Results of review of private JavaFX API for consideration to make public in JDK 9
jonathan.giles at oracle.com
Thu Aug 6 23:10:47 UTC 2015
Hi all. In April of this year a discussion began when news broke that
with JDK 9 access to private com.sun.* APIs would be disappearing . A
while back I posted a request to openjfx-dev for people to send me their
JDeps output so that it could be analysed and used to inform our
decisions around which API we should try to promote into public API. The
response was very useful (and I should note: its too late now, please
don't send me anymore JDeps files), and I believe we have the beginnings
of a plan on how to move forward.
Before I outline the plan, please note that this discussion would
ideally _not_ devolve into a feature requests discussion. What we are
wanting to talk about today is simply API that exists in the com.sun.*
package namespace which we can conceivably bring out of this namespace
for JDK 9. Developing new API is expressly out of scope (unless it is
related to simplifying or wrapping the com.sun.* API).
Another important point - UI control skins and a lot of very useful CSS
API are being made public under JEP 253 . A lot of the skin code has
already been cleaned up, simplified, documented, etc, and will be
merging into a repo very soon. I'll also post a separate post about JEP
So, what does my JDeps analysis show (ignoring UI Controls and CSS
usage, which has been largely resolved by JEP 253)? I can sum it up in
the following categories:
== 'Toolkit' API ==
A lot of people use a small amount of API from Toolkit, such as the API
for nested event loops, to fire a pulse, and to add / remove pulse
listeners. Based on this analysis, the current thinking is to add API
into the javafx.application.Platform class to enable the first two use
cases above (nested event loops and pulse firing). The third use case
needs more engineering effort, and is a far less common use case, so
isn't being considered for JDK 9.
== 'Traversal' API ==
This API lives in com.sun.javafx.scene.traversal, and is quite useful
when writing custom controls to ensure that keyboard traversal puts the
focus in the right node at the right time. My ControlsFX open source
project is a common (ab)user of this API, so I have a vested interest in
making this public. Having said this, the API is actually in quite good
shape, and it is possible with just a little JavaDoc work it could make
the move into javafx.scene.traversal.
== 'Collections Event' API ==
There exists classes in com.sun.javafx.collections that are quite useful
if you create your own custom ObservableList implementation and want to
fire events at certain times. In my analysis there are only two projects
using these APIs: ControlsFX and JVx by SIB Visions. The other pertinent
point is that this code is quite easy to reproduce, so, whilst I would
like to see this API public, it doesn't seem to make sense for JavaFX 9.
== 'Utils' API ==
There exists three classes that are quite commonly used by people for
the various utility methods contained within. These classes are
com.sun.javafx.util.Utils, com.sun.javafx.PlatformUtil, and
com.sun.javafx.application.PlatformImpl. As most of these classes are
just a collection of self-contained methods, it is quite likely that a
number of these methods will find public API alternatives in a new class
(although there are no plans to move all the methods over!).
== Miscellaneous API ==
Finally, there are a few classes that popped up quite frequently. Here
is the list, and my thoughts on what to do with them:
1) com.sun.javafx.runtime.VersionInfo: Questionable about usefulness -
not a likely candidate for JDK 9.
2) com.sun.javafx.event.EventHandlerManager: Only used in ControlsFX -
not a likely candidate for JDK 9.
3) Robot: A good API to make public, but not a small API, so the scope
is possibly too great for JDK 9.
4) PerformanceTracker: Same as Robot - good, but API might require more
time than is available for JDK 9.
== What about other private API ==
If I've stated that an API you use isn't likely to make the cut for 9,
there is another option: pull up your sleeves and work with us to get
the API into a shape where it is good enough to commit to as public API.
I should note that you shouldn't just dive in and do this - ping us and
let us know first, so we can sync up and make sure the plan is feasible
(and not overlapping). Because any large chunk of work would require
moving through the JEP process, it is unlikely that anything other than
small tweaks would be acceptable. One such example might be the
== Where to from here? ==
The first milestone is to get JEP 253 into the main repo. That should
hopefully be done before the end of August. Once that is done, focus can
shift to the areas identified in this email. In the mean time, if there
is any community feedback, please get it in ASAP so it can be included
in the consideration.
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