| How to know when a child of Composite is removed [message #668174] |
Wed, 04 May 2011 10:36  |
 David Luengo
Messages: 3
Registered: May 2011 |
Junior Member |
|
|
Hi all there.
I'm using SWT (i'm relatively new) and i had a problem i'm trying to solve but after read a lot, search a lot and think a lot i don't know how to solve it.
The problem is quite simple, i want to know when a child inside a Composite is disposed. I have extended the class Composite and i need to do some things when a child inside this new composites is disposed. First of all i thought that SWT had an Event and EventListener to handle that, something like ChildAddedEvent and ChildAddedEventListener but there wasn't something like that. I tried to use a Listener for the SWT.Modify event, something like this:
Composite my_comp = new Composite(new Shell(), SWT.NONE);
my_comp.addListener(SWT.Modify, MyOwnChildAddedListener())
Where MyOwnChildAddedListener is obviously another class i had created and that implements EventListener.
The most effective approach i had found is create a class that implements DisposeListener interface and everytime i add a new child to my composites also add explicitly an instance of this listener to that child, something like this:
public class MyDisposeListener implements DisposeListener {
@Override
public void widgetDisposed(DisposeEvent event) {
...
}
}
public class MyComposite extends Composite {
...
}
...
MyComposite my_comp = new MyComposite(new Shell(), SWT.NONE);
Control child = new Control(my_comp, SWT.NONE);
child.addDisposeListener(new MyDisposeListener());
This will do what i want to do, execute some code when a child of my composites is removed.
BUT this solution imho is quite ugly because i'm forcing the users of MyComposite to EXPLICITLY add the listener to every child s/he adds... Seriously, doesn't SWT have a way to know when a child is disposed from the composites or when a child is added?!?!
Thanks for the attention.
--
David
PD: Sorry about my English, I made my best :S
|
|
|
| Re: How to know when a child of Composite is removed [message #668362 is a reply to message #668174] |
Thu, 05 May 2011 12:18  |
 |
Lakshmi P Shanmugam
Messages: 279
Registered: July 2009
Location: India |
Senior Member |
|
|
Hi,
When a child control is disposed the child control sends the dispose event, the Composite will not send any dispose event in this case.
You can use the Display#addFilter (int eventType, Listener listener) with eventType = SWT.Dispose to listen to all the dispose events on the widgets in the display. You could then add a check to verify if the controls's parent is your Composite.
Lakshmi P Shanmugam
|
|
|
Powered by
FUDForum. Page generated in 0.03619 seconds
] 
Search
Help
Register
Login
Home
