CHAR);
            this->p->Input ()->Keyboard ()->Listeners ()->OnKeyDown (c);
            break;

        case WM_KEYUP:
            WPARAM param = mssg.wParam;
            char c = MapVirtualKey (param, MAPVK_VK_TO_CHAR);
            this->p->Input ()->Keyboard ()->Listeners ()->OnKeyUp (c);
            break;
    }
    // dispatch the message
    TranslateMessage (&mssg);
    DispatchMessage (&mssg);
}