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Calling a function in the Main application from a DLL

Posted on 2003-12-04
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Last Modified: 2013-11-20
Hi,

There is this application that has a scenario like this:

Main Application:
SDI with CListView
BaseDialog

DLL:
MFC Extension DLL
Derived Dialog (base from BaseDialog)

I'm using dynamic loading to create an instance of the DeriveDialog and pass it to the BaseDialog so that I can manipulate the functions of DeriveDialog in the Main Application.

But this is the problem, how about if there is an event in the DeriveDialog that it needs to call a function in the Main Application?

I tried to pass a pointer of the main application to function inside the DerivedDialog (implemented also as virtual in the BaseDialog) but I'm having a link error when I call the function inside the main Application

Example:

Main Application: (Implemented as SDI with CListView)
TestView::Hello() - function
BaseDialog:
virtual void Test(TestView* m_pView)

DLL: (Implemented as MFC Extension DLL)
DerivedDialog:

void Test(TestView* m_pView)
{
   m_pView->Hello() - Linking error
}


I hope someone can help on my problem.

Mhelinx


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Comment
Question by:mhelinx09
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7 Comments
 
LVL 23

Expert Comment

by:Roshan Davis
ID: 9880255
Use PostMessage.
Pass the view handle (not pointer) to the dll function
Good luck
0
 

Author Comment

by:mhelinx09
ID: 9880294
Rosmon,

You're my savior!!!

Can you elaborate it? I checked MSDN but they have a small definition about it.

Thanks!!!

Mhelinx
0
 
LVL 23

Expert Comment

by:Roshan Davis
ID: 9880376
Main Application: (Implemented as SDI with CListView)


in header
afx_msg long Hello();

#define WM_USER_HELLO WM_USER+100

BEGIN_MESSAGE_MAP()
      ON_MESSAGE(WM_USER_HELLO, Hello)
END_MESSAGE_MAP()

TestView::Hello() - function




BaseDialog:
virtual void Test(HWND hWnd)

DLL: (Implemented as MFC Extension DLL)
DerivedDialog:

#define WM_USER_HELLO WM_USER+100

void Test(HWND hWnd)
{
      ::PostMessage(hWnd, WM_USER_HELLO, 0, 0);
}


Call this dll function from view like this

*pfnTest(this->m_hWnd);

here this->m_hWnd is the window handle of the View class

Good Luck
0
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Author Comment

by:mhelinx09
ID: 9880453
Many thanks rosmon,

How about if you have parameter on the function (e. g. CString)

TestView::Hello(CString sInput) - function

Thanks!

Mhelinx
0
 
LVL 23

Accepted Solution

by:
Roshan Davis earned 100 total points
ID: 9880492
PostMessage with String is unsafe....

Use another function in DLL like GetString.... that will read the string when that event comes.....


or use

char *psz = new cha[100];
lstrcpy(psz, "Test String");
::PostMessage(hWnd, WM_USER_HELLO, (ULONG)psz, 0);



Main Application: (Implemented as SDI with CListView)


in header
afx_msg long Hello(WPARAM wParam, LPARAM lParam);

#define WM_USER_HELLO WM_USER+100

BEGIN_MESSAGE_MAP()
    ON_MESSAGE(WM_USER_HELLO, Hello)
END_MESSAGE_MAP()

TestView::Hello(WPARAM wParam, LPARAM lParam) - function
{
       char *psz = (char *) wParam;

    // DELETE THE STRING AFTER USE

    delete []psz;
}

Rosh :)


0
 

Author Comment

by:mhelinx09
ID: 9882411
Thanks a lot savior.

This what I did.

Base Dialog:
GetHandle(HWND hWnd)
protected:
HWND m_hWndHandle;

Main Application:
GetHandle(this->hWnd);

DO you think this is safe?

Thanks again.
Mhelinx
0
 
LVL 23

Expert Comment

by:Roshan Davis
ID: 9882429
Yes, its fine...
0

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