[C#] Updating the form half way through a function?

Inquisitor · 3 Feb 2006 at 00:27

[C#] Updating the form in real time?

I've written a little backup utility in C# which copies the contents of one directory to another with several options, and I want to be able to add an item to a listbox for each file that is copied, in real time.

So far, I have a class that does the file copying, and raises an event every time a file is copied, which is handled back in the form file, and an item is added to the listbox. However, the changes can't be seen until the backup object has finished doing its thing and control has passed back into and through the buttonBackup_Click() event handler.

Is there a way of getting the changes to be visible as the files are being copied? :confused:

Any help appreciated

Mickey · 3 Feb 2006 at 00:59

Just stick "Application.DoEvents();" directly after you've done your form updates and that should sort it for you.

To do what you're doing properly though you'd normally make the application threaded, doing the actual work in another thread and make the changes to the main form using a delegate.

Mick.

Inquisitor · 3 Feb 2006 at 01:16

Brilliant, thanks

One more question, is there a way of scrolling to the bottom of the ListBox after each update?

Inquisitor · 3 Feb 2006 at 01:17

Mickey said:
To do what you're doing properly though you'd normally make the application threaded, doing the actual work in another thread and make the changes to the main form using a delegate.

I did think of that, but I thought it would probably be overkill for such a simple application, and I'm probably not experiened enough with C# to do that yet. I'll look into it though

Mickey · 3 Feb 2006 at 02:04

Inquisitor said:
Brilliant, thanks

One more question, is there a way of scrolling to the bottom of the ListBox after each update?

You can get this behaviour using the SelectedIndex or SelectedItem properties of the listbox.

Something like:

listbox1.SelectedIndex = listbox1.Items.Count - 1;

If you don't want to be changing the selected item in the list box you'll have to call some windows API functions to send a message to the listbox AFAIK.

Mick.

Inquisitor · 3 Feb 2006 at 02:07

I found a way of doing it without Selecting the bottom item actually:

Code:

int maxVisibleItems = listBoxProgress.Height / listBoxProgress.ItemHeight;
listBoxProgress.TopIndex = listBoxProgress.Items.Count - maxVisibleItems;

Works perfectly!

Thanks for the help

Mickey · 3 Feb 2006 at 02:10

Inquisitor said:
I did think of that, but I thought it would probably be overkill for such a simple application, and I'm probably not experiened enough with C# to do that yet. I'll look into it though

Threading will usually make a massive difference to performance too you know, even on smallish tasks like this. Even just one worker thread

Mick.

Mickey · 3 Feb 2006 at 02:13

Inquisitor said:
I found a way of doing it without Selecting the bottom item actually:

Code:

int maxVisibleItems = listBoxProgress.Height / listBoxProgress.ItemHeight; listBoxProgress.TopIndex = listBoxProgress.Items.Count - maxVisibleItems;

Works perfectly!

Thanks for the help

Ah, didn't spot that property. Its a while since i've worked on any windows forms projects. Thats my excuse anyway

Mick.

roboffer · 3 Feb 2006 at 08:50

Just another note to agree with Mickey, you really should look into threading, for something like this it wont be too complicated

Inquisitor · 3 Feb 2006 at 17:02

roboffer said:
Just another note to agree with Mickey, you really should look into threading, for something like this it wont be too complicated

Aye I'm very interested in it and will look into it

Inquisitor · 3 Feb 2006 at 20:57

Edit: Nevermind, got it all working now! Much faster than it was before, and the UI is fully responsive during backup :cool:

Hurrah for multithreading, thanks for the help all