Hi all,
This request is to change the API for Cell.updateItem(T item, boolean
empty) from protected to public. Clearly this will not be a breaking
change, but it does make the API more public than ideal :-)
I've not discussed this issue with anyone else, so this is a rather
early review request seeking peoples first impressions. The driving
reason for this request is RT-31274 (link below). The general issue that
RT-31274 highlights is that ComboBox can not properly render custom
'button cells' (i.e. the cell that shows inside the button, rather than
the dropdown list) when the updateItem method is overridden. This is
because the ComboBox skin can't call updateItem, and therefore currently
falls back to calling setText(text) and setGraphic(null) (which works
well when the developer has set a StringConverter, as this can be done
in the skin).
I should note that this will bring Cell.updateItem(..) in line with
IndexedCell.updateIndex, which has been public for as long as I can recall.
Because of RT-31274, my current thinking is to make the following changes:
1) Make Cell.updateItem(T item, boolean empty) public, rather than
protected. It will continue to be 'expert' API that should not be called
(as is the public setItem(T item) method, updateIndex(..), etc).
2) Update ComboBoxListViewSkin to continue calling setText(...) and
setGraphic(null), but then also subsequently call updateItem(item). This
will have the effect of not breaking existing users, but also give
custom button cells a chance to draw themselves properly. Of course, if
these custom cells depend on the ComboBox string converter they will
have to handle this themselves (but, of course, the proper converted
string will already be in the Cell text property, so this shouldn't be a
concern).
An alternative approach is to override the Cell.item invalidated()
method such that this calls down to updateItem(...), but that seems a
little magic and a lot smelly, so I'd definitely rather not go down that
path.
https://javafx-jira.kenai.com/browse/RT-31274
Thanks,
Jonathan
