Monochrome Bitmap Issue

[Bram van Kampen]

Don't know an awfull lot about the issues, but it appears to be at first sight to be a problem about loss of information.It would appear to me that you first create a monochrome bitmap from a source, which you select into the CDC. At that stage the Die is cast as far as the CDC is concerned. The Monochrome bitmap is all it knows about. The CDC has built a Monochrome picture which it knows your Device can display. All Colour Info has been discarded. If at a later stage you want the Bitmap in colour, you have to start again from scratch in the same or another CDC, This time indicating yont to keep the colour. Mind you,to do so you could recycle most of the code. Just leave an indication somewhere about what way you want it, Monocrome or Colour. A Device Context is a Uniform Construct that Converts things like bitmaps etc into something your Hardware can display. (That's the way device-independence is Implemented). Hope this is Usefull. :)

LateNightsInNewry

[Mark Salsbery]

To add to LateNightsInNewry's reply... To fix it... When you call CreateCompatibleBitmap(), you should use the screen or paint DC, not the memory DC. The memory DC you created with CreateCompatibleDC() is the one with a monochrome bitmap selected into it. If you create a bitmap compatible with that, it will also be monochrome. Outside of OnPaint, you can get a screen DC with ::GetDC(0) or something like CDC ScreenDC; ScreenDC.CreateCompatibleDC(0); Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[CoffeeAddict19]

Thanks, both of you. I think it'll work. I'll try it tommorow when I wake up.

[Mark Salsbery]

:java:

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[CoffeeAddict19]

Actually I just got a cup about 30 minutes ago. :) Unfortunatly, the problem still remains. :( I tried using GetDC:

CDC* ScreenDC = NULL;
CreateResult = CWnd::Create(CPIEGRAPH_CLASSNAME, _T(""), dwStyle, rect, pParentWnd, nID);

TextDCResult = TextMemDC.CreateCompatibleDC(NULL);
PieDCResult = PieMemDC.CreateCompatibleDC(NULL);

ScreenDC = GetDC();
ASSERT(ScreenDC == NULL);
SelectText = m_textBitmap.CreateCompatibleBitmap(ScreenDC, 250, 20);
SelectPie = m_pieBitmap.CreateCompatibleBitmap(ScreenDC, 300, 300);
ReleaseDC(ScreenDC);

At first the assert statement wasn't in there and I just got black and white, then I put it in and I got a debug assertation on the same line, indicating that ScreenDC was null, and that GetDC didn't do the job. Any idea why?

[CoffeeAddict19]

Well the assert statement was wrong...it should have been ASSERT(ScreenDC != NULL), but it is still not rendering color for some reason. Fonts, brushes, and pens work fine, just not color.

[Mark Salsbery]

CoffeeAddict19 wrote:

indicating that ScreenDC was null

Is Create() failing? Never mind, I see you fixed the ASSERT I steered you wrong with the CreateCompatibleDC, sorry :doh: *EDIT* I DID show you a way to do what you were already doing though :) This should work from anywhere:

CWindowDC ScreenDC(0);

CBitmap bitmap;
bitmap.CreateCompatibleBitmap(&ScreenDC, 20, 20);

//**Test - Check the resulting bitmap's format...
BITMAP bitmapstruct;
bitmap.GetObject(sizeof(BITMAP), &bitmapstruct);

You'll see in the BITMAP struct, the format matches the screen format. Try this:

CreateResult = CWnd::Create(CPIEGRAPH_CLASSNAME, _T(""), dwStyle, rect, pParentWnd, nID);
CWindowDC ScreenDC(0);
TextDCResult = TextMemDC.CreateCompatibleDC(&ScreenDC);
PieDCResult = PieMemDC.CreateCompatibleDC(&ScreenDC);
SelectText = m_textBitmap.CreateCompatibleBitmap(&ScreenDC, 250, 20);
SelectPie = m_pieBitmap.CreateCompatibleBitmap(&ScreenDC, 300, 300);

Mark -- modified at 14:54 Thursday 31st May, 2007

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[Mark Salsbery]

CoffeeAddict19 wrote:

but it is still not rendering color for some reason.

Hopefully my modified post below will help :)

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[CoffeeAddict19]

Thanks mark! I HAVE MADE COLOR! Check it out: http://img.photobucket.com/albums/v50/blackdwarf/piechart_color.jpg[^] Shouldn't take me long to get long of the pesky black area around the edges. Maybe I'll write a simple tutorial on making controls someday. There already is one, but another viewpoint couldn't hurt.

[Mark Salsbery]

mmmm Pie! :) Cool!

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder