C / C++ / MFC

Re: MFC: calling a menu item from another menu item

12-Feb-10 0:04

I have two menu items under the File menu - Call My Dialog & Call MessageBox. Call MessageBox will invoke a message box. I am trying to do the same thing when the user hits Call My Dialog menu item.

void CMainFrame::OnFileCallmessagebox()
{
	// TODO: Add your command handler code here
	MessageBox(_T("hello world!!"), _T("Sample message box"));
}

void CMainFrame::OnFileCallmydialog()
{

	/*this->SendMessage(,
		HIBYTE(ID_APP_CALL_MESSAGEBOX),
		LOBYTE(ID_APP_CALL_MESSAGEBOX));*/

	HWND hwnd = AfxGetMainWnd()->GetSafeHwnd();
	::SendMessage(hwnd, WM_COMMAND, 
		HIBYTE(ID_APP_CALL_MESSAGEBOX),
		LOBYTE(ID_APP_CALL_MESSAGEBOX));
}

Whatever I do I keep getting some failure assertion

Richard MacCutchan12-Feb-10 0:19

Re: MFC: calling a menu item from another menu item

12-Feb-10 0:19

deostroll wrote:
Whatever I do I keep getting some failure assertion

First thing to do is look at the assertion message and figure out what is going wrong; or post it here so we can help you.

Secondly your ::SendMessage[^] syntax is not correct.

Thirdly, why not just tie both menu items to the OnFileCallmessagebox() function?

txtspeak is the realm of 9 year old children, not developers. Christian Graus

deostroll12-Feb-10 2:12

Re: MFC: calling a menu item from another menu item

12-Feb-10 2:12

suppose I had a modal dialog box. I click a button on it, I'd want to call the same routine (i.e. the Call Message Box click event) via SendMessage(). Is this not possible?

I've rewritten and debugged my code...and found out that the values I am sending for wParam and lParam are wrong

this->SendMessage(WM_COMMAND,
  HIWORD(ID_APP_CALL_MESSAGEBOX),
  LOWORD(ID_APP_CALL_MESSAGEBOX));

what are the correct values?

Richard MacCutchan12-Feb-10 3:16

Re: MFC: calling a menu item from another menu item

12-Feb-10 3:16

deostroll wrote:
suppose I had a modal dialog box. I click a button on it, I'd want to call the same routine (i.e. the Call Message Box click event) via SendMessage().

I have no idea why you would want to do this. A modal dialog provides a break in an application where the user is asked for some information, or to make a decision, before returning to the main application. If your dialog needs to call another dialog or (terrible idea) itself, then your design is flawed.

deostroll wrote:
what are the correct values(for SendMessage())?

I cannot be certain, but I suspect it is something along the lines of

this->SendMessage(WM_COMMAND, ID_APP_CALL_MESSAGEBOX, 0L);

I suggest you take a look at the MSDN Documentation[^] for further information.

txtspeak is the realm of 9 year old children, not developers. Christian Graus

deostroll12-Feb-10 3:51

Re: MFC: calling a menu item from another menu item

12-Feb-10 3:51

What if the dialog was non-modal? Wouldn't this be a valid scenario? Btw how do u do a modeless dialog box?

Richard MacCutchan12-Feb-10 4:01

Re: MFC: calling a menu item from another menu item

12-Feb-10 4:01

deostroll wrote:
What if the dialog was non-modal?

The same considerations apply; it's a question of design and usability. If I am running an app on my PC and select a menu item which pops up a dialog box, and then press a button on that dialog which pops another dialog, I tend not to feel too kindly towards the designer. As I said before you need to understand what dialogs are for and use them sparingly. Programs that just throw dialogs and other clutter at users tend to be consigned fairly quickly to the dustbin of history.

deostroll wrote:
Btw how do u do a modeless dialog box?

You read the MSDN documentation[^] to start with.

txtspeak is the realm of 9 year old children, not developers. Christian Graus

deostroll12-Feb-10 4:18

Re: MFC: calling a menu item from another menu item [modified]

12-Feb-10 4:18

Hey, I don't mean to call another dialog from another dialog. I just put a messagebox in one of my menu item's event handler. It is just to test if the code executes...which it apparently does not?

k, on the topic on non-modal dialogs I don't understand the difference between the following 2 snippets:

/* Snippet 1 */
CMyDialog* dlg = new CMyDialog();
dlg->Create(IDD_MY_DIALOG);
dlg->ShowWindow(SW_SHOW);

/* Snippet 2 */
CMyDialog dlg = new CMyDialog();
dlg.Create(IDD_MY_DIALOG);
dlg.ShowWindow(SW_SHOW);

Snippet 2 doesn't work! Why is that so?

Richard MacCutchan12-Feb-10 4:32

Re: MFC: calling a menu item from another menu item

12-Feb-10 4:32

deostroll wrote:
Snippet 2 doesn't work! Why is that so?

~~I don't really know MFC that well, but I guess the CMyDialog() constructor returns a pointer to a new object.~~ Sorry, senior moment there, new returns a pointer to the object created. You can check what actually happens when you run your app by using the debugger.

txtspeak is the realm of 9 year old children, not developers. Christian Graus

modified on Friday, February 12, 2010 12:11 PM

David Crow12-Feb-10 7:06

David Crow

12-Feb-10 7:06

Richard MacCutchan wrote:
If I am running an app on my PC and select a menu item which pops up a dialog box, and then press a button on that dialog which pops another dialog, I tend not to feel too kindly towards the designer.

Really? This sort of thing happens all over Windows (XP and Vista), Office (2003 and 2007), IE (6 and 8), Visual Studio (6 and 2005), etc.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"Man who follows car will be exhausted." - Confucius

Re: MFC: calling a menu item from another menu item

Richard MacCutchan12-Feb-10 9:11

Is it possible to open file twice?

12-Feb-10 9:11

DavidCrow wrote:
This sort of thing happens all over Windows, Office, IE, Visual Studio, etc.

Strange, it doesn't on the versions I have!

txtspeak is the realm of 9 year old children, not developers. Christian Graus

Member 439977111-Feb-10 23:13

Member 4399771

11-Feb-10 23:13

Hi All,

Is it possible to open the file twice? I am using CStdioFile, i created two objects of type CStdioFile and assigning the same file for both the objects. one file opened for writing(modeReadWrite) the data and the other file opened for reading(modeRead) the data. In this case my application is crashing. please give me some solution.

CStdioFile obj1;
CStdioFile obj2;

obj1.Open("file1.txt", CStdioFile::modeReadWrite);
.....
.....
.....
obj2.open("file1.txt", CStdioFile::modeRead);
.....
.....
obj2.close();
....
...
obj1.close();

Thanks in advance!

Regards,
Anil

Cedric Moonen11-Feb-10 23:24

Cedric Moonen

11-Feb-10 23:24

Why do you want to do such a thing ? Why don't you simply open and read the full file in memory, make the changes in memory and then write back everything to the file afterwards ?

Cédric Moonen
Software developer

Charting control [v3.0]
OpenGL game tutorial in C++

Member 439977111-Feb-10 23:35

Member 4399771

11-Feb-10 23:35

yes, thankyou!

David Crow12-Feb-10 3:12

David Crow

12-Feb-10 3:12

Member 4399771 wrote:
In this case my application is crashing.

At what point?

Rozis12-Feb-10 11:25

Rozis

12-Feb-10 11:25

Yes you can, simply use 2 handles (or objects or whatever your language wants you to use). Be aware of the folloing:
- The OS sees this as file sharing, so open in shared mode.
- You will have 2 independent filepointers.

Rozis

Form Background color change - Reg.

Rozis12-Feb-10 11:32

Rozis

12-Feb-10 11:32

To Cedric and David: There are many cases opening a file twice can be handy. The simplest example is a Word document on a network. The first user reads it shared, read-write, the next shared, readonly. Be aware many DBMS use this for concurrent access (with some intelligence around).

Rozis

Paulraj G11-Feb-10 23:00

Paulraj G

11-Feb-10 23:00

Hi..

In CView application I am showing a dialog(Like toolbar/ Status bar).
I have to change the dialog background color.

I used the following code. But background color not changing. If i use this same in new dialog application the background color is changing.

ON_WM_ERASEBKGND()

BOOL CTech::OnEraseBkgnd(CDC* pDC)
{    
	CRect rect;    GetClientRect(&rect);    
	CBrush myBrush(RGB(255, 0, 255));    
	// dialog background color    
	CBrush *pOld = pDC->SelectObject(&myBrush);    
	BOOL bRes = pDC->PatBlt(0, 0, rect.Width(), rect.Height(), PATCOPY);    
	pDC->SelectObject(pOld);    
	// restore old brush    
	return bRes;                      
}

How to solve this problem.
Any help will be appriciated..
Thanks...

G.Paulraj

Re: Form Background color change - Reg.

Richard MacCutchan11-Feb-10 23:30

Re: Form Background color change - Reg.

11-Feb-10 23:30

I do not think that this is the message for the dialog's background repaint. Take a look at the WM_CTLCOLORDLG[^] notification.

txtspeak is the realm of 9 year old children, not developers. Christian Graus

Paulraj G11-Feb-10 23:40

Paulraj G

11-Feb-10 23:40

It is working fine in form based applications...

G.Paulraj

Re: Form Background color change - Reg.

Richard MacCutchan12-Feb-10 0:13