> We considered doing something like this originally, and I think it's the
> right approach for Swing/SWT. However, when you have to implement these
> layouts in (...) impossible to change a panel's layout after it's
> constructed, because it forces you to reconstruct the entire DOM.
>
I understand, It could be interesting to have a look at how GXT guys have
solved this pb, I guess they have this separation between
XXLayout/ContentPanel
LayoutData has always been there, but it was just package-protected. The doc
> states explicitly that it may only be used by the panel that owns the
> widget, and it really does help avoid lots of extra maps, which can get
> pretty expensive. The userData on Layer should probably have been called
> userObject (like in TreeItem), and I should have made it invariant rather
> than having a setter (the next patch will include this change). I admit it's
> a bit odd, but the "user data" pattern (to the extent one can call it a
> pattern) can really make things a lot easier in this case. It's also worth
> pointing out that most users won't really be exposed to Layer.userObject,
> since they'll mostly be using panels and widgets.
>
Ok I understand.
>
> I'm not a huge fan of attach() and detach() either, now that I think of it
> (actually, I *really* wish I could get rid of them, but this appears to be
> impossible because of requirements imposed by the IE6 implementation). What
> about calling them something like onElement[De A]ttached()? Would that make
> it a bit clearer?
>
That would definitively be better names
>
> Actually, if you're using a LayoutPanel (or similar widget, more are on
> their way, such as DockLayoutPanel, StackLayoutPanel, and the like), you
> shouldn't ever have to use the Layout class directly. The above code could
> simply be:
>
> Does that make sense? I would prefer to modify add() to return the Layer
> directly, but it's inherited from HasWidgets (unfortunately, it was a bad
> idea to have add() there in the first place, but it's too late to fix now).
>
Yes, that's right. That said, I would have probably chosen a name like
"LayerConstraints" instead of "Layer" because of the specific nature of the
data passed to attachChild
> explicitly). The RootLayoutPanel is meant to solve this problem in a pretty
> simple way -- please let me know if it's not sufficient for some reason I'm
> not seeing.
>
That's it. I have replaced RootPanel by RootLayoutPanel and things are
better. I still have the problem to find an equivalent of
RootPanel.get("slotId").
As it is designed, that seems difficult. Does it mean that embedding
LayoutPanel in an existing DOM will be forbidden by design ? I don't see how
you could infer the existing raw HTML to add all the layout data stuff
> Also, I can't quite follow all the logic here, but do remember that you
> have to explicitly call layout() on these LayoutPanel (and RootLayoutPanel)
> instances once all the children are added and their layers' constraints set.
> Once I get the patch updated to take this (and other) feedback into account,
> I'll have a deeper look at the code to provide a simple example that I
> believe captures what it's trying to do.
>
Ok great
> I realize it's probably not immediately obvious quite how all these classes
> fit together, so please let me know if you have any ideas on how I can make
> it clearer. Once it's all done, we'll be updating the samples, which should
> help, but I'm open to other ideas as well.
>
With those explanations, things are clearer. That said, I still have a
problem with my previous sample. I have updated it to reflect the changes
you made in LayoutPanelExample and I want to be sure I didn't make any
mistake. Here is a small snippet
//HorizontalPanel hp = new HorizontalPanel();
LayoutPanel hp = new LayoutPanel();
Widget childOne = hp, childTwo = getTabPanel();
FlexTable ft = getTable() ;
hp.add(ft);
hp.layout();
childOne.setStyleName("red");
childTwo.setStyleName("yellow");
LayoutPanel p = new LayoutPanel();
p.add(childOne);
p.add(childTwo);
Layer layerOne = p.getLayer(childOne), layerTwo = p.getLayer(childTwo);
layerOne.setBottomHeight(0, Unit.PCT, 50, Unit.PCT);
layerTwo.setTopHeight(0, Unit.PCT, 50, Unit.PCT);
p.layout();
RootLayoutPanel rp = RootLayoutPanel.get();
rp.add(p);rp.layout();
When I use a LayoutPanel ("hp" reference), the FlexTable would shrink as
expected in terms of height and width (don't behave consistently across all
browsers). When I use an HorizontalPanel, the childs components won't grow
to fill all the parent space. This use case will be very common in the
future as many users will try to compose legacy panels with the new Layout
widgets.
Do you see a simple way to apply the layout to the newly added FlexTable if
its parent is not a LayoutPanel ?
>
> Ça aide beaucoup, merci :)
>
I have been told that your French was excellent, that's proved now ;-)
Many thanks for you help Joel.
Sami
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