[news.eclipse.platform.swt] Re: Event bubbling

["Steve Northover" <steve_northover@xxxxxxxxxx>]

Events are captured in SWT, not bubbled.  However, you can use
Display.addFilter() to see every event for every widget.

"Ondrej Kucera" <ondrej.kucera@xxxxxxxxxx> wrote in message
news:op.stkar7icvhco6m@xxxxxxxxxxxxxxxxx
> Hello,
>
> I'm sort of new to SWT (and definitely new to this newsgroup), although
> after reading some material, writing a few code samples and going through
> almost all the official snippets I think I know the basics. But I can't
> figure out something about the event handling and can't find a decent
> article or something that would go deeper then simple telling how to add a
> listener (typed or untyped) and how to write a simple one.
> I'm mostly familiar with the event model of web browsers as stated in DOM
> 2 Events specification where there's possible either event capturing or
> event bubbling - for example if there is a list item (LI) inside an
> unordered list (UL) inside the body of the document and user clicks over
> the list item, this event can be caught on all of these elements (LI, UL,
> BODY), some of them or none of them (bubbling vs. capturing only differs
> in the order of the call of the appropriate event handlers).
> I desperately need to do something like that in SWT, but I don't know how.
> For example I need to catch every MouseDown over o Composite, whether it
> is an empty Composite or it is full of Labels. If I try the code below and
> I click somewhere in the Label, only the Listener for the Label is called
> (and not the ones for Group, Composite and Shell). I thought the the rest
> would be called automatically but they're obviously not, so I was
> wandering that maybe I should "do something" to the event in the Listener
> to pass the event to the widget's parent but just from looking to the
> javadoc documentation I couldn't figure out what would do the trick. Or
> maybe I'm going completely wrong direction but I really need to solve
this.
>
> Regards, Ondrej
>
>
> import org.eclipse.swt.SWT;
> import org.eclipse.swt.events.*;
> import org.eclipse.swt.widgets.*;
>
> public class EventExample {
>
>      public static void main (String[] args) {
> Display display = new Display();
> Shell shell = new Shell(display);
> Composite composite = new Composite(shell, SWT.BORDER);
> Group group = new Group(composite, SWT.NONE);
> group.setText("group");
> Label label = new Label(group, SWT.BORDER);
> label.setText("label");
> label.pack();
> label.setLocation(10, 100);
> group.setSize(100, 200);
> group.setLocation(10, 100);
> composite.setSize(200, 300);
> composite.setLocation(10, 100);
> shell.setSize(300, 450);
>
> Listener listener = new Listener() {
> public void handleEvent(Event event) {
>     if (event.type == SWT.MouseDown) {
> System.out.println("MouseDown: " + event.widget.toString());
>     }
> }
>     };
>
> shell.addListener(SWT.MouseDown, listener);
> composite.addListener(SWT.MouseDown, listener);
> group.addListener(SWT.MouseDown, listener);
> label.addListener(SWT.MouseDown, listener);
>
> shell.open ();
> while (!shell.isDisposed()) {
>     if (!display.readAndDispatch ()) display.sleep ();
> }
> display.dispose ();
>      }
> }