Insert new row in CListCtrl: need to improve the speed

tataxin

I have a CListCtrl, each row has a specified color.

// the list ctrl
CListCtrl myList;

// function to set color to a row
myList.SetRowColor(j, crRows.GetAt(j));

Then I need to insert some new rows, the latest is at top. Here is source code

CArray crRows;
CArray newData;
int nNew = newData.GetCount();
for (int i=0; i		// insert new row at top
	CString txt = newData.GetAt(i);
	myList.InsertItem(0, txt);

	// get color, depends on the real data
	COLORREF aColor = GetRowColor(txt);
	crRows.InsertAt(0, aColor)		

	// change the rest of list ctrl
	int nCnt = myList.GetItemCount();
	for (int j = 0; j                     myList.SetRowColor(j, crRows.GetAt(j));
	}
}

I works, but because of 2 loop for, the performance speed is very slow, so I have to improve it Does anyone know what should I do in this case?? Thanks in advance :)

SandipG

Instead of for loop you can just maintain a stack so no movements required. Does it makes sense.

Regards, Sandip.

Nibu babu thomas

tataxin wrote:

but because of 2 loop for, the performance speed is very slow, so I have to improve it

You can call SetRedraw( FALSE ) before the for loop and SetRedraw( TRUE ) in the end or use a virtual list control (http://www.codeproject.com/KB/list/virtuallist.aspx[^]).

Nibu thomas Microsoft MVP for VC++ Code must be written to be read, not by the compiler, but by another human being. Programming Blog: http://nibuthomas.wordpress.com

tataxin

thank for your reply but actually, i'm afraid that I don't understand how to maintain a stack??

SandipG

why you want to maintain STL is there you just have to use it :)

Regards, Sandip.

tataxin

do you mean that:

SetRedraw(false);

// insert data here
....

SetRedraw(true);
myList.RedrawWindow();

I applied it, it looks better but the actual time is the same with previous. And I'll try virtual list control now, thks, :)

tataxin

STL? is that Standard Template Library? sorry SandipG, I really don't understand what you mean. Can you explain more detail, :sigh: :confused:

Nibu babu thomas

tataxin wrote:

do you mean that:

Hope you are adding this above and after the "for" loop. :) Is it necessary to call RedrawWindow?

tataxin wrote:

I applied it, it looks better but the actual time is the same with previous. And I'll try virtual list control now, thks, [Smile]

It's better to use virtual list if volume of data is high!

Nibu thomas Microsoft MVP for VC++ Code must be written to be read, not by the compiler, but by another human being. Programming Blog: http://nibuthomas.wordpress.com

tataxin

yes, for loops are inside, like this

SetRedraw(false);

// insert data here
for()
{
......
for()
{
......
}
}

SetRedraw(true);
myList.RedrawWindow();

it takes same time with the previous, in my project. And, without RedrawWindow(), nothing is showed, myList is empty. Ahh, the idea of virtual list is very nice. I'm reading now, :)

SandipG

Yes tataxin i mean Standard template library. instead of using CArray you can use stack which is LIFO so you dont need to move elements down after every element added.

Regards, Sandip.

Jijo Raj

tataxin wrote:

// get color, depends on the real data COLORREF aColor = GetRowColor(txt); crRows.InsertAt(0, aColor)

containers like CArray, vector are not suitable for insertion. Because those containers keep the data in contagious memory block and if you want to insert one item to middle, they've do a lot of memory moving to keep the items contagious. Go for other insertion friendly containers such as std::list. Check there about how to use it - http://www.cplusplus.com/reference/stl/list/[^]

tataxin wrote:

// get color, depends on the real data COLORREF aColor = GetRowColor(txt); crRows.InsertAt(0, aColor)

If you've lot of items to be added to your listctrl, better lock the control by LockWindowUpdate() then after insertion of all items, unlock by UnlockWindowUpdate(). It will avoid the flicker. Check this - http://weseetips.com/2008/04/19/how-to-update-bulk-amount-of-data-to-gui-controls-without-flicker/[^] Regards, Jijo.

_____________________________________________________ http://weseetips.com[^] Visual C++ tips and tricks. Updated daily.

tataxin

ah, thank you Jijo, I will check it now

tataxin

Nice SandigG, that's what I want, :) but I dont know how to implement this. Can you show me more details.

tataxin

can anyone give me more details or give me some document to read about this? thanks in advance !!

SandipG

Look here [^] Few more.. [^] [^]

Regards, Sandip.

tataxin

hi all, I found a solution, just use the custom draw, do not use a SetRowColor() method. So I just insert new row at top, like this

    CArray crRows;
CArray newData;
int nNew = newData.GetCount();
for (int i=0; i<nnew;>		// insert new row at top
	CString txt = newData.GetAt(i);
	myList.InsertItem(0, txt);

	// get color, depends on the real data
	COLORREF aColor = GetRowColor(txt);
	crRows.InsertAt(0, aColor)		

	// change the rest of list ctrl
}

and then, in custom draw of the list control, I implement like this:

void CExample1Dlg::OnNMCustomdrawList2(NMHDR *pNMHDR, LRESULT *pResult)
{
NMLVCUSTOMDRAW* pLVCD = reinterpret_cast<nmlvcustomdraw*>( pNMHDR );

int nItem = static\_cast (pLVCD->nmcd.dwItemSpec);

pLVCD->clrTextBk = RGB(0, 0, 0); // select background color

\*pResult = CDRF\_DODEFAULT;

// First thing - check the draw stage. If it's the control's prepaint

// stage, then tell Windows we want messages for every item.


if ( CDDS\_PREPAINT == pLVCD->nmcd.dwDrawStage )
{
	\*pResult = CDRF\_NOTIFYITEMDRAW;
}
else if ( CDDS\_ITEMPREPAINT == pLVCD->nmcd.dwDrawStage )
{
	// This is the prepaint stage for an item. Here's where we set the

	// item's text color. Our return value will tell Windows to draw the

	// item itself, but it will use the new color we set here.

	// We'll cycle the colors through red, green, and light blue.


	COLORREF aColor = crText.GetAt(nItem);		
	pLVCD->clrText = aColor;
	
	\*pResult = CDRF\_DODEFAULT;
}

}

that's all, and it doesn't take any time to change the color (time is almost 0) Thank you everyone :)