OnEraseBkgnd erases drawn picture.

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VC6

C++

MFC

I have a dialog and Tab Control on it. I need draw a picture in the definite rectangle on a page of the Tab Control. So I declare an object of a class that is responsible for bitmap work for example as CDIBitmap m_bmpBackground. Bitmap file is loaded with:

BOOL CDIBitmap :: Load( CFile* pFile ) {
    ASSERT( pFile );
    BOOL fReturn = TRUE;
    try {
        delete [] (BYTE*)m_pInfo;
        delete [] m_pPixels;
        m_pInfo = 0;
        m_pPixels = 0;
        DWORD       dwStart = pFile->GetPosition();
        //
        // Check to make sure we have a bitmap. The first two bytes must
        // be 'B' and 'M'.
        BITMAPFILEHEADER fileHeader;
        pFile->Read(&fileHeader, sizeof(fileHeader));
        if( fileHeader.bfType != 0x4D42 )
            throw TEXT("Error:Unexpected file type, not a DIB\n");

        BITMAPINFOHEADER infoHeader;
        pFile->Read( &infoHeader, sizeof(infoHeader) );
        if( infoHeader.biSize != sizeof(infoHeader) )
            throw TEXT("Error:OS2 PM BMP Format not supported\n");

        // Store the sizes of the DIB structures
        int cPaletteEntries = GetPalEntries( infoHeader );
        int cColorTable = 256 * sizeof(RGBQUAD);
        int cInfo = sizeof(BITMAPINFOHEADER) + cColorTable;
        int cPixels = fileHeader.bfSize - fileHeader.bfOffBits;
        //
        // Allocate space for a new bitmap info header, and copy
        // the info header that was loaded from the file. Read the
        // the file and store the results in the color table.
        m_pInfo = (BITMAPINFO*)new BYTE[cInfo];
        memcpy( m_pInfo, &infoHeader, sizeof(BITMAPINFOHEADER) );
        pFile->Read( ((BYTE*)m_pInfo) + sizeof(BITMAPINFOHEADER),
                     cColorTable );
        //
        // Allocate space for the pixel area, and load the pixel
        // info from the file.
        m_pPixels = new BYTE[cPixels];
        pFile->Seek(dwStart + fileHeader.bfOffBits, CFile::begin);
        pFile->Read( m_pPixels, cPixels );
		CreatePalette();
		m_bIsPadded = TRUE;
#ifdef _DEBUG
    } catch( TCHAR * psz ) {
		TRACE( psz );
#else
    } catch( TCHAR * ) {
#endif
        fReturn = FALSE;
    }
    return fReturn;
}

Then I call Invalidate() function and get into OnEraseBkgnd where a picture is actually being drawn:

BOOL CAtmNcr::OnEraseBkgnd(CDC* pDC) 
{
	if(m_bmpBackground.GetPixelPtr() != 0) 
	{
		CRect rc;
		
		m_myWnd.GetWindowRect(rc);
		ScreenToClient( &rc );
		int x = 0, y = 0;

		// center the bitmap
		/*
		CDialog::OnEraseBkgnd(pDC);
		x = (rc.Width() - m_bmpBackground.GetWidth()) / 2;
		y = (rc.Height() - m_bmpBackground.GetHeight()) / 2;
		m_bmpBackground.DrawDIB(pDC, x, y);
		*/

		// stretch
		m_bmpBackground.DrawDIB(pDC, rc.left, rc.top, rc.Width(), rc.Height());
	} 
	else
		// no bitmap set. behave like a normal dialog
		return CDialog::OnEraseBkgnd(pDC);

	return true;
}

DrawDIB is defined as follows:

// DrawDib uses StretchDIBits to display the bitmap.
void CDIBitmap :: DrawDIB( CDC* pDC, int x, int y, int width, int height ) {
    ASSERT( pDC );
    HDC     hdc = pDC->GetSafeHdc();

    if( m_pInfo )
        StretchDIBits( hdc,
                       x,
                       y+GetHeight(),
                       width,
                       -height,
                       0,
                       0,
                       GetWidth(),
                       GetHeight(),
                       GetPixelPtr(),
                       GetHeaderPtr(),
                       DIB_RGB_COLORS,
                       SRCCOPY );
	
}

The loaded picture is definitely drawn in the rectangle and you see it but untill OnEraseBkgnd is left. How come? If you apply the same code to parent dialog window then it works perfectly.