[vtkusers] Using context views in a QVTKRenderWindowInteractor from Python

[Elvis Stansvik]

2016-05-23 16:28 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:

> I'm trying to use a context view (my goal is to show an XYChart) inside a
> QVTKRenderWindowInteractor, but I'm struggling to get the initialization of
> render window / interactor right.
>
> The docs for vtkRenderViewBase (base class for vtkContextView) says:
>
> "In order to use the view with a QVTKWidget the following code is required
> to ensure the interactor and render window are initialized properly.
>
> QVTKWidget *widget = new QVTKWidget;
> vtkContextView *view = vtkContextView::New();
> view->SetInteractor(widget->GetInteractor());
> widget->SetRenderWindow(view->GetRenderWindow());"
>
> but this is about QVTKWidget, the C++ widget class, which is quite
> different from the Python QVTKRenderWindowInteractor class.
>
> My failed attempt to recreate this initialization sequence when using
> QVTKRenderWindowInteractor is this:
>
>
> class TestWidget(QVTKRenderWindowInteractor):
>
>     def __init__(self, parent=None):
>
>         # We need a render window and interactor to pass to
>         # QVTKRenderWindowInteractor constructor.
>         self.renderWindow = vtkRenderWindow()
>         self.interactor = vtkGenericRenderWindowInteractor()
>         self.interactor.SetRenderWindow(self.renderWindow)
>
>         super(TestWidget, self).__init__(
>             parent, rw=self.renderWindow, iren=self.interactor)
>
>         # Create a context view and set it to use the same
>         # interactor as the QVTKRenderWindowInteractor.
>         self.contextView = vtkContextView()
>         self.contextView.SetInteractor(self.interactor)
>
>         # Create chart and add it to the scene of the context view.
>         self.chart = vtkChartXY()
>         self.contextView.GetScene().AddItem(self.chart)
>
>         # Initialize and start.
>         self.Initialize()
>         self.Start()
>
>
> if __name__ == '__main__':
>
>     app = QApplication(argv)
>
>     widget = TestWidget()
>     widget.show()
>
>     exit(app.exec_())
>
>
> But something goes wrong here, because two windows show up (see attached
> screenshot). The application also segfaults on exit. Besides, it looks very
> kludgy to have to do stuff before the call to super() here. Is this really
> the right way to use the API?
>
> If anyone has worked with QVTKRenderWindowInteractor and vtkContextView,
> I'd much appriciate some advice.
>

Inspired by an older post on this subject [1], I was able to get it partly
working with:

class TestWidget(QVTKRenderWindowInteractor):

    def __init__(self, parent=None):
        super(TestWidget, self).__init__(parent)

        self.contextView = vtkContextView()
        self.chart = vtkChartXY()
        self.contextView.GetScene().AddItem(self.chart)

        # Add renderer of context view to the render window of the widget.
        self.GetRenderWindow().AddRenderer(self.contextView.GetRenderer())

        self.Initialize()
        self.Start()

The chart is empty here, but I've verified by adding some items to it that
it at least shows up correctly, in a single window.

The problem is that interaction of course doesn't work, and if I also add

        self.contextView.SetInteractor(self._Iren)

to set the interactor of the context view to the
vtkGenericRenderWindowInteractor backing the QVTKRenderWindowInteractor,
I'm back to the problem with two windows showing up.

I need interaction to work, because my goal is to show an opacity function
editor item in the chart.

Thankful for any and all advice!

Elvis

[1] http://www.vtk.org/pipermail/vtkusers/2011-July/068893.html


>
> Cheers,
> Elvis
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20160523/cf1869d9/attachment.html>