How add huge number of items to listctrl with minimum delay?

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1.00/5 (1 vote)

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I have a List control which about 280000 items should be added to that and then display. it takes about 4 minutes for me and my UI goes disable during the time.

how can I reduce the Delay time?

What I have tried:

pTable = new CListCtrl;
CString strtemp;
for (unsigned int i = 1; i <= size; i++)
{
    pTable->InsertItem(i, strtemp);
}

Posted 16-Jul-18 0:33am

saide_a

Updated 16-Jul-18 0:54am

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2 solutions

Solution 1

Have you considered paging or infinite scrolling? Items may be created/retrieved in a different thread but updating a control always blocks UI thread unless the control supports some kind of virtualization. The best approach is add items by parts (for example 200 items at a time) but you should decide when to add specific part: the one approach is paging. You can also add the next batch o of items when user scrolls to the bottom (infinite scrolling).

Posted 16-Jul-18 0:50am

Ajcek84

Comments

saide_a 16-Jul-18 7:00am

In My Case almost always complete scrolling is needed, only at the "open" click I want the list to update an show, and in other thread nothing related to the listctrl. what do you suggest for me?

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Jochen Arndt · Accepted Answer · 2018-07-16T00:55:00

Who will read (and scroll through) 280,000 items?

A solution would be using a virtual list control that handles only the items actually visible. See Virtual List Controls | Microsoft Docs[^].

For a non virtual list control you can (and should always even with smaller lists) disable the screen update while modifying the list:

pTable->SetRedraw(FALSE);

// Modify list here

pTable->SetRedraw(TRUE);

// Invalidate the entire list
pTable->Invalidate();
// Force painting
pTable->UpdateWindow();

[EDIT]
When knowing the number of items in advance, use SetItemCount() initially. Even when not knowing the count in advance, it might be finally faster to determine and set it.

For further improvements make the code inside the loop as fast as possible (simple). That includes avoiding any function that allocates memory in the loop. Use for example preallocated CStrings or plain text buffers defined outside the loop using the max. possible string length. If possible, avoid also any string formatting function.
[/EDIT]