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:
- 开启NUMLOCK
- 按SHIFT
- 按 NumPad8
- 释放 SHIFT
- 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 )。
-
<None>
-
WM_KEYDOWN
,VK_SHIFT
-
WM_KEYUP
,VK_SHIFT
WM_KEYDOWN
,VK_UP
WM_KEYDOWN
,VK_SHIFT
-
WM_KEYUP
,VK_SHIFT
-
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。
最佳答案
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;
}
关于c++ - Numpad 键事件导致 GetKeyboardState 卡住键,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/18499859/