Determining directory contents quickly

[Pete Davis]

I'm implementing a folder browser style control in a tree view.

Windows Explorer, when it comes up with a tree view, almost immediately,
knows if folders contain other folders or not (unless it's a networked
drive).

How does it accomplish this? Obviously doing Directory.GetDi rectories() for
each subdirectory is not going to give me that sort of immediate response.

Pete

[Alexander Kolliopoulos]

Really, have you tried it? Is it noticeably slow?

[Pete Davis]

Yes, beyodn trying, I've actually got it written and I'm dissatisified with
the performance, which is why I'm now asking here. It's particularly
affected by the number of subdirectories. So if I do a
Directory.GetDi rectories() on a folder that has say, 1000 sub directories,
it's going to be far slower, which makes sense.

Pete

"Alexander Kolliopoulos" <ak******@gmail .com> wrote in message
news:11******** **************@ o13g2000cwo.goo glegroups.com.. .

Really, have you tried it? Is it noticeably slow?

[Robert Jeppesen]

Make sure that GetDirectories( ) is the culprit. Try calling it on a large
folder without displaying anything and time it.

My first bet would be the treeview.
Try suspending layout when adding items:
treeView1.Suspe ndLayout();
.... add stuff
treeView1.Resum eLayout();

Also try adding the items to the tree using AddRange().

Oh, and obviously don't forget to NOT populate the whole tree at once
recursively.
--
Robert Jeppesen
Durius
http://www.durius.com/

"Pete Davis" <pdavis68@[nospam]hotmail.com> wrote in message
news:4I******** ************@gi ganews.com...

Yes, beyodn trying, I've actually got it written and I'm dissatisified
with the performance, which is why I'm now asking here. It's particularly
affected by the number of subdirectories. So if I do a
Directory.GetDi rectories() on a folder that has say, 1000 sub directories,
it's going to be far slower, which makes sense.

Pete

"Alexander Kolliopoulos" <ak******@gmail .com> wrote in message
news:11******** **************@ o13g2000cwo.goo glegroups.com.. .

Really, have you tried it? Is it noticeably slow?

[Pete Davis]

Ah, SuspendLayout did make a big difference. For very large directories,
there's a bit of a period where it blanks out, but it's still far faster
than before. Definitely acceptable.

And yes, I'm not populating the entire tree at once. Just a level at a time
as branches are expanded.

Thanks.

Pete

"Robert Jeppesen durius (dot) com>" <robert<at> wrote in message
news:ey******** ********@TK2MSF TNGP09.phx.gbl. ..

Make sure that GetDirectories( ) is the culprit. Try calling it on a large
folder without displaying anything and time it.

My first bet would be the treeview.
Try suspending layout when adding items:
treeView1.Suspe ndLayout();
... add stuff
treeView1.Resum eLayout();

Also try adding the items to the tree using AddRange().

Oh, and obviously don't forget to NOT populate the whole tree at once
recursively.
--
Robert Jeppesen
Durius
http://www.durius.com/

"Pete Davis" <pdavis68@[nospam]hotmail.com> wrote in message
news:4I******** ************@gi ganews.com...

Yes, beyodn trying, I've actually got it written and I'm dissatisified
with the performance, which is why I'm now asking here. It's particularly
affected by the number of subdirectories. So if I do a
Directory.GetDi rectories() on a folder that has say, 1000 sub
directories, it's going to be far slower, which makes sense.

Pete

"Alexander Kolliopoulos" <ak******@gmail .com> wrote in message
news:11******** **************@ o13g2000cwo.goo glegroups.com.. .

Really, have you tried it? Is it noticeably slow?