ListView and performance

Here's the deal.

I've got a class which is the root of an object hierarchy. Within this
class I create a private member variable of type Form. In the form class, I
have created a public LoadFile method that reads a text file (960 KB),
creates an array of ListViewItems(~33,000) based on the file and the I add
those items to the ListView via the AddRange method.

I instantiate the form from the root class, no problem.

I call the LoadFile method, although it measures out to ~1.5 seconds, still
no problem (I execute this method from the root class as a new thread, btw)

Back in the root class, I call Form.Show(), big problem. It takes 25
seconds to simply display the form!??!?!!!!? This HAS to do with the
ListView.

Anyone have a tip or suggestion as to how to improve the display speed of
this form?

Best

Troy


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Hello,

"Troy Hilbert" <thilbert@spamfree.hotmail.com> schrieb:
> I've got a class which is the root of an object hierarchy.
> Within this class I create a private member variable of
> type Form. In the form class, I have created a public
> LoadFile method that reads a text file (960 KB),
> creates an array of ListViewItems(~33,000) based on the

You may want to use a virtual listview:

http://www.vbcity.com/forums/topic.asp?tid=13777

Regards,
Herfried K. Wagner
--
MVP · VB Classic, VB .NET
http://www.mvps.org/dotnet

Thanks for the suggestion, but I don't think I am at the point where I want
to use non-standard methods to solve the problem. It's always an option
though. I was hoping to find a quick solution. As I said earlier, I fill
the listview very quickly, it's displaying the form that takes all the time.

Best

"Herfried K. Wagner" <hirf.nosp@m.activevb.de> wrote in message
news:eXBZ$B0ODHA.2480@tk2msftngp13.phx.gbl...
> Hello,
>
> "Troy Hilbert" <thilbert@spamfree.hotmail.com> schrieb:
> > I've got a class which is the root of an object hierarchy.
> > Within this class I create a private member variable of
> > type Form. In the form class, I have created a public
> > LoadFile method that reads a text file (960 KB),
> > creates an array of ListViewItems(~33,000) based on the
>
> You may want to use a virtual listview:
>
> http://www.vbcity.com/forums/topic.asp?tid=13777
>
> Regards,
> Herfried K. Wagner
> --
> MVP · VB Classic, VB .NET
> http://www.mvps.org/dotnet
>
>


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Another good idea. I really think that I want to display them all due to
the nature of the information (it's a list of news groups). I've tried
several aproaches and think I've found an acceptable (not optimal) level of
performance. The main problem I was having was that the user interface was
unresponsive while I was adding the items. The solution I came up with was
to create a function to wrap the population of the ListView and then create
a new thread to run that function. Viola, the UI became responsive. I've
got it to the point where I can open the file, read all the items,
instantiate an array of type ListViewItem and populate the ListView with
36000 items (no sub items) in ~15-20 seconds.

Thanks for your suggestions.

Best


"Norm Yuan" <noormanyuan@shaw.ca> wrote in message
news:K0rKa.311827$Vi5.8183671@news1.calgary.shaw.ca...
> Painting Listview on screen is a very slow processing, especially when
each
> ListViewItem has many ListViewSubItems.
>
> I used to have a .NET win form app with a ListView to display up to 2000
> items with each item has uo to 10 subitems. It was too slow to paint the
> ListView, then I used DataGrid instead. It was a lot faster.
>
> But, why display 33000 items once? Do you expect user scrolls through all
> these items for what? Better approach would be to use some kind of paging
> display. Say, you load data (33000 records) into an array, or DataTable;
> place 10 buttons beside the ListView with text "1", "2",..."10"; when
> button1 is clicked, the listview displays the first 1000 records, button2
> for 1001 to 2000 records.... Or, you can sort records in alphabetical
order,
> then button "A" for all records beginning with "A..." and so on. This way,
> the display time is shortened and user does not have to scoll through huge
> amount of records.
>
>
> "Troy Hilbert" <thilbert@spamfree.hotmail.com> wrote in message
> news:%23mPjFj1ODHA.1720@TK2MSFTNGP11.phx.gbl...
> > Thanks for the suggestion, but I don't think I am at the point where I
> want
> > to use non-standard methods to solve the problem. It's always an option
> > though. I was hoping to find a quick solution. As I said earlier, I
> fill
> > the listview very quickly, it's displaying the form that takes all the
> time.
> >
> > Best
> >
> > "Herfried K. Wagner" <hirf.nosp@m.activevb.de> wrote in message
> > news:eXBZ$B0ODHA.2480@tk2msftngp13.phx.gbl...
> > > Hello,
> > >
> > > "Troy Hilbert" <thilbert@spamfree.hotmail.com> schrieb:
> > > > I've got a class which is the root of an object hierarchy.
> > > > Within this class I create a private member variable of
> > > > type Form. In the form class, I have created a public
> > > > LoadFile method that reads a text file (960 KB),
> > > > creates an array of ListViewItems(~33,000) based on the
> > >
> > > You may want to use a virtual listview:
> > >
> > > http://www.vbcity.com/forums/topic.asp?tid=13777
> > >
> > > Regards,
> > > Herfried K. Wagner
> > > --
> > > MVP · VB Classic, VB .NET
> > > http://www.mvps.org/dotnet
> > >
> > >
> >
> >
> > ---
> > Outgoing mail is certified Virus Free.
> > Checked by AVG anti-virus system (http://www.grisoft.com).
> > Version: 6.0.491 / Virus Database: 290 - Release Date: 6/18/2003
> >
> >
>
>


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