Listview multiple selection slow

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Long ago (and far away) I wrote a video library application (just for myself), and apart from slight alterations along the way I have recompiled it for each new computer over many years.

A key part is the ListView, I show filtered Icon views of all of my videos etc, so I can categorize them or play/copy them.

On this particular machine (had it about a month now) everything works fine except when I try to select a lot of videos in one go. Click on the first, Shift-click on the last, I can sit here and watch it slowly hi-lighting each of the icons. Even (say) ten icons I can watch for a few seconds before the interface catches up with me.

Try as I might I just can not find a reason why this one operation should be slow.

So I put together another test application, gave it 100 items (just written in code) select the first, shift-select the last, and it trundles through slowly hi-lighting the selected icons.

The only difference between this compile and the one on my old computer is that I am using the newest Visual Studio (went from VS15 to VS17) and it's library of controls, but I am not aware of any upgrades of the controls library.

Do you have a reason or ideas for the slow selection that I could look at?

What I have tried:

In the debug and process loading there is nothing noticeable that suggests excessive CPU or memory use.

Posted 10-Apr-18 6:47am

Rassler48

Updated 10-Apr-18 8:27am

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#realJSOP · Accepted Answer · 2018-04-10T08:06:00

Solution 1

You could try this (no guarantees):

C#

stView1.SelectedIndexChanged-=listView1_SelectedIndexChanged;
listView1.SuspendLayout();

try
{
 // selection loop
}
finally
{
  listView1.SelectedIndexChanged+=new EventHandler(listView1_SelectedIndexChanged);
  listView1.ResumeLayout();
}

Posted 10-Apr-18 8:06am

#realJSOP

Comments

Nelek 10-Apr-18 15:08pm

Hi John. OP wrote in a non solution below:
------------------
That did work. I just double checked the version running on the old machine, and I did not need to use suspendLayout on that.

Something must have changed between the versions, but now I know what it is I can work with it.

Thank you John.
-------------

Just in case