Windows上VTK中的箭头键事件

Question

Why are arrow key-press events not forwarded to the vtkRenderWindowInteractor on Windows? Is there a workaround? Is there a general difference between arrow-key events on Windows and Mac?

I can reproduce the problem with the following sample code. On Mac OS, I see 'Up', 'Down', 'Left' and 'Right' if I press the arrow keys. But on Windows, I don't see anything (the callback is not entered). I wondered why this is the case.

I use VTK 6.2.0 for python 2.7. I tested on Windows Server 2012 (similar to Windows 8) and Windows 7 (on a virtual machine), showing both the same behaviour.

# -*- coding: utf-8 -*-
import vtk
import sys

class ClickInteractorStyle(vtk.vtkInteractorStyleTrackballCamera):
    def __init__(self, parent=None):
            self.AddObserver("CharEvent",self.onKeyPressEvent)

    def onKeyPressEvent(self, renderer, event):        
        key = self.GetInteractor().GetKeySym()
        print key
        self.OnChar()

def run():
    sphereSource = vtk.vtkSphereSource()
    sphereSource.SetCenter(0.,0.,0.)
    sphereSource.SetRadius(1.)
    sphereSource.Update()

    sphereMapper = vtk.vtkPolyDataMapper()
    sphereMapper.SetInputConnection(sphereSource.GetOutputPort())

    sphereActor = vtk.vtkActor()
    sphereActor.SetMapper(sphereMapper)

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

    renderWindowInteractor = vtk.vtkRenderWindowInteractor()
    renderWindowInteractor.SetRenderWindow(renderWindow)
    style = ClickInteractorStyle()
    renderWindowInteractor.SetInteractorStyle(style)
    style.SetCurrentRenderer(renderer)

    renderer.AddActor(sphereActor)
    renderWindow.Render()
    renderWindowInteractor.Start()



###############################################################################
# MAIN
###############################################################################
if __name__ == "__main__":
    try:
        run()
    except:
        print "Unexpected error: %s", sys.exc_info()[0]
        raise

Answer 1

This fixed my problem: Replace

self.AddObserver("CharEvent",self.onKeyPressEvent)

with

self.AddObserver("KeyPressEvent",self.onKeyPressEvent)