C / C++ / MFC

To the one with the empty head

22-Jan-07 3:19

   FWIW, I love the "Ask a friend" link...

   The easter egg section also has some interesting content.

   Peace!

-=- James
Please rate this message - let me know if I helped or not!<HR>If you think it costs a lot to do it right, just wait until you find out how much it costs to do it wrong!
Avoid driving a vehicle taller than you and remember that Professional Driver on Closed Course does not mean your Dumb Ass on a Public Road!
See DeleteFXPFiles

Waldermort22-Jan-07 2:33

Waldermort

22-Jan-07 2:33

If you are too lazy to even write your own name into account, then I ( and I am sure many others ) will not even bother to read your posts. PLEASE FIX IT!!!

Re: Windows Message handling in Debug and Release build of Dialog Based MFC Application

Mike O'Neill22-Jan-07 13:30

Mike O'Neill

22-Jan-07 13:30

wrote:
I want to know what is the reason behind this?? why such difference in Debug and Release build ??

Stack corruption causes the crash. The correct signature of a message handler, the function takes a WPARAM and an LPARAM (which are pushed onto the stack when the function is called) and returns an LRESULT (which is popped from the stack when the function returns). In the incorrect version of your code, the fun() function is being called as if it had this signature, even though the fun() function does not, and as a result there is stack corruption.

The fact that it works in debug mode is a coincidence, possibly due to padding added by the compiler in debug compilations.

Incidentally, are you still using VC 6.0? The error in signatures for message handlers is flagged as a compiler error in newer versions of Visual Studio.

Mike

How to capture mouse events from a control within a Dialog Box?

Arris7422-Jan-07 2:02

Re: How to capture mouse events from a control within a Dialog Box?

22-Jan-07 2:02

Hi,

I do not really understand the intricacies of MFC messages , especially with Dialog boxes and their controls.
Could you please explain me what does not work with the following example?

I use a Dialog box containing a ListCtrl control.
I derived MYDlgClass class from CDialog.

At first I overloaded OnLButtonDown function because I would like to intercept Mouse events from within the ListCtrl.
I realized that mouse events are captured only when the mouse is outside the controls.

Then I tried to derive a new Class from CListCtrl. Before doing so I removed OnLButtonDown from MYDlgClass.
The first issue is that no ClistCtrl class was available for derivation therefore I derived from CDialog and mofified code within the new class that I Call MyListCtrl.
Finally I overloaded OnLButtonDown but the message is not captured.

Please could you tell me what should I do?
Many thanks for your help.

prasad_som22-Jan-07 2:20

prasad_som

22-Jan-07 2:20

Arris7 wrote:
I realized that mouse events are captured only when the mouse is outside the controls

You need to see OnNotify handler of parent(dilaog in this case) class.

Arris7 wrote:
The first issue is that no ClistCtrl class was available for derivation

What ? Strange !
Which version of VS you are using ?

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: How to capture mouse events from a control within a Dialog Box?

Arris7422-Jan-07 6:07

Re: How to capture mouse events from a control within a Dialog Box?

22-Jan-07 6:07

What ? Strange !
Which version of VS you are using ?

I use VS2003. Actually When I right click the ListCtrl control and I select Add Class, There are only 3 or classes available ( CDialog, Cpropertypage etc..) but no CListCtrl.

prasad_som24-Jan-07 17:32

prasad_som

24-Jan-07 17:32

Use class view to add class, instead.

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: How to capture mouse events from a control within a Dialog Box?

Arris7427-Jan-07 6:52

Re: How to capture mouse events from a control within a Dialog Box?

27-Jan-07 6:52

That's ok. I've got the solution.
thanks anyway.

Waldermort22-Jan-07 2:28

Waldermort

22-Jan-07 2:28

You have derived from CDialog, but the trouble is mouse messages are sent to the controls ( your list control ) not the dialog itself. You need to derive a class from the list control and handle the messages from there.

Another way you could handle this is checking the message paramater of the MSG struct after each call to GetMessage(). Though I'm not exactly sure how you adjust the message loop in MFC.

Re: How to capture mouse events from a control within a Dialog Box?

Arris7422-Jan-07 6:33

Pass a sting to a dll that neads a WCHAR

22-Jan-07 6:33

You have derived from CDialog, but the trouble is mouse messages are sent to the controls

Actually, the messages are correctly routed to the CDialog. But when the mouse is within the control, I do not know where the messages are routed.

You need to derive a class from the list control and handle the messages from there

I derived a class from CListCtrl but no messages are routed to this class.

Though I'm not exactly sure how you adjust the message loop in MFC.

What is the procedure to do this? What is entry point in VC++ to setup Confused | :confused:

this?

Calvin Streeting22-Jan-07 2:02

22-Jan-07 2:02

Hi..

I am having trouble passing a string of a file name (from VB to my c++ DLL)

the function StgOpenStorage requires a "const WCHAR*" for the filename. so what type should i pass to it. I would prefer to pass a VB string and let the DLL do the relevant transulation of types (i don't want to use strPtr(filename) in VB

many thanks

sample code
//-------------------------------------------------------------
SSFILEDLL_API bool __stdcall OpenEmail(fileName)
{
if (bIsopen == false)
{
HRESULT hr;

hr = MAPIInitialize(NULL);
if (FAILED(hr))
return false;

hr = OleInitialize(NULL);
if (FAILED(hr))
return false;

//get storage from msg file
//here is the bit where the filename is used
//hr = StgOpenStorage(L"C:\\Email.msg" works but i want to pass it from vb

hr = StgOpenStorage(filename ,
NULL,
STGM_READWRITE | STGM_TRANSACTED | STGM_SHARE_EXCLUSIVE,
NULL,
0,
&pStorage);
if (FAILED(hr))
return false;

//open a IMessage session
hr = OpenIMsgSession (pMalloc, 0 , &pMsgSession);
if (FAILED(hr))
return false;

//open an IMessage on the IStorage object
hr = OpenIMsgOnIStg(pMsgSession,
MAPIAllocateBuffer,
MAPIAllocateMore,
MAPIFreeBuffer,
pMalloc,
NULL,
pStorage,
NULL,
0,0,&pSourceMsg);
if (FAILED(hr))
{
return false;

}
else
{
bIsopen = true;
return true;
}
}
else
{
return false;
}
}

toxcct22-Jan-07 2:15

toxcct

22-Jan-07 2:15

read the posting guidelines[^], especially when you post huge code blocks.

Calvin Streeting wrote:
Pass a sting

wow, that'll be hard Laugh | :laugh:

Don't know where to start ?
Refer the Forums Guidelines and ask a friend

[VisualCalc 3.0][Flags Beginner's Guide]

James R. Twine22-Jan-07 3:01

22-Jan-07 3:01

   I was under the impression that VB strings were wide/Unicode by default, and would be in the form of a BSTR (BSTR == BASIC String, IIRC), which is already a wide string.

   You can pass a BSTR in place of a const wchar_t* or const WCHAR* just fine. As far as how to get that BSTR directly to the function in the DLL, I cannot help you there - I do not do VB, nor am I 100% certain that the internal format of the BSTR is exactly the same as its external/COM format.

   Peace!

Calvin Streeting22-Jan-07 3:30

22-Jan-07 3:30

I thought so but if I...

SSFILEDLL_API bool __stdcall OpenEmail(BSTR FileName)

then the StgOpenStorage fails but if i hard code in the filename L"c:\\email.msg" it works...

am i missing some thing

James R. Twine22-Jan-07 4:27

22-Jan-07 4:27

StgOpenStorage(...) fails when? At compile time, at run time, and with what error? Oh, and that should be a const BSTR parameter - you are not going to modify it so it can be constant.

Peace!

Calvin Streeting22-Jan-07 4:53

22-Jan-07 4:53

if i use "const BSTR filename" it compiles ok but fails at run time (StgOpenStorage(..) returns -2147287038) when called. it also sometimes crashes the vb app.

Many thanks for your help

James R. Twine22-Jan-07 5:08

22-Jan-07 5:08

Examine the string in the debugger (run the DLL under the debugger by specifying the VB application as the executing application), and see if the string looks valid or not.

Peace!

Calvin Streeting22-Jan-07 5:21

22-Jan-07 5:21

ok now you are hitting the limit of my c++ (this is my first c++ program ).. i feel i might need to read the section on debuging... but for you info it shows

szString = 0x0013c884
|__ 12849

which i take it is ram address?... is there any way to get it to print out the BSTR or msgbox it....

calvin

James R. Twine22-Jan-07 8:09

22-Jan-07 8:09

You need your debugger configured to show Unicode strings, and that will allow you to see if the value you are seeing can be treated as a BSTR or not.

You can use MessageBoxW(...) to see the value by doing something like this:

::MessageBox<code>W</code>( szString, L"The String", MB_OK );

Pay attention to the "W" in ::MessageBoxW(...). The call to MessageBoxW will either show the contents of the string (if the string pointer is valid), or will likely crash or show garbage if not.

Peace!

Calvin Streeting22-Jan-07 9:30