compilation error of the day ... - C / C++ / MFC Discussion Boards

Restore focus to child window in CScrollView

Sara Burns6-Dec-02 10:54

6-Dec-02 10:54

Using VC++ 6.0 and MFC
I am dynamically creating child windows in a derivative of CScrollView. This is working really well.

How can I save the child window which has the focus when another application is activated so that this can be restored when the focus is returned to my application.

Example is when user switches to Explorer then back to my app using the buttons in the start bar.

I have tried a few methods but they do not seem to behave consistently. Any suggestions will be very welcome.

Sara

Windows 2000 VS. NT

Shay Harel6-Dec-02 10:41

Shay Harel

6-Dec-02 10:41

Hi,

If I draw a rectangle on a dialog using this code it draws a nice rectangle with black frame on NT but nothing on 2000, any idea ?

CRect rect;
CClientDC dc (dlg); //get our device context
dlg->GetClientRect (&rect); //get the pointer to our window
CBrush brush (RGB (192,192,192));
dc.SelectObject(&brush);

dc.Rectangle(20,30,40,70);

Poke tongue | ;-P

When do you build a DLL?

Nitron6-Dec-02 10:16

Nitron

6-Dec-02 10:16

How many Dialogs and stuff do you usually have before you start putting them into DLL's? Also, do you put more than just the dialogs into DLL's? When would I consider building a class as a DLL?

- Nitron

"Those that say a task is impossible shouldn't interrupt the ones who are doing it." - Chinese Proverb

Re: When do you build a DLL?

Paul M Watt6-Dec-02 10:24

Paul M Watt

6-Dec-02 10:24

I think the main criteria for putting stuff in a DLL is its ability to share the content of the DLL.

or

If the data is rarely used, and your program would benefit from only loading the DLL when it is needed.

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

Re: When do you build a DLL?

Nitron6-Dec-02 10:40

Nitron

6-Dec-02 10:40

So if my application is pretty much canned in one main class and no one else interfaces with it, forget the DLL? Except if I have some functions and classes which aren't used often, so put them away into the DLL to avoid the overhead when they are not in use...

I guess if you don't have an explicit reason for a DLL, you probably don't need one?

- Nitron

"Those that say a task is impossible shouldn't interrupt the ones who are doing it." - Chinese Proverb

Re: When do you build a DLL?

Paul M Watt6-Dec-02 10:47

Paul M Watt

6-Dec-02 10:47

Nitron wrote:
I guess if you don't have an explicit reason for a DLL, you probably don't need one?

Yep. I see applications that go over 2 MB in size. Alot of that is resources and images, but still your EXEs can get as large as you want.

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

Re: When do you build a DLL?

Nitron6-Dec-02 10:56

Nitron

6-Dec-02 10:56

Cool. Thx. Well, I had enough for one week... Have a good weekend!

Oh, I'll be sure to have a Beer | [beer]

for you!

- Nitron

"Those that say a task is impossible shouldn't interrupt the ones who are doing it." - Chinese Proverb

compilation error of the day ...

Maximilien6-Dec-02 9:47

Maximilien

6-Dec-02 9:47

I just made my mainframe class inherite from another simple class ( standalone, class, does not inherite from anything else ), and I get these errors :

  // prototypes...
  afx_msg void OnStandardToolBar(NMTOOLBAR* pnmh, LRESULT* plRes);	
  afx_msg void OnViewToolBar    (NMTOOLBAR* pnmh, LRESULT* plRes);

...
  // errors on those...
  ON_NOTIFY(TBN_DROPDOWN, ITB_STANDARD_TOOLBAR, OnStandardToolBar)
  ON_NOTIFY(TBN_DROPDOWN, ITB_VIEW_TOOLBAR, OnViewToolBar)
...

D:\\MainFrm.cpp(287) : error C2440: 'type cast' : cannot convert from 'void (__thiscall CMainFrame::*)(struct tagNMTOOLBARA *,long *)' to 'void (__thiscall CCmdTarget::*)(struct tagNMHDR *,long *)'
        Pointers to members have different representations; cannot cast between them
D:\\MainFrm.cpp(288) : error C2440: 'type cast' : cannot convert from 'void (__thiscall CMainFrame::*)(struct tagNMTOOLBARA *,long *)' to 'void (__thiscall CCmdTarget::*)(struct tagNMHDR *,long *)'
        Pointers to members have different representations; cannot cast between them

I'm assuming it's name conflict somewhere ...

Any Ideas ?

Max
P.S. I hate fridays!

Re: compilation error of the day ...

Alvaro Mendez6-Dec-02 9:58

Alvaro Mendez

6-Dec-02 9:58

Maximilien wrote:
P.S. I hate fridays!

Smile | :)

Well, I like Fridays myself -- it's the start of the weekend!

But anyway, your problem is not related to name conflicts. If you look at the error, it's expecting you to pass it a function with this signature:

void (__thiscall CCmdTarget::*)(struct tagNMHDR *,long *)

And you're passing it this:

void (__thiscall CMainFrame::*)(struct tagNMTOOLBARA *,long *)

I believe that changing the first parameter to be of type NMHDR (instead of NMTOOLBAR) should take care of the problem.

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Re: compilation error of the day ...

Maximilien6-Dec-02 10:31

Maximilien

6-Dec-02 10:31

even if it actually expect to have a NMTOOLBAR ?

I assume it's safe to do :

NMTOOLBAR* pnmh = (NMTOOLBAR* ) pNBHDR;

in the handler ?

anyway, seems to be working !
Big Grin | :-D

Thanks, now I can go home free as a bird !

Max.

Re: compilation error of the day ...

Michael Dunn6-Dec-02 16:44

Michael Dunn

6-Dec-02 16:44

Maximilien wrote:
I assume it's safe to do :
NMTOOLBAR* pnmh = (NMTOOLBAR* ) pNBHDR;

Not only is it safe, it's correct. Wink | ;)

All the WM_NOTIFY structs have a NMHDR as their first member, think of it as inheritance for C.

--Mike--
Friday's GoogleFight results: Britney Spears 2,190,000 - Erica Weichers 23 Frown | :(

1ClickPicGrabber - Grab & organize pictures from your favorite web pages, with 1 click!
My really out-of-date homepage
Sonork-100.19012 Acid_Helm

Help File

act_x6-Dec-02 8:55

act_x

6-Dec-02 8:55

How do I add Help File Functionality to my VC++ MDI application ? Please help

Re: Help File

lucy6-Dec-02 9:33

lucy

6-Dec-02 9:33

compile your help files using HTMLHelp Workshop, so that you got the *.chm ready. Then in your method to serve the help menu item, just add:

HWND hwnd = ::HtmlHelp(this->m_hWnd, szBuff, 0, HH_DISPLAY_TOPIC);

to display the help file.

remember to include the #include <htmlhelp.h>
and the library.

Re: Help File

act_x6-Dec-02 9:43

act_x

6-Dec-02 9:43

Thanks for the help but unfortunately I am getting a Linker error saying

Linking...<br />
MainFrm.obj : error LNK2001: unresolved external symbol _HtmlHelpA@16<br />
Debug/MDI2.exe : fatal error LNK1120: 1 unresolved externals<br />
Error executing link.exe.<br />
<br />
MDI2.exe - 2 error(s), 0 warning(s)

I copied the htmlhelp.h file to the VC98 include directory
and copied the htmlhtlp.lib file to th eVC98 lib directory.
Also I my .cpp I included like #include "htmlhelp.h"

What am I Doing wrong ? Please help

Re: Help File

Paul M Watt6-Dec-02 10:27

Paul M Watt

6-Dec-02 10:27

did you reference the HTMLHEML.lib file in your projects link settings? You need to actually reference the lib in your project, otherwise the linker will not know that it needs to link that file in.

Hit Alt + F7 then go to the link tab. In the "Object/Library Modules" edit field add HTMLHelp.lib and that should fix your problems.

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

Thank you all

act_x6-Dec-02 10:39

act_x

6-Dec-02 10:39

Thanks a lot for the suggestions . I was able to invoke a File. THanks

Re: Help File

Gaul7-Dec-02 19:14

Gaul

7-Dec-02 19:14

What do you recommend for creating/editing the help file text/source?

Gaulles

Re: Help File

lucy9-Dec-02 2:21

lucy

9-Dec-02 2:21

I am using HTMLHelp Workshop. You can download it from Microsoft's web site.

HWND to a UIThread

David_Leikis6-Dec-02 8:35

David_Leikis

6-Dec-02 8:35

I am trying to create a thread to monitor a USB-connected ADC module. Its driver uses a callback function for the configuration of the module. It requires a CWnd handle given to it such that when it has a buffer filled, it sends a OLDA_WM_BUFFER_DONE message to the thread. I created a UIThread so that it would have a message handler and I could create my OnBufferDone function. (Which is working and tested in a single thread situation.) It needs to be in a separate thread so that I can empty the buffer quickly
and move the sample data into my internal buffers and return it back to the ADC module driver before the next buffer_full message comes in.

Does anyone know how to create or get a HWND for a UIThread so that this driver can know where to send messages to my thread?

Thanks in advance,
Dave
Cry | :((

Re: HWND to a UIThread

KaЯl7-Dec-02 1:59

KaЯl

7-Dec-02 1:59

Have you had a look to PostThreadMessage[^] ?

HTH,

K.

I hurt so bad inside
I wish you could see the world through my eyes
It stays the same
I just wanna laugh again

Problem with auto_ptr !!!

Luc Bergeron6-Dec-02 8:30

Luc Bergeron

6-Dec-02 8:30

Hello to all.

I've checked this following article (http://www.cuj.com/experts/1906/hyslop.htm?topic=experts) at CUJ web site and decided to use it in my own application.

So here we go. I have managed to implement the factory inside a windows DLL. But i'm having weird problems with it. Mainly the genericFactory::create method.

This is how i've implemented it (with the modification that I use a pointer to a function with three std::string parameters) :
template <class manufacturedobj,="" typename="" classidkey="">
std::auto_ptr<manufacturedobj>
genericFactory<manufacturedobj, classidkey="">::create(const classIDKey &className,
const std::string& p1,
const std::string& p2,
const std::string& p3) const
{
std::auto_ptr<manufacturedobj> ret(0);
FN_REGISTRY::const_iterator regEntry=registry.find(className);
if (regEntry != registry.end())
{
ret = regEntry->second(p1, p2, p3);
}

return ret;
}

And in my client code this is how I call it :
std::auto_ptr<mysqltable> tbl(0);
tbl = genericFactory<mysqltable>::instance().create("HistoricalDataTbl", host, user, pwd);
-----------------------------------------------------------------------------------------------

When I trace inside the create method, the "ret" variable is fine and points to a valid MySQLTable object. BUT, when the function returns to the client code... I get an unhandled exception error. This error is generated inside the auto_ptr<>::reset() method. To be more precise, the "tbl" auto_ptr in the client code is supposed to be initialized with a NULL pointer but when getting back from genericFactory::create method the "tbl" pointer points to an invalid MySQLTable object.

The quilty code inside auto_ptr :
void reset(_Tp* __px=0) {
_Tp* __pt = this->get();
if (__px != __pt)
delete __pt; //offending line...
this->__set(__px);
}

So i'm currently puzzled has to why the "tbl" variable points to a bad MySQLTable object!?!?!?!

Any help would be greatly appreciated Big Grin | :-D

Luc.

Re: Problem with auto_ptr !!!

Alvaro Mendez6-Dec-02 9:50

Alvaro Mendez

6-Dec-02 9:50

Well, your sample code doesn't look good since the template parameters were lost by the HTML translation. Try putting the code inside pre tags next time.

However, I did take a quick peek it and it seems like the problem is with your regEntry variable. It's a local variable which, I assume, is returning to you a pointer to a MySQLTable object via the second function which it created internally. My guess is that when the create function returns, regEntry goes away and so does the MySQLTable pointer that it was holding -- which is also in your ret variable. So ret is left holding on to a pointer which is no longer valid.

That's one guess, based on my complete lack of knowledge on FN_REGISTRY.

Another guess is that it has to do with how ret variable is being copied and freed when it gets returned. But it shouldn't be that since ret would be "released" before being copied to tbl, and then it would be freed with a NULL pointer -- should be no problem.

BTW, I noticed you're not using Microsoft's auto_ptr implementation, which doesn't even have a reset (at least not the one in VC6.0)

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Re: Problem with auto_ptr !!!

Luc Bergeron6-Dec-02 10:01

Luc Bergeron

6-Dec-02 10:01

Here is how FN_REGISTRY is defined...

typedef std::auto_ptr<manufacturedObj> (*BASE_CREATE_FN)(const std::string&,
                                                         const std::string&,
                                                         const std::string&);

// FN_REGISTRY is the registry of all the BASE_CREATE_FN
// pointers registered.  Functions are registered using the
// regCreateFn member function (see below).
typedef std::map<classIDKey, BASE_CREATE_FN> FN_REGISTRY;
FN_REGISTRY registry;

And I use STLPort !!!

P.S. How come, after using the pre tags, that my "<" and ">" gets deleted !?!?!?

Dynamic CEdit can't call DoDataExchange()?

dazinith6-Dec-02 8:20

dazinith

6-Dec-02 8:20

Hey there.. ive never created CEdits without the dialog editor.. now i am trying to create a bunch and have DoDataExchange() when they lose focus.. it doesn't look like DoDataExchange ever gets called in my view tho.. here is how i am creating my fields:

CEdit* pEdit = new CEdit;
pEdit->Create(WS_CHILD | WS_VISIBLE | WS_TABSTOP | WS_BORDER | ES_AUTOHSCROLL,
    CRect(10, 10, 110, 30), this, 1);

how can i make a field like this call DoDataExchange() when it gains focus? or better yet, how can i make it call a function when it loses focus? i only know how to use the BEGIN_MESSAGE_MAP and END_MESSAGE_MAP.. is there a way to make this message map dynamically?

thanks for the help Smile | :)

still a newb.. cut me some slack :P
-dz

Re: Dynamic CEdit can't call DoDataExchange()?

Sara Burns6-Dec-02 11:00

Sara Burns

6-Dec-02 11:00

I think you need to handle this using the OnCommand message if you have created a dynamic control.

Sara

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