C / C++ / MFC

What is Callback Function?

3-Jun-03 13:07

Thank's Dean

-Rocky Smile | :)

Anonymous3-Jun-03 10:43

Re: What is Callback Function?

3-Jun-03 10:43

Just wondering if someone can point to any tutorial onCallback Functions
with some good examples

act_x3-Jun-03 12:41

act_x

3-Jun-03 12:41

It is a mechanism by which you can call another static function by using its function pointer . Very useful when u do a layered class architecture . U could pass data from one class to another and provide filtering too.

Re: What is Callback Function?

ucs3-Jun-03 12:43

ucs

3-Jun-03 12:43

http://www.codeproject.com/cpp/callbacks.asp?target=callback%7Cmfc

How to make a dynamic modal dialog.

Wormhole52303-Jun-03 10:02

Wormhole5230

3-Jun-03 10:02

Dynamic dialog is a dialog of which controls
can be created or removed manually depends on the situation.

It is easy to make a dynamic modaless dialog as follows.

////////////////
CDialog *menu;

menu = new CDialog;
menu->Create(IDD_MY_BLANK_DIALOG, this);

// add a edit control if IsEdit is true
if(IsEdit) {
CEdit* pEdit = new CEdit();
RECT rctEdit = {5, 5, 100, 30};
pEdit->Create(WS_VISIBLE | WS_CHILD | WS_TABSTOP, rctEdit,
FromHandle(menu->m_hWnd), 1100);
}

// add a button control if IsBtn is true
if(IsBtn) {
CButton* pButton = new CButton();
RECT rctButton = {5, 35, 100, 60};
pButton->Create(_T("Button"), WS_VISIBLE | WS_CHILD | WS_TABSTOP, rctButton,
FromHandle(menu->m_hWnd), 1101);
}

menu->ShowWindow(SW_SHOW);
///////////////

But I want to make a dynamic modal dialog.
I heard about the InitModalIndirect function but it is somewhat complex to use.
I want a compact code.
Is there any simple method like an above code?

Thanks.

Joan M3-Jun-03 22:44

Joan M

3-Jun-03 22:44

well...

When you call the DoModal function you must have the dialog created, then just before to call DoModal, you can add all the controls you want...

Hope this helps...

Wormhole52303-Jun-03 23:00

Wormhole5230

3-Jun-03 23:00

That's exactly what I want.
But the question is how to implement it?
I tried many ways, but I failed because of lack of knowledge about creating controls
in blank dialog.

Could you show me an example which is really working?

The important thing is that it should be a modal dialog.

Thanks.

Joan M3-Jun-03 23:17

Joan M

3-Jun-03 23:17

In order to create dynamically a combobox, you should do this:

<br />
CRect r;<br />
<br />
if (this->m_ccbParametritzacio.GetSafeHwnd() == NULL)<br />
{<br />
	this->m_ccbParametritzacio.Create(WS_CHILD | WS_VSCROLL | WS_HSCROLL | CBS_DROPDOWNLIST,																			r,																			this,																			UNIQUE_ID);<br />
<br />
	this->m_ccbParametritzacio.SetFont(this->GetFont());<br />
}

NOTE0:
you should change "this->" for the parent dialog... (this is only supposed I've not tried it)

NOTE1:
there was an article referring on this topic here in CP or in codeguru (I don't remember exactly...)

NOTE2:
I recommend you to use a derived listctrl with buttons, comboboxes, editboxes... in order to do what you are searching for because this control is extendable and if there are lots of controls to be created dynamically you'll be able to go through them using the implemented scrollbars, and moreover you'll avoid to recalculate the place where to put the control and where to put the text referred to the same control...

Hope this helps...

CImage::StretchBlt does not work!?

Wormhole52304-Jun-03 22:35

Wormhole5230

4-Jun-03 22:35

Actually, I had found an article exactly matched to this topic before I post
my first question. In that article, one can use similar method like dynamic
modaless dialog to make a dynamic modal dialog by including supplied codes.
Spending many times, I was finding other method
to do that without the code.

I decided to use that code and now it works well.

If you have interests in this article,
please refer this.

http://www.codeproject.com/dialog/dynamicdialog.asp?target=dynamic%7Cdialog%7Cmodal

schaereran@gmx.net3-Jun-03 9:36

schaereran@gmx.net

3-Jun-03 9:36

I have a problem with the CImage::StretchBlt Function! I made a little application, based on the "SimpleImage" -Sample Application from Microsoft.
I tryed to stretch a picture to the screen (dynamic..)
in the OnPaint() Function i have the following line:

m_imgOriginal.StretchBlt(dc,0,0,m_imgOriginal.GetWidth()*dFactor, m_imgOriginal.GetHeight()*dFactor, SRCCOPY);

dFactor is a Factor, calculated earlier.

so the problem is, when dFactor is higher than 1 everithing looks fine, the picture is stretched properly. but when the factor is below 1, the picture looks very poor and distorted! is there a sloution to the problem?
is it possible to make a CImage-Picture smaller at all without distorting it??

thanx for any input!!

Re: CImage::StretchBlt does not work!?

RaajaOfSelf4-Jun-03 19:10

RaajaOfSelf

4-Jun-03 19:10

Try doing this ,

SetStretchBltMode(destDC,HALFTONE);

where destDC is teh destination DC

Re: CImage::StretchBlt does not work!?

schaereran@gmx.net5-Jun-03 0:36

schaereran@gmx.net

5-Jun-03 0:36

very cool! now it works! thanx a lot!

How do i create a random number?

Redeemer-dk3-Jun-03 9:36

Redeemer-dk

3-Jun-03 9:36

Is there a function for retreiving a random integer lying in the range from one integer to another? I'm using Win32...

THanks in advance.

C^hris L^osinger3-Jun-03 9:53

C^hris L^osinger

3-Jun-03 9:53

see rand() and srand(..)

srand(-1);
int v = (rand() % (low + high)) + low;

To vote with no response is to follow the way of the coward.

Dean Goodman3-Jun-03 11:38

Dean Goodman

3-Jun-03 11:38

Check out this page -- shows a better way to get your random numbers. When you use modular arithmetic, you focus on the low-order bits that aren't as "random" as the high-order ones.

The page shows many examples of how to get a random number (int or floating point) in a given range.

--Dean

David Crow3-Jun-03 10:21

David Crow

3-Jun-03 10:21

No, but you can get a pseudo-random number with srand() and rand().

RedZenBird3-Jun-03 10:49

RedZenBird

3-Jun-03 10:49

See article by:

Stephen K. Park and Keith W. Miller.
RANDOM NUMBER GENERATORS: GOOD ONES ARE HARD TO FIND.
Communications of the ACM, New York, NY.,October 1988 p.1192

Just trying to keep the forces of entropy at bay

EnableMenuItem does not work

Anders Molin3-Jun-03 12:14

Anders Molin

3-Jun-03 12:14

#define GetRandom(min, max) ((rand() % (int)(((max) + 1) - (min))) + (min)) //get a random number between min and max

Remember something like srand(GetTickCount()); first...

- Anders

Money talks, but all mine ever says is "Goodbye!"

Shay Harel3-Jun-03 9:25

Shay Harel

3-Jun-03 9:25

I have an application with a menu that I want to disable one command in it.

I write:

<br />
CMenu *pmenu;<br />
pmenu=CMaimFrame::GetMenu();<br />
pMenu->EnableMenuItem (ID_FILE_OPEN,MF_BYCOMMAND|MF_GRAYED);<br />

But the item will not go gray !!!

Shay

Re: EnableMenuItem does not work

valikac3-Jun-03 9:34

valikac

3-Jun-03 9:34

Include MF_DISABLED. See if that does it.

EnableMenuItem (ID_FILE_OPEN, MF_BYPOSITION|MF_DISABLED|MF_GRAYED)

Kuphryn

Re: EnableMenuItem does not work

Shay Harel3-Jun-03 9:48

Shay Harel

3-Jun-03 9:48

Not working.
I have a strange feeling that it's not pointing to my menu,
If I type

<br />
CMeny *pmenu=GetMenu();<br />
pmenu->DestroyMenu();<br />

Nothing happened .....

Re: EnableMenuItem does not work

Mike Upton4-Jun-03 0:22

Mike Upton

4-Jun-03 0:22

Since you're using an MFC app, you should probably be using command update handlers to deal with enabling/disabling menu items.

See Mike Dunn's C++ FAQ section 7.1[^] for more information.

"We are the knights who say Ni" _{(The Knights Who Say Ni)}

activex including a dll/lib

Anonymous3-Jun-03 9:10

3-Jun-03 9:10

Hi all

I am trying to create an activeX control which includes a dll.

At the linking stage of compilation, it gives a dllmain already defined.

exact error is:
Linking...
mfcs42.lib(dllmodul.obj) : error LNK2005: _DllMain@12 already defined in MSVCRT.lib(dllmain.obj)
mfcs42.lib(dllmodul.obj) : warning LNK4006: _DllMain@12 already defined in MSVCRT.lib(dllmain.obj); second definition ignored
Creating library Release/ShpEditAFX.lib and object Release/ShpEditAFX.exp
Release/ShpEditAFX.ocx : fatal error LNK1169: one or more multiply defined symbols found

Can anyone help me with it please? I appreciate your help.

Thanks
Yogi

Event like CEvent

act_x3-Jun-03 8:52

act_x

3-Jun-03 8:52

Hi
I needed the functionality for the CEvent object in MFC . I am working in a non MFC environment and needed a similar synchronization object.
Basically I want to have a request , Wait and response type of mechanism .

I want to be able to use the WaitforSingleObject call to wait for a duration on a event object .

How do I go about it. Is there a non MFC event class or object available ?

Re: Event like CEvent

Anonymous3-Jun-03 9:14