How to Display a Bitmap in a CStatusBar Pane

WINDOWS             | WINDOWS NT

The information in this article applies to:

• The Microsoft Foundation Classes (MFC), included with:

      - Microsoft Visual C++ for Windows, versions 1.0, 1.5, 1.51, 1.52
      - Microsoft Visual C++, 32-bit Edition,
        versions 1.0, 2.0, 2.1, 2.2, 4.0, 4.1
  

SUMMARY

The standard status bar in an MFC application easily allows the application to display its status. Sometimes it is a good idea to display the status using bitmaps or other graphic entities. MFC's CStatusBar class directly supports displaying text, but not graphics, in its panes. This article shows by example 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

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
      ...
      }
   
   

REFERENCES

Visual C++ Books Online and the Windows SDK docuemntation.