MultiThreaded Progress bar

[SamirSood]

I have a program in which i have a background process running and i have to update the progress of the Progress bar according to the activities of the Background process . Can Anyone suggest a solution. Samir Sood

[Jon Hulatt]

put your "background process" in a worker thread. Then your main (UI) thread is free to redraw the screen. Signature space for rent. Apply Within.

[SamirSood]

Could u please post a code snippet of that. Samir Sood

[Hesham Amin]

Hi.. I know two ways to do so: The first: to pass a handle of a progress bar to the worker thread and use it as follows 1. Create a helper class that will hold data passed to the worker thread: class CData { HWND m_hWnd; //Athor class members.. } 2. In the dialog class create a member variable of type CData: private: CData MyData; 3. Before the call to AfxBeginThread() fill members of CData : { //.. //.. some of your code MyData.m_hWnd=(GetDlgItem(IDC_PROGRESS))->m_hWnd; //where IDC_PROGRESS is the ID of the progress bar.. //now call AfxBeginThread AfxBeginThread(WorkerFn,&MyData, /*Ather args..*/); } 4. In the Worker thread function write the following code: UINT WorkerFn(LPVOID pData) { CData* data=(CData*)pData; CProgressCtrl* progBar=CWnd::FromHandle(data->m_hWnd); //Now use progBar as you wish! progBar->SetRange(0,100); //etc } The second: Pass the handle of the dialog enstead of the progress bar then use: ::PostMessage(data->m_hWnd,WM_USER+1,0,0) and handle the message in the dialog.. Send again if you find any problems..

[Todd Smith]

Or put your progress dialog in its own thread. Either way will work. Todd Smith

[Stephen C Steel]

Multithreaded apps are simplest if only the main thread deals with drawing the UI, as in your second solution. There is, however, no need to introduce a new message handler in your dialog. Just have the worker thread post a messages directly to the progress control:

Before starting the worker thread, save the window handle of the progress control in a variable that will be accessible to the worker thread (e.g. m_hProgressCtrl). Then in your worker thread code, post messages to update the progress control directly ::PostMessage (m_hProgressCtrl, PBM_SETRANGE, 0, MAKELPARAM (min, max)); ::PostMessage (m_hProgressCtrl, PBM_SETPOS, position, 0);

Using ::PostMessage() (instead of the ::SendMessage() inside the CProgressBar member functions) means that the messages to update the progress controls will be queued for the main GUI thread. Stephen C. Steel Kerr Vayne Systems Ltd.