[vtkusers] custom vtkAbstractWidget + vtkWidgetRepresentation in Java

[Sebastien Jourdain]

Hi Petr,

I think you have to implement your code in C++ and then use it within Java.

Seb

On Thu, Sep 7, 2017 at 8:08 AM, Petr Matoušek <p3tr.matousek at gmail.com>
wrote:

> Hello,
>
> can anybody suggest how to implement custom vtkAbstractWidget and
> vtkWidgetRepresentation in Java? Is it even possible?
>
> I tried it but failed.
>
> 1. The first problem I encountered was that vtkAbstractWidget uses its
> protected field WidgetRep, but there is no way how to set it from Java
> code. Only public methods are accessible from Java. So I introduced my own
> field in the Java class and overrided the GetRepresentation() method to
> return it. So far so good:
>
> public class CoordRangeVtkLineWidget extends vtkAbstractWidget {
>
>     private final vtkLineRepresentation representation;
>
>     public CoordRangeVtkLineWidget(final CoordRange coordRange) {
>         super();
>         this.representation = new vtkLineRepresentation();
>     }
>
>     @Override
>     public vtkWidgetRepresentation GetRepresentation() {
>         return this.representation;
>     }
> }
>
> 2. But then the SetInteractor() method started to fail for my widget with
> SIGSEGV crash. I guess this is due to the fact that the observer mechanism
> is implemented a bit differently in Java. So it is not possible to call the
> original AddObserver() methods with Java object instances.
>
> So I skipped the interactor for the moment:
>
> @Override
> public void SetInteractor(final vtkRenderWindowInteractor interactor) {
>     // TODO
> }
>
> 3. Then vtkAbstractWidget::SetEnabled() started to fail with SIGSEGV of
> course.
>
> So I stopped and start to think: this would be quite difficult. In fact I
> will probably have to reimplement the whole vtkAbstractWidget in Java to
> make it work.
>
> So does anybody any experience with this. Any suggestions? Am I going
> wrong direction? Please.
>
> Best regards, Petr Matousek
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