Setting graphics of a Labeled does not show the Label correctly

[Andy Goryachev]

Does wrapping the action code in runLater() help?

b1.setOnAction((ev) -> {
Platform.runLater(() -> {
  if (b1.getParent() == cb1) {
  ...


-andy

From: openjfx-dev <openjfx-dev-retn at openjdk.org> on behalf of John Hendrikx <john.hendrikx at gmail.com>
Date: Thursday, 2022/12/01 at 09:14
To: Nir Lisker <nlisker at gmail.com>
Cc: openjfx-dev at openjdk.org <openjfx-dev at openjdk.org>
Subject: Re: Setting graphics of a Labeled does not show the Label correctly

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
On 01/12/2022 15:21, Nir Lisker wrote:
Technically it doesn't appear elsewhere in the scenegraph, it is the child of only one label. It's set as the graphics property of 2 labels though. The mismatch is that being set as a graphics property isn't a 1-to-1 relationship with being a child of the label.

Something has to be fixed along this chain of inconsistency, I just wasn't sure where. It seems like the IAE that you mentioned should be thrown, but isn't. I can write a PR for that. One thing I'm not sure about is: in a situation where the graphic belongs to a label that is detached from a scene, and that graphic is set to a label that *is* part of a scene, should an IAE be thrown as well.
Even if the Labeled is part of the Scene, the graphic may not be (depending on Skin used and on Content Display property for the default skin).


By the way, changing to throwing an IAE is going to cause some new exceptions. There is a possibility that some VirtualFlow things will break because that mechanism recycles nodes and re-attaches their properties. Then again, it might just mean that it was done wrong.

On Thu, Dec 1, 2022 at 3:49 PM John Hendrikx <john.hendrikx at gmail.com<mailto:john.hendrikx at gmail.com>> wrote:

Sorry, I meant on the first click already.

--John
On 01/12/2022 14:46, John Hendrikx wrote:

Setting the same Node for multiple graphics is not allowed.  Your program should IMHO throw "IllegalArgumentException" on the 2nd click.

     * An optional icon for the Labeled. This can be positioned relative to the
     * text by using {@link #setContentDisplay}.  The node specified for this
     * variable cannot appear elsewhere in the scene graph, otherwise
     * the {@code IllegalArgumentException} is thrown.  See the class
     * description of {@link Node} for more detail.

--John
On 01/12/2022 13:38, Nir Lisker wrote:
That's my point. Currently, a node can serve as the graphics property for multiple Labels, but will appear only in 1 because it can only have a single parent in the scenegraph. While this is technically fine, it causes issues like the one I showed above. I'm not sure if a node is supposed to be able to serve as multiple graphics (and displayed only in the last Label it was set to?), or removed from other Labels' graphic properties just like is done for children in the scenegraph. Personally, I find it confusing that label.getGraphics() will return a node that isn't shown in that label.

On Thu, Dec 1, 2022 at 2:21 PM John Hendrikx <john.hendrikx at gmail.com<mailto:john.hendrikx at gmail.com>> wrote:
Internally the graphics is just a child node, and nodes can't be part of
the scene graph twice (this is done in LabeledSkinBase).

It showing up only once is probably because it is getting removed from
the other labels.

I think things are probably getting out of sync, where the graphics
property may think it still has a certain node as its graphics, but it
is no longer a child of the label.

--John

On 01/12/2022 11:23, Nir Lisker wrote:
> Hi,
>
> Given the following code
>
>         var cb1 = new Label("1");
>         var cb2 = new Label  ("2");
>         var b1 = new Button("A");
>         cb1.setGraphic(b1);
>         b1.setOnAction(e -> {
>             if (b1.getParent() == cb1) {
>                 // cb1.setGraphic(null);
>                 cb2.setGraphic(b1);
>             } else {
>                 // cb2.setGraphic(null);
>                 cb1.setGraphic(b1);
>             }
>         });
>
> Pressing the first button will move it (the graphic) to the second
> label, however, pressing it again will not move it back to the first
> label. It's required to set the graphics to null prior to moving them
> as in the commented lines. This looks like a bug to me. I would think
> that when a graphic is moved, it will appear in its new label
> immediately, like moving a child. Apparently a single node can be the
> graphics for multiple Labeled nodes, but it will appear only in 1. Is
> this intentional?
>
> - Nir
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