C / C++ / MFC Discussion Boards

Re: Something about TAPI -- call picked up ?

manio19-Feb-02 22:12

manio

19-Feb-02 22:12

Thanks ! Your response really helps !! Smile | :)

Re: Something about TAPI -- call picked up ?

Michael P Butler20-Feb-02 0:08

Michael P Butler

20-Feb-02 0:08

A lot depends on the capabilities of your modem. Most modems send a Connected Call State as soon as they connect and the other end starts ringing, not when the person answers at the other end.

Michael Smile | :)

Developing Custom Exception Handler :: C++

valikac19-Feb-02 19:57

valikac

19-Feb-02 19:57

Hi.

I would like to create a custom class exception handler. I want to use it for arbitrary exceptions that are not part of the exception library.

I am having a problem with such a class. Here is the code for that exception class.

-----
#ifndef CEXCEPTIONHANDLE_H
#define CEXCEPTIONHANDLE_H

class ExceptionHandle
{
public:
ExceptionHandle(const char *error) : eMessage(error) {}
const char *what() const throw()
{
return eMessage;
}

private:
const char *eMessage;
};

#endif
-----

I basic want to *throw* a character string to the exception handle. Afterward, have a catch function to call what().

Here is an example of a try/catch.

----
try
{
function(x);
}

catch (ExceptionHandle *e)
{
cerr << e->what();
}
-----
function(int X)
{
if (X == 0)
throw ExceptionHandle("Error: X equals zero.");
}
-----

The program I am working on works, but it crashes whenever "throw ExceptionHandle("Error: X equals zero.");" occurs.

Does anyone know what is wrong with my design and/or implementation?

Thanks,
Kuphryn

Re: Developing Custom Exception Handler :: C++

Derek Waters19-Feb-02 20:22

Derek Waters

19-Feb-02 20:22

I'm just guessing here, but a simple problem is the fact that you're storing a const char pointer in your exception class.

Regardless of the throw/catch stuff, when you call the exception constructor with the static text, all you're doing is setting your char * to point to the start of the "Error: X equals..." stuff. As soon as that goes out of scope, the memory allocated to the string is destroyed, and your const char * in the exception class will point at garbage.

Instead, either create a new char buffer and copy the string into it, or use a CString instead (it will keep a copy of the string for later use):

class ExceptionHandle 
{ 
public: 
  ExceptionHandle(const char *error) : eMessage(error) {} 
  const char *what()
  { 
    return (LPCTSTR)eMessage; 
  } 

private: 
  CString eMessage; 
};

------------------------
Derek Waters
derek@lj-oz.com

Re: Developing Custom Exception Handler :: C++

valikac19-Feb-02 20:44

valikac

19-Feb-02 20:44

Okay. Thanks.

Oluseyi mentioned something about added "const throw()" to the constructor and derived it from exception.

I will try that and use a string instead of char * tomorrow.

I will post an update.

Kuphryn

Re: Developing Custom Exception Handler :: C++

Joaquín M López Muñoz19-Feb-02 20:53

Joaquín M López Muñoz

19-Feb-02 20:53

Although the objection posed by Derek is IMHO a valid one, it is not what is causing the problem in your particular example. function throws an ExceptionHandle, whereas the catch block accepts a pointer to ExceptionHandle: thus it is not catching the exception thrown by function. Replace the exception handler with

catch (ExceptionHandle& e) 
{ 
cerr << e.what(); 
}

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: Developing Custom Exception Handler :: C++

valikac20-Feb-02 4:11

valikac

20-Feb-02 4:11

Okay. Thanks.

I believe the problem was due to these pointer related calls:

-----
const char *eMessage
-----

and/or

-----
catch (ExceptionHandle *e)
-----

I will do two things.

1) I will replace "const char *eMessage" with "const string eMessage."
2) I will replace "catch (ExceptionHandle *e)" with "catch (ExceptionHandle &e)."

First, is the problem caused by "*e" pointing to something that no longer exists? How can that be if I am throwing an exception each time?

I can also add "new" to "throw...new."

-----
throw new ExceptionHandle("test");
-----

Which ones of these changes should *fix* the problem most elegantly?

Thanks,
Kuphryn

P.S. A member at Gamedev mentioned about deriving exception classes from the *exception* library. How important is that?

CFile::Duplicate

Le centriste19-Feb-02 14:43

Le centriste

19-Feb-02 14:43

In my MFC MDI App, I need to keep the pointer to the CFile object from CArchive in CMyDocument::Serialize (my override). This pointer must point to a valid object after the exit from Serialize, hence the use of a member variable to hold the CFile * returned from CArchive::GetFile()->Duplicate().

My question is: when my CMyDocument object is destroyed, what do I do with the CFile * I hold in my class.

Logically, I would flush the file and close it. closing it poses no problem, but the flush throws an exception. What do I do with the pointer? Do I call
delete on it?

Is there a more elegant way doing this?

Tx

Michel

Re: CFile::Duplicate

Nish Nishant19-Feb-02 15:53

Nish Nishant

19-Feb-02 15:53

Michou wrote:
My question is: when my CMyDocument object is destroyed, what do I do with the CFile * I hold in my class.

Don't do anything. The CFile object gets destroyed along with the CArchive object. What you have is a duplicarte pointer. Internally it uses _dup I believe, to get an additional handle.

Nish

CPUA # 0x0666

Sonork ID 100.9786 voidmain
www.busterboy.org

AppWizard

blink4me19-Feb-02 13:50

blink4me

19-Feb-02 13:50

Hi,

I would like to know if anyone knows a good link to an article or a tutorial that would explain how to create an AppWizard.

// JS Paquet
cout << "Thank you all" << endl;

Re: AppWizard

Matt Newman19-Feb-02 15:24

Matt Newman

19-Feb-02 15:24

I think the MSDN cd kit that came with VC 6 had an example appwizard.

- Suspicious | :suss:

Matt Newman Suspicious | :suss:

-Sonork ID: 100.11179:BestSnowman
Frankly AOL should stick to what it does best: Fooling millions of americans into believing that it, AOL, is the web. -Paul Watson

ActiveX "shim" for a Netscape plugin

David Ness19-Feb-02 11:16

David Ness

19-Feb-02 11:16

I want to write an ActiveX shim for a Netscape-style plugin; however, I cannot locate the plugin code Smile | :)

Plugins apparently do not contain a type library so #import doesn't work. Can anyone with some experience accessing a plugin dll from C++ give me a tip as to how to accomplish this or point me to some documentation?

David Ness

CWnd dynamic creation and deletion problem

yellowine19-Feb-02 10:45

yellowine

19-Feb-02 10:45

I want to create, show, and delete various CWnd or CWnd derived Windows:

<br />
void MyFoo(CRuntimeClass *pWndClass,...)<br />
{<br />
<br />
  CWnd* pWnd = pWndClass->CreateObject();<br />
  pWnd->Create(..);   // Create the Window associated with pWnd;<br />
                      // The actual Create will be based on the type of Window<br />
  ...<br />
  pWnd->ShowWindow(SW_SHOW);<br />
  ...<br />
  pWnd->DestroyWindow();   //Destroy the Window<br />
  delete (pWnd)            // Delete the CWnd or CWnd derived object<br />
}<br />

pWnd can be any type of windows (e.r., CDialog, CFormView, CView,...). The problem is: if pWnd is a dialog or CDialog-derived object, it works ok. But if pWnd is derived from CView or CWnd but not from CDialog, the delete statement in the above function doesn't work with an error message as access denied (0xc0000005). So why doing that?

//

Re: CWnd dynamic creation and deletion problem

Nish Nishant19-Feb-02 15:56

Nish Nishant

19-Feb-02 15:56

CView objects delete themselves using a delete this

So you should not delete CView and CView derived classes.

I am confused about your CWnd problem though.

Nish

CPUA # 0x0666

Sonork ID 100.9786 voidmain
www.busterboy.org

Re: CWnd dynamic creation and deletion problem

yellowine20-Feb-02 4:22

yellowine

20-Feb-02 4:22

Do you mean that every CView type class dynamically created should be deleted by itself within its class?

In my original example, the pWnd has a valid memory address, but the members of pWnd are not "valid", e.g., pWnd->hWnd = 0xddddddddd. I don't know how comes that.

changing CView styles

19-Feb-02 10:45

Hi,

could you please answer a simple question:
my view shows initially grayed (not active) vertical and horizontal scrollbars, and I only want the first one.

I tried

BOOL CMyEditView::PreCreateWindow(CREATESTRUCT& cs) 
{
	cs.style &= ~WS_HSCROLL;

	return CEditView::PreCreateWindow(cs);
}

but the horizontal scrollbars stayed.

How can I get rid of them?

Thanks

R.

Re: changing CView styles

Joaquín M López Muñoz19-Feb-02 10:58

Joaquín M López Muñoz

19-Feb-02 10:58

This is just a guess, but have you tried reversing the order of the lines?

BOOL CMyEditView::PreCreateWindow(CREATESTRUCT& cs) 
{
	if(!CEditView::PreCreateWindow(cs))return FALSE;
	cs.style &= ~WS_HSCROLL;
	return TRUE;
}

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: changing CView styles

19-Feb-02 11:32

Perfect!
Thank you!

R.

An icon recieving a file

Optic19-Feb-02 10:10

Optic

19-Feb-02 10:10

Hi there,

I want to write a system tray icon that will recieve a file and then store that file in a specific directory.

I have written system tray icon classes before but I have never done any drag drop type stuff. Can anyone tell me where to start looking? I am not sure of the technologies/APIs/functions that I have to use.

Cheers in advance

Optic

A bit miffed about the doc/view architecture...

funbag19-Feb-02 10:10

funbag

19-Feb-02 10:10

Hi there,
Please forgive my ignorance, I'm a little new to MFC.

I wish to create an MDI program that uses the CHTMLEditView, to create HTML documents. When the document has been created, and the user wishes to save the document, instead of saving the file out to the file system, I'd like to write it out to a database.

I've thought that the way to go about this is to override the view's ID_FILE_SAVE and ID_FILE_SAVE_AS events.

Given that an HTML document is media rich, into what type of variable would I read the document contents?

I'm assuming that once read, the document content can be written to the database as a BLOB?

Thanx for any input!

skydiving....if at first you don't succeed, you're fecked!

Re: A bit miffed about the doc/view architecture...

Michael P Butler19-Feb-02 10:33

Michael P Butler

19-Feb-02 10:33

The HTML portion of the document can be saved in a string because HTML is basically an overblown text file. Any images or media that the document references will have to be parsed for and then the elements found be stored as a BLOB.

Michael Smile | :)

Loading a resource bitmap in GDI+ ?

19-Feb-02 9:40

Hi,

I can't laod a bitmap which is a resource in my exe. To just test a simple image loading, I also tried the MSDN sample:

HICON hIcon = LoadIcon(NULL, IDI_APPLICATION);
Bitmap bitmap(hIcon);

It can't load the icon (hIcon is correct).
bitmap.lastResult = InvalidParameter !!

I have the latest platform SDK update and I call GdiplusStartup() correctly.

Thanks a lot for your help.

Nicolas

Re: Loading a resource bitmap in GDI+ ?

Jay Beckert19-Feb-02 10:24

Jay Beckert

19-Feb-02 10:24

Hello Nicolas!
I just had the same question about bitmap and icon resources the other day. Try this, you need to include the MAKEINTRESOURCEW macro:

HICON hIcon = LoadIcon(NULL, MAKEINTRESOURCEW(IDI_APPLICATION));

Straight from the SDK documentation:

Pointer to a null-terminated string that contains the name of the icon resource to be loaded.

^^^^^ That is what confused me. If your loading the icon from file then use the pointer to a string identifying the icon.

Alternatively, this parameter can contain the resource identifier in the low-order word and zero in the high-order word. Use the MAKEINTRESOURCE macro to create this value.

^^^^ This is what you need.

Cheers.
Jay Beckert

Re: Loading a resource bitmap in GDI+ ?

19-Feb-02 11:59

Good try

But I had already tried that and it doesn't work more. I can only load bitmaps from external files but it never works for resources event with MAKEINTRESOURCEW>

Nicolas

Re: Loading a resource bitmap in GDI+ ?

Jay Beckert19-Feb-02 17:02

Jay Beckert

19-Feb-02 17:02

Sorry Nicolas,
Is the icon a resource of your application or are you trying to load one of the default icons? If the icon is a resource of your app then you need to pass the instance of your app instead of NULL. If its one of the default icons then you pass NULL as the first parameter. I would still use the MAKEINTRESOURCE macro.

Second, I didn't realize your Bitmap was for GDI+ and just realized what your missing. GDI+ is a bit different with respect to GDI. I still confuse the two. I would try this,

HICON hIcon = LoadIcon(NULL, MAKEINTRESOURCE(IDI_APPLICATION));
Bitmap* bitmap;
bitmap = Bitmap::FromHICON(hIcon);//This is where you went wrong

Then use your graphics object to display your bitmap.
For some reason you just can't call a function alone from any GDI+ class without referencing the class it's from. ie. Bitmap::FromHICON(hIcon). Off the top of my head I can't remember why that is.

This should work if the icon is a resource of your application

HICON hIcon = LoadIcon(AfxGetApp()->m_hInstance, MAKEINTRESOURCE(ID_ICONRESOURCE));
Bitmap* bitmap;
bitmap = Bitmap::FromHICON(hIcon);

Then use a graphics object to display your bitmap.

Let me know what happens. Smile | :)

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