How to change the mouse pointer for a window in MFC by using Visual C++ (131991)

MORE INFORMATION

Here are some situations when you might want an MFC application to display different pointers at different times:

• When the default pointer isn't a good user-interface object for a particular application. For example, an I-beam pointer is more suitable than the arrow for a text editor window in NotePad. This could involve changing the pointer for the entire run of the application.
• When an application performs a lengthy operation, such as disk I/O, an hourglass pointer is more appropriate than the arrow. By changing the pointer to an hourglass, you provide good visual feedback to the user. This could involve changing the pointer for a limited period of time.

Three methods

Here are three ways an application can change the mouse pointer in a window:

• Override the CWnd::OnSetCursor() function. Call Windows API SetCursor() function to change the pointer.
• Register your own window class with the desired mouse pointer, override the CWnd::PreCreateWindow() function, and use the newly-registered window class to create the window.
• To show the standard hourglass pointer, an application can call the CCmdTarget::BeginWaitCursor(), which displays the hourglass, and call CmdTarget::EndWaitCursor() to revert back to the default pointer. This scheme works only for the duration of a single message. If the mouse is moved before a call to EndWaitCursor is made, Windows sends a WM_SETCURSOR message to the window underneath the pointer. The default handling of this message resets the pointer to the default type, the one registered with the class, so you need to override CWnd::OnSetCursor() for that window, and reset the pointer back to the hourglass.

Code to illustrate the three methods

The following code shows by example how to change the mouse pointer of a CView derived class window by using the three methods. m_ChangeCursor is a member variable of CMyView class and is of type BOOL. It indicates whether a different pointer type needs to be displayed.

Method one

Change the mouse pointer for the CMyView object by overriding CWnd::OnSetCursor() function. Use ClassWizard to establish the message map function CMyView::OnSetCursor() for Windows message WM_SETCURSOR and supply the body of the function as follows:

      BOOL CMyView::OnSetCursor(CWnd* pWnd, UINT nHitTest, UINT message)
      {
            if ( m_ChangeCursor )
              {
                  ::SetCursor(AfxGetApp()->LoadStandardCursor(IDC_WAIT));
                  return TRUE;
              }

            return CView::OnSetCursor(pWnd, nHitTest, message);
      }
				

Method two

Register your own window class containing the desired mouse pointer by using either the AfxRegisterClass() or AfxRegisterWndClass() function. Then create the view window based on the registered window class. For more information on registering window classes in MFC, please see MFC Tech Note 1, "Window Class Registration."

      BOOL CMyView::PreCreateWindow(CREATESTRUCT& cs)
      {
          cs.lpszClass = AfxRegisterWndClass(
            CS_DBLCLKS | CS_HREDRAW | CS_VREDRAW, // use any window styles
            AfxGetApp()->LoadStandardCursor(IDC_WAIT),
            (HBRUSH) (COLOR_WINDOW + 1));         // background brush

          return CView::PreCreateWindow(cs)
      }
				

Method three

Call the BeginWaitCursor() and EndWaitCursor() functions to change the mouse pointer.

NoteCWinApp::DoWaitCursor(1) and CWinApp::DoWaitCursor(-1) work similarly to BeginWaitCursor() and EndWaitCursor(), respectively.

      void CMyView::PerformLengthyOperation()
      {
            BeginWaitCursor();  // or AfxGetApp()->DoWaitCursor(1)

            //...

            EndWaitCursor();    // or AfxGetApp()->DoWaitCursor(-1)
      }
				

Note If calls to BeginWaitCursor() and EndWaitCursor() are not in the same handler, you must override OnSetCursor as follows:

      BOOL CMyView::OnSetCursor(CWnd* pWnd, UINT nHitTest, UINT message)
      {
            if (m_ChangeCursor)
              {
                  RestoreWaitCursor();
                  return TRUE;
              }

            return CView::OnSetCursor(pWnd, nHitTest, message);
      }
				

In this example, set m_ChangeCursor to TRUE just before the call to BeginWaitCursor(), and set it back to FALSE after the call to EndWaitCursor().