Re: Using bitmaps with CPaintDC

From:

"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp>

Newsgroups:

microsoft.public.vc.mfc

Date:

Tue, 04 Jul 2006 23:03:56 -0400

Message-ID:

<efAuS$9nGHA.816@TK2MSFTNGP05.phx.gbl>

cdg wrote:

Is the code below the right approach to displaying bitmaps to a dialog.
And is there any obvious problems with it, such as not being consistently
displayed on other monitors. Also I would need to display a number of
(small) bitmaps side by side on rows, and will need to add scroll
functionability to this dialog. Does anyone know of the best approach to
displaying these bitmaps in rows, and then adding a scroll for just a
certain area of the dialog where the bitmaps are displayed.

The member variables bmp and cdc are declared in the class declaration.

void CDCBmpTestDlg::OnPaint()
{
CPaintDC dc(this);

bmp.LoadBitmap(IDB_DEMO);

cdc.CreateCompatibleDC(&dc);
CBitmap *pOld = cdc.SelectObject(&bmp);

BITMAP BmpInfo;
bmp.GetObject(sizeof(BmpInfo), &BmpInfo);
dc.BitBlt(50, 50, BmpInfo.bmWidth, BmpInfo.bmHeight,
&cdc, 0, 0, SRCCOPY);

cdc.SelectObject(pOld);
cdc.DeleteDC();
bmp.DeleteObject();
}

It is rarely a good idea to paint directly on a dialog. The dialog does
its own background painting and this can confuse things.

To put one or more bitmaps on a dialog you would typically put CStatic
controls on the dialog. They paint a bitmap for you.

But for rows of bitmaps that can be scrolled a somewhat unobvious
approach is probably best: Use an owner-drawn list box. Each "item" in
the list box can be a bitmap, and you will get all the scroll management
for free.

--
Scott McPhillips [VC++ MVP]