MainFrame Bitmap

[Igor Kondrasovas]

Hello, I'm working on a MDI project and I'd like to insert a bitmap in the background of my application, in other words, on my MainFrame window, behind the children windows. This bitmap will be always there. I'm workin with VC++ 6.0 and Windows 2000. If anybody know how to this, please, help me. Best Regards, Igor Kondrasovas

[Mazdak]

It's very easy use GDI+.Check this and this Mazy Don't Marry a Person You Can Live With... Marry Someone You Can Not Live Without

[Joaquin M Lopez Munoz]

It's simple task, but many steps are required:

1. Create a new CWnd-derived class, say CBackgroundWnd.

2. Add these two members to CBackgroundWnd:

   CBitmap m_bitmap_background;
   BITMAP m_bmInfo_background;

   along with this piece of code in CBackgroundWnd ctor:

   m\_bitmap\_background.LoadBitmap(IDB\_BACKGROUND); // change IDB\_BACKGROUND to whatever your resource-located bitmap is called.
   ::GetObject(m\_bitmap\_background,sizeof(BITMAP),&m\_bmInfo\_background);
   

3. Add a handler for WM_ERASEBKGND in CBackgroundWnd and plug this code (which draws the bitmap in tesellation mode)

   BOOL CBackgroundWnd::OnEraseBkgnd(CDC* pDC)
   {
   CRect rect;
   GetClientRect(rect);

   CDC dcMem;
   dcMem.CreateCompatibleDC(pDC);
   
   HBITMAP\* pBmpOld=(HBITMAP\*)::SelectObject(dcMem.m\_hDC,m\_bitmap\_background);
   
   for(int y=rect.top;y<rect.bottom;y+=m\_bmInfo\_background.bmHeight){
       for(int x=rect.left;x<=rect.right;x+=m\_bmInfo\_background.bmWidth){
           pDC->BitBlt(x,y,m\_bmInfo\_background.bmWidth,m\_bmInfo\_background.bmHeight,
                       &dcMem,0,0,SRCCOPY);
       }
   }
   
   ::SelectObject(dcMem.m\_hDC, pBmpOld);
   
   return TRUE;
   

   }

4. Add a member of type CBackgroundWnd to your CMainFrame class, say m_wndClient.

5. Override CMainFrame::OnCreateClient with this:

   BOOL CMainFrame::OnCreateClient(LPCREATESTRUCT lpcs, CCreateContext* pContext)
   {
   if(!CMDIFrameWnd::OnCreateClient(lpcs, pContext))return FALSE;
   m_wndClient.SubclassWindow(m_hWndMDIClient);
   return TRUE;
   }

That's it, I think. Good luck. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

[Christian Graus]

Why couldn't he just erase background in the mainframe ? Christian I have come to clean zee pooollll. - Michael Martin Dec 30, 2001 Picture the daffodil. And while you do that, I'll be over here going through your stuff.

[Joaquin M Lopez Munoz]

Good question... I created a test MDI project and tried that approach first, to discover that my tesellation got overdrawn by the standard dark-grey background (I noticed because of the flickering). I remembered then about that funky, mostly unknown CMainFrame::m_hWndMDIClient member and how it seems to take on some of the roles people tend to ascribe to CMainFrame itself... got it subclassed and WM_ERASEBKGND-handled, and it worked. Couldn't say if this is the most direct approach. Any ideas? Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

[Christian Graus]

Interesting - I've only ever done this in a view, so I had no idea of this problem. Sounds like it's worth a fiddle sometime. Christian I have come to clean zee pooollll. - Michael Martin Dec 30, 2001 Picture the daffodil. And while you do that, I'll be over here going through your stuff.

[Joaquin M Lopez Munoz]

...so I had no idea of this problem Neither did I :) Thought I'd write a test before submitting an answer, and came to this (to my surprise). Joaquín M López Muñoz Telefónica, Investigación y Desarrollo