C / C++ / MFC

Re: Using a member from the view class of an mfc program in a dialog box

30-Nov-11 8:40

AndrewG1231 wrote:
It compiles fine, but in runtime the program crashes.

Because you create the variable but never initialise it:

C++

CWinSTMView *pView; // this does not point to any object so
pView->OnImageAutoPlane();  // this will fail

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

Chuck O'Toole30-Nov-11 8:27

Chuck O'Toole

30-Nov-11 8:27

These two statements don't do what you expect

CWinSTMView *pView;
pView->OnImageAutoPlane();

All it does is declare that pView is a pointer to "something" but you don't actually initialize it to point to anything. Then you try to use it.

I assume that the CWinSTMView object was instantiated somewhere else and you are trying to access it. You need to find that object and initialize pView to point to it. How you find that object is your problem as the amount of code posted is not enough for me to guess at it.

Re: Using a member from the view class of an mfc program in a dialog box

AndrewG123130-Nov-11 8:53

Re: Using a member from the view class of an mfc program in a dialog box

30-Nov-11 8:53

Thanks, I will look for where it is instantiated

David Crow30-Nov-11 8:47

Re: Using a member from the view class of an mfc program in a dialog box

30-Nov-11 8:47

Have you tried something like:

// casting not provided
AfxGetApp()->GetMainWnd()->GetActiveView()->OnImageAutoPlane();
// or
AfxGetMainWnd()->GetActiveView()->OnImageAutoPlane();

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AndrewG123130-Nov-11 9:00

Re: Using a member from the view class of an mfc program in a dialog box

30-Nov-11 9:00

I have not, but when I use your suggestion:

class "Cwnd" has no member "GetActiveView"

David Crow30-Nov-11 9:35

Re: Using a member from the view class of an mfc program in a dialog box

30-Nov-11 9:35

Which is why I added the "casting not provided" comment. As I don't know the name of your frame/doc/view classes, you'll need to cast some of those function calls to your specific situation.

AndrewG12311-Dec-11 9:25

Re: Using a member from the view class of an mfc program in a dialog box

1-Dec-11 9:25

I was able to solve the problem after I did some research on the MSDN site about the suggestions of sending messages and GetActiveView().:

// TODO: Add your control notification handler code here
    OnPlaceData();
    //Get the main window which doesn't have a view
    CMDIFrameWnd *pFrame =
             (CMDIFrameWnd*)AfxGetApp()->m_pMainWnd;

    // Get the active MDI child window.
    CMDIChildWnd *pChild =
             (CMDIChildWnd *) pFrame->GetActiveFrame();

    // Get the active view attached to the active MDI child
    // window.
    CWinSTMView *pView = (CWinSTMView *) pChild->GetActiveView();
    pView->OnImageAutoPlane();

Now my pointer points to something and I was able to access that member (and others that I wanted to use as well). Thanks for the help!

JackDingler5-Dec-11 9:38

JackDingler

5-Dec-11 9:38

Before you get too far into finding view pointers and accessing them directly....

This is not a good practice in MDI Programming. The framework supports multiple view types for every document. So the Active View, in theory could return a different class type than you expect. Obviously if you don't have other view types explicitly written then this won't happen... There are also cases where you'll see no Active View, even though from the user's perspective it looks like there is one.

The better solution is to get a pointer to your CDocument instantiation and call a notification method there, instead of your view. I good way to do this is to pass the doc pointer to the dialog when you create the dialog. I like to pass the doc * in the constructor.

Then in the doc, have the notification method, call UpdateAllViews() with a hint as to what data has been changed, and let the view respond to this message.

Re: Using a member from the view class of an mfc program in a dialog box

AndrewG12316-Dec-11 11:49

Re: Using a member from the view class of an mfc program in a dialog box

6-Dec-11 11:49

Thanks, the code works to modify data in the same window when I have only one active child window...but I have been running into problem when the data is saved to a new document and displayed in a second child window. I was working with the view pointers to try and cycle through child windows, but your method seems interesting. The member I am calling, Autoplane(), creates another document already as shown here:

void CWinSTMView::OnImageAutoPlane()
{

    CWinSTMDoc *pDoc = CreateNewDoc(GetDocument());

Can I use this doc pointer as you described?

JackDingler6-Dec-11 13:16

JackDingler

6-Dec-11 13:16

Is it your goal to have two view windows?

The MDI Framework doesn't lend itself well, to creating new documents from user code.

It's easier to add and create additional views.

The way the framework is intended to be used:
1. The document holds your data and resources.
2. The views are intended to be presentation classes that provide a view of the data to the users.

This is why we have a one to many relationship between documents and views.

Re: Using a member from the view class of an mfc program in a dialog box

JackDingler6-Dec-11 13:41

JackDingler

6-Dec-11 13:41

Check out the CSplitterWnd Class

CSplitterWnd

How to use SYSTEM function for specified time

MKC00230-Nov-11 6:37

MKC002

30-Nov-11 6:37

how to use system API for given time
some times a when i call system api, my computer hangs and i need to reboot
can i use for given time

Software_Developer30-Nov-11 7:20

Software_Developer

30-Nov-11 7:20

The API function [SetTimer ] executes a function every x milliseconds or any given time.

MFC version [here].

Console example:
The following console program works like this: It sets a timer using SetTimer
then loops in a message loop. The message loop receives and processes WM_TIMER messages
and the timer callback also is called for each time interval.
Simply put the stuff you want done in the TimerProc() function.

#define STRICT 1 
#include <windows.h>
#include <iostream.h>
 
VOID CALLBACK TimerProc(HWND hWnd, UINT nMsg, UINT nIDEvent, DWORD dwTime) 
{
   //put the stuff you want done in here

  cout << "Doing stuff Time: " << dwTime << '\n';
  cout << "--------------------------------------------------\n" ;
  cout.flush();
}
 
int main(int argc, char *argv[], char *envp[]) 
{
    int Counter=0;
    int usage_Time_millisec=500;
    MSG Msg;
 
    UINT TimerId = SetTimer(NULL, 0, usage_Time_millisec, &TimerProc); //bind TimerProc() to SetTimer() 
 
    cout << "TimerId: " << TimerId << '\n';

   if (!TimerId) return 16;
    
   while (GetMessage(&Msg, NULL, 0, 0)) 
   {
    	++Counter;
    	if (Msg.message == WM_TIMER)
		cout << "Doing stuff Counter: " << Counter << "; timer message\n";
    	else
		cout << "Doing stuff Counter: " << Counter << "; message: " << Msg.message << '\n';
    	DispatchMessage(&Msg);
   }
    
   KillTimer(NULL, TimerId);

return 0;

}

Richard MacCutchan30-Nov-11 7:29

30-Nov-11 7:29

MKC002 wrote:
how to use system API for given time

What exactly do you mean by this; which API and what time?

MKC002 wrote:
some times a when i call system api, my computer hangs and i need to reboot

Perhaps if you show an extract of the code that does this we may be able to help.

MKC002 wrote:
can i use for given time

Use what and for what time - time of day, time interval, ...?

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

MKC00230-Nov-11 17:28

MKC002

30-Nov-11 17:28

our server maintains large amount of data. Everyday new files/folders created on it. A serevice set some special properties for files/folders. One service checkes if some property does not exist in file/folder then move the file to another location for further processing.
Here one service call GetFileAttributes and GetVolumeInformation for disk where file will be move. From this function we get volume label and other information to store in database. Sometimes system hangs and i need to reboot. I noticed system hangs due to GetVolumeInformation.
So, can i set time limit for this function. If after given time i dont get volume label then move the file to another disk.

Richard MacCutchan30-Nov-11 22:06

30-Nov-11 22:06

It's more important to discover why the system hangs on this function; perhaps it is trying to access a network disk and you are having network problems, or the drive is failing. You could also move this code into a background thread and then kill it after a fixed time interval from your main thread.

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

MKC0021-Dec-11 18:17

MKC002

1-Dec-11 18:17

Thanks for your reply. To play with thread is little difficult.
Please give any link to kill thread which is safe and does not result in any type of crash.

Richard MacCutchan1-Dec-11 22:49

trying to find the status of contacts from Office Communicator

1-Dec-11 22:49

MKC002 wrote:
Please give any link to kill thread which is safe and does not result in any type of crash.

You do realise what you are asking! How can I possibly know what code could be added to your program that will not crash it, even if I could be bothered to go and look for such a link? You are the developer it's up to you to do the work.

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

tasumisra30-Nov-11 4:33

tasumisra

30-Nov-11 4:33

Hi Guys,

I am trying to find status of may contacts but not able to find appropriate function

here is the sample for that

#include <windows.h>
#include <tchar.h>
#include "c:\program files\Microsoft Office Communicator\SDK\msgrua.h"

const GUID IID_IMessenger =
{0xD50C3186,0x0F89,0x48f8,{0xB2,0x04,0x36,0x04,0x62,0x9D,0xEE,0x10}};

const GUID CLSID_Messenger =
{0x8885370D,0xB33E,0x44b7,{0x87,0x5D,0x28,0xE4,0x03,0xCF,0x92,0x70}};

const GUID IID_MessengerContacts =
{0xE7479A0F,0xBB19,0x44a5,{0x96,0x8F,0x6F,0x41,0xD9,0x3E,0xE0,0xBC}};

IMessenger* m_pIMessenger;
int _tmain(int argc, _TCHAR* argv[])
{
	CoInitializeEx(NULL, COINIT_APARTMENTTHREADED);
	HRESULT  hr = CoCreateInstance(CLSID_Messenger,NULL,CLSCTX_LOCAL_SERVER,
	IID_IMessenger, (LPVOID *)&m_pIMessenger);

	BSTR myName;
	MISTATUS sMyStatus;

	hr = m_pIMessenger->get_MyFriendlyName(&myName);
	hr = m_pIMessenger->get_MyStatus(&sMyStatus);

	BSTR serviceId;
	m_pIMessenger->get_MyServiceId(&serviceId);

	IDispatch *pContacts;
	IMessengerContacts *pCon;

	m_pIMessenger->get_MyContacts(&pContacts);
	pContacts->QueryInterface(__uuidof(IMessengerContacts),(void**)&pCon);
	
	IDispatch *pDispatch;

	hr=pCon->Item(1,&pDispatch);
	long lCount=0;
	pCon->get_Count(&lCount);

        //here lCount is total number of contacts 
        //now i am not getting appropriate method to iterate through
	CoUninitialize();

	return 0;
}

Please help me in finding appropriate function to get information about each contact.

vikas da

disabling ctrl+scrolllock in my application

VCProgrammer29-Nov-11 22:39

VCProgrammer

29-Nov-11 22:39

Hi all,

I have made a dialog based application and my application is closing if i press ctrl+scrolllock.

I want to disable this action in my application.

Thanks in advance

Software_Developer29-Nov-11 23:27

Software_Developer

29-Nov-11 23:27

Use PreTranslateMessage to intercept the CTRL+SCROLLLOCK key. Add the function to the dialog using the class wizard.

BOOL myDlg::PreTranslateMessage(MSG* pMsg) 
{
	if(pMsg->message==WM_KEYDOWN)
	{
		 if( GetKeyState( VK_CONTROL )
		 {
		     if( pMsg->wParam == VK_SCROLL) ) { return TRUE; }
		 }
	}

return CDialog::PreTranslateMessage(pMsg);
}

More [here]

David Crow30-Nov-11 2:50

30-Nov-11 2:50

Start with a blank dialog application. Run it and press the Ctrl+ScrLck keys. Does anything happen?

modified 1-Dec-11 9:22am.

VCProgrammer30-Nov-11 21:18

VCProgrammer

30-Nov-11 21:18

yes it closes the dialog box

David Crow1-Dec-11 4:06