Re: MFC and GDI+ - more woes

From:

"David Ching" <dc@remove-this.dcsoft.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Tue, 24 Apr 2007 15:11:25 GMT

Message-ID:

<x6pXh.566$RX.524@newssvr11.news.prodigy.net>

"David Webber" <dave@musical.demon.co.uk> wrote in message
news:uG8IYflhHHA.4288@TK2MSFTNGP03.phx.gbl...

Has anyone tried to make a few GDI+ calls from the standard MFC
application framework?

Are they compatible?

Yes, I've put both GDI+ calls and GDI calls into my OnPaint().

Is there a way of making GDI+ calls completely independent of the GDI
calls?

====
I am getting some strange results as follows.

1. I initialise GDI+ in my InitInstance stuff and tidy it up at the end.

2. When beginning painting with CDC *pDC, I create a GDI+ Graphics object

Graphics *pGr = new Graphics( pDC->m_hDC );

and delete it when finished. [I am wondering what might happen to
pDC->m_hDC when I delete pGr, but it doesn't seem to be the problem - see
below.]

Easer to do:

Graphics Gr(pDC->m_hDC);

3. When ever I call

pDC->SetMapMode( MM_TEXT );
pDC->SetWindowOrg( Origin );

I also call

pGr->SetPageUnit( UnitPixel );
pGr->ResetTransform();
pGr->TranslateTransform( REAL(Origin.x), REAL(Origin.y) );

[Again I am wondering what might happen to pDC->m_hDC when I transform pGr
like this, but see below.]

4. Almost all the drawing is standard GDI, but I have some lines drawn by
pGr->DrawLine().

5. Results:

When the window is scrolled to the top left, the results are almost ok.
When I scroll down, not only are the GDI+ lines in the wrong place, *some*
of the GDI items are also drawn in the wrong place.

So I was starting to suspect that the pGr->... calls were also affecting
the underlying HDC, thus throwing the GDI drawing out as well.

However if I just comment out the pGr->DrawLine() statement, the GDI+
items vanish of course, but everything else is now drawn correctly again!

===
Any ideas? Similar experience?

I've not changed the map mode, window origin, etc. Maybe you should do the
GDI stuff first, then set everything for GDI+ and do all that next instead
of intermixing them.

-- David