Re: Disabling Keys - C / C++ / MFC Discussion Boards

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Re: STL container of multiple types

Shankar Chandra Bose30-Jul-01 21:05

Shankar Chandra Bose

30-Jul-01 21:05

Hmmm, off the top of my head, may I suggest you try creating your own struct/class that holds a string, float, int, etc. Infact, this is how VARIANTs in VB/COM are implemented under the hood anyway. Then use this struct/class in your maps, lists, and other STL structures. You might want to experiment with unions as well.

You could also take a look at MFC's COleVariant, and see if you can bend it to meet your needs (this is mostly used for database related stuff, but am sure you can use it for other needs as well).

Re: STL container of multiple types

Not Active31-Jul-01 3:34

Not Active

31-Jul-01 3:34

If I understand you want one place to hold variables of different type(long, int, string, etc.).

The only way I'm aware of is to use VARIANT, but this has its draw backs. Using a VARIANT adds bulk and slows down your code. If you don't need to support VB or scripting languages then don't use VARIANT.

Is this for MFC? Then you can COleVariant << and >> operators, otherwise I don't beleive _variant_t has that capability.

Can you use seperate containers for each type? list<int>, list<long>, etc.

Re: STL container of multiple types

Philippe Mori31-Jul-01 4:25

Philippe Mori

31-Jul-01 4:25

If this is what you want to do, I suggest that you uses a wrapper class like COleVariant or _variant_t (or maybe your own class).

At least those class properly handle memory managment and help a with initialisation. The one to uses depends on your needs. If you need more functionaly, then you should create your own class that may derive or embed a COleVariant or _variant_t.

_variant_t class may be a bit easier to uses since it allows conversion from the variant to another type:

_variant_t v(3.2);
double d = v;

but it does not support writting to CArchive...

You may also uses _variant_t for the container and create ColeVariant object at place you need extra functionaly.

Philippe Mori

Re: STL container of multiple types

Todd Smith31-Jul-01 5:52

Todd Smith

31-Jul-01 5:52

I think this will work

http://www.boost.org/libs/any/index.html

gonna try it out...

How can I move mouse cursor from my program?

30-Jul-01 14:21

subj

Re: How can I move mouse cursor from my program?

Carlos Antollini30-Jul-01 15:47

Carlos Antollini

30-Jul-01 15:47

with SetCursorPos(x,y);
cheers!!! Big Grin | :-D

Carlos Antollini.

Disabling Keys

Orbitalne30-Jul-01 12:23

Orbitalne

30-Jul-01 12:23

In MFC, if I didn't want my program to close by hitting Esc or Alt+F4, or any other escape sequence, how would I disable that? I can't find any code that works.

I Want Chicken, I Want Liver, Meow Mix, Meow Mix, Please Deliver...

Re: Disabling Keys

Matt.W.30-Jul-01 15:47

Matt.W.

30-Jul-01 15:47

I am not sure what you mean by "program". But one way to stop the user closing your dialog would be to overload the OnCancel or OnOK methods of your CDialog inherited class. (eg. They could do nothing at all.)

Accept that some days you are the pigeon and some days the statue.

Re: Disabling Keys

31-Jul-01 4:52

WM_CHAR

palmap32.dll <-pretty impossible !?!

30-Jul-01 11:42

Hello every1!

I am looking at some sample code that microsoft is giving out with MSDN and i can't understand what is going on...if some1 knows it...

Here's the problem - the project palmap(can be found in any MSDN library) is a dll file that is used as an extension of aviview(a prog for viewing avi files and also can be found in the MSDN). A part of the source of palmap.c says:

typedef struct {
IAVIStreamVtbl FAR * lpVtbl;

ULONG ulRefCount;

//
// instance data
//
PAVISTREAM pavi;
PGETFRAME pgf;
AVISTREAMINFO sinfo;
HPALETTE hpal;
LPBYTE lp16to8;
LONG lLastFrame;
LPBITMAPINFOHEADER lpdibLast;
} PALMAPSTREAM, FAR*PPALMAPSTREAM;

There is something sneaky in this struct since IAVIStreamVtbl is defined nowhere(i checked the headers and tried to see if any IDLs exist). I searched the whole project directory for that string and there is no match. It is obviously the vtable and also has an interface prefix but i don't find any interface definitions too. BTW: i tried to look for the definition by clicking with the right button on the "IAVIStreamVtbl" and choosing "Goto definition...." but there is no brosing files with that project. After building the project there are no errors or warnings. so - Where could this IAVIStreamVtbl be defined?

Thanks for any reply!

Vladimir Ralev

Synchronizing a global function

PJ Arends30-Jul-01 11:37

PJ Arends

30-Jul-01 11:37

Hi, I'm hoping someone here can help me with a synchronization question.
I have a global function that adds entries to a log file. This function can be accessed by several threads in my program, and this function will also be used in different programs to write to the same log file. Because the log file is opened with the CFile::shareDenyWrite flag, I can only allow one thread to have access to this function at one time.

////////////////////////////////////////////////////////////////////////////
// WriteLog - writes the 'EntryString' log entry to the 'Bird_Log.txt' log file
// with a date and time stamp. 'EntryString' will be truncated to 80 characters.

void WriteLog (LPCTSTR EntryString)
{
    CMutex mutex(FALSE, _T("WriteLog - {AE4E28C0-84E6-11d5-B625-F80C283F7922}"));
    CSingleLock lock(&mutex, FALSE);
    while (lock.IsLocked());    // wait for this function to be free
    lock.Lock();                // deny other threads access
    COleDateTime dt = COleDateTime::GetCurrentTime();
    CString LogEntry = dt.Format("%d/%m/%y %H:%M:%S - ");
    LogEntry += EntryString;
    CRotatingLog rl(_T("C:\\Bird_Log.txt"), 1000, 100);
    rl.AddLine(LogEntry);
}

As this is the first time I am using this method, I would like to know if this is the correct way of doing this, or will this just give me problems in the future? Is there a better way to wait for the CSingleLock object to unlock? The while loop seems to be very processor intensive. Any advice appreciated.
TIA

---
Multitasking: Screwing up several things at once.

Re: Synchronizing a global function

Tomasz Sowinski30-Jul-01 11:42

Tomasz Sowinski

30-Jul-01 11:42

You can delete the 'while' loop. The default value of Lock method parameter is INFINITE, this means that CSingleLock::Lock will wait until mutex is released. This waiting will have no impact on CPU usage - it's implemented using ::WaitForSingleObject.

Tomasz Sowinski -- http://www.shooltz.com

Re: Synchronizing a global function

PJ Arends30-Jul-01 11:44

PJ Arends

30-Jul-01 11:44

Thanks, I'll try it;)

---
Multitasking: Screwing up several things at once.

Degree to pixel

Not Active30-Jul-01 11:26

Not Active

30-Jul-01 11:26

Does anyone know of any algorithms to convert degrees to pixels. I need to be able to rotate a bitmap by a given degree.

Re: Degree to pixel

Tomasz Sowinski30-Jul-01 11:47

Tomasz Sowinski

30-Jul-01 11:47

I need to be able to rotate a bitmap by a given degree.

Good startpoint is http://www.faqs.org/faqs/graphics/algorithms-faq/. Look at item 3.01, "How do I rotate a bitmap?"

Tomasz Sowinski -- http://www.shooltz.com

Re: Degree to pixel

Wolfram Steinke30-Jul-01 11:49

Wolfram Steinke

30-Jul-01 11:49

As degrees are an angular measure and pixels lateral the convertion would depend on how far from the rotation point you are. I have been playing with images for a while now and was going to write a lot of the code myself, but found it was better to concentrate on the rest of the project and do the image handling with a library written be someone who has more experience than I do. In the end I opted for ImgSource

http://www.smalleranimals.com/

It is inexpensive (note I don't say 'cheap') and does a very good job for what I need to do. Have a look it may do what you want.

Happy programming!!

UDP Socket

orcun colak30-Jul-01 10:37

orcun colak

30-Jul-01 10:37

Is there a way to understand if a port is listened by a server process on winsock ? If you know how to do this can you post a code sample.

Orcun Colak
orcuncolak@yahoo.com

Re: UDP Socket

EiSl2-Aug-01 1:52

EiSl

2-Aug-01 1:52

What do you actually mean?!?!

You want a 'client' be able to test if a 'server/service' exist on a service-port over UDP?

UDP is a connectionless protocol, so the only way for the 'client' is to check the connection is waiting for any response on your message.

I write 'client' and 'server' between brackets, since client-server in UDP environment is not really a client-server architecture. With TCP/IP you split a socket when a connection is make (by listen -> accept), UDP doesn't do this, but you can use recvfrom to collect the others ip-address+port.

EiSl

multirow buttons in CToolBar

gaylen30-Jul-01 9:55

gaylen

30-Jul-01 9:55

I'm using CToolbar in an MDI w/ sliders,edits,comboboxes,etc.
And I need to place multiple rows of buttons for
one toolbar.I can make the toolbar wider, but I
don't know how to wrap the buttons on the toolbar
to make multiple rows.I've tried getctoolbarctrl(?)
but i can't get a wrap.

Re: multirow buttons in CToolBar

EiSl2-Aug-01 1:55

EiSl

2-Aug-01 1:55

One of the examples on this site explaines the usage of multiple checkboxes in one 'placeholder' In stead of checkboxes buttons should be possible to. Be care full about keeping the GUI user friendly!

Give a yell if you need more help

EiSl

Encryption

Frank Deo30-Jul-01 9:48

Frank Deo

30-Jul-01 9:48

Does anyone know of a quick and easy way to encrypt / decrypt a phrase stored in a CString variable?

I'm looking for 40 bit (or lower) encryption that uses a hardcoded key for encryption / decryption.

Can anyone point me to a good resource, or give me some pointers?

Thanks,
Frank

Re: Encryption

Joaquín M López Muñoz30-Jul-01 11:46

Joaquín M López Muñoz

30-Jul-01 11:46

You might try Wei Dai's Crypto++ library. It is:

easy to use,
very C++ oriented,
cross-platform,
open source and royalty free.

There's an article on CodeProject with an example of use.
Regards,

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: Encryption

Frank Deo30-Jul-01 12:31

Frank Deo

30-Jul-01 12:31

I looked at Crypto++ and backed away from it for these reasons:

<l>

Way too much for what I need...I just need a simple encrypt/decrypt function.

Import / Export restrictions. I think that 40 bit is cool with the US DOD, but i'm not exactly sure.

All I really need is a way to encrypt registration information for my app that is secure but at the same time not too difficult to implement. I've tried XoR and a few other "Simple" encrypt / decrypt methods but they dont seem to fit well into my scheme of things. If I could be specific, I'm looking for something that will give me an output similar to a PGP public key signature you would receive in an email. Big Grin | :-D

Thanks for the suggestions,

Frank

How can I create read-only file ???

30-Jul-01 9:45

But it's need to allow the writing only to my program.
Is it possible ???;)

Re: How can I create read-only file ???

Carlos Antollini30-Jul-01 10:09

Carlos Antollini

30-Jul-01 10:09

When you crete the file, you must not put the otion shared

Cheers!!!!

Carlos Antollini.

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