vtk_callback_example.py

# Ref: https://github.com/Beastmaster/itk-python-example/blob/master/vtkSlidebar.py
# Ref: https://kitware.github.io/vtk-examples/site/Cxx/Widgets/Slider/

import vtk

sphereSource = vtk.vtkSphereSource()
sphereSource.SetCenter(0.0,0.0,0.0)
sphereSource.SetRadius(4.0)
sphereSource.Update()

mapper = vtk.vtkPolyDataMapper()
mapper.SetInputData(sphereSource.GetOutput())

actor = vtk.vtkActor()
actor.SetMapper(mapper)
actor.GetProperty().SetInterpolationToFlat()

renderer = vtk.vtkRenderer()
renderWin = vtk.vtkRenderWindow()
renderWin.AddRenderer(renderer)

renWinInteractor = vtk.vtkRenderWindowInteractor()
renWinInteractor.SetRenderWindow(renderWin)

renderer.AddActor(actor)
renderWin.Render()

#build a slide bar
slideBar = vtk.vtkSliderRepresentation2D()

slideBar.SetMinimumValue(3.0)
slideBar.SetMaximumValue(20.0)
slideBar.SetValue(sphereSource.GetPhiResolution())

slideBar.GetSliderProperty().SetColor([c/255. for c in (0,204,204)])
slideBar.GetSelectedProperty().SetColor([c/255. for c in (153,255,255)])

slideBar.GetPoint1Coordinate().SetCoordinateSystemToNormalizedDisplay()
slideBar.GetPoint1Coordinate().SetValue(0.1 ,0.07)
slideBar.GetPoint2Coordinate().SetCoordinateSystemToNormalizedDisplay()
slideBar.GetPoint2Coordinate().SetValue(0.9, 0.07)

slideBar.SetSliderLength(0.02)
slideBar.SetSliderWidth(0.04)
slideBar.SetEndCapWidth(0.04)
slideBar.SetEndCapLength(0.005)
slideBar.SetTubeWidth(0.005)

sliderWidget = vtk.vtkSliderWidget()
sliderWidget.SetInteractor(renWinInteractor)
sliderWidget.SetRepresentation(slideBar)
sliderWidget.EnabledOn()

class vtkSliderCallback:
    def __init__(self, Sphere):
        self.Sphere = Sphere
    def execute(self, obj, event):
        slider = obj
        value = int(slider.GetRepresentation().GetValue())
        self.Sphere.SetPhiResolution(value)
        self.Sphere.SetThetaResolution(value)
        self.Sphere.Update()

cb = vtkSliderCallback(sphereSource)
sliderWidget.AddObserver("InteractionEvent", cb.execute)

renderer.ResetCamera()
renWinInteractor.Initialize()
renderWin.Render()
renderWin.SetWindowName('VTK Viewer')
renWinInteractor.Start()