C / C++ / MFC

10-Nov-03 7:39

Hi,

I pop up a window with my application, using:

<br />
<br />
//pTaskViewSplitFrame is a member variable of type CTaskViewSplitFrame *;<br />
<br />
CRuntimeClass* pRuntimeClass = RUNTIME_CLASS( CTaskViewSplitFrame );<br />
CObject* pObject = pRuntimeClass->CreateObject();<br />
pTaskViewSplitFrame = (CTaskViewSplitFrame *)(pObject);<br />
pTaskViewSplitFrame->LoadFrame(IDR_TASK_VIEW_SPLIT_FRAME,WS_OVERLAPPEDWINDOW | FWS_ADDTOTITLE, pParent,NULL);<br />
pTaskViewSplitFrame->ShowWindow(SW_SHOWNORMAL);<br />

Everything works fine but if at the end of my application I want to close this window I will probably use delete or pTaskViewSplitFrame->CloseWindow and the window is already closed by the user I will get an exception.

The problem is that the pointer is not really NULL but 0xdddd or something like that so I can't verify it...

Any solution ?

Shay

Nitron10-Nov-03 8:04

Nitron

10-Nov-03 8:04

what about putting delete this; in the dtor?

- Nitron

"Those that say a task is impossible shouldn't interrupt the ones who are doing it." - Chinese Proverb

Shay Harel10-Nov-03 8:07

10-Nov-03 8:07

If I put delete this is the destructor, it will fail since PostNCDestroy does it by default.

the problem is not deleting the window, the problem is how to know weather the window deleted itself (after the user closed it) or weather it's open...

If I try pWindow->IsWindowOpen() but pWindow is already deleted, I am dead in the water....

Shay

David Crow10-Nov-03 9:12

David Crow

10-Nov-03 9:12

Shay Harel wrote:
If I try pWindow->IsWindowOpen() but pWindow is already deleted, I am dead in the water....

Will this work:

if (NULL != pWindow)
{
    if (pWindow->IsWindowOpen())
        ...
}

This ensures that a NULL pointer is not dereferenced.

Five birds are sitting on a fence.
Three of them decide to fly off.
How many are left?

Shay Harel10-Nov-03 9:26

10-Nov-03 9:26

The problem is that when the user close the window for me, pWindow is not turning to NULL (0x000000) it may turn to 0xddddd or anything else....

ha !

Shay Harel10-Nov-03 9:43

10-Nov-03 9:43

Well, After I thought about it again, I saw what you mean..
And it actually worked (The NULL as the first operand)

Thanks

David Crow10-Nov-03 8:58

David Crow

10-Nov-03 8:58

Shay Harel wrote:
The problem is that the pointer is not really NULL but 0xdddd...

Which indicates freed memory. However, that value is subject to change.

Five birds are sitting on a fence.
Three of them decide to fly off.
How many are left?

Shay Harel10-Nov-03 9:04

10-Nov-03 9:04

Well,

I can't count on it to be always 0xddddd... this is unprofessional.
I am sure my problem is less complecated that I described it.

Basicall, if I pop up a window with a pointer and go on, how do I check if this window is either open/close/destroyed ?

Shay

Antti Keskinen11-Nov-03 0:43

Antti Keskinen

11-Nov-03 0:43

I take it you have a derived CWnd or CSplitterWnd class you are using. How about overriding the default handlers so, that each of them sets a boolean before calling the base class ?

<span style='cpp-keyword'>class</span> CMyDerivedWnd : <span style='cpp-keyword'>public</span> CWnd
{
    ...
    RESULT Create(PARAMS) 
    { 
        <span style='cpp-keyword'>this</span>->bIsCreated = TRUE; 

        <span style='cpp-keyword'>return</span> CWnd::Create(PARAMS);
    }
    ...

<span style='cpp-keyword'>private</span>:
    BOOL bIsCreated;
    BOOL bIsOpen;
    BOOL bIsDestroyed;
}

This, of course, assumes that you've marked the base class as virtual. I am unsure whether the original Create functions are virtual in the CWnd class (why wouldn't they be ? Ask MS)..

-Antti Keskinen

----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.

Shay Harel11-Nov-03 3:21

11-Nov-03 3:21

Thank you but I found another way to do it:
Shay Harel wrote:
If I try pWindow->IsWindowOpen() but pWindow is already deleted, I am dead in the water....

Will this work:

if (NULL != pWindow){ if (pWindow->IsWindowOpen()) ...}

This ensures that a NULL pointer is not dereferenced.

How to use a region

Eugene Pustovoyt10-Nov-03 7:29

Eugene Pustovoyt

10-Nov-03 7:29

My application contains skins which changed by user. Procedure of change occurs as follows:

::OnChangeSkin()
{
    //Delete previously skin
    if (NULL != m_rgnWindow)
    {
        ::DeleteObject(m_rgnWindow); //Error for second skin
        m_rgnWindow = NULL;
    }
    //Gets new skin
    m_rgnWindow = GetRegionFromFile(...);
    SetWindowRgn(m_rgnWindow, TRUE);
}

For any paint to call a following method

::OnDisplayWindow()
{
    ...
    ::FrameRgn(hMemDC, m_rgnWindow, hBrush, 1, 1); //Error
    ...
    ::SelectClipRgn(hMemDC, m_rgnWindow); //Error
    ::BitBlt();
    ::SelectClipRgn(hMemDC, NULL);
    ...
}

In the places specified as "//Error" BoundsChecker finds out a mistake

In what a mistake?

Best regards,
Eugene Pustovoyt

Re: How to use a region

JWood10-Nov-03 16:01

JWood

10-Nov-03 16:01

I had this same problem with CPen - I think it applies to any GDIObject. The object doesn't seem to be completely destroyed. In addition, you should be careful to separate the freeing of resources verses the actual deletion of the object, although Microsoft tries to make them the same with the questionable practice of self deleting functions. I can't be more helpful without seeing more code.

J.
----------------------------

using messagebox....

Member 210374010-Nov-03 7:05

Member 2103740

10-Nov-03 7:05

Hi Everyone,

I'm having problems using messagebox

There is a parameter defined with messagebox, called MB_SERVICE_NOTIFICATION.

I use this parameter in my code:

MessageBox(NULL, "some text", "error", MB_SETFOREGROUND + MB_SERVICE_NOTIFICATION);

But i'm getting a compiler error, MB_SERVICE_NOTIFICATION : Undeclared identifier.

I went on the msdn that describes using messagebox, and it says that i should define _WIN32_WINNT.

So i did, and my preprocessor definition looks like: #define _WIN32_WINNT = 0x0400

I'm still getting the undeclared identifier error message, can someone please help me??? i'm looking at this problem for several hours without any luck.

Thank you in advance

Rico

jmkhael10-Nov-03 7:14

jmkhael

10-Nov-03 7:14

just
#define _WIN32_WINNT 0x0400

You can find in winuser.h in the include
#ifdef _WIN32_WINNT
#if (_WIN32_WINNT >= 0x0400)
#define MB_SERVICE_NOTIFICATION 0x00200000L
#else
#define MB_SERVICE_NOTIFICATION 0x00040000L
#endif
#define MB_SERVICE_NOTIFICATION_NT3X 0x00040000L
#endif

Papa

while (TRUE)
Papa.WillLove ( Bebe ) ;

ricolee0310-Nov-03 7:18

ricolee03

10-Nov-03 7:18

Thanks for your response,

I already have winuser.h and windows.h defined in the preprocessor definitions.

I also have the code: #define _WIN32_WINNT 0x0400 defined in the preprocessor definitions.

i'm not sure what you're suggesting in your response, can you please clarify?

Thank you

Rico

jmkhael10-Nov-03 7:23

jmkhael

10-Nov-03 7:23

Then make sure
NOUSER and NOMB are not defined.

if MB_SERVICE_NOTIFICATION_NT3X works then you have a problem defining or undefining these constants

Papa

while (TRUE)
Papa.WillLove ( Bebe ) ;

ricolee0010-Nov-03 7:32

ricolee00

10-Nov-03 7:32

Hi there,

i don't have nouser and nomb defined anywhere.

the error happens during compilation. i'm still confused as to what i'm doing wrong Frown | :(

Thanks for your responses.

jmkhael10-Nov-03 7:34

jmkhael

10-Nov-03 7:34

did MB_SERVICE_NOTIFICATION_NT3X work?

Papa

while (TRUE)
Papa.WillLove ( Bebe ) ;

ricolee0010-Nov-03 7:38

ricolee00

10-Nov-03 7:38

Hi Papa

replacing MB_SERVICE_NOTIFICATION with MB_SERVICE_NOTIFICATION_NT3X still does not work.

I have the #define _WIN32_WINNT 0x0400 declared

also, changed it to #define _WIN32_WINNT 0x0300 and it still doesn't work.

The error message that I'm recieving is the same, undeclared identifier.

Rico

Shay Harel10-Nov-03 8:15