Monochrome Bitmap Issue

CoffeeAddict19

I'm having a problem with memory device contexts and bitmaps in MFC. I've gotten to the point to where I can create and use them, but natrually they are all in black in white. See here: http://img.photobucket.com/albums/v50/blackdwarf/piegraphcontrol.jpg[^] With a CreateCompatibleDC(NULL) call, a monochrome bitmap gets created for and selected into the CDC. When I actually create my bitmap based off of that CDC, I'm stuck with the monochrome. So my question is, how do I initialize the bitmaps with color outside of OnPaint when I can't just use CPaintDC? Here is some of the code... Creating the two bitmaps without a CPaintDC (where I think the problem is): BOOL CPieGraph::Create(CWnd* pParentWnd, const RECT& rect, UINT nID, DWORD dwStyle /*=WS_VISIBLE*/) { BOOL OverallSuccess = FALSE; BOOL CreateResult = FALSE, TextDCResult = FALSE, PieDCResult = FALSE; int SelectText = 0, SelectPie = 0; CreateResult = CWnd::Create(CPIEGRAPH_CLASSNAME, _T(""), dwStyle, rect, pParentWnd, nID); TextDCResult = TextMemDC.CreateCompatibleDC(NULL); PieDCResult = PieMemDC.CreateCompatibleDC(NULL); SelectText = m_textBitmap.CreateCompatibleBitmap(&TextMemDC, 250, 20); SelectPie = m_pieBitmap.CreateCompatibleBitmap(&PieMemDC, 300, 300); OldtextBitmap = TextMemDC.SelectObject(&m_textBitmap); OldpieBitmap = PieMemDC.SelectObject(&m_pieBitmap); TextMemDC.SetBkColor(RGB(255,255,255)); PieMemDC.SetBkColor(RGB(255,255,255)); if((CreateResult == TRUE) && (TextDCResult == TRUE) && (PieDCResult == TRUE) && (SelectText != 0) && (SelectPie != 0)) { OverallSuccess = TRUE; ControlRect = rect; } else OverallSuccess = FALSE; return OverallSuccess; } And OnPaintDC:

afx_msg void CPieGraph::OnPaint()
{
	CPaintDC dc(this);

	CDC ControlMemDC;
	CBitmap ControlBitmap;
	CBitmap* OldBitmap = NULL;

	ControlMemDC.CreateCompatibleDC(&dc);
	ControlBitmap.CreateCompatibleBitmap(&ControlMemDC, 300, 360);
	OldBitmap = ControlMemDC.SelectObject(&ControlBitmap);
	ControlMemDC.SetBkColor(RGB(255,255,255));

	if(UpdateNeeded == true)
	{
		RedrawPieText(TextMemDC);
		RedrawPieChart(PieMemDC);
		ControlMemDC.BitBlt(0, 0, 250, 20, &TextMemDC, 0, 0, SRCCOPY);
		ControlMemDC.BitBlt(0, 25, MainPieGraph.radius * 2, 
			MainPieGraph.radius * 2, &PieMemDC,

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