Re: save DC as bitmap to file

From:

Stuart Redmann <DerTopper@web.de>

Newsgroups:

microsoft.public.vc.mfc

Date:

Tue, 13 Mar 2007 13:33:25 +0100

Message-ID:

<et68v3$cn4$1@news.dtag.de>

Matthias Pospiech wrote:

I have a derived CStatic class CGraphCtrl which I use to paint 2D Data
to the screen. The same data shall be saved to a file as a bitmap (bmp
or other standard file format)

The OnPaint() function looks like this:

void CGraphCtrl::OnPaint()
{
    CPaintDC dc(this); // device context for painting

    CRect rc;
    GetClientRect(rc);

    CMemDC pDC(&dc, &rc);
...
        for (int ix=0; ix < m_PixelNumberX; ix++)
        {
            for (int iy=0; iy < m_PixelNumberY; iy++)
            {
...
pDC->FillSolidRect(getX(x),getY(y),getX(x+1)-getX(x),getY(y+1)-getY(y),c);

You may consider using bitmaps here, as well. If you have one call to
GDI just to set a single pixel, you're not very quick. I paint my images
into bitmaps and let GDI do the scaling for me (I guess that you use
FillSolidRect in order to scale the images).

...
}
}
}

Google for the Win32 API function CreateDIBSection or CreateBitmap for
creation of a bitmap. For saving the bitmap you should google for
BITMAPINFO. If you don't want to spend to much time wrestling with the
plain Win32 API, you can use GDI+ (available from WinXP on, but can be
downloaded for free). The GDI+ class that does the trick is called Image.

Regards,
Stuart