How to use a region - C / C++ / MFC Discussion Boards

David Crow10-Nov-03 9:12

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?

Re: A pointer to a closed window

Shay Harel10-Nov-03 9:26

Shay Harel

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 !

Re: A pointer to a closed window

Shay Harel10-Nov-03 9:43

Shay Harel

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

Re: A pointer to a closed window

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?

Re: A pointer to a closed window

Shay Harel10-Nov-03 9:04

Shay Harel

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

Re: A pointer to a closed window

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.

Re: A pointer to a closed window

Shay Harel11-Nov-03 3:21

Shay Harel

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

Re: using messagebox....

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 ) ;

Re: using messagebox....

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

Re: using messagebox....

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 ) ;

Re: using messagebox....

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.

Re: using messagebox....

jmkhael10-Nov-03 7:34

jmkhael

10-Nov-03 7:34

did MB_SERVICE_NOTIFICATION_NT3X work?

Papa

while (TRUE)
Papa.WillLove ( Bebe ) ;

Re: using messagebox....

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

Re: using messagebox....

Shay Harel10-Nov-03 8:15

Shay Harel

10-Nov-03 8:15

What are you trying to do, just to pop a messagebox ?

Re: using messagebox....

David Crow10-Nov-03 9:06

David Crow

10-Nov-03 9:06

You need #define _WIN32_WINNT 0x0400 in the stdafx.h file, above any #include statement.

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

Re: using messagebox....

ricolee0010-Nov-03 10:01

ricolee00

10-Nov-03 10:01

oh, thank you very much!

i thought i was going to be stuck forever with that error!

just wondering, if the app. i'm building should be compatible with any nt version, should i use
0x0300 instead of 0x0400?

THanks

Rico

missing menu on windows 98

Anonymous10-Nov-03 6:29

Anonymous

10-Nov-03 6:29

Hey ,I've a dialog based application with a menu (menu bar). It works very well on windows 2000 Professional and Windows XP. But when I open it on Windows 98, there is no menu bar. Instead of the menu you can see a part of the desktop.

What can I do?

I work with Visual Studio 6.0 and I create the menu with the Ressource -Editor. To include the ressource I use this code:

CMenu menu;
menu.LoadMenu(IDR_MAINFRAME);
ASSERT(menu);
SetMenu(&menu);

Thnak's

Beppo

Re: missing menu on windows 98

David Crow10-Nov-03 6:59

David Crow

10-Nov-03 6:59

Just a guess, but it sounds like Internet Explorer (the Common Control DLL, actually) is not up-to-date on the Windows 98 machine.

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

Re: missing menu on windows 98

Roger Allen11-Nov-03 0:47

Roger Allen

11-Nov-03 0:47

Your CMenu object is local, so it will delete its HMENU object in its destructor when it goes out of scope, this could mean that your window has an invalid HMENU selected.

CMenu menu;
menu.LoadMenu(IDR_MAINFRAME);
ASSERT(menu);
SetMenu(&menu);
menu.Detach(); // stop menu being destroyed in destructor

Roger Allen
Sonork 100.10016

Death come early, death come late,
It takes us all, there is no reason.
For every purpose under heaven,
To each a turn, to each a season.
A time to weep and a time to sigh,
A time to laugh and a time to cry,
A time to be born and a time to die.
Dust to dust and ashes to ashes,
And so I end my song.

Re: missing menu on windows 98

Anonymous12-Nov-03 7:22

Anonymous

12-Nov-03 7:22

Thanks Roger, now it works Smile | :)

IExtractImage::GetLocation() brings up a "Thumbnail could not be created" message-box

ohadp10-Nov-03 5:31

ohadp

10-Nov-03 5:31

This happens for shortcuts to web-pages that can't be reached or something in that area.

My program can't have this message-box popup when a thumbnail cannot be fetched, what can i do about it ?

thank you

Help!!!---ATL COM Full Control can't cooperate with MFC?

Dev-xiang10-Nov-03 5:30

Dev-xiang

10-Nov-03 5:30

I'm developping programs on wince using evc3.0

I made a new project using WCE ATL COM AppWizard with MFC support.I got no compile errors when i create a simple object.But when i create a full control or lite control,i got compile errors like this:
......error C2504: 'IBindStatusCallback' : base class undefined
......error C2061: syntax error : identifier 'IBinding'
......

the same project under vc6.0 i got no problem.I knew there are many limitations in evc.Does my problem stands for "mfc and atl won't cooperate with each other under wce?"

i have struggled on this problem for one day. i'm too tired now.
But i need to use CInternetSession class(MFC class) in my ATL COM Control(full control) project. Anybody can give me a hand?
Thanks a lot!

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