Setting graphics of a Labeled does not show the Label correctly

[John Hendrikx]

Yes, I always felt something was off about how graphics and clips worked 
and that in some cases these are actually inaccessible children (you can 
still look them up) -- it feels like they should allow sharing (clips 
especially) but things then break.

On 01/12/2022 18:42, Michael Strauß wrote:
> There's a larger picture here: from a user perspective, there's a
> difference between the scene graph and the "document graph".
> The document graph is what users actually work with, for example by
> setting the `Labeled.graphic` property. In some cases, document nodes
> don't correspond to scene nodes at all (`MenuItem` or `Tab` come to
> mind).
> The document graph is later inflated into a scene graph of unknown
> structure (because skins are mostly black boxes with regards to their
> internal structure).
>
> I've proposed an enhancement that would make the document graph a
> first-class citizen:
> https://mail.openjdk.org/pipermail/openjfx-dev/2022-June/034417.html
>
> With this in place, we could simply disallow the same node appearing
> multiple times in the document graph, which would not only solve the
> problem for `Labeled`, but for all controls with a similar problem.

And also when Nodes are shared between different types of properties:

      Label label;
      Button button;

      label.setGraphic(button);
      label.setClip(button);

Even with the logic in `setClip` (using `clipParent`) this will still go 
undetected.

--John

>
>
> On Thu, Dec 1, 2022 at 6:17 PM John Hendrikx <john.hendrikx at gmail.com> wrote:
>> The mechanism does seem like it is a bit poorly designed, as it is easy to create inconsistencies.
>>
>> Luckily it seems that you can't remove a graphic yourself from a Control (getChildren is protected).
>>
>> I don't think there is an easy solution though...
>>
>> I think that once you set a graphic on a Labeled, you need to somehow mark it as "in use".  Normally you could just check parent != null for this, but it is trickier than that.  The Skin ultimately determines if it adds the graphic as child, which may be delayed or may even be disabled (content display property is set to showing TEXT only).
>>
>> Perhaps Skins should always add the graphic and just hide it (visible false, managed false), but that's going to be hard to enforce.
>>
>> Marking the graphic as "in use" could be done with:
>>
>> - a property in `getProperties`
>> - a new "owner" or "ownedBy" property
>> - allowing "parent" to be set without adding it to children (probably going to mess up stuff)
>>
>> --John