what s the problem with my code?

[Entrant_phil]

hi guys:
everbody knows how to displaying a bitmap to screen.we just need a memory dc and a display dc. and i try to simulate this on OnPaint and it failed to work. anyone knows why? plz . ty so much

CXXX::OnPaint()
{
CPaintDC dc(this);//default code

CDC memdc;
memdc.CreateCompatibleDC(&dc);

memdc.TextOut(0,0,"hello");

dc.BitBlt(0,0,100,30,&memdc,0,0,SRCCOPY);

}


have a nice day

[Wisby]

CPaintDC dc(this);//default code

CDC memdc;
CBitmap bmp;

CRect rc;
GetClientRect(&rc);

bmp.CreateCompatibleBitmap(&dc,rc.Width(),rc.Height());

memdc.CreateCompatibleDC(&dc);
memdc.SelectObject(&bmp);
memdc.FillRect(&rc,&CBrush(RGB(255,255,255)));
memdc.TextOut(0,0,"hello");

dc.BitBlt(0,0,100,30,&memdc,0,0,SRCCOPY);

[Wisby]

PS:if necessary, you can store the the Old bitmap object of the memdc when selecting the new bitmap:

CBitmap *pOldBmp = memdc.SelectObject(&bmp);

then at the last steps you can recover it:

memdc.SelectObject(pOldBmp);

[Entrant_phil]

thanks wisby