HoverWidget

#!/usr/bin/env python3

# noinspection PyUnresolvedReferences
import vtkmodules.vtkInteractionStyle
# noinspection PyUnresolvedReferences
import vtkmodules.vtkRenderingFreeType
# noinspection PyUnresolvedReferences
import vtkmodules.vtkRenderingOpenGL2
from vtkmodules.vtkCommonColor import vtkNamedColors
from vtkmodules.vtkFiltersSources import vtkSphereSource
from vtkmodules.vtkInteractionWidgets import vtkHoverWidget
from vtkmodules.vtkRenderingCore import (
    vtkActor,
    vtkPolyDataMapper,
    vtkRenderer,
    vtkRenderWindow,
    vtkRenderWindowInteractor,
)


def main():
    colors = vtkNamedColors()

    sphere_source = vtkSphereSource()

    # Create a mapper and actor
    mapper = vtkPolyDataMapper()
    sphere_source >> mapper
    actor = vtkActor(mapper=mapper)
    actor.property.color = colors.GetColor3d('MistyRose')

    # A renderer and render window
    renderer = vtkRenderer(background=colors.GetColor3d('SlateGray'))
    render_window = vtkRenderWindow(window_name='HoverWidget')
    render_window.AddRenderer(renderer)

    renderer.AddActor(actor)

    # An interactor.
    render_window_interactor = vtkRenderWindowInteractor()
    render_window_interactor.render_window = render_window

    # Create the widget
    hover_widget = vtkHoverWidget()
    hover_widget.interactor = render_window_interactor
    hover_widget.SetTimerDuration(1000)

    # Create a callback to listen to the widget's two VTK events.
    hoverCallback = HoverCallback()
    hover_widget.AddObserver('TimerEvent', hoverCallback)
    hover_widget.AddObserver('EndInteractionEvent', hoverCallback)

    render_window.Render()

    render_window_interactor.Initialize()
    render_window.Render()
    hover_widget.On()

    render_window_interactor.Start()


class HoverCallback:

    def __call__(self, caller, ev):
        if ev == 'TimerEvent':
            print('TimerEvent -> The mouse stopped moving and the widget hovered.')
        if ev == 'EndInteractionEvent':
            print('EndInteractionEvent -> The mouse started to move.')


if __name__ == '__main__':
    main()