C / C++ / MFC

17-Dec-03 23:44

I have an MDI application with a CDialogBar. Immediately after I have created the dialogbar, I can access the controls on it with GetDlgItem, but when I try to to access them at a later stage, GetDlgItem fails and I get a failed assertion for ASSERT(::IsWindow(m_hWnd)), where m_hWnd is the window handle of the dialogbar. Looking in the debug locals window I can see that CDialogBar::m_hWnd is now NULL. Yet I can still see it fine on the screen.

Why would it lose its HWND? How does it work without it? How can I access the controls on it? Thanks.

Monty²18-Dec-03 0:14

Monty²

18-Dec-03 0:14

did you do this ?
hDlgWnd = m_wndDialogbar.m_hWnd;
instead do this
hDlgWnd = m_wndDialogBar.GetSafeHwnd();

MFC clears its temp map and the entry goes in permanent map if you do this GetSafeHWnd()

Live as if your were to die tomorrow. Learn as if you were to live forever.
-Mahatma Gandhi

Rowan Seymour18-Dec-03 0:30

18-Dec-03 0:30

I was just calling CDialogBar::GetDlgItem and letting it sort out its own window handle. I've tried GetSafeHwnd() and I still get 0xCDCDCDCD

Monty²18-Dec-03 0:41

Monty²

18-Dec-03 0:41

such situations can arise in multithreaded environment , are there any threads ?
did you use SPY ++ to see the windows handle

Live as if your were to die tomorrow. Learn as if you were to live forever.
-Mahatma Gandhi

Rowan Seymour9-Jan-04 1:05

please help C++ and video..

9-Jan-04 1:05

I gave up on this prob for about a month there but now I really really want to get it sorted. Its a single threaded MDI app in VC7. I can't find anyway to access the controls on the dialogbar after it has been created. I've tried DDX_Control, GetDlgItem, creating everything on the heap and everytime I get failed asserts like ASSERT(::IsWindow(m_hWnd)) from GetDlgItem etc

Any help very much appreciated

ahmed_html17-Dec-03 23:34

ahmed_html

17-Dec-03 23:34

hi all i am a student in Computer science engineering 1st year..new guy in the field of programming..i am asked to make a program that runs its own type of video files...

ex: i have a *.AVI file i must convert to a type of my own like *.itp for example then this file is not runnable on any player except my own one..

can anyone help me with how to edit header for the video and how to render it using my program

Re: please help C++ and video..

Rowan Seymour17-Dec-03 23:51

Re: please help C++ and video..

17-Dec-03 23:51

You could use the old Win32 AVIFile functions, or the newer DirectShow objects.

The old AVIFiles are really easy to use if you just want to grab individual frames from a video, without sound, but they don't work with new formats like DV. Look for AVIFileInit in MSDN.

DirectShow is a bit trickier as its all COM objects, but its very powerfull, and allows you to create your own media player with relatively little code if you want. You'll need IMediaDet if you want to grab individual frames.

Good luck!

Monty²18-Dec-03 0:44

Monty²

18-Dec-03 0:44

wow that is soe project for a first year guy
video files of own format !
you can simply put series of images in a file and display them you won't get a good fps but good for learning

or use directshow or AVIapi to display avi files but that's not what you want right

Live as if your were to die tomorrow. Learn as if you were to live forever.
-Mahatma Gandhi

Re: please help C++ and video..

ahmed_html18-Dec-03 7:14

ahmed_html

18-Dec-03 7:14

sure it is big for me to do..can you please tell my teacher that information.....so he may discard me from this project...

so if you please can you help me...with some more technical information for a beginner....thanks

int limits

Jerome Conus17-Dec-03 23:16

17-Dec-03 23:16

Hi !

Is there a way in standard C++ to programmatically get the limits of an int (i.e the smallest possible number and the biggest possible number) ?

Thanks !
Jerome

Prakash Nadar17-Dec-03 23:29

Prakash Nadar

17-Dec-03 23:29

int max=0,min=0;
min = min-1; //smallest possible number;
max = -min + 1; //largest possible number;

My God is more powerfull Than Your God. (the line that divides the world)

Jerome Conus17-Dec-03 23:35

17-Dec-03 23:35

Mr.Prakash wrote:
int max=0,min=0;
min = min-1; //smallest possible number;
max = -min + 1; //largest possible number;

????

Well, I don't see how it could work.
min = min -1 gives -1 for min.
max = -min + 1 gives 2 for max, isn't it ?

Jerome

Prakash Nadar18-Dec-03 16:04

Prakash Nadar

18-Dec-03 16:04

Yak!! what was i thinking.

My God is more powerfull Than Your God. (the line that divides the world)

Rowan Seymour17-Dec-03 23:53

17-Dec-03 23:53

std::numeric_limits<int>::min()
std::numeric_limits<int>::max()

Jerome Conus18-Dec-03 0:05

18-Dec-03 0:05

Thanks for your help !

I still have a problem though :

I do :

#include <limits>void main()
{
int LowerLimit=std::numeric_limits<int>::min();
}

And I get these errors when I compile :

warning C4003: not enough actual parameters for macro 'min'
error C2589: '(' : illegal token on right side of '::'
error C2059: syntax error : '::'

I'm using VS 6.

Any idea ?
Thanks !
Jerome

Rowan Seymour18-Dec-03 0:14

18-Dec-03 0:14

First time I posted, the forum removed my <int> - I forgot to check the checkbox "Do no treat <'s as HTML tags".

I should be:

#include <limits>
LowerLimit=std::numeric_limits<int>::min();

its a template class - you can use it for any primitive data type, eg.

std::numeric_limits<float>::min();
std::numeric_limits<double>::max();

Jerome Conus18-Dec-03 0:23

18-Dec-03 0:23

Rowan Seymour wrote:
I forgot to check the checkbox ¨

So did I !!!

Here is the line I have in my code :
int LowerLimit=std::numeric_limits<int>::min();

and the errors I get :
warning C4003: not enough actual parameters for macro 'min'
error C2589: '(' : illegal token on right side of '::'
error C2059: syntax error : '::'

It looks like 'min' has many definitions, but the namespace should do it, right ?

I don't see what I'm doing wrong !
Jerome

Rowan Seymour18-Dec-03 0:31

18-Dec-03 0:31

you including <limits> ?

Jerome Conus18-Dec-03 0:34

18-Dec-03 0:34

yes, and using namespace std !

strange....

markkuk18-Dec-03 1:05

markkuk

18-Dec-03 1:05

Try the following program:

#include <limits>;
#include <iostream>;

int main()
{
  int LowerLimit=std::numeric_limits<int>::min();
  int UpperLimit=std::numeric_limits<int>::max();
  std::cout << LowerLimit << '\n' 
	    << UpperLimit << std::endl;
}

Don't use any other include statements.

Robert A. T. Káldy18-Dec-03 2:37

Robert A. T. Káldy

18-Dec-03 2:37

min is a Win32 macro computing minimum of two parameters. It intererferes with the numeric_limits<>::min() function. The similar example is min(x, y) and max(x, y) function in <algorithm>, so in stl header files distributed with VC are defined as _cpp_min and _cpp_max. But there isn't any similar definition in numeric_limits.
You can use the INT_MIN, INT_MAX macros from limits.h. The numeric_limits class is only a STL wrapper around these macros.

HTH.....Robert-Antonio

berndg18-Dec-03 2:44

berndg

18-Dec-03 2:44

INT_MIN, SHRT_MIN, SCHAR_MIN, SCHAR_MAX, UCHAR_MAX, SHRT_MAX, USHRT_MAX, INT_MAX, UINT_MAX - all defined in ANSI-C and C++, including VS6, see limits.h

Bernd