Re: Message Queues for MFC windows classes - C / C++ / MFC Discussion Boards

Re: What is the difference among the OnClose(),OnDestroy() and the DestroyWindow()?

Ali Tavakol28-Sep-08 4:47

28-Sep-08 4:47

WM_DESTROY is sent as a result of calling DestroyWindow.

WM_CLOSE is sent to you to close the window. but you may close it or not. it's just a request. you can accept the request by calling the parent class's OnClose().

WM_DESTROY is sent when the window is about to be destroyed even if you don't like to close it. It will be closed anyway and then the class destructor will be called.

Re: What is the difference among the OnClose(),OnDestroy() and the DestroyWindow()?

Michael Dunn28-Sep-08 12:34

Michael Dunn

28-Sep-08 12:34

WM_CLOSE is sent when you click the close button (or hit Alt+F4 or close the window some other way). Normally, you would do some cleanup and then call DestroyWindow(). If you let DefWindowProc handle WM_CLOSE, it will call DestroyWindow() for you. WM_DESTROY notifies you that the window is being destroyed.

--Mike--
Visual C++ MVP Cool | :cool:

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reading text file

nomi khan27-Sep-08 12:55

nomi khan

27-Sep-08 12:55

Im new in C++. I want to read a text file in my Win32 Console Application of C++.net 2005, how can i do it? Kindly tell me in .net 2005 unmanaged code plz.

nOmI

Re: reading text file

David Crow27-Sep-08 16:40

David Crow

27-Sep-08 16:40

Check out CreateFile() and <codereadfile()>. C++ also has stream classes like ifstream.

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

Re: reading text file

Hamid_RT29-Sep-08 7:31

Hamid_RT

29-Sep-08 7:31

I dont see this[^] article but I think it has some helpful info for you. Smile | :)

Message Queues for MFC windows classes

sawerr27-Sep-08 7:51

sawerr

27-Sep-08 7:51

Hi
We know that Windows keeps a message queue for every thread.
If i am not wrong for win32 applications, only one message loop is enough.

But in MFC applications, we have Message Map macros(DECLARE_MESSAGE_MAP/BEGIN_MESSAGE_MAP/END_MESSAGE_MAP) for every window class. Mainfrm, chidfrm, childview, doc etc..

Do all of the message map macros that we see in the source code indicate there is a message loop that buried in MFC source code?

I couldn't make relation between win32 message handling and MFC message handling.

Thanks...

Re: Message Queues for MFC windows classes

Mark Salsbery27-Sep-08 8:24

Mark Salsbery

27-Sep-08 8:24

sawerr wrote:
We know that Windows keeps a message queue for every thread.

Only if you call a function that causes a queue to be created on a thread.

sawerr wrote:
for win32 applications, only one message loop is enough.

Yes, one is sufficient, but not necessary unless you create at least one window.
For example, you don't need a message loop in a console app.

sawerr wrote:
Do all of the message map macros that we see in the source code indicate there is a message loop that buried in MFC source code?

Yes, but not a separate message loop for each window/class.
There's still one per UI thread. See the source code for
CWinThread::Run() - the per-thread message loop is there.
The CWinApp class derives from CWinThread, so for an MFC GUI app,
your required CWinApp object generally provides the first/main
message loop.

Once messages are extracted from the queue in a message loop, then
they are dispatched to their destination window via a call to the destination
window's windowproc (window procedure). That's basic Windows windowing[^].
The message map table macros generate compiled code that maps a message
received in the windowproc to a call to the appropriate window class method.

Hope that makes a little sense.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Message Queues for MFC windows classes

sawerr27-Sep-08 9:58

sawerr

27-Sep-08 9:58

For example if we want to use Edit control in win32 app, the code will be:

hEdit = CreateWindowEx(WS_EX_CLIENTEDGE, "EDIT", "", 
            WS_CHILD | WS_VISIBLE | WS_VSCROLL | WS_HSCROLL | ES_MULTILINE | ES_AUTOVSCROLL | ES_AUTOHSCROLL, 
            0, 0, 100, 100, hwnd, (HMENU)IDC_MAIN_EDIT, GetModuleHandle(NULL), NULL);
//<a href="http://www.winprog.org/tutorial/app_one.html">http://www.winprog.org/tutorial/app_one.html</a>[<a href="http://www.winprog.org/tutorial/app_one.html" target="_blank" title="New Window">^</a>]

Here we create a "control". That control has a message loop in its source code which was written by controls developer. If an event happens, it is sent to its module(for example user32.dll) not to our application. It sends to our program a notification.
OK.

But in MFC, We use CEditView which is derived from CView. So we create a new window.
And CreateWindowEx(WS_EX_CLIENTEDGE, "EDIT", "",...) is in the CEditView.
Has that view window got a message loop too?
If no, how can we handle for example WM_CLOSE

//class CTextView : public CEditView

void CTextView::OnClose()
{
	// TODO: Add your message handler code here and/or call default

	CEditView::OnClose();
}

You said:

Mark Salsbery wrote:
The CWinApp class derives from CWinThread, so for an MFC GUI app,
your required CWinApp object generally provides the first/main
message loop

If view window has a message loop, is that mean it is created by a new thread?

For example, When user close this CeditView window, is this message sent to Main Window or View Window?
If it is sent to main window, does main window route it to view window?

I'm sorry, i really don't solve/understand the mechanism...

Thank you.

Re: Message Queues for MFC windows classes

Mark Salsbery27-Sep-08 10:08

Mark Salsbery

27-Sep-08 10:08

sawerr wrote:
Here we create a "control". That control has a message loop in its source code which was written by controls developer.

No, it doesn't. It has a window procedure implemented by the control developer.
You are still responsible for providing a message loop.

You're confusing message loops with window procedures.

Window procs are related to the window class. MFC subclasses windows so
the MFC framework gets first peek at messages before forwarding unhandled
(i.e. no message map entry) messages to the original window proc.

sawerr wrote:
If view window has a message loop, is that mean it is created by a new thread?

That doesn't make sense. Windows don't have message loops.
Threads can implement a message loop. Windows have window procedures,
which are functions called by the system to send a window a message.

Study the link I gave you on windowing. It's the fundamentals
of Windows programming, and in my opinion, essential to know and
understand completely to be an effective Windows programmer.

If you need more drawn-out documentation on how it all works, then I
recommend the book "Windows Programming" by Charles Petzold.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Message Queues for MFC windows classes

sawerr27-Sep-08 10:46

sawerr

27-Sep-08 10:46

Mark Salsbery wrote:
You're confusing message loops with window procedures.

Yes, that's right. And now i understand.
-One loop
-Get Message and
-DispatchMessage finds the right window procedure.

Thank you for help... Rose | [Rose]

an always-wrong password

Joseph Marzbani27-Sep-08 4:50

Joseph Marzbani

27-Sep-08 4:50

I'm trying to access my eMail contents using a POP3 client app I'm trying to design (something like a simple command line). My eMail Address is testpopid@yahoo.com (I've made it temprarily and will delete it after your answers Big Grin | :-D

). here is my conversation with the server:

telnet pop.mail.yahoo.com 110

<br />
+OK hello from popgate 2.4 ...<br />
USER testpopid<br />
+OK Password required.<br />
PASS MyPassword<br />
-ERR [AUTH] invalid user/password

where "telnet" connects to a server (in this case "pop.mail.yahoo.com") and '110' is the port number used to connect to server.

I use the password I defined when creating the eMail account. When I try to log into my account within my brower, ther's no problem and the above password works (I use www.yahoo.com to log in)

Thank you masters!

Re: an always-wrong password

Paul Conrad27-Sep-08 7:18

Paul Conrad

27-Sep-08 7:18

How are you passing your password? Plaintext? I'm not familiar with how yahoo will handle doing logins, but perhaps the password doesn't go in as plaintext? Suspicious | :suss:

"The clue train passed his station without stopping." - John Simmons / outlaw programmer

"Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

"Not only do you continue to babble nonsense, you can't even correctly remember the nonsense you babbled just minutes ago." - Rob Graham

Re: an always-wrong password

Iain Clarke, Warrior Programmer27-Sep-08 11:23

Iain Clarke, Warrior Programmer

27-Sep-08 11:23

I'm pretty sure yahoo only allows POP3 access if you're using a paid account.

If I'm right, then yahoo is waiting to verify who you are, looking you up, and rejecting you [*].

Iain.

[*] Don't take it personally.

How to decode a wav file

ice87111727-Sep-08 4:04

ice871117

27-Sep-08 4:04

I'd like to read a wav file, not using playsound() function. I want to get the wave of the sound and draw them out. Which function can solve this problem? Please give me some tips.

Re: How to decode a wav file

followait27-Sep-08 4:11

followait

27-Sep-08 4:11

As cool as your name.
BTW, it may be easy for UNIX, coz everything in UNIX is a file.

logics

Re: How to decode a wav file

Joseph Marzbani27-Sep-08 4:54

Joseph Marzbani

27-Sep-08 4:54

No UNIX Please Mad | :mad:

Thank you masters!

Re: How to decode a wav file [modified]

CPallini27-Sep-08 6:04

CPallini

27-Sep-08 6:04

followait wrote:
BTW, it may be easy for UNIX, coz everything in UNIX is a file.

Is it the joke?
Big Grin | :-D

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

modified on Saturday, September 27, 2008 12:14 PM

Re: How to decode a wav file

Hamid_RT29-Sep-08 7:28

Hamid_RT

29-Sep-08 7:28

It depends to you. Laugh | :laugh:

Re: How to decode a wav file

Hamid_RT29-Sep-08 7:27

Hamid_RT

29-Sep-08 7:27

I think i saw your answer on the codeproject I think it was for avi files but you can use of its code for wav files.

Print all the running Applications using C++, win APIs.

Subrat 470826627-Sep-08 1:16

Subrat 4708266

27-Sep-08 1:16

Hi all
I need to print all the <b>'Running Applications'</b> in windows(XP/VISTA) using C++, win APIs.

Thanks & Regrads,
Subrat

Re: Print all the running Applications using C++, win APIs.

CPallini27-Sep-08 1:21

CPallini

27-Sep-08 1:21

Have a look to EnumWindows [^] function.
Smile | :)

Re: Print all the running Applications using C++, win APIs.

Subrat 470826627-Sep-08 2:46

Subrat 4708266

27-Sep-08 2:46

I am using vs 2005.I need native c++ code to perform the same task.
It'd be great if your are telling me how to implement that CALLBACK func which is used in EnumWindows() API.

Re: Print all the running Applications using C++, win APIs.

CPallini27-Sep-08 3:28

CPallini

27-Sep-08 3:28

Implementing the callback isn't difficult. Anyway, to fullfill your requirements, maybe this example [^] is more appropriate.
Smile | :)

Re: Print all the running Applications using C++, win APIs.

Subrat 470826627-Sep-08 3:51

Subrat 4708266

27-Sep-08 3:51

Thanks a lot for you quick response.
This exmple is for enumurating all processes.I need only Applications those are are displyed in Task Manager->Application tab.

Re: Print all the running Applications using C++, win APIs.

Mark Salsbery27-Sep-08 8:45

Mark Salsbery

27-Sep-08 8:45

You could use the tool help library:

#include <Tlhelp32.h>
...

	HANDLE hProcessSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
	if (INVALID_HANDLE_VALUE != hProcessSnapshot)
	{
		PROCESSENTRY32 processentry;
		processentry.dwSize = sizeof(PROCESSENTRY32);
		if (::Process32First(hProcessSnapshot, &processentry))
		{
			do
			{
				// do something with the info in processentry

				TRACE("%S\n", processentry.szExeFile);
			}
			while (::Process32Next(hProcessSnapshot, &processentry));
		}
		::CloseHandle(hProcessSnapshot);
	}

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

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