C / C++ / MFC Discussion Boards

Antti Keskinen13-Sep-04 4:15

13-Sep-04 4:15

If you want to be sure by what name a function is exported, use a module definition file and rebuild the DLL. For example:

// In DLL code, somewhere
__declspec(dllexport) int Setup(void);<DIV>

// The module definition file
LIBRARY   "MyDLL.DLL"<DIV>

EXPORTS
     Setup   @1

This would export the Setup function from the DLL with it's true name, and GetProcAddress will not fail if you ask it to look for a function called "Setup". Also, using both the __declspec and the definition file is just about making sure it works. It will not get exported twice.

Also, you can rename the exported symbols in the module definition file. Assuming that Setup is still the function name inside the DLL you wish to export, the following statement under EXPORTS would rename this symbol:

Exported1 = Setup   @1

Now, requesting "Exported1" with GetProcAddress would return the address of "Setup". However, asking for "Setup" would return an error.

Basically, the difference on which one to use depends on if you want a library file (.LIB) or not. The __declspec(dllexport) adds an entry to the library file, so that if you link with this library file, you can call the exported functions, and the DLL will be loaded and the function executed (static linking). However, if you use dynamic (run-time) loading, the module definition file is the only way to specify the names of the exported functions explicitly. It is not possible to use a library file with dynamic loading. This will not work, it is just not designed to work that way.

-Antti Keskinen

----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.

Re: Link/C-calling convention ?

0v3rloader14-Sep-04 1:47

0v3rloader

14-Sep-04 1:47

Great stuff Antti!

That is exactly what I was looking for!

Thanks a lot for the invaluable feedback, Antti.

- David

Environment macro

Rome Singh12-Sep-04 6:31

Rome Singh

12-Sep-04 6:31

I would like to put the output of one of my projects in the SYSTEM32 directory but I can't find the macro to use. I'm trying to set it in the Project->Properties->General->Output Directory.

I'm looking for something similiar to $(OutDir), $(TargetDir)...

Thanks in advance,

RS

Re: Environment macro

Andrew Walker12-Sep-04 14:46

Andrew Walker

12-Sep-04 14:46

You can use all of the visual studio pre-defined macros, or you can use standard environment variables.

This works on my win2k box

$(SYSTEMROOT)\system32

If you can keep you head when all about you
Are losing theirs and blaming it on you;
If you can dream - and not make dreams your master;
If you can think - and not make thoughts you aim;
Yours is the Earth and everything that's in it.

Rudyard Kipling

Re: Environment macro

Rome Singh13-Sep-04 5:12

Rome Singh

13-Sep-04 5:12

Thanks Andrew that works fine on my win2k machine as well. I'll have to test it out on XP.

In you signature you have "If you can think - and not make thoughts you aim;"

Should it be "thoughts YOUR aim"?

Thanks again...

RS

Re: Environment macro

Andrew Walker13-Sep-04 12:52

Andrew Walker

13-Sep-04 12:52

Rome Singh wrote:
Should it be "thoughts YOUR aim"?

Blush | :O

and it's been like that for almost 18 months, Blush | :O

If you can keep you head when all about you
Are losing theirs and blaming it on you;
If you can dream - and not make dreams your master;
If you can think - and not make thoughts your aim;
Yours is the Earth and everything that's in it.

Rudyard Kipling

Warning: no message line prompt for ID *????

jettocrack12-Sep-04 6:13

jettocrack

12-Sep-04 6:13

Hi! I have a little problem

When running my mfc mdi app, I get that message from the debugger whenever my cursor flyes over certain toolbar buttons. Next to the ID, apears the buttons identifier

Those buttons have an update message handler (CCmdUI stuff) directly linked with the current CView, so their state change as you switch between views, depending on the view internal state. Buttons without update handlers don't show that behaviour

What that does the message exactly mean? On the other side, the app works ok, so it's a bit strange. I surfed the web, but no infor related to this was found.

Thanks in advance to all.

Re: Warning: no message line prompt for ID *????

Ravi Bhavnani12-Sep-04 7:13

Ravi Bhavnani

12-Sep-04 7:13

That's the application framework letting you know that you haven't defined a fly-by message and tooltip for the toolbar button's id. To fix the problem, define a string resource (with the toolbar button's id) of the following form:

"Command description\nTooltip"/ravi

My new year's resolution: 2048 x 1536
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Problem Regarding Tree in DOTNET

eshban28412-Sep-04 6:08

eshban284

12-Sep-04 6:08

Hello,

I attach a "TREE CONTROL" in VC++.net, and add a parent and some child nodes.

It works well.

Now i want that, When i click on 1st Child, it display a Message Box with a text, "You clicked on 1st Child".

And when i click on "Second Child", it prints in a Message Box "You Clicked" on 2nd Child.

Kindly help me, that how can i do this.

Regards,
Eshban

EsHbAn BaHaDuR

Re: Problem Regarding Tree in DOTNET

Antti Keskinen12-Sep-04 10:12

Antti Keskinen

12-Sep-04 10:12

The message TVN_SELCHANGED is generated when the selection in the tree control is changed. It gives you a pointer to the item structure which the user selected.

To capture the TVN_SELCHANGED message in MFC, write the following code inside the BEGIN_MESSAGE_MAP and END_MESSAGE_MAP macros located in the window class that is the parent for the tree control:

ON_NOTIFY( TVN_SELCHANGED, tree-ctrl-id, OnSelChanged )

Then add a member function to the class like this:

afx_msg void OnSelChanged( NMHDR * pNotifyStruct, LRESULT * result );

Then write the following skeleton for the handler function:

afx_msg void memberFxn( NMHDR * pNotifyStruct, LRESULT * result )
{
    // Cast to correct structure. See TVN_SELCHANGED in Platform SDK for details
    NMTREEVIEW* pTreeView = dynamic_cast<NMTREEVIEW*>( pNotifyStruct );<DIV>

    // Using the new pointer, fetch the name of the newly selected node
    CString strNodeName( pTreeView->itemNew->pszText );

    // Your code here
}

If you need to identify the items based on their ID, you need to originally store this ID as the lParam value in the TVITEM structure. It can be an integer, for example. When you store it there, you can use the itemNew pointer to get it via the lParam member. An example as follows:

// Add a new item. The '1' specifies the ID
pTreeCtrl->InsertItem( TVIF_PARAM | TVIF_TEXT, _T("Child node 1"), 0, 0, 0, 0, 1, hParentNode, NULL );<DIV>

// Later, in the handler function, get the ID
int ID = (int) pTreeView->itemNew->lParam;

I hope this will help you. If you have further questions/problems, post them here.

-Antti Keskinen

----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.

Double buffering in MFC

amigaguy12-Sep-04 6:07

amigaguy

12-Sep-04 6:07

I'm having problem getting double buffering to work in MFC.

I have tried to implement it based on the information found on this page http://codeproject.com/gdi/flickerfree.asp

The problem is that I don't really understand how to "override" the OnDraw method. There are no OnDraw method in the code that was generated when I created the project, and I have tried to just add the method in there but it's never called.

I'm using Visual C++ 7.0 (.net) and the ClassWizard that is mentioned on a lot of examples regarding this issue seems to be removed from the new version of Visual Studio.

I would be greatfull for some pointers on how to do this.

Re: Double buffering in MFC

Antti Keskinen12-Sep-04 10:33

Antti Keskinen

12-Sep-04 10:33

What is the project type you created ? A MDI application ? An SDI application ? A dialog project ? The OnDraw method is only there if you are handling a class based on CView. CView::OnDraw is a virtual function that you can override in order to define custom behaviour.

The concept of overriding is related to the object-oriented programming model. Consider that you have a class, call it class Alpha, for now. Class Alpha has a member function called Func1 that is declared as virtual. If you derive a class called Class Beta from Alpha, and write a function called Func1 in there, this new function will override the old Func1 from Alpha.

In the MFC world, the class thinking is at large. What OnDraw does is answer to WM_PAINT windows message.

The Visual Studio .NET doesn't boast ClassWizard anymore. It is replaced by a more functioning event list in the Properties of the class. I assume you know how to use the Class View, which shows all the classes your project contain. In this view, right-click on the class name you wish to write a message handler to, then select 'Properties'. In the properties view, look for a row of buttons in the top section. From these, find one which gives a tooltip 'Messages' or 'Events'. Click on it. A list of Windows messages you can react to is displayed. Find 'WM_PAINT', and write 'OnPaint' into the box next to it and press enter.

Now write the code to first create a CMemDC, and draw your stuff there. Then destroy the CMemDC or let it go out of scope, and it will blit the new graphic into the target device context.

-Antti Keskinen

----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.

Re: Double buffering in MFC

Anonymous12-Sep-04 11:50

Anonymous

12-Sep-04 11:50

It's a dialog project. Basicly I have a bitmap image that stretches as the background when the window is resized,
and I don't want it to flicker when I resize the window. The bitmap is drawn in the OnEraseBkgnd method, I dont know if that is all that clever but... Smile | :)

I have moved the drawing to the OnPaint() method. Should I call Invalidate() in the OnResize() method to for an WM_ONPAINT event?

CDaoDatabase connection string in Windows XP

olis12-Sep-04 5:36

olis

12-Sep-04 5:36

Hello.

I try to Open CDaoDatabase object in Windows XP (the user has the Excel
2000), and I use the "Excel 8.0" connect string. It returns the following
error "Couldn't Find Installable ISAM". BUT the same code works in Windows
2000. I tried the "Excel 9.0" and "Excel 10.0", but without success...

CDaoDatabase* p_daoDB = NULL;

p_daoDB = new CDaoDatabase;
p_daoDB->Open(_T("SCCardOS.XLS"), // file name
FALSE, // exclusive
FALSE, // read only
_T("Excel 8.0;")); // connect string

I found the post with the same problem, but without solution ;(
I need some tips for solving...

Thank you in advance.

Process help

swarup12-Sep-04 4:40

swarup

12-Sep-04 4:40

Hi there,

i want to know some things regarding process in windows. how to hide a process name. i know there is a sample in codeproject. i want to know what are the steps or what is logic behind it. what is the process difference in windows 95 series and windows nt series.

and how to hide my appication icon that comes up when you press alt+tab. in that small dialog your app icon shows up if there is more then one app running. can i remove my icon from there.

reagrds
swarup

Toolbar in views

Jens Christiansen12-Sep-04 3:26

Jens Christiansen

12-Sep-04 3:26

Hi,

how can I add a toolbar on a view, and not the mainframe ?

How can I export my class in "Regular DLL that statically linked MFC"?

Behzad Ebrahimi12-Sep-04 3:20

Behzad Ebrahimi

12-Sep-04 3:20

How can I export my class in "Regular DLL that statically linked MFC"?

My class does NOT inheritance from CObject.
But it use MFC class such as CString.

Also if my class inheritance from CObject, how can I do it?

Thanks Hmmm | :|

Dialog in taskbar steals focus from children

PEK12-Sep-04 1:49

PEK

12-Sep-04 1:49

I have a dialog in my application that I want to be shown in the taskbar (it's not the main window). I do this by calling this in OnInitDialog:

::SetWindowLong( m_hWnd, 
 GWL_EXSTYLE,
 GetWindowLong(m_hWnd, GWL_EXSTYLE)|WS_EX_APPWINDOW
 );

This works quite well but there is one minor bug. If that dialog has a children, for example a message box, the message box doesn't get the focus when the user click on the button in the taskbar. Instead the dialog receive the focus. If the user use Alt+Tab or trying to click on the dialog, the message box gets the focus as expected. Any suggestion how to solve this?

I'm using VC6 and have tested this in NT4.

Re: Dialog in taskbar steals focus from children

Gary R. Wheeler12-Sep-04 2:44

Gary R. Wheeler

12-Sep-04 2:44

You need to ensure that the parent window of the message box is the dialog.

Software Zen: delete this;

Re: Dialog in taskbar steals focus from children

PEK12-Sep-04 4:55

PEK

12-Sep-04 4:55

Thanks, but I get it same result if I do this:

::MessageBox( m_hWnd, "Bla bla bla", NULL, MB_OK);

I have checked with Spy++ and the handles are set up correctly.

However, I have found a workaround. I handle the WM_SETFOCUS message in the dialog. If the dialog gets focus and the window isn't enabled, it tries to change the focus to the popup window:

LRESULT CDialog2::OnSetfocus(WPARAM wParam, LPARAM lParam)
{
  //Window is not enabled if popup window
  if(!IsWindowEnabled())
  {
    HWND child = ::GetWindow(m_hWnd, GW_HWNDPREV);
    if(child != NULL)
    {
       TRACE(_T("Has child!\n"));
       ::SetFocus(child);
    }
  }

  return 0;
}

I don't like this solution sense I doesn't understand what's going on, but I guess I could live with that.

background color

Joerg Warthemann12-Sep-04 1:42

Joerg Warthemann

12-Sep-04 1:42

Hi,

i'm developing an MDI-application with mfc .net . Now i have the question how to change the Background-Color, so that Menu, Toolbar and Statusbar - even everything - has the same style.
I first thought that updating the Function AfxRegisterWndClass(...) with my own background-brush will help. But it doesn't work. Than I tried CWinApp::SetDialogBkColor() but its not available in Visual C++ 7.
Handling the WM_CTLCOLOR or WM_ERASEBKGND messages also did no effect.

Is there any way or am i hit with blindness?

Thanx
Jo

Getting the -REAL- printable area of a page

Ernesto D.11-Sep-04 21:48

Ernesto D.

11-Sep-04 21:48

Hi all, to get the real printable area of a page (on a printer of course)
is it correct to do it like this?
assuming that i want to use HIMETRIC, mydc is a device context (CDC class), and it has allready been "opened" to my printer...

dc.SetMapMode(MM_HIMETRIC);
CSize pagesize;
// get the "physical" size of the page...
pagesize.cx=dc.GetDeviceCaps(PHYSICALWIDTH);
pagesize.cy=dc.GetDeviceCaps(PHYSICALHEIGHT);

// now take off the non printable area
pagesize.cx-=dc.GetDeviceCaps(PHYSICALOFFSETX);
pagesize.cy-=dc.GetDeviceCaps(PHYSICALOFFSETY);

// returned values were in device units, we need himetric
dc.DPtoHIMETRIC(&pagesize);

// pagesize now has the real printable area of the page

is this correct? is there a better way?
thanks!

Re: Getting the -REAL- printable area of a page

Blake Miller13-Sep-04 6:10

Blake Miller

13-Sep-04 6:10

In some, if not most cases, I have found that the PHYSICALOFFSETX and PHYSICALOFFSETY would apply to BOTH edges of the page, so you might want to do your math like this:

// now take off the non printable area
pagesize.cx-= (2 * dc.GetDeviceCaps(PHYSICALOFFSETX));
pagesize.cy-= (2 * dc.GetDeviceCaps(PHYSICALOFFSETY));

I also don't think this accounts for any of the margins the user might have set for the printing area.

You might want to also obtain the printer device context (CreateDC) and examine the DEVMODE fields:

dmYResolution - Specifies the y-resolution, in dots per inch, of the printer. If the printer initializes this member, the dmPrintQuality member specifies the x-resolution, in dots per inch, of the printer.

Or you can get the from associated with a print job and check these fields:
Size - Specifies the width and height, in thousandths of millimeters, of the form. ImageableArea - Specifies the width and height, in thousandths of millimeters, of the form.

how to find which port is active?

anuchelvi11-Sep-04 20:55

anuchelvi

11-Sep-04 20:55

hai,
I need to find the port which is precently active and set the port settings and send date to that particular port and to receive data from that port,how am i to do it?

mithila

Re: how to find which port is active?

Mad__13-Sep-04 4:49

Mad__

13-Sep-04 4:49

What kind of ports you meen : COM, LPT, USB ? Cool | :cool:

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.