Disable interactions of interactor in python

Support
1

I use vtk in an application (qt) where I would like to define my own events for right-mouse button (context menu) as well as some of the key presses.

Problem is that they are already used by the interactor.
(https://vtk.org/doc/nightly/html/classvtkInteractorStyle.html#details) Is there a way to keep the interactor from handling these events?

I’m using python so subclassing the interactor (like sugested here: Selectively disable and enable default mouse interactions in vtk) is not an option.

Is there any other way to disable some of the default interactions?

2

You can override the interaction in the vtkInteractorStyle classes.

First, choose a vtkInteractorStyle that most closely matches your desired behavior, e.g. vtkInteractorStyleTrackball or vtkInteractorStyleUser.

Then, add Python observers to the events you want to override or disable:

style.AddObserver("KeyPressEvent", callback)
style.AddObserver("KeyReleaseEvent", callback)
style.AddObserver("CharEvent", callback)
3

Hi @dgobbi , yes that’s what I thought I was doing but it didn’t work.

I now realize that I need to add the oberservers to the STYLE and not to the renderWindowInteractor (which is what I was doing).

Thanks!

Posting a full example here for the next person running into this:

vtkInteractorStyleTrackballCamera with keys and right button features disabled.

import vtk
# noinspection PyUnresolvedReferences
import vtkmodules.vtkInteractionStyle
# noinspection PyUnresolvedReferences
import vtkmodules.vtkRenderingOpenGL2
from vtkmodules.vtkCommonColor import vtkNamedColors
from vtkmodules.vtkFiltersSources import vtkCylinderSource
from vtkmodules.vtkRenderingCore import (
    vtkActor,
    vtkPolyDataMapper,
    vtkRenderWindow,
    vtkRenderWindowInteractor,
    vtkRenderer
)


def main():
    colors = vtkNamedColors()

    # Create a sphere
    cylinderSource = vtkCylinderSource()
    cylinderSource.SetCenter(0.0, 0.0, 0.0)
    cylinderSource.SetRadius(5.0)
    cylinderSource.SetHeight(7.0)
    cylinderSource.SetResolution(100)

    # Create a mapper and actor
    mapper = vtkPolyDataMapper()
    mapper.SetInputConnection(cylinderSource.GetOutputPort())
    actor = vtkActor()
    actor.GetProperty().SetColor(colors.GetColor3d('Cornsilk'))
    actor.SetMapper(mapper)

    # Create a renderer, render window, and interactor
    renderer = vtkRenderer()
    renderWindow = vtkRenderWindow()
    renderWindow.SetWindowName('Cylinder')
    renderWindow.AddRenderer(renderer)

    style = vtk.vtkInteractorStyleTrackballCamera()

    style.AddObserver("CharEvent", lambda x, y: print('key char'))
    style.AddObserver("RightButtonPressEvent", lambda x, y: print('right press'))
    style.AddObserver("RightButtonReleaseEvent", lambda x, y: print('right release'))

    renderWindowInteractor = vtkRenderWindowInteractor()
    renderWindowInteractor.SetInteractorStyle(style)
    renderWindowInteractor.SetRenderWindow(renderWindow)


    # Add the actor to the scene
    renderer.AddActor(actor)
    renderer.SetBackground(colors.GetColor3d('DarkGreen'))

    # Render and interact
    renderWindow.Render()
    renderWindowInteractor.Start()


if __name__ == '__main__':
    main()