Adding components to Node created by GraphicFactory

[deadpoll]

Hi Tomas,

I'm creating a custom graphic factory much more complicated than your LineNumberFactory example, in that rather than just create a Label, it creates a Pane which contains Labels and HBoxes etc.

Throughout the life of the application, the user can perform certain actions on each line, and one of these actions requires the addition of new components into the Pane aforementioned above.

The scenario is: the user right clicks on a line and chooses an action from the displayed context menu. The action attempts to add a Label to the HBox within the Pane, however 50% of the time (possibly even less) the Label does not get rendered. What I found was that I needed to resize the height of the codearea so that it was compressed small enough so that the Pane in question was being hidden, and it was only when I then expanded it back out (making the Pane visible again) that the apply() method within the graphic factory was fired, and hence the Label was then properly rendered.

I must note that the action in question did not involve removing or adding new lines. I've tried calling requestLayout() and layout()/layoutChildren() after adding the Label but that doesn't seem to implicitly call the apply() method.

Could you please help me in this matter? I don't understand why most of the time the Label isn't displayed immediately. Any help would be greatly appreciated. Thanks.

[JordanMartinez]

I've tried calling requestLayout() and layout()/layoutChildren() after adding the Label but that doesn't seem to implicitly call the apply() method.

It does seem odd that it's not updating your graphic automatically..

Which object's requestLayout() and layout() method are you calling? Does this fix it?

Pane pane = // the root pane of your graphic factory;
Parent paragraphBox = pane.getParent();
paragraphBox.layout(); // or one of the other layout methods...

[TomasMikula]

The "paragraph graphic" node is (re-)created (i.e. the factory's apply() method is called to create the node) when

• the paragraph becomes visible; or
• text of the paragraph was edited; or
• paragraph number changed (i.e. added or deleted paragraphs before this one); or
• paragraphGraphicFactory changed.

The action attempts to add a Label to the HBox within the Pane

I wonder how you do this. Where do you get the reference to the mentioned Pane from? I'm suspicious that you are modifying some Pane that is not even part of the scene.

The above are the only cases when the factory is invoked to create a new graphic node. If you need to update existing graphic node in circumstances other than above, the created node will have to register a listener to an appropriate event. It is also its responsibility to unregister such a listener once it is removed from the scene. An example of such case, including taking care of clean-up, can be found here.

[deadpoll]

@JordanMartinez: I was calling requestLayout() and layout() on the CodeArea instance. Also, I have already tried that and it always results in a NullPointerException, where the parent is always being returned as null for some reason.

@TomasMikula: Ok so I'll describe how I add a Label to the HBox inside the Pane. Essentially the apply() method creates a class (which I'll refer to as) GutterController. This GutterController loads an FXML structure and creates a Node from it, returned as a BorderPane like so:

@Override
public Node apply(int idx)
{
    GutterController gutter = new GutterController(observable);
    return gutter.getRootPane();
}

Now inside the GutterController class, I have something like this:

@FXML
private HBox hbox;

public GutterController(ObservableValue observable)
{
    observable.addListener((obs, oldValue, newValue) -> addLabel());
}

private void addLabel()
{
    hbox.getChildren().add(new Label("Test Label"));
}

When observable changes (a consequence of the action I described in my original post), the listener responds by adding a Label to the hbox container. The action does not result in any of the 4 scenarios that you listed above, however the Label does render and appear correctly in the rare occasion, but the majority of the time the Label does not appear until I force the apply() method to be called under the first scenario that you describe, which is the paragraph becomes visible. The listener that I'm using.... is this what you were referring to?

I hope I've clarified my issue. Please let me know if you can reproduce it or at least provide some sort of guidance. Thank you.

[TomasMikula]

where the parent is always being returned as null for some reason.

That indeed sounds like the node you are trying to force layout on is indeed not part of the scene.

What is the observable?

Also, if you don't take care of removing that listener, you will get a memory/cpu leak. (The apply() method is called often (see the four cases above) and each invocation registers a listener.)

[deadpoll]

@TomasMikula Sorry for the late reply. Been away for a week.

That indeed sounds like the node you are trying to force layout on is indeed not part of the scene.

Hmm but the Label is displayed like 10% of the time. 90% of the time the Label isn't added, however the other 10% it is successful. But of course the ideal is 100%.

observable is an ObservableList which changes size. The GutterController adds a listener to this observable and adds or removes a Label to the hbox depending on whether the ObservableList has added or removed elements.

Also, if you don't take care of removing that listener, you will get a memory/cpu leak. (The apply() method is called often (see the four cases above) and each invocation registers a listener.)

Understood, it's an issue I want to deal with once I've dealt with this rendering issue.

Do you have any suggestions?

[TomasMikula]

It is hard to tell from this description. Can you provide a simple self-contained example?

[deadpoll]

@TomasMikula I created a sample application for you to see the issue, however, it didn't produce the same issues, and the labels were being added correctly. So it was definitely something that I was doing. The observable I was passing was being garbage collected and hence the listener wasn't even firing in the first place. Sorry to bother you and thanks for your time in trying to help me resolve it.