Create a bitmap file

[Francis B]

I'm trying to create a bitmap file from a memory device context but the only thing I create is a complete white bitmap. X| Here my code:

MyFunction()
{
CClientDC dc(this); //dc of dialog
CRect rectBF(0,0,450,450);
CBitmap bmp, *poldbmp;
CDC memdc;

     // Load the bitmap resource
     bmp.CreateCompatibleBitmap(&dc, 450, 450);

     // Create a compatible memory DC
     memdc.CreateCompatibleDC( &dc );

		 
     // Select the bitmap into the DC
     poldbmp = memdc.SelectObject( &bmp );
     //CGraphWnd was created by Paul Barvinko - [A 2D data visualisation class](http://www.codeproject.com/miscctrl/graph2d.asp)
m\_ctlGraphWnd.DrawGraphToDC(&memdc, rectBF); //Copy graph to DC

     memdc.SelectObject(poldbmp);

CPalette palette;

     //Initialize palette
if( dc.GetDeviceCaps(RASTERCAPS) & RC\_PALETTE )
{
	UINT nSize = sizeof(LOGPALETTE) + (sizeof(PALETTEENTRY) \* 256);
	LOGPALETTE \*pLP = (LOGPALETTE \*) new BYTE\[nSize\];
	pLP->palVersion = 0x300;

	pLP->palNumEntries = 
			GetSystemPaletteEntries( dc, 0, 255, pLP->palPalEntry );

	// Create the palette
	palette.CreatePalette( pLP );

	delete\[\] pLP;
}

This code above works correctly. The graph was drawn in memdc.

     //Function was created by Zafir Anjum - [Converting DDB to DIB](http://www.codeguru.com/bitmap/ddb_to_dib.shtml)
HANDLE hDIB = DDBToDIB(bmp, BI\_RGB, &palette);

if( hDIB == NULL )
	return ;

     //Function was created by Zafir Anjum - [Writing a bitmap to a BMP file](http://www.codeguru.com/bitmap/bitmap_to_file.shtml)
WriteDIB(\_T("graph.bmp"), hDIB);

GlobalFree( hDIB );

}

I don't know why but operations done on memdc aren't reflected in CBitmap bmp. Thanks in advance!