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When I don't have classes I do this to export my entry points:
//########################
//C++
extern "C" __declspec(dllexport) int __stdcall SumUp_unmgdCPP(int a, int b, int* c)
{
c[0]=4; c[1]=3; c[2]=2; c[3]=1;
//########################
//C#
[DllImport("NameOfDLL", CallingConvention = CallingConvention.StdCall)]
public static extern int SumUp_unmgdCPP(int a, int b, int[] f);
public int SumUp(int a, int b, ref int[] f)
{
return SumUp_unmgdCPP(a, b, f);
How do you do it in a C++ dll-project with classes? I did this:
class FMS
{
public:
extern "C" __declspec(dllexport) int __stdcall SumUp_unmgdCPP(int a, int b, int* c);
private:
float m_WheelSpeed; // 1
}
It complains about the string "C" above being part of the declaration above. I don't think this is the way you do it when you have classes. Just paste the equivalent of what I'm doing in at the top in a dll-project with no classes but now instead in a C++ dll-project with classes and I will be very thankful.
/Lars
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See here.
"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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Hi,
I could not get the link file path using IContext. I hope if I could read the property of that file I can get it.
Because In this articalhttp://www.codeproject.com/KB/shell/shellextguide5.aspx[^]">The Complete Idiot's Guide to Writing Shell Extensions - Part V, you set the link file path in a static control. I just want to get using InvokeCommand() or using any technique but with right click on my menu item not property item of file.
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Hi, Im a MFC bigginer and neeed help to understand the crash which is caused by my program. I have created a Dialog i MFC and in the method OnInitDialog, I create a class which it creates a function in a thread and there is a loop in the method which sends the values to dialog via a interface. When I try to update the dialog by UpdateData(FALSE)the application crashes.
Please help me out of this problem
Thanks in advance.
M.H
BOOL CThreadDlg::OnInitDialog()
{
CDialog::OnInitDialog();
// Add "About..." menu item to system menu.
// IDM_ABOUTBOX must be in the system command range.
ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
ASSERT(IDM_ABOUTBOX < 0xF000);
CMenu* pSysMenu = GetSystemMenu(FALSE);
if (pSysMenu != NULL)
{
CString strAboutMenu;
strAboutMenu.LoadString(IDS_ABOUTBOX);
if (!strAboutMenu.IsEmpty())
{
pSysMenu->AppendMenu(MF_SEPARATOR);
pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
}
}
// Set the icon for this dialog. The framework does this automatically
// when the application's main window is not a dialog
SetIcon(m_hIcon, TRUE); // Set big icon
SetIcon(m_hIcon, FALSE); // Set small icon
// TODO: Add extra initialization here
Thread1 *pThread = new Thread1(this);
return TRUE; // return TRUE unless you set the focus to a control
}
void CThreadDlg::setValueAlt1(int inValue1, int invalue2)
{
m_Value1.Format("%.3d", inValue1);
UpdateData(FALSE);
}
DWORD WINAPI ThreadFunc( LPVOID lpParam )
{
ISetValue * pISetValue = (ISetValue *)lpParam;
int a=44;
int b = 45;
for (int i=40; i<100; i++)
{
pISetValue->setValueAlt1(i, b );
Sleep(10);
}
return 0;
}
Thread1::Thread1(ISetValue *pISetValue)
{
DWORD dwThreadId;
HANDLE hThread;
LPVOID param = pISetValue;
m_pISetValue = pISetValue;
//pISetValue->setValueAlt1(44, 99);
//return;
hThread = CreateThread(
NULL, // no security attributes
0, // use default stack size
ThreadFunc, // thread function
param, // argument to thread function
0, // use default creation flags
&dwThreadId); // returns the thread identifier
}
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You can't access the user interface from another thread than the main thread. What you need to do instead is send a message to your window with some specific information.
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Please, can somebody show me how I can do that?
Thanks
M.H
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merh wrote: Please, can somebody show me how I can do that?
Sure. Joseph M. Newcomer can: Threads and Processes Article Series[^]
Let's think the unthinkable, let's do the undoable, let's prepare to grapple with the ineffable itself, and see if we may not eff it after all.
Douglas Adams, "Dirk Gently's Holistic Detective Agency"
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Try this:
the thread function:
DWORD WINAPI ThreadFunc( LPVOID lpParam )
{
CWnd * pDlg = (pDlg*)lpParam;
int a = 44;
int b = 45;
for (int i=40; i<100; i++)
{
pDlg->PostMessage(WMU_SETVALUE1, (WPARAM)i,(LPARAM)b);
Sleep(10);
}
return 0;
}
in the dialog.h file
#define WMU_SETVALUE1 (WM_USER+1)
in the message map add following line:
ON_MESSAGE(WMU_SETVALUE1,OnSetValue1)
And add following function:
LRESULT CSurveyUpdateDlg::OnSetValue1(WPARAM wParam, LPARAM lParam)
{
setValueAlt1((int)wParam, (int)lParam);
}
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First of all thanks a lot.
It dosent work. I have the following interface
you mentioned that I could use pDlg->PostMessage(WMU_SETVALUE1, (WPARAM)i,(LPARAM)b);
where is comming pDlg? I have got error at CWnd * pDlg = (pDlg*)lpParam; and pDlg->PostMessage(WMU_SETVALUE1, (WPARAM)i,(LPARAM)b);
I have copied all files maybe you can see my problem better
Thanks
M.h
// ThreadDlg.cpp : implementation file
//
#include "stdafx.h"
#include "Thread.h"
#include "ThreadDlg.h"
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
#ifndef GLOGAL
#define GLOBAL
int Globalvariable;
#endif
class CAboutDlg : public CDialog
{
public:
CAboutDlg();
// Dialog Data
//{{AFX_DATA(CAboutDlg)
enum { IDD = IDD_ABOUTBOX };
//}}AFX_DATA
// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CAboutDlg)
protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
//}}AFX_VIRTUAL
// Implementation
protected:
//{{AFX_MSG(CAboutDlg)
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
};
CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)
{
//{{AFX_DATA_INIT(CAboutDlg)
//}}AFX_DATA_INIT
}
void CAboutDlg::DoDataExchange(CDataExchange* pDX)
{
CDialog::DoDataExchange(pDX);
//{{AFX_DATA_MAP(CAboutDlg)
//}}AFX_DATA_MAP
}
BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)
//{{AFX_MSG_MAP(CAboutDlg)
// No message handlers
//}}AFX_MSG_MAP
END_MESSAGE_MAP()
/////////////////////////////////////////////////////////////////////////////
// CThreadDlg dialog
CThreadDlg::CThreadDlg(CWnd* pParent /*=NULL*/)
: CDialog(CThreadDlg::IDD, pParent)
{
//{{AFX_DATA_INIT(CThreadDlg)
m_Value1 = _T("");
//}}AFX_DATA_INIT
// Note that LoadIcon does not require a subsequent DestroyIcon in Win32
m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);
}
void CThreadDlg::DoDataExchange(CDataExchange* pDX)
{
CDialog::DoDataExchange(pDX);
//{{AFX_DATA_MAP(CThreadDlg)
DDX_Text(pDX, IDC_VALUE1, m_Value1);
//}}AFX_DATA_MAP
}
BEGIN_MESSAGE_MAP(CThreadDlg, CDialog)
//{{AFX_MSG_MAP(CThreadDlg)
ON_WM_SYSCOMMAND()
ON_WM_PAINT()
ON_WM_QUERYDRAGICON()
ON_MESSAGE(WMU_SETVALUE1,OnSetValue1)
//}}AFX_MSG_MAP
END_MESSAGE_MAP()
/////////////////////////////////////////////////////////////////////////////
// CThreadDlg message handlers
BOOL CThreadDlg::OnInitDialog()
{
CDialog::OnInitDialog();
// Add "About..." menu item to system menu.
// IDM_ABOUTBOX must be in the system command range.
ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
ASSERT(IDM_ABOUTBOX < 0xF000);
CMenu* pSysMenu = GetSystemMenu(FALSE);
if (pSysMenu != NULL)
{
CString strAboutMenu;
strAboutMenu.LoadString(IDS_ABOUTBOX);
if (!strAboutMenu.IsEmpty())
{
pSysMenu->AppendMenu(MF_SEPARATOR);
pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
}
}
// Set the icon for this dialog. The framework does this automatically
// when the application's main window is not a dialog
SetIcon(m_hIcon, TRUE); // Set big icon
SetIcon(m_hIcon, FALSE); // Set small icon
// TODO: Add extra initialization here
Thread1 *pThread = new Thread1(this);
return TRUE; // return TRUE unless you set the focus to a control
}
LRESULT CSurveyUpdateDlg::OnSetValue1(WPARAM wParam, LPARAM lParam)
{ setValueAlt1((int)wParam, (int)lParam);
}
void CThreadDlg::setValueAlt1(int inValue1, int invalue2)
{
m_Value1.Format("%.3d", inValue1);
UpdateData(FALSE);
}
void CThreadDlg::OnSysCommand(UINT nID, LPARAM lParam)
{
if ((nID & 0xFFF0) == IDM_ABOUTBOX)
{
CAboutDlg dlgAbout;
dlgAbout.DoModal();
}
else
{
CDialog::OnSysCommand(nID, lParam);
}
}
void CThreadDlg::OnPaint()
{
if (IsIconic())
{
CPaintDC dc(this); // device context for painting
SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0);
// Center icon in client rectangle
int cxIcon = GetSystemMetrics(SM_CXICON);
int cyIcon = GetSystemMetrics(SM_CYICON);
CRect rect;
GetClientRect(&rect);
int x = (rect.Width() - cxIcon + 1) / 2;
int y = (rect.Height() - cyIcon + 1) / 2;
// Draw the icon
dc.DrawIcon(x, y, m_hIcon);
}
else
{
CDialog::OnPaint();
}
}
void CThreadDlg::setValueAlt1(int inValue1, int invalue2)
{
CThreadDlg::PostMessage(WMU_SETVALUE1, (WPARAM)inValue1,(LPARAM)invalue2);
/*m_Value1.Format("%.3d", inValue1);
UpdateData(FALSE);*/
}
// The system calls this to obtain the cursor to display while the user drags
// the minimized window.
HCURSOR CThreadDlg::OnQueryDragIcon()
{
return (HCURSOR) m_hIcon;
}
ThreadDlg.h
// ThreadDlg.h : header file
//
#if !defined(AFX_THREADDLG_H__5BBFDBD6_3EF8_4FD2_8DAD_0C3E22DD797B__INCLUDED_)
#define AFX_THREADDLG_H__5BBFDBD6_3EF8_4FD2_8DAD_0C3E22DD797B__INCLUDED_
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
#include "ISetValue.h"
#include "Thread1.h"
#define WMU_SETVALUE1 (WM_USER+1)
/////////////////////////////////////////////////////////////////////////////
// CThreadDlg dialog
class CThreadDlg : public CDialog, ISetValue
{
// Construction
public:
CThreadDlg(CWnd* pParent = NULL); // standard constructor
void setValueAlt1(int inValue1, int invalue2);
void setValueAlt2(int inValue1, int invalue2);
afx_msg void OnTimer(UINT nIDEvent);
CTime tmeSet;
HANDLE hEvent1 ;
// Dialog Data
//{{AFX_DATA(CThreadDlg)
enum { IDD = IDD_THREAD_DIALOG };
CString m_Value1;
//}}AFX_DATA
// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CThreadDlg)
protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
//}}AFX_VIRTUAL
// Implementation
protected:
HICON m_hIcon;
// Generated message map functions
//{{AFX_MSG(CThreadDlg)
virtual BOOL OnInitDialog();
afx_msg void OnSysCommand(UINT nID, LPARAM lParam);
afx_msg void OnPaint();
afx_msg HCURSOR OnQueryDragIcon();
afx_msg LRESULT OnSetValue1(WPARAM wParam, LPARAM lParam);
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
};
//{{AFX_INSERT_LOCATION}}
// Microsoft Visual C++ will insert additional declarations immediately before the previous line.
#endif // !defined(AFX_THREADDLG_H__5BBFDBD6_3EF8_4FD2_8DAD_0C3E22DD797B__INCLUDED_)
IsetValue.h
#ifndef _test_
#define _test_
//#include <afx.h>
class ISetValue {
public:
//Backend sends the value to GUI
virtual void setValueAlt1(int value1, int value2) = 0; // set value
};
#endif
//////////////////////////////////////////////////
//
// CPaApp.cpp: implementation of the CPaApp class.
//
//
#include "stdafx.h"
#include "Thread1.h"
#include <stdio.h>
//#include "CPaPort.h"
//////////////////////////////////////////////////////////////////////
// Other Member Functions
//////////////////////////////////////////////////////////////////////
#include <windows.h>
#include <conio.h>
static int TestNum = 0;
int PaAppTestNum = 0;
DWORD WINAPI ThreadFunc( LPVOID lpParam )
{
CWnd * pDlg = (pDlg*)lpParam;
int a=44;
int b = 45;
for (int i=40; i<100; i++)
{
pDlg->PostMessage(WMU_SETVALUE1, (WPARAM)i,(LPARAM)b);
Sleep(10);
}
return 0;
}
Thread1.CPP
// set port address
Thread1::Thread1(CDialog *pISetValue)
{
DWORD dwThreadId;
HANDLE hThread;
LPVOID param = pISetValue;
m_pISetValue = pISetValue;
//pISetValue->setValueAlt1(44, 99);
//return;
hThread = CreateThread(
NULL, // no security attributes
0, // use default stack size
ThreadFunc, // thread function
param, // argument to thread function
0, // use default creation flags
&dwThreadId); // returns the thread identifier
}
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
#include "ISetValue.h"
Thread.h
class Thread1
{
protected:
public:
//Thread1(ISetValue *pISetValue);
Thread1(CDialog *pISetValue);
virtual ~Thread1(){};
private:
//ISetValue * m_pISetValue;
//ISetValue *pISetValue;
ISetValue* m_pISetValue;
ISetValue *pISetValue;
};
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You can see I didn't test this ... 
That should have been:
CWnd * pDlg = (CWnd*)lpParam;
If that doesn't work, I'll test it myself! 
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Hi Thanks,
It still dosent work. I get the following error
'CSurveyUpdateDlg' : is not a class or namespace name
'WMU_SETVALUE1' : undeclared identifier
If you have a email adress I can send you my workspace which you can test it easier. For your information I have VC++ 6.0
Thanks
M.H
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I copy-pasted the OnSetValue1 function of a project of mine, and forgot to edit the class name, so CSurveyUpdateDlg::OnSetValue1 should be CThreadDlg::OnSetValue1
And don't forget to add the function prototype in the ThreadDlg.h header file too:
afx_msg LRESULT OnSetValue1(WPARAM wParam, LPARAM lParam);
The WMU_SETVALUE1 error is caused by a missing
#include "Thread.h"
in the file where you're calling PostMessage(WMU_SETVALUE1, ...)
That should do it.
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Hi, have got the crash at BOOL AFXAPI AfxAssertFailedLine(LPCSTR lpszFileName, int nLine)
{
#ifndef _AFX_NO_DEBUG_CRT
// we remove WM_QUIT because if it is in the queue then the message box
// won't display
MSG msg;
BOOL bQuit = PeekMessage(&msg, NULL, WM_QUIT, WM_QUIT, PM_REMOVE);
BOOL bResult = _CrtDbgReport(_CRT_ASSERT, lpszFileName, nLine, NULL, NULL);
if (bQuit)
Thanks
Mehran
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merh wrote: 'CSurveyUpdateDlg' : is not a class or namespace name
'WMU_SETVALUE1' : undeclared identifier
If these basic errors are troubling you, perhaps multithreaded applications should be postponed for a while. They're not a trivial concept.
"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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Hi, I need how I can use PostMessage for sending the message with some parameters to main thread(window) and then how I can read the data from It.
Best regards
Mehran
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Thanks a lot it works.
Have a nice weekend
M.H
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See here.
"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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can anybody tell me how i can call a vb activex dll from c++
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Follow this steps
1) Click on Tools->OLE/COM Object Viewer.
2) Press View TypeLib.
3) Select your VB dll location.
4) This will show you coclass and interfaces of the VB dll.
5) Save this file.This file is an IDL file.
6) Add this IDL file in your project.
7) Right click on IDL file and compile it.This will create a header
file of the IDL file.Now include this file where you want.
8) Use this file which has defination of the coclass and its interfaces.
ritz1234
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philiptabraham wrote: can anybody tell me how i can call a vb activex dll from c++
Find the physical location of the VB file on the disk and use the #import directive to get the declarations into your program. I think if you use a recent enough version of Visual C++, you can #import by lib id.
Nathan
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They can.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
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Hi,
i am saving a HDC in one fuction of a class by using the following code
<br />
MyClass::MyFunction()<br />
{<br />
CDC dc;<br />
AfxGetApp()->CreatePrinterDC(dc);<br />
m_Hdc = dc.GetSafeHdc( );<br />
dc.Detach();<br />
}
Now in some other classes i am Creating a CDC class objcet using this HDC.
CDC *pDC = CDC::FromHandle(MyClasss::getMyHDC());
But some time it is causing my application to crash. But if i replace FromHandle() by Attach() and detach() the application is working fine.
So, i just want to know whether it is safe to use FromHandle() or not. If not should i replace all my FromHandle() by Attach and detach.
Thanks Ashwani
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ashtwin wrote: CDC *pDC = CDC::FromHandle(MyClasss::getMyHDC());
Are you storing the pDC beyond a function call, CDC::FromHandle returns a temporary CDC object if HDC is not already attached. CDC::DeleteTempMap will delete the temporary CDC objects in idle processing. so if you using the object beyond a function call and there by alowing the idle processing to delete the object, application can crash if you access the temp object.
CDC::FromHandle() is less error-prone in the sense you do not have to remember to "detach". but remember it is used only in immediate processing.
In your MyClass::MyFunction(), you are Detaching the CDC, so it is sure that FromHandle creates temp map object, and possibly you are storing beyond a function call.
I suggest you to Keep attached the Printer DC with a member variable CDC and use it everywhere or use attach detach you should match the two calls then, or use FromHandle but with in a function call.
If the frequency of the call is high reduce the number of attach - detach.
modified on Friday, March 14, 2008 8:50 AM
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Hi,
Currently i am using the pDC within the same fuction call though i am calling a seperate function to create it which is returning this pDC to the parent function and again from the parent function i am calling a seperate function which has pDC as one of its parameter.
<br />
CDC* dc = myPrintObj.createDCForPrint(printRect);<br />
doPrintWfReport(dc, printJob);<br />
The Funtion where i am getting the CDC object is as follows
<br />
CDC* PrintJob::PrintJobToPrinterType::createDCForPrint(const NcWfPrintJob& client, const CRect& printRect)<br />
{<br />
REQUIRE(!printRect.IsRectEmpty());<br />
<br />
DOCINFO DI;<br />
ZeroMemory(&DI, sizeof(DOCINFO));<br />
DI.cbSize = sizeof(DOCINFO);<br />
DI.lpszDocName = NcCommonResources().getWFReportDocName();<br />
<br />
CDC* pDC = CDC::FromHandle(client.getPrintInfo().hDC);<br />
pDC->SetMapMode(MM_HIMETRIC);<br />
<br />
pDC->StartDoc(&DI);<br />
pDC->StartPage();<br />
<br />
return pDC;<br />
}<br />
In the current design it is not possible for me to have a CDC object as a member varaible. Is it OK to use FromHandlePermanent() instead of FromHandle().
Thanks
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Do you have FromHandlePermanent for CDC, i think it is for CWnd::FromHandlePermanent.
ashtwin wrote: Currently i am using the pDC within the same fuction call
I assume this is your new change, and works without crash.
ashtwin wrote: In the current design it is not possible for me to have a CDC object as a member varaible
why it is not possible, in createDCForPrint why don't you attach the printer DC to a member variable CDC::Attach and when you done printing you can call cleanup function like DeleteDCForPrint and detach and delete the DC stored in member variable. If you are using the DC within the function call as said above it is ok, make sure the idle processing which deletes the temp DC object not allowed to execute in between.
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