windows lock and unlock event in C++

Question

I want to create a program that "locks" my work station as soon as I leave or move away from my computer. And automatically starts again as soon as the user login.

I'm using Opencv to track my movement and its working.

now I want to know how can I automatically start a function again as soon as the user login using c++

I'm using

LockWorkStation();

to lock my system

I have a C# implementation for it which I got from
Programmatically Determine a Duration of a Locked Workstation?

const int SessionUnlockParam = 0x8;

if (m.WParam.ToInt32() == SessionUnlockParam)
{OnSessionUnlock(); // Do something when unlocked
}

void OnSessionUnlock()
{
 // Do something......  
}

can someone tell me how to to do this in C++ and which libraries to use

or

How can I access Event IDs in C++ such as: " Event_ID = 4801 - The workstation was unlocked".

for windows 8

Technically, asking for libraries is off-topic for stack overflow. However, I see no reason why the rest of your question wouldn't be on topic. I don't know the answer, though. — , Sep 10 '19 at 17:01
I don't believe this is actually a duplicate of checking if the workstation is locked. Muhammad wants to be notified of session changes, the linked solution would require polling. — Alex Broadwin, Sep 10 '19 at 17:09
I have tried This https://stackoverflow.com/questions/29326685/c-check-if-computer-is-locked But It doesn't work on visual studio 2015 — Muhammad Bin Ali, Sep 10 '19 at 18:27

score 2 · Accepted Answer · answered Sep 10 '19 at 17:06

2

You can register a window to receive events for session changes using WTSRegisterSessionNotification.

Then listen for WM_WTSSESSION_CHANGE with a wParam value of WTS_SESSION_UNLOCK.

answered Sep 10 '19 at 17:06

Alex Broadwin

1,288
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Thanks for an early response actually I'm with C++ I'll be grateful If u could tell me how to implement it – Muhammad Bin Ali Sep 10 '19 at 17:52
do i have to download or configure any .dll or library – Muhammad Bin Ali Sep 10 '19 at 18:07
You do need to link to the library Wtsapi32.lib. – Alex Broadwin Sep 10 '19 at 18:08
already did it. – Muhammad Bin Ali Sep 10 '19 at 18:14
BOOL WTSRegisterSessionNotification( HWND hWnd, DWORD dwFlags ); – Muhammad Bin Ali Sep 10 '19 at 18:14
what values I have to give as argument? – Muhammad Bin Ali Sep 10 '19 at 18:15
1

See the link for details. It takes the window handle that will receive the events and a flag whose value is either NOTIFY_FOR_THIS_SESSION or NOTIFY_FOR_ALL_SESSIONS. Assuming you have a standard win32 message loop and WndProc set up for the window handle you can receive the messages there. – Alex Broadwin Sep 10 '19 at 18:39
hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL); how to implement ** HINSTANCE hInstance ** – Muhammad Bin Ali Sep 10 '19 at 19:28
You can simply pass in GetModuleHandle(NULL) for the HINSTANCE parameter to use your program's own module/instance. – Alex Broadwin Sep 10 '19 at 19:35
WTSRegisterSessionNotification() is returning same value before lock and after lock – Muhammad Bin Ali Sep 12 '19 at 11:02
The return value only indicates whether or not the function succeeded, then your window handle receives messages when the session status changes (eg. locked, unlocked). – Alex Broadwin Sep 12 '19 at 15:05
how to get these messages? and what data type I have to use for message ? will Strings work? – Muhammad Bin Ali Sep 12 '19 at 16:37
You don't define the type for the messages, they are unsigned integers. See these two tutorial pages: https://learn.microsoft.com/en-us/windows/win32/learnwin32/window-messages and https://learn.microsoft.com/en-us/windows/win32/learnwin32/writing-the-window-procedure – Alex Broadwin Sep 12 '19 at 16:49

windows lock and unlock event in C++

1 Answers1