end hooking key board

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Hi i have this code

C++

#include <QApplication>
#include <QMainWindow>
#include <QTime>
#include <QChar>
#include <iostream>
#include <Windows.h>
#include <QDebug>
#pragma comment(lib, "user32.lib")
using namespace std;
HHOOK hHook=NULL;

void UpdateKeyState(BYTE *keystate,int keycode)
{
	keystate[keycode]=GetKeyState(keycode);
}


LRESULT CALLBACK MyLowLevelKeyBoardProc(int nCode,WPARAM wParam,LPARAM lParam)
{
	KBDLLHOOKSTRUCT cKey=*((KBDLLHOOKSTRUCT *)lParam);
	wchar_t buffer[5];
	BYTE keyboard_state[256];
	GetKeyboardState(keyboard_state);
	UpdateKeyState(keyboard_state,VK_SHIFT);
	UpdateKeyState(keyboard_state,VK_CAPITAL);
	UpdateKeyState(keyboard_state,VK_CONTROL);
	UpdateKeyState(keyboard_state,VK_MENU);
	HKL keyboard_layout=GetKeyboardLayout(0);
	char lpszName[0x100]={0};
	DWORD dwMsg=1;
	dwMsg +=cKey.scanCode<<16;
	dwMsg +=cKey.flags<<24;
	int i=GetKeyNameText(dwMsg,(LPTSTR)lpszName,255);
	int result = ToUnicodeEx(cKey.vkCode,cKey.scanCode,keyboard_state,buffer,4,0,keyboard_layout);
	buffer[4]=L'\0';
	HWND hwnd;
	POINT p;
	int xsave,ysave;
	GetCursorPos(&p);
	qDebug()<<"Key:"<<cKey.vkCode<<" "<<QString::fromUtf16((ushort*)buffer)<<" "<<QString::fromUtf16((ushort*)lpszName)<<" X:"<<p.x<<" Y:"<<p.y;

	return CallNextHookEx(hHook,nCode,wParam,VK_SPACE);
}
int main(int argc, char *argv[])
{
	QApplication a(argc, argv);
	QMainWindow w;
	w.setWindowTitle("2Key");
	w.show();
	hHook = SetWindowsHookEx(WH_KEYBOARD_LL,MyLowLevelKeyBoardProc,NULL,0);
	int as;
	return a.exec();
}

it has some qt to but that doesn't mater i need to end the hook function i want to come out from the MyLowLevelKeyBoardProc func but i cant How i can get out from that
i want unhook and after a while hook again

Posted 6-Sep-12 5:19am

ZiDoM

Updated 6-Sep-12 7:07am

v3

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Comments

[no name] 6-Sep-12 11:31am

If I understood you correctly, you need to call UnhookWindowsHookEx

ZiDoM 6-Sep-12 13:07pm

yes buy in this case i cant because i want unhook and after a while hook again

Sergey Alexandrovich Kryukov 6-Sep-12 14:04pm

Not clear what prevents you from unhooking and hooking again. But I would suggest to keep the hook at all times, but process it differently depending on some status. This would be much saver and simpler technique.

Please explain the purpose of all that if you want more specific advice.
--SA

ZiDoM 6-Sep-12 14:11pm

I want to create hotkey but the hotkey should be active sometimes in the middle of the program i want to deactivate and active another time again

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Sergey Alexandrovich Kryukov · Accepted Answer · 2012-09-06T09:44:00

After the clarification from OP, I can see that my original suggestion is applicable.

Instead of un-hooking the event handler temporarily, hook and unhook it only once per application lifetime. In the middle of lifetime, if temporary deactivation of hooked activity is required, preserve some status flag and check its value to see if the functionality is enabled or disabled. You also may need to assign a value to the flag in the interlocked manner due to multi-threading nature of this task. Please see:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms684122%28v=vs.85%29.aspx[^].

C++

static LONG enableCount = 0; 

//...

LRESULT CALLBACK MyLowLevelKeyBoardProc(int nCode,WPARAM wParam,LPARAM lParam) {
   if (enableCount < 1) return;
   //... do all your processing here
}

//...

void Enable() {
   InterlockedIncrement(&enableCount);
}
void Disable() {
   InterlockedDecrement(&enableCount);
}

This way, the calls to Enable and Disable could be nested and performed in any thread; which is the best to do with try-finally statement. It's also good to use the RAII technique. Please see:
http://en.wikipedia.org/wiki/RAII[^],
http://stackoverflow.com/questions/7779652/try-catch-finally-construct-is-it-in-c11[^].

—SA