[FIXED] vtk: how to remove all observers

Issue

I am using VTK in my project. Now, I want to remove all observers and implement my-self observer. But the RemoveAllObservers do not work. My code is:

from PyQt5.QtWidgets import *
import sys, os
import vtk
from vtk.qt.QVTKRenderWindowInteractor import QVTKRenderWindowInteractor

def mouseMoveEvent(iren, event):
    print('move')

class MyWin(QWidget):
    def __init__(self):
        super().__init__()

        layout = QVBoxLayout()
        self.setLayout(layout)

        self.vtkWidget = QVTKRenderWindowInteractor()
        layout.addWidget(self.vtkWidget)
        self.ren = vtk.vtkRenderer()
        self.vtkWidget.GetRenderWindow().AddRenderer(self.ren)

        interactor = self.vtkWidget.GetRenderWindow().GetInteractor()
        interactor.Initialize()
        interactor.RemoveAllObservers()
        interactor.AddObserver('MouseMoveEvent', mouseMoveEvent)
        interactor.Start()

        self.imageViewer = vtk.vtkImageViewer2()
        self.imageViewer.SetupInteractor(interactor)
        self.imageViewer.SetRenderWindow(self.vtkWidget.GetRenderWindow())

        img = vtk.vtkDICOMImageReader()
        img.SetFileName('C:\\Users\\MLoong\\Desktop\\dicom_data\\Chang Cheng\\TOF\\IM_0174')
        img.Update()

        self.imageViewer.SetInputData(img.GetOutput())
        self.imageViewer.Render()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MyWin()
    window.show()
    app.exec_()

Even I remove all observers by interactor.RemoveAllObservers(), the image can still be zoom in/out by right mouse. How can I remove all the observers?

Solution

The problem is the order of your setup.

imageViewer.SetupInteractor() recreate some default observers. So you should remove / create observer after.

        interactor = self.vtkWidget.GetRenderWindow().GetInteractor()

        self.imageViewer = vtk.vtkImageViewer2()
        self.imageViewer.SetupInteractor(interactor)
        self.imageViewer.SetRenderWindow(self.vtkWidget.GetRenderWindow())

        # img = vtk.vtkDICOMImageReader()
        # img.SetFileName('C:\\Users\\MLoong\\Desktop\\dicom_data\\Chang Cheng\\TOF\\IM_0174')
        # using a source for testing
        img = vtk.vtkRTAnalyticSource()
        img.Update()

        self.imageViewer.SetInputData(img.GetOutput())
        self.imageViewer.Render()

        interactor.RemoveAllObservers()
        interactor.AddObserver('MouseMoveEvent', mouseMoveEvent)
        interactor.Initialize()
        interactor.Start()

Answered By - Nico Vuaille