Question

当下面的代码片段运行时，每次敲击一个键时，都会调用函数 LowLevelKeyboardProc 。但问题是它在按下一个键和释放一个键时被调用。这意味着，每按一次该函数被调用两次。但是我希望函数只在一个键被调用时才被调用。当钥匙被释放时按下而不是按下。

即使我可以在函数 LowLevelKeyboardProc 中过滤按键和释放按键，也没关系。有什么方法可以做到这一点。

static LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam, LPARAM lParam) {
  // call the function only if the key is pressed,else ( i.e key released) do nothing
}

BOOL WINAPI installHook(HINSTANCE hinstDLL, DWORD fwdReason, LPVOID lpvReserved){
  handleKeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc, hinstDLL, 0);
  MSG msg;

  while(GetMessage(&msg, NULL, 0, 0)){
    TranslateMessage(&msg);
    DispatchMessage(&msg);
  }
  return msg.wParam;
}

BOOL WINAPI DllMain( HINSTANCE hinstDLL, DWORD fwdReason, LPVOID lpvReserved) { // ENTRY POINT
 if(hookThreadHandle==NULL) { 
    LPTHREAD_START_ROUTINE lpStartAddress = &installHook;
    hookThreadHandle = CreateThread(NULL, 0, lpStartAddress, NULL, 0, &hookThreadId);
 }
 return TRUE;
}

Answer 1

你无法改变调用LowLevelKeyboardProc的方式，但在函数内你可以知道调用的原因：

static LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam, LPARAM lParam) 
{
     if ( nCode < 0 )
     {
         return CallNextHookEx(handleKeyboardHook, nCode, wParam, lParam);
     }

     if ( wParam == WM_KEYDOWN )  // possibly you want also WM_SYSKEYDOWN
     {
         // do what you need
     }
}

仅在按下某个键时调用一个函数而不是在释放它时调用一个函数

1 个答案: