Treeview Slow to Clear Nodes

[MattSTech]

I am not seeing this as a discussion topic which leads me to believe I am the only one who has this problem. When using a Treeview control, you clear it using the .Nodes.Clear Method. For some reason when I use this method with a latge amount of data in the control, the control hangs for a short period while it erases the contents of the control.
I am using the following loop to clear the control instead and it works quite a bit faster. Any thoughts on why I am seeing this?

For i = tvwList.Nodes.Count To 1 Step -1
    tvwList.Nodes.Remove (i)
Next

vs.

tvwList.Nodes.Clear

 

[MattSTech]

Ick. Even worse than I thought.
If I don't scroll the control, it clears quickly. If I scroll to the bottom it takes forever (3 sec or so) to clear even with my loop.

I decided to make the control invisible, clear it, then make it visible again. It clears instantly now regardless of scroll position. Must be a refresh thing??

 

[Hypetia]

Try using the LockWindowUpdate API function which enables/disables drawing in a specific window.

You should call [tt]LockWindowUpdate tvwList.hWnd[/tt] before clearing the treeview and [tt]LockWindowUpdate 0[/tt] after the treeview is clear to re-enable drawing.

It will improve performance in both cases.

 

[dilettante]

Maybe even set its .Visible = False and then back to True.

 

[strongm]

>Try using the LockWindowUpdate

And read the documentation in the link provided, and then use WM_SETREDRAW instead ... (IMHO)

 

[Hypetia]

Good read strongm. I did not see the documentation in detail. In fact, I never got a chance to use this function myself. Never needed so.