C / C++ / MFC

Allow only one instance of my app at a time

28-Jul-04 8:14

Use Attach() just like Papa prescribed.

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

Anonymous28-Jul-04 7:10

Anonymous

28-Jul-04 7:10

Hai,
I do not want to have more than one instance of my app running at a given time. If the app is already running on the machine, I want the invocation of the app to just bring the already running app in focus. I would assume there is a standard way of doing this since a lot of apps do it. Can someone give me an example? Thanks a lot.

Re: Allow only one instance of my app at a time

David Crow28-Jul-04 8:12

SetWindowText problem - please look at that

28-Jul-04 8:12

See here and here.

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

28-Jul-04 6:48

Can anybody help in this problem:

There's an edit control - hwnd_edit.

SetWindowText(hwnd_edit, "A line #1\nHere goes next line");

I need to do this:
|-------------------|
|A line #1 |
|Here goes next line|
| |
| |
|-------------------|

Bus what's up? I see the following:

|---------------------------------|
|A line #1[]Here goes next line |
| |
| |
|---------------------------------|

[] is a small square

How to deal with it?

jmkhael28-Jul-04 6:56

jmkhael

28-Jul-04 6:56

Try a \r\n
Make sure that the style multiline is checked

Papa

while (TRUE)
Papa.WillLove ( Bebe ) ;

Igor Mihailov28-Jul-04 7:54

Igor Mihailov

28-Jul-04 7:54

\n\r doesn't work - now there are two squares instead of CR LF.
Multiline is certainly checked

XPiS

David Crow28-Jul-04 8:17

28-Jul-04 8:17

XPiS wrote:
\n\r doesn't work

It's important that you use \r\n (not \n\r) as was prescribed.

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

Jaime Stuardo28-Jul-04 8:42

Jaime Stuardo

28-Jul-04 8:42

Try \r\n, or even \r allone.

Jaime

bikram singh28-Jul-04 9:17

bikram singh

28-Jul-04 9:17

As far as I know, nothing like that will cause a multil-line title bar. Simply because Windows is meant to be user-friendly (read: consistent).

I dont think using owner-draw for the title bar can accomplish multi-line title bars either.

I suggest u change your strategy and display the required data in an appropriate place.

Again, one of the reasons Windows is popular is because of the GUI consistency it maintains.

Bikram Singh

David Crow28-Jul-04 9:30

Re: Window OnPaint overrding

28-Jul-04 9:30

Where is there mention of a multi-line title bar? Unless the OP changed his post, he wanted a multi-line edit box. Yes?

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

whups

bikram singh28-Jul-04 9:46

bikram singh

28-Jul-04 9:46

sorry ! my mistake! Roll eyes | :rolleyes:

Bikram Singh

Window OnPaint overrding

act_x28-Jul-04 6:34

act_x

28-Jul-04 6:34

I have an MFC based app that uses the SDI methodology .

I have a View that creates and maintains a CWnd derived class pointer (CScreen *ptr) .

Now this app is an interactive GUI and I have to display various Screens for which I have implemented classes that derive from CScreen .CScreenDerived1 , CScreenDerived2

Now based on the stage of the GUI the view creates objects of different types = CScreenDerived1 , CScreenDerived2 using the *ptr to point to derived class objects !

like this in the view.cpp file

<br />
 case 1:<br />
	   ptr = (CScreen *) new CScreenDerived1(this);<br />
	   break;<br />
 case 2:<br />
          ptr=(CScreen *) new CScreenDerived2(this);<br />
           break;

Now i have handled the WM_PAINT message in CScreen by implementing OnPaint

Screen.h file ---------------------------

//{{AFX_MSG(CScreen)<br />
	afx_msg void OnPaint();

Screen.cpp -------------------------------

<br />
BEGIN_MESSAGE_MAP(CScreen, CWnd)<br />
   ON_MESSAGE(ID_SCREEN_REPAINT, ScreenRefresh)     // handler for posted message refresh<br />
   //{{AFX_MSG_MAP(CScreen)<br />
	ON_WM_PAINT()<br />
	ON_WM_LBUTTONDOWN()<br />
	ON_WM_ERASEBKGND()<br />
	//}}AFX_MSG_MAP<br />
END_MESSAGE_MAP()

Also I want to do specific rendering tasks for which I thought of overriding the OnPaint in the derived classes so Using classView I added an OnPaint Function in CScreenDerved1 and CScreenServied 2 , but I found that the breakpoints that i set in the entry points of these functions was never called .

I found a way that worked where I added the afx call (.h) and the MESSAGE MAP entry(.cpp) in the derived classes and the call was made .

I was assuming that polymorphism will help me out when I directly overrode the OnPaint method in the derived class .

I would be grateful if someone can expalin the mechanism used in this case .
is it because ive done this
ptr=(CScreen *) and forced the type cast !

Johan Rosengren28-Jul-04 9:05

Johan Rosengren

28-Jul-04 9:05

That you instantiate the CWnd-derived classes does not mean that they will be displayed. You'll have to call Create and - depending on the styles you set - ShowWindow. You'll also have to move the windows in response to the parent resizing. This is accomplished by handling WM_SIZE in the view (you'll get a function called OnSize), checking for window existence by testing the m_hWnd member of CScreenX.

Win Xp vs 2K error

doctorpi28-Jul-04 5:43

doctorpi

28-Jul-04 5:43

Hi guys
I have a problem , but only happens in XP.
When I open a dialog in my app, I do a movewindow related to the parent position. In W2K the windows is placed exactly where I want and when I execute my app in XP it appears in a higher place than in W2K.
Do you know why could this happens?
What is different in XP that my window is not placed in the same place than in w2K?
Another related question.
Why depending the size of the dialog in W2K it appears correctly and in XP the scrollbars appear?
Best Regards
Doc

bikram singh28-Jul-04 9:20

bikram singh

28-Jul-04 9:20

Thank you for your Best Regards Smile | :)

This is intriguing.

I cant be sure exactly, but if you're sure you're code complies with MS dox completely, it wud help if you posted the relevant code.

I would sure like to replicate this !

Bikram Singh

doctorpi28-Jul-04 9:45

doctorpi

28-Jul-04 9:45

Thanks in advance for your help
CRect rect,rect3;
m_pParent->GetWindowRect(rect3);
GetWindowRect(rect);
MoveWindow(rect3.left+381,rect3.top+123,rect.Width(),rect.Height(),TRUE);

m_pParent it's a pointer to the dialog parent class.
And Best Regards Wink | ;)

Doc

User 58385228-Jul-04 14:49

User 583852

28-Jul-04 14:49

I suspect there are two problems here.
In MoveWindow() you are using two rects that have different origins
This is from CWnd::MoveWindow in MSDN...

For a top-level CWnd object, the x and y parameters are relative to the upper-left corner of the screen. For a child CWnd object, they are relative to the upper-left corner of the parent window’s client area.

so you need to change the code like this

CRect rect,rect3;
m_pParent->GetWindowRect(rect3);
GetWindowRect(rect);
GetParent()->ClientToScreen(&rect);
MoveWindow(rect3.left+381,rect3.top+123,rect.Width(),rect.Height(),TRUE);

The second problem is the use of constants (381 & 123). All sizing and position calculations need to be relative ALWAYS or you will get lots of problems when you change resolution or other display settings.

I suspect that you had to add these because you didnt call ClientToScreen()

What are you trying to acheive here? Is it to put the child window in the center of the parent?