Re: Listening to Keyboard Input - C / C++ / MFC Discussion Boards

PotatisPulver24-Mar-04 6:04

24-Mar-04 6:04

Hello,

I need to control a webcam and analyze picture by picture (and pixel by pixel) but I do not really know where to to start. Do you have to have the manufacturers API or is there any windows standard interface that you may use? Can you use VC++ or VB classes? Do you poll frame by frame or do you get a continuous stream? What format would you expect to get on the pics/stream, complete pics or changes? etc etc.

Thanks for any help I may get.

kodvar

compile from command line

skoizumi2911024-Mar-04 5:56

skoizumi29110

24-Mar-04 5:56

I am trying to compile my application from command line
but somehow i can't do it here is the input for compiling my application with
registry tool and i want to use the different .exe file for this application
cl RegistryTools.cpp MyApplication.cpp -Fe MyApplication2.exe

thanks
Shin

Re: compile from command line

Steve S24-Mar-04 6:26

Steve S

24-Mar-04 6:26

There are lots of options that are set in project settings, things like INCLUDE paths, DEFINE-d symbols, and the like.

You say it doesn't do it, but you aren't giving any clues as to what errors you see.

Steve S

Re: compile from command line

skoizumi2911024-Mar-04 6:35

skoizumi29110

24-Mar-04 6:35

now i am one step forward and only problem is the following
cl RegistryTools.cpp MyApplication.cpp -FeMyApplication2.exe

> nafxcw.lib(thrdcore.obj) : error LNK2001: unresolved external symbol
> __endthreadex
> nafxcw.lib(thrdcore.obj) : error LNK2001: unresolved external symbol
> __beginthreadex

Re: compile from command line

John M. Drescher24-Mar-04 6:49

John M. Drescher

24-Mar-04 6:49

http://www.codeproject.com/cpp/cppforumfaq.asp?target=FAQ#cl_linkerrthread[^]

John

Re: compile from command line

vancouver77726-Mar-04 11:09

vancouver777

26-Mar-04 11:09

thanks,
i decided to use namke instead of cl.exe

thanks for your input.

Shinya

Listening to Keyboard Input

0v3rloader24-Mar-04 5:29

0v3rloader

24-Mar-04 5:29

Hello,

I was wondering if anyone here knows how to listen to keyboard input in Windows platform by means of using MFC.

To be more exact, whenever this specific application of mine is running, CTRL + DEL (among other keyb combinations) cannot reach the OS and must be filtered by the App, which will prevent the user from invoking Task Manager / Logging Off / Shutding Down (though there is always Reset/Power Off), etc.

Any idea would be much appreciated.

________________________

dNimrod#X

Re: Listening to Keyboard Input

Dudi Avramov24-Mar-04 5:48

Dudi Avramov

24-Mar-04 5:48

Read about hooking starting from SetWindowsHookEx using WH_KEYBOARD_LL hook type.
You can hook ALT+CTRL+DEL by i think that the OS won't let yu block it. The dialog will be opened anyway.
However,you can disable the buttons of the opened window by setting some values in the registry Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\Explorer.
Read Disable Windows NT alt-ctrl-del dialog button

Re: Listening to Keyboard Input

0v3rloader24-Mar-04 7:39

0v3rloader

24-Mar-04 7:39

Dudi Avramov wrote:
However,you can disable the buttons of the opened window by setting some values in the registry Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\Explorer.
Thanks a lot for the reply. I have heard certain OSes do not allow you to have full control over the CTRL+ALT+DEL feature.

However, what's so important about the app ?
Well I have an app which needs to be invulnerable to the more naive (or ignorant, should I say) users because some extremelly important analysis & update process has to be carried out and whilst it is being done, no keyboard input should be allowed.

Does anyone have any ideas as to what I should do?

Thanks very much for the replies. Big Grin | :-D

dNimrod#X
________________________

Re: Listening to Keyboard Input

Steve S24-Mar-04 6:34

Steve S

24-Mar-04 6:34

If it's NT, 2K or 2.03K, you can't do it that way, the SAS will always be picked up, for obvious security reasons. If it's Win9x/ME then it is simpler.
However, what's so important about the app ? Smile | :)

Steve S

'class' type redefinition error

Mughi24-Mar-04 5:13

Mughi

24-Mar-04 5:13

I got this error in my program
error C2011: 'CRichText' : 'class' type redefinition.

I added a RichText ActiveX Control and added a variable for it.
Once when i compiled, I got stuck with the above error.
Iam unable to proceed further.
Please help me out.
I thank in advance.

Mughi

Re: 'class' type redefinition error

David Crow24-Mar-04 7:56

David Crow

24-Mar-04 7:56

What does the line in question look like? Are you including a .h file more than once?

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

C++ Generic Autorun app ?

Marc Piulachs24-Mar-04 4:38

Marc Piulachs

24-Mar-04 4:38

Hi , I've been searching the internet and CodeProject but I haven't found any customizable autorun app , All we know autorun dialogs present in every Microsoft CD . I'm a C# programmer and I don't have good c++ skills I'm sure that lots of programers like my are looking for some solution does anyone has any code to share ?

Thanks,

Re: C++ Generic Autorun app ?

jhwurmbach24-Mar-04 5:34

jhwurmbach

24-Mar-04 5:34

There is basically a Autorun.inf file in the root directory of the CD containing the name of a program to run when the CD is inserted.
This can be prevented by holding down the 'shift' key when inserting the CD. Also, it does not work with operating systems other than Windows.
I thought I just say that, because recently some very smart guy (SunnComm Technologies) invented a CD copy protection scheme on autoloading a program that prevented access to the CD. They sued the one who found out: Link here Roll eyes | :rolleyes:

"We trained hard, but it seemed that every time we were beginning to form up into teams we would be reorganised. I was to learn later in life that we tend to meet any new situation by reorganising: and a wonderful method it can be for creating the illusion of progress, while producing confusion, inefficiency and demoralisation."

-- Caius Petronius, Roman Consul, 66 A.D.

How to use CryptExportkey blob

chakra_r24-Mar-04 3:32

chakra_r

24-Mar-04 3:32

Hi
I like to use Blob data(non-encrypted) before calling CryptExportkey. So i can customize in such a way i can implement my own algorithm. How to do that.

chak

_control87 and signal(SIGFPE....)

prcarp24-Mar-04 3:03

prcarp

24-Mar-04 3:03

I have a very large mathematical model that runs continuously. I am trapping for math errors via _control87(_EM_INEXACT, _MCW_EM) and signal(SIGFPE, MyFPHandler). This part works and my routine (MyFPHandler) is called whenever there is a divide by zero, invalid operation, etc.. What I would like to do is get the program location of the offending operation. Is there a way to do this? The code must know somehow because, if I wanted to, I could resume execution from that point. However, in my case, I do a an _fpreset, and then longjump to a safe area that does some simple error reporting and cleanup.

Thanks,
Paul

GetDIBits and 98 Problem

Ceri24-Mar-04 2:43

Ceri

24-Mar-04 2:43

Hi I have a problem where I cannot use GetDIBits on 98, works fine on XP. I read somewhere that in 98 the width and height have to be divisable by 4 so I even tried that with no avail.

Here is a snippet which works in XP but doesn't in 98. Has anybody got any clue why it's not working in 98

<br />
        <br />
        ...<br />
<br />
	HDC hBmDC = CreateCompatibleDC(NULL);<br />
	HBITMAP hB = CreateBitmap(16,16,1,24,pPixels);<br />
<br />
	bmiInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);<br />
<br />
	// get pixels from the original bitmap con verted to 24bits<br />
	int iRes = GetDIBits(hBmDC,hB,0,16,NULL,&bmiInfo,DIB_RGB_COLORS);<br />
<br />
        ...<br />
<br />

Thanks

Help - CPrintDialog as a child

Jason Carter24-Mar-04 2:41

Jason Carter

24-Mar-04 2:41

I am trying to use the CPrintDialog functionality, with my own template, as a child on a tabbed dialog in VC6. If I make the child dialog a CPrintDialog it does not initialise with the printer details. So I tried to make the Main dialog a CPrintDialog, still the child does not respond. I then put the Controls on the Main dialog, then MoveWindow them to the Child, this inits ok but no longer responds to any user interaction ( change of printer combo ). I have played a little with message routing and can now respond to combo change, but not Properties Button. Anyone any thoughts

Overloading operator [ ]

Imtiaz Murtaza24-Mar-04 0:58

Imtiaz Murtaza

24-Mar-04 0:58

What is the correct method to overload the operator []. I am doing something like:

class MyClass
    {
      
      const int operator[](const int i ) const;
  
      int& operator[](const int i );
      //...
    }

Now i want to invoke the operator [] as follows:

MyClass foo;

    int i = foo[j]; 
    foo[j] = i;

Strange that in both cases second operator of the above class always gets called. Can anyone tell me whats the problem and why not first operator gets called ??

Imtiaz

Re: Overloading operator [ ]

Mike Dimmick24-Mar-04 2:20

Mike Dimmick

24-Mar-04 2:20

IIRC, the rules of C++ say that if two functions differ only by const, the non-const version is preferred for a non-const object.

If foo was const, the first assignment would call const int MyClass::operator[](int) const while the second wouldn't compile (the error would probably say something like "'const int' is not an l-value").

C++ doesn't know the context of an array access, so you return a reference to the object to be assigned to if you want to allow assignment. If you want to be able to control assignment (e.g. inspect the value before assigning it), you typically need to return a proxy object from operator[]. The proxy object overloads operator= and is also convertible to the contained type (in this case, you'd probably supply operator int). You would place your 'setter' logic in operator=.

Stability. What an interesting concept. -- Chris Maunder

Re: Overloading operator [ ]

David Crow24-Mar-04 2:36

David Crow

24-Mar-04 2:36

From what I can tell, you only need one of the overridden methods. The second one can be used on either the left or the right side of an assignment statement. Consider this example:

class MyClass
{            
public:
    MyClass()
    {
        arr[0] = 2;
        arr[1] = 4;
        arr[2] = 6;
    }
 
    int& operator[](const int i )
    {
        return arr[i];
    }
 
    int arr[3];
};
 
MyClass foo;    
int j = 0,
    i = foo[j]; // assigns the value 2 to i
foo[2] = i;     // assigns the value 2 to the third item in the array

The reason has to do with the function returning a reference to arr. It's being treated as if you had written:

MyClass foo;    
int j = 0,
    i = foo.arr[j];
foo.arr[2] = i;

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Re: Overloading operator [ ]

Ryan Binns24-Mar-04 3:44

Ryan Binns

24-Mar-04 3:44

DavidCrow wrote:
From what I can tell, you only need one of the overridden methods. The second one can be used on either the left or the right side of an assignment statement.

Unless you want to call it on a const object to read the value...

Ryan

"Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"

System performance comparison

Shree24-Mar-04 0:55

Shree

24-Mar-04 0:55

I need to watch for a particular window on the screen. There are two approaches - to use a timer, say with an interval 500 ms, and use the FindWindow() function to check if that window has appeared. Another would be to use a system wide hook to monitor all events, filter out the window create events, and check the caption. Which one would take less system resources.

Is there a way to compare system performance with background processes running?

MFC Views Documents, and Modal windows :_-)

_psh_24-Mar-04 0:41

_psh_

24-Mar-04 0:41

Hi all,

I have two views, one of which is associated with a document. this view can be used to open a modal window which performs an operation on some data, and then it is closed. This window creates an array which i need the other view to access; the other view also needs access to the document data!

i can't see how to do this !
can anybody help ?

Paul.

When does it occur the worst case in Quicksort algorithm ?

nguyen_nd24-Mar-04 0:34

nguyen_nd

24-Mar-04 0:34

Hi Everybody !
Could you tell me when it occurs the worst case (n*n) and the best case in quick sort algorithm ?

Thank,
Nguyen

nguyen_nd

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