C / C++ / MFC

5-Sep-05 23:09

Hi,

I have an SDI Application with 3 views: CLeftView, CTopRightView, CBottomRightView. CTopRightView has a CListCtrl. In the code for CLeftView, if some condition is met, I want to add an item to the list control in CTopRightView.

To do this, in CLeftView I set a Doc var to the item i want to add. Next, I call UpdateAllViews() so it can call my Overridden OnUpdate functions in my views. My overriden OnUpdate function in CtopRightView adds the item set in Doc class to the list control.

The Problem: UpdateAllViews() seems to call OnCreate() before it calls my OnUpdate function, thus clearing all the contents I had in the list control, and then calls OnUpdate(). Is there any way to prevent it from calling the OnCreate()? I don't want to recreate the list control, just add an item to it. Unsure | :~

TraileR ParK LifE 4Ever

MailtoGops6-Sep-05 2:30

MailtoGops

6-Sep-05 2:30

UpdateAllViews() should not call OnCreate() method. Could you please make sure, you have created all views and initialized before calling UpdateAllViews() method.

Show us some code snipet..

" Action without vision is only passing time,
Vision without action is merely day dreaming,
But vision with action can change the world "

- Words from Nelson Mandela

Thanks & Regards,

Gopalakrishnan

/*Trucker*\6-Sep-05 9:49

6-Sep-05 9:49

Hi MailToGops,

Thanks for the reply. All views are created and initialized. Below is some code you requested of what I am trying to do:

in CLeftView:

GetDocument()->FileAction(&strFileName,1);

in Doc class:

void Ca1interfaceDoc::FileAction(CString* fl, int acn)<br />
{<br />
	fileName = *fl;<br />
	action = acn;<br />
<br />
	SetModifiedFlag();<br />
	UpdateAllViews(NULL);<br />
<br />
	fileCount++;<br />
}

in CTopRightView:

int CTopRightView::OnCreate(LPCREATESTRUCT lpCreateStruct)<br />
{<br />
	if (CView::OnCreate(lpCreateStruct) == -1)<br />
		return -1;<br />
<br />
	//creating listview<br />
	folderContents.Create(WS_VISIBLE|WS_CHILD|WS_BORDER|<br />
						LVS_LIST|LVS_SINGLESEL,<br />
						CRect(10,10,300,180), this, <br />
						IDC_FOLDERCONTENTS);<br />
<br />
	LV_ITEM lvItem;<br />
	::memset(&lvItem, 0, sizeof(LV_ITEM));<br />
	lvItem.mask = LVIF_TEXT|LVIF_STATE;<br />
	lvItem.state = 0;<br />
	lvItem.stateMask = 0;<br />
	lvItem.pszText = "an item";<br />
	lvItem.iItem = 0;<br />
<br />
	folderContents.InsertItem(&lvItem);<br />
<br />
	return 0;<br />
}<br />
<br />
void CTopRightView::OnUpdate(CView* pSender, LPARAM lHint, CObject* pHint)<br />
{<br />
	//folderContents.DeleteAllItems();<br />
<br />
	if(GetDocument()->action == 1 /*&& !GetDocument()->fileCount*/){<br />
		LV_ITEM lvItem;<br />
		::memset(&lvItem, 0, sizeof(LV_ITEM));<br />
		lvItem.mask = LVIF_TEXT;<br />
		lvItem.pszText = GetNTS(GetDocument()->fileName);<br />
		lvItem.iItem = GetDocument()->fileCount;<br />
<br />
<br />
		if(folderContents.InsertItem(&lvItem) == -1)<br />
			folderContents.DeleteAllItems();<br />
<br />
		GetDocument()->action = 0;<br />
	}<br />
}

The reason I believe OnCreate gets called every time UpdateAllViews() runs is this:
*In CTopRightView::OnCreate() I create the list control along with a test item and add this test item.
*When I run the application I only see 2 items in the CTopRightViews's list control. The test item added in OnCreate() and the last item that was supposed to be added to the list control (many items are supposed to be added to the list control).

So it looks like every time UpdateAllViews is executed it recreates the list control with the test item and the most recent item to be added. Sniff | :^)

TraileR ParK LifE 4Ever

David Crow6-Sep-05 4:31

6-Sep-05 4:31

For an SDI application, this is normal behavior. When a view asks the document for the data to be rendered, it has the choice of adding only new items, or adding all the items (again). I prefer the latter as it is much easier to clear the list control and add all of the items, contrasted with figuring out which items in the document are already in the view's list and which are not.

The MSDN article Q103982 might be remotely related to what you are seeing.

"One must learn from the bite of the fire to leave it alone." - Native American Proverb

/*Trucker*\6-Sep-05 9:24

6-Sep-05 9:24

Hi David,

Thanks for the reply.

So how would I specify that I want the View to add only new items?

The article refers to VC++ 6.1 and older. I am using VC++ .NET. I did not find OnInitialUpdate() function in the .NET Framework for CView, which they talk about in the article.

TraileR ParK LifE 4Ever

David Crow6-Sep-05 9:49

6-Sep-05 9:49

/*Trucker*\ wrote:
So how would I specify that I want the View to add only new items?

How many total items are we talking about here?

/*Trucker*\ wrote:
The article refers to VC++ 6.1 and older. I am using VC++ .NET. I did not find OnInitialUpdate() function in the .NET Framework for CView, which they talk about in the article.

That's why I indicated it might only be remotely related. Big Grin | :-D

"One must learn from the bite of the fire to leave it alone." - Native American Proverb

/*Trucker*\6-Sep-05 10:00

6-Sep-05 10:00

I am not sure why this is relevent but anyways... to give you an idea I will tell u what my application is.

It is Like Windows Explorer. So left pane is the directory tree, but the right pane holds just the files of selected folder in directory tree (dont worry about the third pane I mentioned earlier). So it could be a little, or it could be a lot of files/items... but lets say it shouldn't be too much because this is just an assignment for school I am doing, not some program for Bill Gates Laugh | :laugh:

TraileR ParK LifE 4Ever

David Crow7-Sep-05 3:47

How to use CRecordset with CByteArray for storing BLOBs

7-Sep-05 3:47

I really don't know of a reason to not do it the way I previously suggested, especially for the volume of items you've indicated. It's just a much smoother approach to a fairly common doc/view situation.

I'm curious why you are creating the list views each time they need updating. That's seems a bit inefficient. Why not create them once at the start of the application, and then update their contents as the need arises? With MFC, this is very easy to do using CSplitterWnd.

"One must learn from the bite of the fire to leave it alone." - Native American Proverb

snprani5-Sep-05 23:08

snprani

5-Sep-05 23:08

How to use CRecordset with CByteArray for storing BLOBs

Re: How to use CRecordset with CByteArray for storing BLOBs

G Haranadh6-Sep-05 0:31

G Haranadh

6-Sep-05 0:31

See the article:
Using CLongBinary for BLOBs - By Shekar Narayanan
http://codetools.com/database/usingblob.asp

This link may give you the answer. Try it.
http://msdn2.microsoft.com/library(d=printer)/07w94zsx(en-us,vs.80).aspx

http://www.codeguru.com/forum/showthread.php?t=120577

Cool | :cool:

HAPPY VINAYAKA CHAVITI
Nice talking to you. Blush | :O

delete[] can't replace delete?

followait5-Sep-05 22:59

followait

5-Sep-05 22:59

I made some small tests, it seems that delete[] can always replace delete, without errors.

But in my working project, it is not the case, I don't know why.

toxcct5-Sep-05 23:03

toxcct

5-Sep-05 23:03

without errors, maybe ! but not without memory leaks !!!!!!!!

TOXCCT >>> GEII power
[toxcct][VisualCalc]

-- modified at 5:05 Tuesday 6th September, 2005

S. Senthil Kumar6-Sep-05 2:35

S. Senthil Kumar

6-Sep-05 2:35

Some implementations might delete all memory, so you might not see any memory leak, but no implementation will call the destructor for every element in the array. If you have resources acquired by elements in the array, they won't get released until the program dies.

Regards
Senthil
_____________________________
My Blog | My Articles | WinMacro

Tim Smith6-Sep-05 3:55

Tim Smith

6-Sep-05 3:55

This is what I call "Programming by Behavior" and it is EVIL EVIL EVIL. You are ignoring the rules and just going by how the program appears to work in specific instances.

The C++ standard specifically states that delete [] and delete are not interchangeable. Doing so might work sometimes, but that doesn't mean it will always work.

If you have a class with a destructor, using delete will only invoke the destructor on the first element. Thus causing all sorts of problems if the class has a non-trivial destructor.

NEVER EVER interchange delete with delete []. It is just wrong.

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

David Crow6-Sep-05 4:34

6-Sep-05 4:34

"Appears to work" is not a synonym for "does work correctly."

"One must learn from the bite of the fire to leave it alone." - Native American Proverb

Bob Ciora6-Sep-05 7:55

Bob Ciora

6-Sep-05 7:55

Works as coded.

Bob Ciora

The problem is...

followait6-Sep-05 15:57

followait

6-Sep-05 15:57

p is a pointer to an array, when running, the 1 fragment is ok, the 2 one is wrong. What's the reason?

//in the destructor

//1
if (p!=NULL) {
for (int i=0;i

Re: The problem is...

David Crow7-Sep-05 4:48