[API Review] RT-27887: introduce a node to embed Swing into JavaFX

[Artem Ananiev]

On 1/25/2013 8:30 PM, Richard Bair wrote:
>>> I wonder if it's not better to require that the method is called
>>> *always* in the swing thread to avoid confusion, I fear that some
>>> programmers will construct their swing components outside the EDT, but
>>> even worse, I fear this can be taken as some kind of allowance to
>>> initialise them, and perhaps in some cases even start them, in the FX
>>> dispatching thread.
>>>
>>> For no reason this consideration should pollute the API, but I guess
>>> either requiring that the method is called in the EDT or putting in the
>>> JavaDoc that the Swing components still need to follow the usual rules
>>> would be a better thing.
>>
>> Well, I think we may disallow calling it on FX thread, thus
>> eliminating doubtful options.
>
> I'm actually of the other opinion, that it ought to be callable from
> the FX thread but not the EDT. The reason is that there is no API
> presently in FX that cannot be called on the FX thread (some APIs on
> Service are spec'd to be called by the platform on a different
> thread, but if you did call it from the FX thread it should still
> work).

Just imagine the code that creates a SwingNode and its content:

public void start(Stage stage) {
   Scene scene = ...;
   final SwingNode swing = new SwingNode();
   scene.getRoot().getChildren().add(swing);
   stage.setScene(scene);
   stage.show();

   SwingUtilities.invokeLater(() -> {
     JComponent content = ...;
     swing.setContent(content);
   });
}

If we require setContent() to be called on FX thread only, the last part 
of the code above will become a little bit more ugly:

   SwingUtilities.invokeLater(() -> {
     final JComponent content = ...;
     Platform.runLater(() -> {
       swing.setContent(content);
     });
   });

> Another thing to think about (and I hope there is a JIRA for it) is
> that I believe Artem had some ideas around how we could make the FX
> thread and the EDT the same thread -- maybe by launching the JRE with
> a command line flag. In that case the distinction would be
> irrelevant.

Even if we implement single-threaded mode for FX/Swing bridge, it will 
be off by default for at least one major release to preserve backwards 
compatibility.

Thanks,

Artem

> Richard