C / C++ / MFC

Re: example c++ application

26-Jan-15 22:22

If you cannot answer your interview questions by your own efforts, then the answers have no value.

jeron1

27-Jan-15 4:59

True.

"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment

"Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst

How do I know my dual display in span mode in windows xp? [modified]

cedricvictor

26-Jan-15 17:49

Dear all:

I have two touch screens and dual monitor, I try to match touch screen for each monitor in windows xp.

I can do it in mirror mode and extended mode, but failed in span
mode.

I use the EnumDisplayMonitor to get the monitor count, but the monitor count is 1 in span mode.

How do I know my dual diplay in span mode and get the monitor count?

best regards, Victor

modified 7 hrs ago.

Win8.1 UEFI block WINIO?

ICEric

25-Jan-15 23:32

Hi All,

I am writing a program to control some I/O card under Win8.1 environment, however, initialisation winio always fail. There is no problem under WinXP or Win7, so I guess it is caused by Win8.1 UEFI blocked the WINIO.

Is there anyone who can give me a solution?

Thanks
Eric

Re: Win8.1 UEFI block WINIO?

Re: Win8.1 UEFI block WINIO?

26-Jan-15 0:25

It is unlikely that anyone can give a solution, unless you provide a lot more information. Where does the failure occur, what are the conditions, what error status or message do you see ... ?

ICEric

26-Jan-15 15:47

When I perform
DWORD dwMemVal;
bool bResult;
HANDLE hPhysicalMemory;
PBYTE pbLinAddr;

// Call InitializeWinIo to initialize the WinIo library.

ShutdownWinIo();

bResult = InitializeWinIo();

the bResult keeps 0, so I cannot initialize WinIO

However, I tried to create a virtual machine with WinXP installed, using the same sourecode without any problem. Thus, I guess it is caused by Win8.1 UEFI which protect the BIOS controlled by WinIO.

Would there be anyone who can help me to fix this problem? Thanks a lot for any help.

Re: Win8.1 UEFI block WINIO? Randor 26-Jan-15 16:24

Hi,

Your WINIO device driver needs to be signed.

Driver Signing Policy[^]

Best Wishes,
-David Delaune

Re: Win8.1 UEFI block WINIO?

ICEric

27-Jan-15 6:13

Hi

I tried to put the same program in Win8.0 and it works without the need to sign-up WINIO.
I would like to know what is the different between Win8 and 8.1?

Thanks

BitBlt() function performance question

23-Jan-15 8:55

Hi, in a windows CE platform, I tested BitBlt() function,
I found it will take about 400 millisecdons to do:

MemBoard.CreateCompatibleDC(&dc);
bmpDashBoard.LoadBitmap( IDB_SCREEN_IMP );
pOldBmp = (CBitmap*)Memboard.SelectObject(&bmpBoard);
...
MemDC.CreateCompatibleDC(dc);
..
MemDC.BitBlt(0,0, 800,600,&Memboard, 0, 0, SRCCOPY);

is there anyway to speed up BitBlt() function?

image processing toolkits | batch image processing

C^hris L^osinger

23-Jan-15 11:39

are you saying it takes 400ms to do all of that, or just the BitBlt?

because you can do the LoadBitmap ahead of time and just keep the CBitmap around for when you need it.

23-Jan-15 14:38

I can't get precise time, but, with old BitBlt(), not a 800*600 bitmap,
I set tick count array in program, tkCount[15]-tkCount[14] = tkCount[14] - tkCount[13] ... = tkCount[1] - tkCount[0] = 170 ms around.

Then I use new BitBlt() to load 800*600 bitmap, it gives 400ms around.

So I should say it added 230 ms.

Old BitBlt() just transport about 1/5 or 1/6 part of 800*600 bitmap.

I expected to use a 800*600(the screen area) memory DC to hold all parts changes, then BitBlt() to screen.

Now that 800*600 tooks so much time, I don't think a double buffer technique is helpful.

image processing toolkits | batch image processing

C^hris L^osinger

27-Jan-15 2:59

what do you mean "old" and "new" BitBlt ?

25-Jan-15 9:19

I doubt it's the BitBlt slowing you down that much. You probably shouldn't be loading a bitmap every single time, load it once and keep it in memory for better results.

26-Jan-15 4:50

Yes, I know redraw picture is a time-costing work.
But, the application need to update picture with the real-time data.

26-Jan-15 5:00

I do real-time drawing... bitblt() is your friend, you're probably doing something else that's slow.

26-Jan-15 6:07

The background picture is 800*600, 24 color depth, so it is about 1.44 MB.
Did you think the picture size would affect the BitBlt() speed?

26-Jan-15 7:34

I'm sure it would... but not to the extent that your numbers reflect. You're doing something else wrong (or... more precisely, you're doing something else that's slowing the process down).

enhzflep

25-Jan-15 15:26

How much time does it take to do the other 4 lines?

26-Jan-15 4:51

It seems 1-3 ms, based on tickcount() result

25-Jan-15 22:12

Do you handled CDC::SetStretchBltMode[^] ? Depend on this settings, you will have rendering speed or render quality ...

26-Jan-15 4:48

Thanks, I will read descriptions of this function

Nitin K. Kawale

26-Jan-15 18:36

Hey why not using DirectX ,it uses Double buffering algorithm

CompatibleDC parameter question

27-Jan-15 8:18

Thanks,image without dirctx components inside

23-Jan-15 5:36

Hi, I have a question, situation like:

 
void funcA() 
{
   CDC	MemDC;
   CDC	*pDC ;
   pDC = GetDC(); 
   memDC.CreateCompatibleDC(pDC);
   
   funcB(memDC);
}
 
void funcB(CDC *pDC) 
{
   HDC hdc;
   HDC hdcMem;
 
   hdc = pDC->m_hDC;
   hdcMem = CreateCompatibleDC(hdc);
   ...
   BitBlt(hdc,0,0,100,100,hdcMem,0,0,SRCCOPY);
}

I think this BitBlt() will copy hdcMem to MemDC(in FuncA), right? just want to confirm it.

23-Jan-15 6:35

What exactly are you trying to achieve?

23-Jan-15 6:52

I want funcB draw picture on it's own temporary DC, then paste on funcA's memory DC, and FuncA paste the whole funcA's DC to screen.

Like:
B -> A
c -> A
...
x -> A

and A -> screen.

And I had another question, I have a big bitmap, represent the screen, many parts of the bitmap need to update independently and frequently.

is it a good idea using one memory DC to hold
all part's temporary DC, then post the whole memory DC to screen? that is, the double buffering technique.

23-Jan-15 7:32

1. Sounds OK. What happens when you try it?
2. Yes, keeping a MemDC with all the information and then updating that, before blitting to screen is probably the best way.

23-Jan-15 7:38

Thanks, have not try it.
Just thinking if the way is reasonable.

CDC bitblt function with HDC parameter?

23-Jan-15 7:45

Trying things is the best way to learn.

Re: CDC bitblt function with HDC parameter?

23-Jan-15 5:17

Hi,I wonder how a bitblt function of a CDC object, which src is a HDC object?
like:

MemDC.BitBlt(Icon.pos_x, Icon.pos_y, bm.w, bm.h,HdcObject,0,0,SRCCOPY);

Re: CDC bitblt function with HDC parameter?

23-Jan-15 5:28

Quote:
which src is a HDC object?

What? That doesn't make sense. Try rephrasing or expand on what you're trying to ask.

Re: CDC bitblt function with HDC parameter?

23-Jan-15 5:38

I mean HdcObject in the code.

I just want to copy a HDC object to CDC object, use CDC object's BitBlt() function.

""Object reference not set to an instance of an object" when creating new project with VS

23-Jan-15 6:15

HDC is a handle not an object....

You can use CDC::FromHandle() to get a temporary object for immediate use. Alternatively, you can CDC::Attach() to keep a more permanent CDC object around. You should make sure you release a device context (DC) when you're done using it (FromHandle sort of automatically handles this situation by going out of scope).

If you have CWnds, you can also get a pointer to an existing CDC with CWnd::GetDC().

There is a lot of info on drawing in GDI online, I suggest you read up on it.

jeff6

23-Jan-15 1:04

Hello, I get this error when I try to create a new project wi h Visual Studio 2010 (XP), Win32, MFC or Forms (only VB works)

"Object reference not set to an instance of an object"

I found nothing with Google for this case (just creating a new project) and tried to uninstall/install, repair, n times, impossible to fix Frown | :-(

Thanks in advance for any idea, I'm desperate, unable to create even an empty Win32 project !

Re: ""Object reference not set to an instance of an object" when creating new project with VS

Re: ""Object reference not set to an instance of an object" when creating new project with VS

23-Jan-15 1:57

Looks like a Visual Studio problem, but impossible to guess what.

jeff6

23-Jan-15 2:16

But it appeared just recently, it had worked for years before

Re: ""Object reference not set to an instance of an object" when creating new project with VS

Get CListCtrl scrollbar rectangle

23-Jan-15 2:31

I can only assume that something has been corrupted somewhere. But as I said before, it's impossible to guess what. Your only chance is to collect all the information that you can, and report it to Microsoft.

22-Jan-15 23:55

How can I get the CListCtrl scrollbar rectangle ? Whether the scrollbar is visible or not, I tested in following way:

	if(GetStyle() & WS_VSCROLL)
	{
	}

but, in order to change the scrollbar background by DrawThemeBackground[^], I need the scrollbar rectangle ... how can I retrieve the scrollbar rectangle ?

Jochen Arndt

23-Jan-15 0:10

Just call GetScrollBarInfo[^] passing OBJID_VSCROLL as idObject parameter.

23-Jan-15 0:45

Thank you Jochen ... the rectangle is retrieve it ... Smile | :)

I have to dig in, because it seems that something is wrong in my code, because though rectangle is correct now, the color of scrollbar is not drawn ...

void CGridCtrlExt::OnDraw(CDC* pDC)
{
//	draw the grid

	HTHEME hTheme = OpenThemeData(m_hWnd, L"WINDOW");
//	HTHEME hTheme = OpenThemeData(m_hWnd, L"MFCGridCtrl");
	if(NULL != hTheme)
	{
		if(WS_VSCROLL & GetStyle())
		{
			SCROLLBARINFO si;
			si.cbSize = sizeof(SCROLLBARINFO);
			GetScrollBarInfo(OBJID_VSCROLL, &si);
			CRect rect(si.rcScrollBar);
			pDC->FillSolidRect(&rect, RGB(255, 255, 0));
			DrawThemeBackground(hTheme, pDC->GetSafeHdc(), WP_VERTSCROLL, VSS_NORMAL, &rect, NULL);
		}
		CloseThemeData(hTheme);
	}
}

Jochen Arndt

23-Jan-15 0:59

This may be because the scroll bar is redrawn by the system.

You may use a custom drawn scroll bar or handle WM_CTLCOLOR when you only need to change the background.

Searching the web may give you some solutions. The article http://www.drdobbs.com/windows/developing-a-custom-windows-scrollbar-in/184416659[^] is rather old but contains a good introduction and shows how to implement a custom drawn scroll bar.

23-Jan-15 2:14

"You may use a custom drawn scroll bar or handle WM_CTLCOLOR when you only need to change the background"

I already tried that ... if I override WM_CTLCOLOR I could color everything, except scrollbars ... Smile | :)

"Searching the web may give you some solutions. The article http://www.drdobbs.com/windows/developing-a-custom-windows-scrollbar-in/184416659[^] is rather old but contains a good introduction and shows how to implement a custom drawn scroll bar."

I saw that article, but is about replacing the original scrollbar with CScrollBarEx control ... well, in this case I will front with 2 issues: hiding the original scrollbar, and second, synchronize the listctrl with CScrollbarEx control ... I think that is the longest road ... and the hardest ...

I thought that trying to use DrawThemeBackground I could change the scrollbars colors ... Frown | :(

I am working on that for weeks ... I have to dig in ...

23-Jan-15 2:38

"This may be because the scroll bar is redrawn by the system"

I wonder if I put properly the scrollbar coloring code ... inside of CMyControl::OnDraw is ok ? I guess not ...

Re: Get CListCtrl scrollbar rectangle [modified]

Jochen Arndt

23-Jan-15 3:08

OnDraw is a CView member function. You probably mean some kind of custom / owner draw. But this won't work for the scroll bars of list controls because only the list control content can be changed by this method. The scroll bar is still drawn by the system when necessary and your drawing vanishes.

If handling WM_CTLCOLOR did not work (and I believe meanwhile that it does not work with list controls), the only solution is using a complety custom drawn control or another GUI framework like Qt.