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MTMDI Sample: Demonstrates an MFC User Interface Thread

Visual Studio 2008

The MTMDI sample illustrates an MFC user interface thread where user interface events are processed in a separate thread from the main application thread. This sample is a modified version of the single-thread MDI sample.

MTMDI does not claim a strong rationale for putting the bouncing ball window in a separate thread. A user would not be able to detect the difference between the MDI and MTMDI samples on a single-processor computer. Even on a multiprocessor computer, the user would not be able to detect the difference, given that the ball movement is based on a window timer.

Nevertheless, MTMDI does illustrate techniques for implementing an MFC user interface thread. Compare the sources for the MDI and MTMDI samples to study the programming overhead associated with using MFC user interface threads.

The programming overhead in MTMDI should be a warning that you should have a good reason for using a user interface thread to justify the programming cost. The much more common type of thread in MFC is the worker thread, illustrated by the MTRECALC sample.

Security noteSecurity Note:

This sample code is provided to illustrate a concept and should not be used in applications or Web sites, as it may not illustrate the safest coding practices. Microsoft assumes no liability for incidental or consequential damages should the sample code be used for purposes other than as intended.

To get samples and instructions for installing them:

  • On the Visual Studio Help menu, click Samples.

    For more information, see Visual Studio Samples.

  • The most recent version and complete list of samples is available online from the Visual Studio 2008 Samples page.

  • You can also locate samples on your computer's hard disk. By default, samples and a Readme file are copied into a folder under \Program Files\Visual Studio 9.0\Samples\. For Express editions of Visual Studio, all samples are located online.

To build and run the MTMDI sample

  1. Open the solution MtMdi.sln.

  2. On the Build menu, click Build.

  3. On the Debug menu, click Start Without Debugging.

You can use the File menu to create new windows of two different types. Once the windows are created, the application will let you change the attributes of the items in the window by using commands in one of these menus: Color, Speed, Window, and Help. Note that the "Hello!" windows do not have a Speed menu.

MTMDI makes use of its own CWinThread-derived class, called CBounceThread. CBounceThread is implemented in the Mtbounce.cpp file. The thread contains all the painting and timing code that the bouncing ball window needs to animate the ball in the window.

The application creates each thread just as the MDI child window is created. This happens in the CBounceMDIChildWnd::Create function, found in Bounce.cpp. This function creates both the window and the thread, associating the thread to the window.

Whenever you close a bounce window, the associated thread is automatically destroyed. The "Hello!" windows do not have a thread of their own; their messages are handled by the application's primary thread.

This sample demonstrates the following keywords:

AfxGetInstanceHandle; AfxMessageBox; AfxRegisterWndClass; CBitmap::CreateCompatibleBitmap; CCmdTarget::OnCmdMsg; CCmdUI::SetCheck; CColorDialog::DoModal; CColorDialog::GetColor; CDC::BitBlt; CDC::CreateCompatibleDC; CDC::DeleteDC; CDC::DrawText; CDC::Ellipse; CDC::FillRect; CDC::GetDeviceCaps; CDC::SelectObject; CDC::SetBkColor; CDC::SetTextColor; CFrameWnd::LoadFrame; CFrameWnd::rectDefault; CGdiObject::DeleteObject; CMDIChildWnd::Create; CMenu::LoadMenu; CRect::Height; CRect::Width; CWinApp::ExitInstance; CWinApp::InitInstance; CWnd::Create; CWnd::DestroyWindow; CWnd::GetClientRect; CWnd::GetCurrentMessage; CWnd::GetDC; CWnd::GetDlgItem; CWnd::GetWindow; CWnd::Invalidate; CWnd::KillTimer; CWnd::MessageBox; CWnd::OnCreate; CWnd::OnDestroy; CWnd::OnLButtonDown; CWnd::OnPaint; CWnd::OnSize; CWnd::OnTimer; CWnd::ReleaseDC; CWnd::SendMessage; CWnd::SetTimer; CWnd::SetWindowPos; CWnd::ShowWindow; CWnd::UpdateWindow; CloseHandle; CreateEvent; CreateThread; EnumChildWindows; GetSysColor; GetVersion; LOWORD; LoadCursor; LoadIcon; LoadMenu; MAKEINTRESOURCE; RGB; SetEvent; Sleep; WaitForSingleObject; max; min


Some samples, such as this one, have not been modified to reflect the changes in the Visual C++ wizards, libraries, and compiler, but still demonstrate how to complete your desired task.

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