Hi
"GWT in Action" has an excellent chapter about "Event Handling". It's an old
book, probably 2007 and GWT 1.6 but as far as I can tell from looking at the
2.1.M3 API (*com.google.gwt.user.client.ui.Widget) *alot of this hasn't
changed much, if at all
I read somewhere that in 2.0 Listeners became handlers,*
*The Chapter has about 20+ pages of great content, hopefully that will help
you out.
Does any know how much the event handling has changed since 1.6?*
*
On Tue, Oct 5, 2010 at 7:13 AM, Brian <hibr...@gmail.com> wrote:
> What's odd (ie, I don't get this stuff yet) is the HTMLPanel's
> onAttach doesn't get called when htmlpanel.add() is called.
>
> Soo.. instead of wrapping the widget, it seems better to wrap the
> HTMLPanel and call onAttach on the panel itself, and add it to
> RootPanel.detachOnWindowClose().
>
> ie,
>
> Label myLabel = new Label("Hey now");
> myLabel.addClickHandler(..);
> MyPanel p = new MyPanel(""); // subclassed HTMLPanel, onAttach is
> public
> p.add(myLabel, "foo");
> p.onAttach(); // just does: super.onAttach();
> RootPanel.detachOnChildClose(p); // ensures everyone's onDetach
> called
>
> Just guessing here...
>
>
> On Oct 5, 9:40 am, Brian <hibr...@gmail.com> wrote:
> > Thanks.
> >
> > I still have to call onAttach() on my widget in order for the
> > ClickHandler to fire.
> >
> > HTMLPanel hpanel = new HTMLPanel("");
> > Wrapper w = new Wrapper("Test");
> > w.addClickHandler(...);
> > w.onAttach();
> > hpanel.add(w, "foo");
> >
> > This does clean up the code a lot -- but I'm still left wondering when/
> > where to call onDetach on the wrapper. I'm guessing I'd need to
> > subclass HTMLPanel, handle onDetach, and call it on my wrapper.
> >
> > On Oct 5, 9:20 am, Thomas Broyer <t.bro...@gmail.com> wrote:
> >
> >
> >
> >
> >
> >
> >
> > > On Oct 5, 2:30 pm, Brian <hibr...@gmail.com> wrote:
> >
> > > > Hi,
> >
> > > > I'm trying to figure out onAttach() onDetatch() onDetachChildren() to
> > > > ensure I'm not leaking, but I don't quite get it. Is there a
> > > > reference somewhere? Am I best digging through the code to figure
> out
> > > > the flow? I've read the javadocs, but am having a hard time putting
> > > > it together.
> >
> > > > Got a gwt app, server sends me down a block of html (a table which is
> > > > a calendar), gwt client takes the html, and calls setInnerHtml() on a
> > > > widget. Perfect.
> >
> > > > The server's html has a <div id="foo"></div> that I want to take
> over,
> > > > and shove widgets into.
> >
> > > Have a look at HTMLPanel then.
> >
> > > > It'd be nice if I could do:
> > > > RootPanel().get("foo").add(...); // but this asserts
> >
> > > > What I've done instead is create a wrapper which subclasses Widget,
> > > > implements HasClickHandlers, and makes onAttach() public.
> >
> > > > Then I create my wrapped Anchor, get the div in the server's html and
> > > > append:
> >
> > > > Anchor link = new Anchor("click me");
> > > > MyWrapper wrapper = new MyWrapper(link.getElement());
> > > > wrapper.addOnClickHandler(...);
> > > > wrapper.onAttach(); // without this, I can't handle the clicks
> >
> > > > HorizontalPanel hp = new HorizontalPanel();
> > > > hp.add(link);
> > > > // add more to hp
> >
> > > > DivElement serverElement =
> > > > Document.get().getElementById("foo").cast();
> > > > serverElement.appendChild(hp.getElement());
> >
> > > > --- This all works great. I've got my panel in the div, and the link
> > > > works.
> >
> > > > I'm just wondering if I need to do more, as I don't really 'get' the
> > > > attach, detach, detachChildren flow.
> >
> > > Not detaching your widgets when you remove them from the document (and/
> > > or on window.unload) will lead to memory leaks in some browsers
> > > (mainly, or maybe even *only*, IE6/7/8).
> > > You'll note that RootPanel, and every widget that has a wrap() static
> > > method, will register itself to be "detached on window close", which
> > > will detach all its children.
> >
> > > But really, what you're trying to do is already there, in HTMLPanel.
>
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