Enhancements for JavaFX 18

[John Hendrikx]

I missed this question.

There are several external libaries available to help with these kinds 
of bindings.  There is EasyBind, ReactFX and an attempt of my own 
(https://github.com/hjohn/hs.jfx.eventstream).

They all have a different way of addressing this, but they do all have 
one thing in common: they all require that you wrap ObservableValues in 
their own extended variant of ObservableValue.  EasyBind has 
"MonadicObervableValue", ReactFX has "Val" and "Var" and my own attempt 
has "ValueStream".

Effectively this means you will get two types of properties in your 
JavaFX application, and you'll need to update standard properties like 
ObjectProperty to the type the framework provides to get the extra 
features. Interop between "old" and "new" code requires wrapping and 
sometimes unwrapping.

Integrating this into JavaFX's ObservableValue directly avoids all these 
wrappers and all the extra work that entails for the user of fluent 
bindings.

With this base in place, external libraries can provide streams and 
complicated mapping functions (ReactFX especially has an overabundance 
of features, most of which too niche to include into JavaFX directly).

That's not the only advantage however. When these are integrated, JavaFX 
internals can take advantage of them as well. Managing of cascading 
properties (usually done manually in JavaFX code, Bindings#select is not 
usually used) will be much cleaner and simpler.

Also the lazy bindings part of this MR can be used to avoid creating 
listeners for properties that aren't used themselves -- this allows for 
example Node to provide convience properties (like tree visibility) 
without having to  pre-emptively add listeners. This is not possible 
currently without consuming additional memory for every Node instance.

Finally, it also would serve as a type safe replacement for 
Bindings#select which is something that I think the team behind FX has 
been wanting to address for quite a while now.

--John

On 12/09/2021 01:38, Tom Schindl wrote:
> I have not looked at the code yet but why does this have to be part of
> OpenJFX and can not be implemented as an external library?
>
> Tom
>
> Am 05.08.21 um 00:25 schrieb John Hendrikx:
>> Perhaps:
>>
>> Fluent bindings for ObservableValue
>> https://github.com/openjdk/jfx/pull/434
>>
>> It was received well I think, and there was some interest from Nir
>> Lisker to work on a proposal.
>>
>> --John
>>
>> On 30/07/2021 14:56, Kevin Rushforth wrote:
>>> Now that JavaFX 17 is in RDP2, we can turn more attention to bug fixes
>>> and enhancement requests for JavaFX 18. It's the summer, so there may be
>>> delays as some people are out at various times (including me), but I
>>> would like to get some of the outstanding enhancement requests moving
>>> over the next few weeks.
>>>
>>> Specifically, I'd like to see the following proceed:
>>>
>>> * Transparent backgrounds in WebView
>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8090547
>>> PR: https://github.com/openjdk/jfx/pull/563
>>>
>>> * Add DirectionalLight
>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8234921
>>> PR: https://github.com/openjdk/jfx/pull/548
>>>
>>> * CSS pseudoclasses :focus-visible and :focus-within
>>> https://bugs.openjdk.java.net/browse/JDK-8268225
>>> PR: https://github.com/openjdk/jfx/pull/475
>>>
>>> * Improve property system to facilitate correct usage (minus the binary
>>> incompatible API change)
>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8268642
>>> PR: https://github.com/openjdk/jfx/pull/590 (Draft)
>>>
>>> And maybe the following:
>>>
>>> * Add CSS themes as a first-class concept (need a consensus on how to
>>> proceed)
>>>
>>> * Undecorated interactive stage style (still in early discussion, but
>>> the concept looks interesting and useful)
>>>
>>> There are probably others I'm forgetting.
>>>
>>> Each of the above should be discussed in their own thread on openjfx-dev
>>> rather than a reply to this thread.
>>>
>>> -- Kevin
>>>
>>>
>