ATL / WTL / STL Discussion Boards

Re: Problems with cvSobel and cvLaplace functions under visual studio 2010

RockwoodGuitar6-Apr-11 0:16

6-Apr-11 0:16

You cannot use any type of images with a sobel operator. If you use a 8U image as the source then the destination image needs to be 16S (not even 16U) because of some overflow issue then you can transform if back to 8U at will.

Displaying html text on windows form

nachiket0710-Feb-11 13:57

nachiket07

10-Feb-11 13:57

Hi,
How can I display html text on a windows form using ATL/WTL in C++? I want to mimic Microsoft Office tooltips in my C++ windows app.

Thanks!

Re: Displaying html text on windows form

Cool_Dev13-Feb-11 20:37

Cool_Dev

13-Feb-11 20:37

web browser activex control is the first option for html.

Re: Displaying html text on windows form

nachiket0714-Feb-11 19:29

nachiket07

14-Feb-11 19:29

Thanks for replying, but I am working with a Windows Form using ATL/WTL.

Re: Displaying html text on windows form

Cool_Dev14-Feb-11 23:35

Cool_Dev

14-Feb-11 23:35

it is an activex control, you can definitely use it with all micosoft programing technologies.

C++ - how to refer any header file from a dll while loading throu loadLibrary ?

DavJes7-Feb-11 1:44

DavJes

7-Feb-11 1:44

Hi I m trying to load the dll using LoadLibrary which works fine.

But for one of the method paramter is an object of class which is refered inside the dll . So in this case in my client app how do i refer the .h file which is already refered in the dll inside ?

As i m trying to link dynamically how does header file references are dealt with ?

Thanks

Re: C++ - how to refer any header file from a dll while loading throu loadLibrary ?

Richard MacCutchan7-Feb-11 5:27

Richard MacCutchan

7-Feb-11 5:27

DavJes wrote:
So in this case in my client app how do i refer the .h file

The same way as any header file is referenced; either add it to your project or add the location to the list of include directories.

If you are saying that you do not have access to the header file, then you have a problem.

I must get a clever new signature for 2011.

encryption using VS C/C++

Alan Kurlansky27-Jan-11 5:25

Alan Kurlansky

27-Jan-11 5:25

What would be an easy way to encrypt/decrypt userID/password data coming in from potential remote user to a secure server? Phase 2 might include encrypting the subsequent data flow as well.
Any ideas would be appreciated.
Thanks

Re: encryption using VS C/C++

jk chan27-Jan-11 6:10

jk chan

27-Jan-11 6:10

in Windows you can use Crypto APIs. see http://msdn.microsoft.com/en-us/library/aa382016(v=vs.85).aspx[^]

If u can Dream... U can do it

Re: encryption using VS C/C++

Alan Kurlansky28-Jan-11 1:19

Alan Kurlansky

28-Jan-11 1:19

Thanks. I'll check that out.

Re: encryption using VS C/C++

Gene OK14-Feb-11 6:22

Gene OK

14-Feb-11 6:22

I wrote a small WTL application to illustrate the crypto functions. I also transform the encrypted string to a Base64 for transmittal across the internet. Might be of help to you, although a little late.

http://www.codewiz51.com/blog/post/2010/11/16/WTL-application-to-encrypt-a-character-string.aspx[^]

~Gene

-- Life is not a spectator sport. I came to play.
My Web Site, Blog & Wiki

how to close document handle

VCsamir26-Jan-11 18:17

VCsamir

26-Jan-11 18:17

hi friends,

i have have a MDI Application. when i close a document using onclosedocument. my document handle remains active though the members used in document are set to null. so i cannot check this condition
if(doc)
as it returns true. whereas in the if block it cannot access the members so app crashes
eg.
<pre>
if(doc) //handle =FAEX000
{
doc->getprivatevariable_or_functions(); // the application crashes here
}
</pre>

thanking in anticipation

REgards
Samir

Re: how to close document handle

Richard MacCutchan26-Jan-11 22:36

Richard MacCutchan

26-Jan-11 22:36

When you close your document set the variable to NULL to indicate that it no longer exists.

I must get a clever new signature for 2011.

Connections points and clients and really hot chicks

Jim Crafton19-Jan-11 7:42

Jim Crafton

19-Jan-11 7:42

OK, the really hot chicks part was just a joke.

Seriously, I have an ATL COM server that runs as a service. The ATL server is run as a singleton (REGCLS_MULTIPLEUSE). I've got a series of "client" apps (on the same machine) that send the server some data. When the server is shutdown, I want to send an event to the clients. Since I'm using COM I figured I'd use connection points. The server does this with ATL's IConnectionPointContainerImpl, and their proxy class wrapper around the dispatch event interface. I can see that the client properly registers with the server. But when the server tries to call back the client interface, it get's an error, and the client gets an access violation.
Is there some obvious step I've missed? On the client side I'm using ATL's IDispEventImpl to implement the dispatch interface callback.

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Re: Connections points and clients and really hot chicks

cariolihome19-Jan-11 12:32

cariolihome

19-Jan-11 12:32

Add Your code and error description, please

Cocoa or Qt4?

Daniel Stefanovski19-Jan-11 5:14

Daniel Stefanovski

19-Jan-11 5:14

Hi,

I'm slowly getting into GUI Development and made first experiences with C++/Qt4 which I really like.
I focus on OSX Development so I decided to give a try to Xcode and Cocoa too. I tried the first tutorial where u build a simple currency converter. And I'm finding this very confusing. Am I really forced into using this Interface Builder App?

I think that GUI Development with Qt is much better to learn and faster to code and I have a much better overview over my Interface and all those signals, slots, senders and so on if I don't have to use those object inspectors just to check what object is connected to what...

What do you think? Should I give XCode another try or do you share my first impression?

Re: Cocoa or Qt4?

Steve Maier19-Jan-11 5:38

Steve Maier

19-Jan-11 5:38

I was using XCode to do iPhone development and found it to be a challenge as well. What I did is to change to use MonoTouch (.NET) for iPhone development. There actually is a version of Mono that works pretty well on the Mac if you are a .NET programmer. Knowing Obj-C is not a bad thing, but it is not that fast when you are used to other things.

Other people have done their Mac apps with Air or Java. I know Qt is definately faster for most people starting out than Obj-C is. So if you do not want to use Air, Java, or Mono, then I would say Qt will be faster, but having the knowledge of Obj-C is good as well since alot of the sample code out there for a Mac is written in Obj-C.

Steve Maier

How to identify the change in SQL database using MFC

ganesh_IT18-Jan-11 19:53

ganesh_IT

18-Jan-11 19:53

Hi guys, am in a MFC project for that i need to notify my client when any data is updated or inserted in my server database.

I am using CSocket for server client connections, how can i identify the change and how to notify my client that's my problem.I am beginner in MFC .

If you know pls guide me .

Thanks in advance

ganesh_IT

interthread messaging in VS/c/c++

Alan Kurlansky12-Jan-11 11:33

Alan Kurlansky

12-Jan-11 11:33

What's the lightest and easiest way to pass a message from on thread to another? The sender thread must be able to do this asynchronously so there's no to minimal time delay. The receiving thread will retrieve the thread and write it to a file. The goal here is to concentrate the hiccups associated with disk i/o to the one logging thread, so that the other working threads are not hiccup prone. It's okay that the logging thread is hiccup prone since that is all it's responsible for.
Thanks for any help with this.

Re: interthread messaging in VS/c/c++

User 742933812-Jan-11 12:29

User 7429338

12-Jan-11 12:29

Say you have a structure like so, accessible by both threads as a global variable:

typedef struct {
    void *data;
    void *next_block;
}block;

The idea is to have a list of data blocks, each with a pointer to the data to be written to file, and a pointer to the next data block to be written.

The sender thread will do its work, and every time data has been generated, it will allocate a new block and add its address to the next_block member of the previously last block. The next_block member of the newly added block is set to null.

The receiver/writer thread will start at the beginning of the array and continuously check if next_block has been changed from a null-pointer to something else. When it's no longer null, the sender thread must have added data. This new data is written to file and may be free'd in memory. The block struct which data was written before this block's data may also be free'd now.
After this, the check loop on next_block will continue, based on the last written block.

modified 13-Sep-18 21:01pm.

Re: interthread messaging in VS/c/c++

Alan Kurlansky13-Jan-11 3:00

Alan Kurlansky

13-Jan-11 3:00

Thanks, I like this solution. Additionally I'd need to manage shared access with mutexes.

Re: interthread messaging in VS/c/c++

User 742933813-Jan-11 5:00

User 7429338

13-Jan-11 5:00

That shouldn't even be necesary in this case:
If you make sure a block is initialised (data pointer valid, next_block pointer initialised) before it's appended to the list by the sender thread, it can't cause multithreading problems since the actual appending action is just one assignment.

modified 13-Sep-18 21:01pm.

Best way to convert from std::wstring to std::string?

David O'Neil8-Jan-11 8:10

David O'Neil

8-Jan-11 8:10

It has been awhile since I've looked this deeply into things. Is the following a good way to convert from a wstring to a string?

std::string dwl::convertWstrToStdString(const std::wstring & wStr) {
   const std::locale & loc = std::wcout.getloc();
   std::string str;
   str.resize(wStr.size());   //If there are cases where the string takes more characters
                              //than the wstring, we've got a problem.
   std::string::iterator it = str.begin();
   for (std::wstring::const_iterator wit = wStr.begin(); wit != wStr.end(); ++wit) {
      *it = std::use_facet<std::ctype<wchar_t> >(loc).narrow(*wit);
      ++it;
      }
   return str;
   }

Or is the 'str.resize' note (or something else) going to bite in the future? Will the str iterator correctly increment if the character it points to will be a Multi Byte character? Should I just use WideCharToMultiByte() and massage it into a std::string?

Thanks,
David

My website :: The astronomy of our ancestors: Book :: Videos

Re: Best way to convert from std::wstring to std::string? [modified]

David O'Neil8-Jan-11 17:32

David O'Neil

8-Jan-11 17:32

After more searching, I went with the following. CStrWrap is just a thin wrapper around a char array, with a destructor that frees the memory.

std::string dwl::convertWstrToStdString(const std::wstring & wStr) {
   //The following code is modified from the examples at http://msmvps.com/blogs/gdicanio/
   //archive/2010/01/04/conversion-between-unicode-utf-16-and-utf-8-in-c-win32.aspx

   if (wStr == L"" || wStr.size()==0) return "";
   //Now, get the size of the required string:
   int origSize = wStr.size();
   origSize++; //For a NULL terminator
   DWORD conversionFlags = 0;
   //First, get the required size:
   int requiredSize = WideCharToMultiByte(CP_ACP, conversionFlags, wStr.c_str(),
               origSize, NULL, 0, NULL, NULL);
   if (requiredSize == 0)
               throw DwlException(_T("Bad Wide String to String conversion"));
   CStrWrap cStr(requiredSize+1);
   int result = WideCharToMultiByte(CP_ACP, conversionFlags, wStr.c_str(),
               origSize, cStr[0], requiredSize, NULL, NULL);
   if (result==0) throw DwlException(_T("Error converting string"));
   *cStr[result] = '\0';
   return std::string(cStr[0]);
   }

If anyone sees any issues with it, please let me know. Thanks!

EDIT - And for std::string to std::wstring:

std::wstring dwl::convertStdStringToWString(const std::string & str) {
   //This converts a string to a UNICODE string by the method taken on
   //http://www.codeguru.com/forum/archive/index.php/t-231165.html.
   if (str.length() == 0) return L"";
   //Get the required length:
   int unicodeLength = MultiByteToWideChar(CP_ACP, 0, str.c_str(), str.length(), 0, 0);
   ++unicodeLength;  //Add space for a NULL terminator.
   if (unicodeLength == 0) throw DwlException(_T("Empty conversion"));
   MbStrWrap wStr(unicodeLength);
   int result = MultiByteToWideChar(CP_ACP, 0, str.c_str(), str.length(), wStr[0],
               unicodeLength);
   if (result==0) throw DwlException(_T("Error converting string"));
   *wStr[result] = L'\0';
   return std::wstring(wStr[0]);
   }

My website :: The astronomy of our ancestors: Book :: Videos

modified on Sunday, January 9, 2011 1:28 AM

Re: Best way to convert from std::wstring to std::string?

«_Superman_»10-Jan-11 7:42

«_Superman_»

10-Jan-11 7:42

You can easily convert if you use an intermediate class like CString or _bstr_t.

Using CString -

wstring wstr(L"Wide String");
CStringA cstr(wstr.c_str());
string str(cstr);

str = "String";
CStringW wcstr(str.c_str());
wstr = wcstr;

Using _bstr_t;

_bstr_t bstr1(wstr.c_str());
str = (char*)bstr1;

_bstr_t bstr2(str.c_str());
wstr = (wchar_t*)bstr2;

«_Superman_»
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