c++ - Numpad 键事件导致 GetKeyboardState 卡住键

Question

我有一个 C++ (MFC) 应用程序需要检查计时器的键状态。如果用户按住某个键，我们会延迟某些代码的处理。

这是 keydown 的支票:

if (!GetKeyboardState(keyState)) 
{
    s_executeDeferredResult = e_executeDeferredButtonCheckFailed;
    return;
}   
s_executeDeferredStuckKeys.clear();
for (int index=0; index<arrsize(keyState); ++index)
{
    if (keyState[index] & 0x80)
    {
        s_executeDeferredStuckKeys.insert(index);
    }
}
if (!s_executeDeferredStuckKeys.empty())
{
    s_executeDeferredResult = e_executeDeferredButtonsActive;
    return;
}

但是，有一些关键组合会卡住:

1. 开启NUMLOCK
2. 按SHIFT
3. 按 NumPad8
4. 释放 SHIFT
5. 释放 NumPad8
   (这是一个例子，还有其他的例子，包括用 CTRL-ALT-DEL 搞得一团糟)

GetKeyboardState现在将报告 VK_UP被按下。

发生的事件是(对应上面的 Action )。

1. <None>
2. WM_KEYDOWN , VK_SHIFT
3. WM_KEYUP , VK_SHIFT
WM_KEYDOWN , VK_UP
WM_KEYDOWN , VK_SHIFT
4. WM_KEYUP , VK_SHIFT
5. WM_KEYUP , VK_NUMPAD8

因此，Windows 无法识别向上键出现，现在 GetKeyboardState坏了。

有什么好的方法可以检查 key 的真实状态吗？ GetAsyncKeyState和 GetKeyState两者都报告 key 也已关闭。

Answer 1

解决了。

我挂接到 InitInstance 中的键盘事件，并通过扫描码跟踪起伏(以扫描码为键，以虚拟键为值的映射)。

m_keyboardHook = SetWindowsHookEx(WH_KEYBOARD, &KeyboardHook, NULL, GetCurrentThreadId());

---

static LRESULT CALLBACK KeyboardHook(
    __in int nCode,
    __in WPARAM wParam,
    __in LPARAM lParam
    )
{
    // According to the docs, we're not allowed to do any "further processing" if nCode is < 0.
    // According to the docs, we should process messages if we get code HC_ACTION. 
    // http://msdn.microsoft.com/en-us/library/windows/desktop/ms644984(v=vs.85).aspx
    // It doesn't specify what to do if another code comes in, so we will just ignore any other codes.
    if (nCode == HC_ACTION)
    {
        uint8 scanCode = (uint8)((lParam & 0x00FF0000) >> 16);
        uint8 virtKey = (uint8)wParam;
        if (lParam & 0x80000000) // key up
            KeyState::SetKeyUp(scanCode);
        else
            KeyState::SetKeyDown(scanCode, virtKey);
    }

    // We must call the next hook in the chain, according to http://msdn.microsoft.com/en-us/library/windows/desktop/ms644975%28v=vs.85%29.aspx
    // First param is ignored, according to http://msdn.microsoft.com/en-us/library/windows/desktop/ms644974%28v=vs.85%29.aspx )
    return CallNextHookEx(0, nCode, wParam, lParam);
}

所以，我的延迟检查变成了:

// Similarly, don't process deferred events if there are keys or mouse buttons which are currently down.
s_executeDeferredStuckKeys.clear();
if (KeyState::AnyKeysDown(s_excludeKeys, arrsize(s_excludeKeys)))
{
    s_executeDeferredResult = e_executeDeferredButtonsActive;
    KeyState::GetDownKeys(s_executeDeferredStuckKeys);
    return;
}