I think there is definitely room for improvement here, but I think most
controls can currently be build externally, if you are willing to do all
the work. Your control may suffer however when you need to integrate
with event, focus handling or keyboard navigation. Skins and Behaviors
are not something that are a requirement to use to build a custom
control, although they can make it easier to adapt existing controls, up
to a point.
The problem with making things public is that this means they must be
specified, and that we must be **very** sure that it is a solid API that
will stand the test of time. That's often a significant time investment
that could seriously delay building a complicated control like TableView.
I think Skins especially are very hard to design in such a way that they
have sensible public/protected methods. They often deal with very
specific layout or design problems, that could restrict the evolution of
the control if there is a fundamental change in how the Skin is
constructed. Just imagine if the very first TableViewSkin had all its
methods public, and that they couldn't be changed up to this day because
the Skin may have been subclassed by 3rd parties.
This is why I would advocate instead to make it easier to replace Skins
entirely (by being able to copy the code). The biggest issue there is
that Skins contain many non-public helpers, primarily their Behaviors.
Making Behaviors public would first require unblurring the lines between
what is Skin and what is Behavior (not doing so will just make it a bad
API that will cause many bugs and problems over the coming years). That
would also mean that some controls need some rework to divide the work
over their Skin and Behavior correctly, as for many controls the split
is there only in name, and is discarded as soon as it was inconvenient.
With Behaviors public and some helpful API's (like Font measurement)
having a public equivalent, the route to just copy only a Behavior or
Skin opens up. Being able to copy them means that you don't need to
fully open up and specify every private method in Skins/Behaviors
(designing API's is hard, but designing API's that can be sub classed
while not restricting an endless set of possibilities that a Skin
subclass may need is impossible).
--John
On 08/03/2024 00:40, Marius Hanl wrote:
One note here regarding that a lot of things are final in JavaFX:
The problem is not that everything is final - this is intended and
makes sense, since we speak mostly of properties here. Overriding
those will not give you any benefit.
You mostly want to override e.g. Controls if you add something new to
it (a new property) or may just want to set another default skin.
This design is mostly superior than e.g. Swing, where you can override
things and easily break something if not too careful.
Pretty sure that this were some lessons learned from the development
of Swing.
The biggest problem is rather that a lot of methods are package
private or 'Accessors' are used to call specific methods, which is not
just a questionable design but also restrict the usage.
It is often not possible to override even a minor feature inside the skin.
So you may rather want to recreate the skin then, and copy the
existing skin and just change some stuff. But this will mostly not
work either, as there is a lot of internal API usage, e.g. Accessors
or some com.sun.javafx.scene.control.skin.Utils usage.
Want to set the width of a TableColumn? Well, the internal
com.sun.javafx.scene.control.TableColumnBaseHelper.TableColumnBaseAccessor can
do that, you can not.
Get the width of a text String? Well, you can use
com.sun.javafx.scene.control.skin.Utils.computeTextWidth...
Offtopic: Maybe we should collect the things which should be public in
our opinion at one point to (better) get this started as well?
-- Marius
*Gesendet:* Montag, 04. März 2024 um 08:13 Uhr
*Von:* "Robert Lichtenberger" <r.lichtenber...@gmail.com>
*An:* openjfx-dev@openjdk.org
*Betreff:* Re: Validation Support
First off, as the original author of ValidatorFX I feel flattered by the
suggestion of including it into the JavaFX core :-).
Some thoughts / insights I gained from developing ValidatorFX:
* ValidatorFX is (with the possible exception of GraphicDecoration.java)
rather trivial code and also very small (< 1k lines of library code).
But it seems to have filled a market gap according (a few thousand
unique ip downloads every month, issues from ca. a dozen people so far,
even a few PRs). These "market gaps" get filled rarely because they are
not a commercially attractive opportunity. On the other hand if you
decide (like I did with ValidatorFX) to take your closed source solution
and make it open source, you are "rewarded" by increased overhead at
first. But the market gaps exist and hinder broader JavaFX adoption.
* ValidatorFX is probably only one part needed for application
developers. The other part is a form library that allows to layout
fields, have buttons (that are connected to field validation, etc.). It
looks like this is written again and again by every application developer.
* To answer John's question if JavaFX could do more to help make tools
like ValidatorFX easy to build:
** There's the TooltipWrapper class in ValidatorFX which works around
JDK-8090379. Not a big deal but something many application developers
will probably be annoyed by.
** On a more general note, if I were the king of the JavaFX universe for
one day, I would forbid anyone to make classes or methods final. As an
application developer I prefer to be able to tweak things easily, even
if they may break in the future (which they will anyway ...). Don't take
that decision away from me, it's patronizing. But I guess this is one of
those things that depend very much on which side of the equation you
are, so don't take my troll bait :-).
--Robert
Am 03.03.24 um 02:10 schrieb John Hendrikx:
> Hi Dirk,
>
> That is a very nice framework, and although I wouldn't be against its
> inclusion in FX, I'm more wondering if JavaFX could do more to help
> make tools like ValidatorFX easy to build.
>
> I'm not quite sure how one can use not having validation as an
> argument against using FX, when there clearly are free alternatives
> available. Surely not everything can or should be part of the base
> framework? A line must be drawn somewhere, especially when there are
> very few core FX developers.
>
> I'd much rather see work being done on things that can't be provided
> by 3rd parties, preferably by opening up more parts of FX with well
> specified API's.
>
> --John
>
> On 01/03/2024 11:59, Dirk Lemmermann wrote:
>> Hi everyone,
>>
>> I updated the validation framework ValidatorFX today in our project
>> to the latest release and I really like it a lot. It is a small
>> compact API and works with any observable as opposed to the
>> validation support provided by ControlsFX.
>>
>> Using it made me wonder whether it would make sense to bundle it or
>> something like it directly with JavaFX. Developers often mention
>> missing validation support as a drawback of using JavaFX. Adding this
>> would take one item off from the list of arguments against using
JavaFX.
>>
>> Many UI frameworks do have built-in validation support, e.g. Vaadin
>> [0], Angular, [1], or QT [2]
>>
>> What do you think?
>>
>> —Dirk
>>
>> [0]
>>
https://vaadin.com/docs/latest/binding-data/components-binder-validation
>> [1] https://angular.io/guide/form-validation
>> [2] https://doc.qt.io/qt-6/qtquick-input-textinput.html
>>
