Hi Stephen, I feel this is just one of those challenging areas in GWT. There's no "event" in GWT that tells you DOM has finished layout activities, but there is a point where you expect this to be the case in the normal lifecycle of a widget.
In the Widget lifecycle there are four key points you can override that in a way act as "events": * onAttach() - called when a widget is attached to the browser's document. * onLoad() - called immediately after a widget becomes attached to the browser's document. * onUnload() - called immediately before a widget will be detached from the browser's document. * onDetach() - called when a widget is detached from the browser's document The one of interest here is onLoad(), where it's fairly safe to assume that everything DOM attribute wise is sorted out by then. I've still found it wise to give the browser some time by wrapping any dimension stuff in a DeferredCommand within the onLoad() method; I'm not 100% convinced it is necessary, but I like to live on the safe side in an effect library I'm building (http://code.google.com/p/gwt-fx/). I have to admit, I'm not aware of a onResize() method to override in Widget or Composite class, so can't really comment on how that would work (out of interest, where is it in standard GWT?). DeferredCommand itself is a little bit of a trick, although it says "allows you to execute code after all currently pending event handlers have completed" it's really based on timers rather than hooking into the browser event queue and checking all is done before firing your command - that said, it works. Hope that gives you a bit more info. //Adam On 3 Maj, 02:00, Stephen Cagle <[email protected]> wrote: > First of all, Thank You Adam. This is one of those things that I spent > like 4 hours on and finally just asked about. > > I put my absolute positioning code inside a DefferedCommand. Have not > seen it fail yet. So thank you, it seems to work. > > Still, I do wonder. What is the deterministically appropriate way to > deal with this? For all I know the DefferedCommand may be the > appropriate way to deal with this, as it may truly guarantee that code > is not run till after all other events are run. Assuming that > "repositioning stuff as things are added to the DOM" is just another > event, then as long as DefferedCommand always guarantees that it will > add to the end, then it is probably correct. > > However, is there some more direct way to do this. Like, could I wrap > a widget in something (or override some handler) such that I can > guarantee execution of code only after the widget has been fully > positioned and their currently exist not other DOM modifying events in > the queue? > > Also, in closing, is there more information somewhere on exactly how > widgets are added, positioned, and rendered. I would also be > interested in any callbacks (or equivalent) that I can override at any > point in said process. Thanks all. > > On May 1, 11:14 pm, Adam T <[email protected]> wrote: > > > sometimes it's worth wrapping any repositioning up in a > > DeferredCommand to give the browser a chance, i.e. take you code that > > does something like this: > > > int x = X.getAbsoluteTop; > > int h = X.getOffsetHeight(); > > W.setWidgetPostition(x,y); > > W.setWidth(h/2+"px"); > > > and make it > > > DeferredCommand.addCommand(new Command(){ > > public void execute(){ > > int x = X.getAbsoluteTop; > > int h = X.getOffsetHeight(); > > W.setWidgetPostition(x,y); > > W.setWidth(h/2+"px"); > > } > > > }); > > > now the positioning code will execute a little later giving the > > browser chance to have redrawn everything and you should get more > > consistent answers. > > > //Adam > > > On 2 Maj, 01:12, Stephen Cagle <[email protected]> wrote: > > > > I have a Composite widget within which I have overridden the onResize > > > () method. Some of the element widgets of this widget position > > > themselves relative to other widgets. That is to say, I sometimes > > > position widget X using .getAbsoluteTop() and .getOffsetHeight(). > > > Unfortunately, sometimes .getAbsoluteTop sometimes returns a pretty > > > random value. I think this is because I am re-populating/creating a > > > lot of the widgets upon resize. So maybe I am getting the size of the > > > widget "as it is being built". What should I do to deal with this. I > > > need to position things absolutely relative to other widgets, but > > > within the onResize() method, I am getting (occasionally) odd results? --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/Google-Web-Toolkit?hl=en -~----------~----~----~----~------~----~------~--~---
