C / C++ / MFC

6-Mar-03 8:54

Hi there,

According to "Using a Doc/View exported from a dynamically loaded DLL (SDI)" article : http://www.codeproject.com/docview/SdiCViewDll.asp[^], I load Form Views from DLLs. Unfortunately, the View loading fails when the exported view contains Custom Controls and advanced controls such calendar, Rich Edit and so on.

Any idea ? Please help me Smile | :)

Thanks !!

Bartosz Bien6-Mar-03 12:33

6-Mar-03 12:33

Have you tried InitCommonControls[Ex], AfxInitRichEdit[2]?

Regards,
BB

DREVET Olivier6-Mar-03 13:06

6-Mar-03 13:06

Thank you for your answer BB, your advice is all right with rich edit control (with the use of AfxInitRichEdit), but the exported form view is still crashing with custom controls Frown | :-(

An assert occurs on the view creation -> hWnd is NULL in CreateDlgIndirect(). I guess that something is not properly initialized but what ? That is the question, hopping that someone could answer to it... Smile | :)

After some searches, I didn't found anything interesting about such initialisation...

Bartosz Bien7-Mar-03 0:33

7-Mar-03 0:33

Following the initialization path, did you register your custom control classes in the DLL?

Regards,
BB

DREVET Olivier7-Mar-03 0:48

7-Mar-03 0:48

Effectively I didn't registered it. Since this custom control works when used in the main application, I was guessing that it would dirctly run.

I'm not very close to DLLs, can you quickly explain me how to register it and why it's needed ?

Thank you very much BB, I begin to see the light at the end of the tunnel Smile | :)

Bartosz Bien7-Mar-03 1:07

7-Mar-03 1:07

There's an important issue here: MFC extension DLLs maintain their own resource handle.

Personally I call such function in the C++ constructor of all my custom controls (I modified it slightly to fit your question):

BOOL CMyCustomCtrl::RegisterClass()<br />
{<br />
    WNDCLASS wndcls;<br />
    HINSTANCE hInst = AfxGetResourceHandle();<br />
<br />
    if(!(GetClassInfo(hInst, "MyWndClassName", &wndcls)))<br />
    {<br />
        wndcls.style            = CS_HREDRAW | CS_VREDRAW | CS_DBLCLKS;<br />
        wndcls.lpfnWndProc      = ::DefWindowProc;<br />
        wndcls.cbClsExtra       = wndcls.cbWndExtra = 0;<br />
        wndcls.hInstance        = hInst;<br />
        wndcls.hIcon            = NULL;<br />
        wndcls.hCursor          = LoadCursor(NULL, IDC_ARROW);<br />
        wndcls.hbrBackground    = NULL;<br />
        wndcls.lpszMenuName     = NULL;<br />
        wndcls.lpszClassName    = "MyWndClassName";<br />
<br />
        if(!AfxRegisterClass(&wndcls))<br />
	{<br />
            AfxThrowResourceException();<br />
            return FALSE;<br />
        }<br />
    }<br />
    return TRUE;<br />
}

The function checks whether the control is registered with current resource handle, and registers it if not yet done. This way we cover both the application and DLL case. The function can be universal if you derive your custom controls from the common base class and use "MyWndClassName" as a function argument.

You may read in the MSDN what the several WNDCLASS members mean, and the code is self-commenting I guess. I hope I didn't miss anything in this explanation, but ask if there's turn out wrong. Smile | :)

Regards,
BB

DREVET Olivier7-Mar-03 1:21

7-Mar-03 1:21

Thank you BB you're great, I'll try this as soon as possible and I'll post the result here in order to let users and you know if it works.

Thank you again !

DREVET Olivier7-Mar-03 4:34

7-Mar-03 4:34

Dear BB,

Your solution doesn't work for the moment. After some debug, it appears that the Form View window handle is not valid. According to http://www.cpp.atfreeweb.com/MFC/LoadFrame/Index.asp[^], AfxHookWindowCreate() does the following things :
- CFrameWnd::OnCreate
- Calls CWnd::OnCreate
- Calls OnCreateClient, which, if a context with a new view class is supplied, calls CreateView (and that is where the view is created) with the context and an id of AFX_IDW_PANE_FIRST
- Sends (using PostMessage) a WM_SETMESSAGESTRING message to set the status bar message to the string with a resource id of AFX_IDS_IDLEMESSAGE
- Calls RecalcLayout

I'm sure the problem cames from CWnd::OnCreate but I don't know why it return a NULL window handle...

Bartosz Bien7-Mar-03 4:49

Dynamic creation (instanciation) of classes

7-Mar-03 4:49

When you are to create the form view, set the resource handle to the DLL one. These are the steps required (file and variable names assumed, use your own):

1. Near the DllMain function in YourDllName.cpp, find a declaration like: AFX_EXTENSION_MODULE YourDLL = { NULL, NULL };

2. In YourDllName.h (if it doesn't exist, create it), declare:
extern AFX_EXTENSION_MODULE YourDLL;

3. Before form creation, set the handle:

HINSTANCE hPrevHandle = AfxGetResourceHandle();<br />
AfxSetResourceHandle(YourDLL);

// TODO: create view here
AfxSetResourceHandle(hPrevHandle);

If the handle is not set to a module where you defined a dialog template, it cannot be loaded and thus creation fails.

Additionally, you may use a class that encapsulates above functionality and restores the original handle in its destructor (when going out of scope):

class CResourceHandler<br />
{<br />
public:<br />
    HINSTANCE m_prevHandle;<br />
<br />
public:<br />
    CResourceHandler(AFX_EXTENSION_MODULE &module);<br />
    {<br />
        m_prevHandle = AfxGetResourceHandle()<br />
        AfxSetResourceHandle(module.hModule);<br />
    }<br />
<br />
    CResourceHandler(HINSTANCE &handle)<br />
    {<br />
        m_prevHandle = AfxGetResourceHandle();<br />
        AfxSetResourceHandle(handle);<br />
    }<br />
<br />
    virtual ~CResourceHandler()<br />
    {<br />
        AfxSetResourceHandle(m_prevHandle);<br />
    }<br />
};

4. With the class, the creation code simplifies as follows:

<br />
void CreateMyFormView()<br />
{<br />
    CResourceHandler rh(YourDLL.hModule);

// TODO: create view here
}

Of course, the CreateMyFormView() function has to be located in a DLL.

Regards,
BB

dherrero6-Mar-03 8:35

dherrero

6-Mar-03 8:35

Hi,
I have a problem. I have to read the name of a class in a data base and then try to instanciate a object of that class. How can i do it?
Example:
CString className = "CMyClass";
CRuntimeClass* ptr = RUNTIME_CLASS(class); -> Error
CObject* o = ptr->CreateObject()

Re: Dynamic creation (instanciation) of classes

Ravi Bhavnani6-Mar-03 8:37

Ravi Bhavnani

6-Mar-03 8:37

Use a class factory to instantiate the class, given its name.

/ravi

Let's put "civil" back in "civilization"
http://www.ravib.com
ravib@ravib.com

Re: Dynamic creation (instanciation) of classes

dherrero6-Mar-03 12:11

dherrero

6-Mar-03 12:11

And how do I do it?

Add about to system menu in dialog box

jimNLX6-Mar-03 8:27

Re: Add about to system menu in dialog box

6-Mar-03 8:27

I have a dialog application and would like to have a menu selection up in the title bar pull down menu for an "about" box. How do I add this?

My dialog has the following options selected:
Popup
Thin
title bar
system menu

Thanks for the help

Ravi Bhavnani6-Mar-03 8:35

Ravi Bhavnani

6-Mar-03 8:35

Add this code in your dialog's OnInitDialog() handler:

// Add "About..." menu item to system menu.

// IDM_ABOUTBOX must be in the system command range.
ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
ASSERT(IDM_ABOUTBOX < 0xF000);

CMenu* pSysMenu = GetSystemMenu(FALSE);
if (pSysMenu != NULL)
   {
     CString strAboutMenu;
     strAboutMenu.LoadString(IDS_ABOUTBOX);
     if (!strAboutMenu.IsEmpty())
        {
          pSysMenu->AppendMenu(MF_SEPARATOR);
          pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
        }
   }

IDM_ABOUTBOX is a string resource with the value "About MyApp..."

/ravi

Let's put "civil" back in "civilization"
http://www.ravib.com
ravib@ravib.com

Re: Add about to system menu in dialog box

jimNLX6-Mar-03 8:37

Re: Add about to system menu in dialog box

6-Mar-03 8:37

I just figured this was missing by doing a compare.

Now I just have to get it to call the dialog I want.

Thanks for the timely responce.

Jim

jimNLX6-Mar-03 9:12

Differnance between MFC extension DL L and regular mfc dll?

6-Mar-03 9:12

Thought I had this wipped, but I can't seem to intercept the OnSystemCommand.

How does the drop down menu on the system title bar get called and where is it located?

It's like it just magically does it on its own.

clintsinger6-Mar-03 8:17

clintsinger

6-Mar-03 8:17

Hi All,

I was wondering what would be the difference and why would I want to use either type. The application wizard let's me make a standard dll using mfc shared/static or an MFC extension dll.

Any clarification would be helpfull.

Cheers,
Clint

Re: Differnance between MFC extension DL L and regular mfc dll?

Bartosz Bien6-Mar-03 12:35

6-Mar-03 12:35

http://www.codeguru.com/cpp_mfc/dill1.html

Regards,
BB

Transparent Icons

jimNLX6-Mar-03 8:17

6-Mar-03 8:17

I'm using CButtonST(posted there too) and am trying to make my buttons transparent, but can't seem to get it to work. Because the controls under the button are more than one color I can't just make it the same color. Is there a way I can set the icons back ground color so it doesn't display it or any other way to get around this?

Thanks

Re: Transparent Icons

DREVET Olivier7-Mar-03 3:10