C / C++ / MFC

Victor Nijegorodov29-May-19 5:28

29-May-19 5:28

Yes, you can use CreateEvent, change the folder, set its value in lpParam, then SetEvent to let the thread to reread lpParam and continue to work with a new folder.
Note, that thread must now wait for multiple objects!

_Flaviu29-May-19 21:23

29-May-19 21:23

Thank you Victor, can you elaborate a little bit ? Even some pseudo-code will be good Smile | :)

Victor Nijegorodov29-May-19 23:01

29-May-19 23:01

Have a look at the WorkerThreads essay of Joe Newcomer.
It is MFC issue, but the main concept is the same as for plain Win32 API. Just look at the sections:
Pausing a Thread and Thread Shutdown
Shutting down a thread from a view or main frame
Thread Shutdown Without Polling
(Well, you would need something similar to "Pausing" event.

_Flaviu29-May-19 23:23

29-May-19 23:23

I have two questions:
1. Why should I use CreateEvent, and if I should, where ?
2. Why should I use WaitForMultipleObjects instead of WaitForSingleObject ?

Victor Nijegorodov30-May-19 0:46

30-May-19 0:46

to inform the worker thread that it must do something (to change the folder in your case). CreateEvent/SetEvent - in the main thread.
Because there is already one object: hFileChange. However the thread should react also to the second object created/set by CreateEvent/SetEvent in the main thread.

_Flaviu29-May-19 23:26

29-May-19 23:26

There will be ideal a little code Smile | :)

leon de boer30-May-19 1:30

leon de boer

30-May-19 1:30

Ask and you shall receive .. that is it straight on the windows API.
GitHub - LdB-ECM/FolderWatcher[^]

There is both the detailed and basic thread monitor code.

There is a compiled exe in release/debug if you just want to run and see it.

In vino veritas

_Flaviu30-May-19 21:08

30-May-19 21:08

Here is what I've done:

C++

// TestFileView.h : interface of the CTestFileView class

protected:
	CEvent m_event;
	CString m_sFolder;
	CWinThread* m_pWinThread;

C++

/*static*/UINT CTestFileView::FilesWatchDogThread(LPVOID lpParam)
{
	CTestFileView* pView = (CTestFileView*)lpParam;

	if (NULL == pView->GetSafeHwnd())
		return 1;

	HANDLE hChange = FindFirstChangeNotification(pView->GetFolder(), FALSE,	FILE_NOTIFY_CHANGE_FILE_NAME);

	if (INVALID_HANDLE_VALUE == hChange)
		return 1;

	HANDLE aHandles[2];
	aHandles[0] = hChange;
	aHandles[1] = pView->m_event.m_hObject;

	BOOL bContinue = TRUE;
	while (bContinue)
	{
		DWORD dwResult = WaitForMultipleObjects(2, aHandles, FALSE, INFINITE);
		switch (dwResult)
		{
		case WAIT_OBJECT_0:
			::PostMessage(pView->GetSafeHwnd(), WMU_NOTIFY_FOLDERCHANGED, 0, (LPARAM)0);
			FindNextChangeNotification(hChange);
			break;
		case WAIT_OBJECT_0 + 1:
			bContinue = FALSE;
			break;
		}
	}

	FindCloseChangeNotification(hChange);

	return 0;
}

and

C++

void CTestFileView::StopThread()
{
	m_event.SetEvent();
	WaitForSingleObject(&m_event, INFINITE);
}

and

C++

void CTestFileView::OnEditStartthread()
{
	// TODO: Add your command handler code here

	m_event.ResetEvent();
	m_sFolder.Format(_T("D:\\Tempx\\"));
	m_pWinThread = AfxBeginThread(&CTestFileView::FilesWatchDogThread, (LPVOID)this, THREAD_PRIORITY_NORMAL, CREATE_SUSPENDED, 0, NULL);
}

there is remain one thing to do: to change the folder (m_sFolder) how can I complete this with CreateEvent/SetEvent ?

_Flaviu30-May-19 22:12

30-May-19 22:12

"Go to ParentYes, you can use CreateEvent, change the folder, set its value in lpParam, then SetEvent to let the thread to reread lpParam and continue to work with a new folder"

To create a third event which stop the thread and restart FilesWatchDogThread method with new folder value ?

Victor Nijegorodov30-May-19 22:39

30-May-19 22:39

yes, you create the third event and NOT to stop thread, but to change the folder!
Something like:

case WAIT_OBJECT_0 + 2:
     FindCloseChangeNotification(hChange);
     hChange = FindFirstChangeNotification(pView->GetFolder(), FALSE,    FILE_NOTIFY_CHANGE_FILE_NAME);
     aHandles[1] = pView->m_event.m_hObject;

And don't forget to set the new folder from the main thread BEFORE setting this event!

_Flaviu30-May-19 23:57

30-May-19 23:57

Do you meant

C++

aHandles[0] = hChange;

instead of

C++

aHandles[1] = pView->m_event.m_hObject;

Victor Nijegorodov31-May-19 0:01

Know when a files has been copied

31-May-19 0:01

Yes! Sorry for the typo! Sigh | :sigh:

_Flaviu28-May-19 5:36

Re: Know when a files has been copied

28-May-19 5:36

I have a MFC app which list some files (from an HDD folder) into a CListCtrl. Is there any windows message to know when a files was deleted/copied with other app (e.g. Windws Explorer) from that folder where I listed the files ? I need that message in order to handle it to refresh my file list ...

Richard MacCutchan28-May-19 5:50

FindFirstChangeNotificationA function (fileapi.h) | Microsoft Docs[^].

28-May-19 5:50

Re: Know when a files has been copied

Victor Nijegorodov28-May-19 20:37

Re: Know when a files has been copied

28-May-19 20:37

Have a look at ReadDirectoryChangesW function (winbase.h) | Microsoft Docs

Dave Kreskowiak31-May-19 2:49

Dave Kreskowiak

31-May-19 2:49

There is nothing that will tell you when a file is "copied". There is really no such operation. All a copy is is a file being opened for read and another being opened for write. The bytes in the first file are read and then written to the second file. You cannot get a notification of the read but you can for the file being created. See the links the other have posted for that.

Asking questions is a skill
CodeProject Forum Guidelines
Google: C# How to debug code
Seriously, go read these articles.

Dave Kreskowiak

I have 3rd party . OCX file. which loads in HTML scripts and do desired work

Gaurav__Kapoor26-May-19 22:12

Gaurav__Kapoor

26-May-19 22:12

I have 3rd party . OCX file. which loads in HTML scripts and do desired work

Below Steps I have used while creating a Wrapper:

1: In visual Studio-> VC++-CLR-ClassLibrary project
2: Project add Reference (.ocx file)
3: Ref: i am abe to see Interop.Filelib.1.0
4: now in Project.h i am trying to use Filelib but not able to create any object or instance.

While i tried to create an Activex project and added .ocx file getting below stuff and i am not able to understand how to use it and create an wrapper for C#. 

class CDNXCardReaderX : public CWnd
{
protected:
DECLARE_DYNCREATE(CDNXCardReaderX)
public:
CLSID const& GetClsid()
{
static CLSID const clsid
= { 0x222BBB5D, 0xE9FC, 0x4EB6, { 0x9E, 0xD0, 0x41, 0x10, 0x2C, 0x95, 0xC0, 0x3A } };
return clsid;
}
virtual BOOL Create(LPCTSTR lpszClassName, LPCTSTR lpszWindowName, DWORD dwStyle,
const RECT& rect, CWnd* pParentWnd, UINT nID, 
CCreateContext* pContext = NULL)
{ 
return CreateControl(GetClsid(), lpszWindowName, dwStyle, rect, pParentWnd, nID); 
}

BOOL Create(LPCTSTR lpszWindowName, DWORD dwStyle, const RECT& rect, CWnd* pParentWnd, 
UINT nID, CFile* pPersist = NULL, BOOL bStorage = FALSE,
BSTR bstrLicKey = NULL)
{ 
return CreateControl(GetClsid(), lpszWindowName, dwStyle, rect, pParentWnd, nID,
pPersist, bStorage, bstrLicKey); 
}

// Attributes
public:

// Operations
public:

long OpenSessionSync(long Timeout)
{
long result;
static BYTE parms[] = VTS_I4 ;
InvokeHelper(0x2d, DISPATCH_METHOD, VT_I4, (void*)&result, parms, Timeout);
return result;
}


I am totally clueless on what approach shall i use to create object and call these functions.

Re: I have 3rd party . OCX file. which loads in HTML scripts and do desired work

Richard MacCutchan26-May-19 22:35

Re: I have 3rd party . OCX file. which loads in HTML scripts and do desired work

26-May-19 22:35

That is MFC code: MFC Desktop Applications | Microsoft Docs[^]. You can also go back to wherever you got the library to see if they have any documentation. I also have a suspicion that CLR and MFC do not mix.

Gaurav__Kapoor27-May-19 2:17

Gaurav__Kapoor

27-May-19 2:17

I got your point. here i tried to get the object from my ocx and tried to access the functions but I am failing to do so i feel the issue is because of

IMPLEMENT_DYNCREATE(CMFCActiveXControl1Ctrl, COleControl)

looking for a sample code if any.

Re: I have 3rd party . OCX file. which loads in HTML scripts and do desired work

Richard MacCutchan27-May-19 3:40

Clever macro to handle consecutive addresses with built-in static_assert

27-May-19 3:40

Gaurav__Kapoor wrote:
i feel the issue is because of

Forget what you feel and study the documentation. That is the only way to understand the code.

arnold_w24-May-19 22:54

arnold_w

24-May-19 22:54

I'm writing code for a microcontroller in standard C and I'm compiling with GCC. My product has registers with addresses:

C++

enum regAddr_e {
   REG_A = 0,
   REG_B = 2,
   REG_C = 4
};

typedef struct {
    regAddr_e regAddr;
    uint16_t regValue;
} regAddrAndValue_s;

When I want to write to registers, I create an array of regAddrAndValue_s and pass it to my write function. However, I have found that I quite often write to consecutive addresses so a lot of times only the start address would be needed:

C++

typedef struct {
    regAddr_e startRegAddr;
    uint16_t regValues[];
} consecutiveRegAddrAndValues_s;

However, as a documentation I would like to keep all registers visible in the code. So, I would like have a macro that does something like this:

C++

#define MY_CLEVER_MACRO(__NAME_OF_STRUCT_VARIABLE__)   \
   REG_A, 0x0123,                                      \
   REG_B, 0x04567,                                     \
   REG_C, 0x89AB

The macro should produce:

C++

consecutiveRegAddrAndValues_s __NAME_OF_STRUCT_VARIABLE__ = {REG_A, {0x0123, 0x4567, 0x89AB}};

Also, if someone changes the register addresses so that a range is no longer consecutive, then I would like to throw a compile-time static_assert. Can someone please help me what MY_CLEVER_MACRO should look like?

Re: Clever macro to handle consecutive addresses with built-in static_assert

Stefan_Lang26-May-19 22:15

Stefan_Lang

26-May-19 22:15

If you want to 'document' where you're writing to, why not just provide several functions that offer this information right in their name? E. g.;

C++

void setreg_A(uint16_t aval);
void setreg_B(uint16_t bval);
void setreg_C(uint16_t cval);
void setreg_all(uint16_t aval, uint16_t bval, uint16_t cval);

If that isn't what you want, what is? Can you show a line of code that would invoke your 'clever macro'? It's hard to say what is your intention without seeing how you're going to use it.

GOTOs are a bit like wire coat hangers: they tend to breed in the darkness, such that where there once were few, eventually there are many, and the program's architecture collapses beneath them. (Fran Poretto)

"A rose by any other name would smell as sweet" - so what is the BEST name for "open_dev" function return?

Vaclav_19-May-19 16:54

Vaclav_

19-May-19 16:54

Just experienced an interesting behavior of my code AFTER getting cute and using "socket" for name of the return from

hci_open_dev

.
The particular return was really described as "socket" - connection between processor and bluetooth "adapter" - but was originally named "sock".

After much search I realized that "hci" API names the return
"device descriptor"

and other known "opening device" function calls it "file descriptor".

Then I discovered "file handle " !
Is "handle" an ancient "windows OS" term ?

After this unpleasant experience I'll definitely NOT name anything "socket" , but I am curious what name would be really descriptive ( no pun intended ) for the return of generic "open_x" function ?

C++

dev_descriptor = hci_open_dev(dev_id);

And if you feel it is a matter of personal preference, you do not need to state that.
Maybe it is covered in today's "ANSI C standards" - if there is such a thing.

Cheers

Re: "A rose by any other name would smell as sweet" - so what is the BEST name for "open_dev" function return?

Richard MacCutchan19-May-19 21:28