C / C++ / MFC Discussion Boards

if you have condition of exceptipon say a
case of divide by zero of double then you get this value 1.#QNAN00000000000.
Where NAN represents Not a Number([^])

Now in this case of divide by zero
double numerator = 0;
double denominator = 0;
double d = static_cast<double>(numerator)/static_cast<double>(denominator);
value of d is not infinite, but it cannot be calculated, so it given as NaN.

well about the second line

int n = (f == numeric_limits<double>::quiet_NaN ());

the value of n is compiler dependent so it will change accordingly.
for Vs 2005 it may be 0 for some other earlier versions it may be 1.

Величие не Бога может быть недооценена.

modified on Thursday, March 4, 2010 6:31 AM

See [^]:

A comparison with a NaN always returns an unordered result even when comparing with itself. The comparison predicates are either signaling or non-signaling, the signaling versions signal an invalid exception for such comparisons. The equality and inequality predicates are non-signaling so x = x returning false can be used to test if x is a quiet NaN. The other standard comparison predicates all signal if they receive a NaN operand, the standard also provides non-signaling versions of these other predicates. The predicate isNaN(x) determines if a value is a NaN and never signals an exception.

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Thanks to the both of you for the explanation!

I ending up changing all the relevant code to use isnan(f) instead of direct comparisons and everything works fine now but I was still wondering why a direct comparison with a NaN always returned 0 on my compiler.

Now I understand!
Big Grin | :-D

Hi
Please guide me How to design OSI layer using C++/VC++ ..For Example if i send raw bits in network layer i need to find the status of raw bits in each layer ..how to do that sir...please Guide me!

Thanks Blush | :O

Failure is Success If we learn from it!!

Please read point 2 here[^]

Cédric Moonen
Software developer

Charting control [v3.0]
OpenGL game tutorial in C++

Hai All..
I need to encode and decode some popular video formats listed below.
Input: avi, mpeg2, mpeg4, h.264, mov, flv, VMW
output: On2VP6 and h.264 avc

I tried with FFMPEG project. But there is only decoding for On2VP6 and H264(Encoding not supported). Is there any library availabe for this purpose? or which is the good way i can go...?Please let me know your valuable suggestions...

Regards,
Rajeev K R

Take a look at DirectShow[^] for instance.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <

Thanks for your reply Thumbs Up | :thumbsup:

... But it will take more time to develope an encoding application from the scratch using DShow. Unfortunately it is an urgent requirement for me in my current project. I am looking for Encoding and Decoding libraries just like FFMPEG.

Check if the codec in the folling link work for you: http://sourceforge.net/projects/hdot264/[^]

I just googled and found it Smile | :)

Thank You Rejeesh for your quick response...

I tried the above link. But Hdot264 video codec supports only H264 format. I need to encode both On2VP6 and h.264 avc.

Hopefully you would find some On2VP6 codecs as well if you google it.

I got some paid libraries. But no free libs...Still trying for a best one... Smile | :)

Hello, Is there any way for a treeview to be shown in a listview control using MFC?

same effect as the one in the link below:
http://www.codeguru.com/img/legacy/vb_listview/1945_sshot.gif[^]

btw, I'm using Visual C++ 2005

thanks a lot.

modified on Thursday, March 4, 2010 2:55 AM

have a look
first
second

Hi,

How to get HWND of dialog box in win32 applucation?

Depends where the dialog box comes from.

If you created a dialog box using CreateDialog, the function returns the handle you are looking for.

You should post a more specific question.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

If you create a dialog (win32) with :

HWND CreateDialog( HINSTANCE hInstance, LPCTSTR lpTemplate, HWND hWndParent, DLGPROC lpDialogFunc );<br />

The HWND of the dialog will be the returned value of the function.

or maybe I do not understand the question.

Watched code never compiles.

Hi all,
I have a code in an applicaiton that I use in many dialogs to display a grayscale data into a color image (using pseudo colors) as follows-

//in header file
LONG		DIBSecWidth;
LONG		DIBSecHeight;
LONG		BitsPerPixel;
LONG		Stride;
BITMAPINFO	bmi;
BYTE		*pDIBSectionBits;
HBITMAP		hbm;

//in cpp file
DIBSecWidth  = 512;
DIBSecHeight = 512; 
BitsPerPixel = 24;
m_bData = VBI_vector(row*col);
Stride = ((DIBSecWidth * BitsPerPixel + 31L) & (~31L)) / 8L;	
memset(&bmi, 0, sizeof(BITMAPINFO));
bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bmi.bmiHeader.biWidth = DIBSecWidth;
bmi.bmiHeader.biHeight = DIBSecHeight;
bmi.bmiHeader.biPlanes = 1;
bmi.bmiHeader.biBitCount = (WORD)BitsPerPixel;
bmi.bmiHeader.biCompression = BI_RGB;
bmi.bmiHeader.biSizeImage = Stride * abs(DIBSecHeight);
hbm = ::CreateDIBSection(NULL, &bmi, DIB_RGB_COLORS, (void**)&pDIBSectionBits, NULL, 0);
memDC.CreateCompatibleDC(NULL);
//colormap
colormap = new COLORREF[256];
int red, blue, green;
for (int i=1; i<257; ++i)
{
	red = (int)(((1+cos((4*PI*double(i))/(3*255)))/2)*255);
	green = (int)(((1+cos((4*PI*double(i)/(3*255))-(2*PI/3)))/2)*255);
	blue = (int)(((1+cos((4*PI*double(i)/(3*255))-(4*PI/3)))/2)*255);
	colormap[256-i] = RGB(red,green,blue);
}
//on paint()

CDC *dc = Display->GetDC();
HGDIOBJ holdbm;
BYTE color;	
short idx;
RGBTRIPLE *pCurRowPixel = (RGBTRIPLE *)(pDIBSectionBits);
short i=-1;
for (int y = 0; y < 512; ++y)
{
	for (int x = 0; x < 512; ++x)
	{
		color = (BYTE) m_dDatatemp[++i];
		pCurRowPixel[x].rgbtBlue = GetBValue(colormap[color]);
		pCurRowPixel[x].rgbtGreen = GetGValue(colormap[color]);
		pCurRowPixel[x].rgbtRed = GetRValue(colormap[color]);
	}
	pCurRowPixel = (RGBTRIPLE *)((BYTE*)pCurRowPixel + Stride);
}	
holdbm = memDC.SelectObject(hbm);
dc->BitBlt(align_left, align_top, bmi.bmiHeader.biWidth, bmi.bmiHeader.biHeight,&memDC,0,0,SRCCOPY);
memDC.SelectObject(holdbm);		
ReleaseDC(dc);

Now I would like to save pDIBSectionBits(or to say the color image being displayed on the dialog) into an avi file. Any ideas or suggestions are really appreciated.

thanks in advance,

PKNT

Have a look at the Microsoft Windows SDK WriteAVI sample - this does what you are trying to do.

I used this WriteAVI sample code (with the assistance of CodeProject members) to save a set of images as a video clip 5 or 6 years ago, so the details are fuzzy. If you have specific issues, I can find a copy of the code and try to do an extract.

Hello,

I have a basic grasp of c/c++ after doing several books and many tutorials but am having trouble making the next step.

Specifically I would like to learn how to do image manipulation. I understand how a RAW image file is formated but I have no idea how on earth to handle the mass of data or how to do for example edge detection. Can anyone recommended a place I can go to learn or an example on this site I can dissect and learn well?

The second thing is how to make good menus. I can easily make a hardcoded menu but when I want to add one new feature I must write quite a bit of code. I have heard that a state machine is a great way to do it. You can add your new menu into a 'choice matrix' or something but I never understood how to actually make them. Is their a better way to do menus? And can you recommended a good state machine tutorial?

Thanks!

May be you can take a look at the folowing C++ library for image processing: http://cimg.sourceforge.net/[^]

You didn't really say whether you wanted to learn image processing from the ground up or simple experiment with image processing. Another well supported and Open Source image processing and machine vision library is OpenCV[^]. It was orininally started by Intel and now actively supported by Willow Garage. It was originally written with a pure C API but they've been retrofitting a C++ interface lately. Lots of samples and extensions available, an active user community, and a book from O'Reilly for documentation.

You measure democracy by the freedom it gives its dissidents, not the freedom it gives its assimilated conformists.

I would like to learn from the ground up. I have no idea how someone can figure out 'edges' in an image and I would like to learn. My test project will have a picture with a known block in it, say a 1x1" square and I would like to detect the edges of an unknown shape and then extrapolate its size. I know program that do this based on mouse clicks and pixel maths but nothing automatic.

There are any number of books on image processing and machine vision around.

This one[^] looks to be a fairly standard introduction and is free to download. It is the 1982 edition but the basics are still the basics.

Another free book[^].

The first one I studied is this[^]. $114, ouch! I have the 2nd edition published in 1987 which is probably about the time I bought it. It's quite readable and understandable.

The book[^] I mentioned on OpenCV actually spends as much or more time discussing the algorithms as it does talking about using the library. It's also very readable but does have a few errors so if you go this route, you should check the errata on the O'Reilly site. I honestly can't recommend reading the OpenCV code as a tutorial on "how" to do an image processing library as it shows its age very badly having started out as a pure C API. Also, from a tutorial standpoint, the cross platform aspects and supporting a large number of image formats transparently makes the code kind of convoluted. In my opinion, like many Open Source projects, the code is rather poor and definitely poorly commented. That said, I do "use" OpenCV in my vision projects.

Of course, there's also a ton of material on the web about image processing and vision once you learn the basic terms.

You measure democracy by the freedom it gives its dissidents, not the freedom it gives its assimilated conformists.