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CWinThread and CDialog - getting them work together

Hello,

I have created a new thread - that works perfect. Now I want to display a CDialog in this thread. In a Thread Montor a new thread with the name of the dialog is shown but i can not see the dialog. I have called the dialog without a thread - that worked. That have I done wrong?

Below some code which may help.

Greedings Sonja
// Call of the thread
//--------------------
 
  CMyThread * MyThread = new CMyThread();
  MyThread ->CreateThread(CREATE_SUSPENDED);
  MyThread ->m_Parameter = Parameter;
  MyThread ->m_pDialog = pDialog;
  MyThread ->ResumeThread();
 
// MyThread.cpp - class CMyThread : public CWinThread
//--------------
 
int MyThread::Run()
{
  //pDialog initialized to NULL in the constructor of CMyWnd class
   CMyDialog* pDialog = new CMyDialog();
   //Check if new succeeded and we got a valid pointer to a dialog object
   if(pDialog != NULL)
   {
      BOOL ret = pDialog->Create(IDD_MYDIALOG,NULL); // <- In the debugger it stops here
      if(!ret)   //Create failed.
         AfxMessageBox("Error creating Dialog");
      pDialog->ShowWindow(SW_SHOW);
   }
   else
      AfxMessageBox("Error Creating Dialog Object");
  return 0;
}

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1
Sonja_M
Asked:
Sonja_M
1 Solution
 
alb66Commented:
You should avoid to open a dialog in a different thread
0
 
AndyAinscowCommented:
There are two types of thread.  A worker thread (does NOT support windows) and a UI thread (does support windows).
Which type are you using?  I suspect the first.
0
 
mrwad99Commented:
>> int MyThread::Run()

Don't forget that when Run() returns, the thread ends.  So your thread will only be around for a split second.  

Generally it is a good idea not to override CWinThread::Run().  A better place to put your code is in InitInstance().  Add this function to your class and move the code to create the dialog into it.  This should resolve the problem.

HTH
0
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mrwad99Commented:
OK this works.  The key is in setting CWinThread::m_pMainWnd to be your dialog:

BOOL MyThread::InitInstance()
{
	CMyDialog* pDialog = new CMyDialog();
	BOOL ret = pDialog->Create(IDD_MYDIALOG,NULL); 
 
	m_pMainWnd = pDialog;
	
	m_pMainWnd->UpdateWindow();
	m_pMainWnd->ShowWindow( SW_SHOW );
 
	return CWinThread::InitInstance();
}

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0
 
mrwad99Commented:
>> The key is in setting CWinThread::m_pMainWnd to be your dialog:

Sorry but that is not true, I made a mistake.  The key is in returning TRUE (not CWinThread::InitInstance(), which returns FALSE, thereby shutting down the thread) from InitInstance().  You don't have to do anything with m_pMainWnd.

Revised code follows.
BOOL MyThread::InitInstance()
{
        CMyDialog* pDialog = new CMyDialog();
        BOOL ret = pDialog->Create(IDD_MYDIALOG,NULL); 
        
        pDialog->UpdateWindow();
        pDialog->ShowWindow( SW_SHOW );
 
        return TRUE;
}

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0
 
Sonja_MAuthor Commented:
Thank you! Now it is working! Problem solved.
0
 
mrwad99Commented:
Glad to help.
0

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