HOWTO: How to Display a Bitmap in a CStatusBar Pane

MORE INFORMATION

It is not very difficult to display a bitmap in a status bar pane. The code at the end of this article will let you display a bitmap in pane 1 of the status bar. Put the code in a Default AppWizard application, and add a new pane to the status bar before the standard panes. Please refer to online documentation for CStatusBar for information on how to add a pane to the status bar.

With Visual C++ 4.0 and later, MFC's CStatusBar uses the status window common control. In earlier versions, CStatusBar was implemented in MFC. Hence the code required for displaying bitmap in a CStatusBar pane is different.

You can add the sample code to an application built with an earlier version of Visual C++ (a version previous to 4.0), and then recompile the application using Visual C++ 4.0 without modifying the code. If you are using Visual C++ 4.0 or later, you need not add code between the

   #if _MFC_VER < 0x400
   ...
   #endif
				

directives.

Step-by-Step Example and Sample Code

1. Derive a class from CStatusBar (for example, CMyStatusBar), and use this class instead of CStatusBar in CMainFrame.
2. Add the following member functions to the class definition in the .h file:

      class CMyStatusBar : public CStatusBar
      {
      ...
      #if _MFC_VER < 0x400
          virtual void DoPaint(CDC* pDC);
      #endif
   
      #if _MFC_VER >= 0x400
          virtual void DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct);
      #endif
      ...
      }

3. Add the following code for the functions in the .cpp file:

      #if _MFC_VER < 0x400
      void CMyStatusBar::DoPaint(CDC* pDC)
      {
          CRect rect;
          GetItemRect(1, &rect);  // get pane rect
          pDC->ExcludeClipRect(&rect);  // exclude pane rect from paint
          CStatusBar::DoPaint(pDC);  // paint remainder of status bar
   
          CRgn paneRgn;
          paneRgn.CreateRectRgnIndirect(rect);
          pDC->SelectClipRgn(&paneRgn); // set clip region to pane rect
   
          CBitmap* pBitmap = /* pointer to current CBitmap */;
          CDC srcDC; // select current bitmap into a compatible CDC
          srcDC.CreateCompatibleDC(NULL);
          CBitmap* pOldBitmap = srcDC.SelectObject(pBitmap);
          pDC->BitBlt(rect.left, rect.top, rect.Width(), rect.Height(),
                    &srcDC, 0, 0, SRCCOPY); // BitBlt to pane rect
          srcDC.SelectObject(pOldBitmap);
      }
      #endif
   
      #if _MFC_VER >= 0x400
      void CMyStatusBar::DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct)
      {
          switch(lpDrawItemStruct->itemID)
          {
          case 1:
              // Attach to a CDC object
              CDC dc;
              dc.Attach(lpDrawItemStruct->hDC);
   
              // Get the pane rectangle and calculate text coordinates
              CRect rect(&lpDrawItemStruct->rcItem);
   
              CBitmap* pBitmap = /* pointer to current CBitmap */;
              CDC srcDC; // select current bitmap into a compatible CDC
              srcDC.CreateCompatibleDC(NULL);
              CBitmap* pOldBitmap = srcDC.SelectObject(pBitmap);
              dc.BitBlt(rect.left, rect.top, rect.Width(), rect.Height(),
                        &srcDC, 0, 0, SRCCOPY); // BitBlt to pane rect
              srcDC.SelectObject(pOldBitmap);
   
              // Detach from the CDC object, otherwise the hDC will be
              // destroyed when the CDC object goes out of scope
              dc.Detach();
   
              return;
          }
   
          CStatusBar::DrawItem(lpDrawItemStruct);
      }
      #endif
   						

4. Add the following code to CMainFrame::OnCreate().

      int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
      {
      ...
          if (!m_wndStatusBar.Create(this) ||
              !m_wndStatusBar.SetIndicators(indicators,
                sizeof(indicators)/sizeof(UINT)))
   
              TRACE0("Failed to create status bar\n");
              return -1;      // fail to create
          }
   
      // Add the following code
      #if _MFC_VER >= 0x400
          UINT nID, nStyle;
          int cxWidth;
   
          m_wndStatusBar.GetPaneInfo(1, nID, nStyle, cxWidth);
          m_wndStatusBar.SetPaneInfo(1, nID, nStyle | SBT_OWNERDRAW,
              cxWidth);
      #endif
      ...
      }