# vtk python doesn't support get key PgUp/PgDn
**URL:** https://discourse.vtk.org/t/vtk-python-doesnt-support-get-key-pgup-pgdn/16284
**Category:** Development
**Tags:** python, code
**Created:** [February 11, 2026, 3:04pm UTC](https://discourse.vtk.org/t/vtk-python-doesnt-support-get-key-pgup-pgdn/16284 "2026-02-11T15:04:07Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Nam\_Le\_Hoang](https://discourse.vtk.org/u/Nam_Le_Hoang)
#### Post date: [February 11, 2026, 3:04pm UTC](https://discourse.vtk.org/t/vtk-python-doesnt-support-get-key-pgup-pgdn/16284/1 "2026-02-11T15:04:07Z")
Hi, I’m using `vtk==9.5.0` with python in PySide2. Below is my simple script that I try to catch user key press and do works. But when I type `PgUp` `PgDn` the `GetKeySym` return None . Just wanna know if vtk doesn’t support it at all or just in python?
```auto
import sys
from PySide2.QtWidgets import QApplication, QMainWindow, QVBoxLayout, QWidget
from vtkmodules.qt.QVTKRenderWindowInteractor import QVTKRenderWindowInteractor
import vtkmodules.all as vtk
class VTKViewer(QMainWindow):
"""
A PySide2 QMainWindow that embeds a VTK 3D viewer to display a point cloud.
"""
def __init__ (self, parent=None):
super(). __init__ (parent)
self.setGeometry(100, 100, 900, 700) # x, y, width, height
# Central widget and layout
central_widget = QWidget()
self.setCentralWidget(central_widget)
layout = QVBoxLayout(central_widget)
# Create the QVTKRenderWindowInteractor widget
# This widget provides the VTK rendering context within a Qt application
self.vtkWidget = QVTKRenderWindowInteractor(central_widget)
layout.addWidget(self.vtkWidget)
# Get the VTK renderer and render window from the interactor
self.renderer = vtk.vtkRenderer()
self.render_window = self.vtkWidget.GetRenderWindow()
self.render_window.AddRenderer(self.renderer)
self.renderer.SetBackground(0.1, 0.1, 0.9) # Set background color
self.interactor = self.render_window.GetInteractor()
self.interactor_style = vtk.vtkInteractorStyleMultiTouchCamera()
self.interactor.SetInteractorStyle(self.interactor_style)
self.interactor.AddObserver(
vtk.vtkCommand.KeyPressEvent, self._when_key_pressed
)
self.interactor.Initialize()
camera = self.renderer.GetActiveCamera()
camera.SetPosition(2.5, 2.5, 2.5) # Example view from top-right-front
camera.SetFocalPoint(0, 0, 0.2) # Focus on the base
camera.SetViewUp(0, 0, 1) # Z-axis up
self.render_window.Render()
def _when_key_pressed(self, obj, event):
key = self.interactor.GetKeySym()
_ctrl_key = self.interactor.GetControlKey()
_shift_key = self.interactor.GetShiftKey()
_alt_key = self.interactor.GetAltKey()
print(f"Key pressed: {key} (ctrl: {_ctrl_key}, shift: {_shift_key}, alt: {_alt_key})")
if __name__ == " __main__":
app = QApplication([])
viewer = VTKViewer()
viewer.show()
sys.exit(app.exec_())
```
---
### Author:  [@dgobbi](https://discourse.vtk.org/u/dgobbi)
#### Post date: [February 11, 2026, 4:52pm UTC](https://discourse.vtk.org/t/vtk-python-doesnt-support-get-key-pgup-pgdn/16284/2 "2026-02-11T16:52:07Z")
I looked through the git history of `QVTKRenderWindowInteractor.py` to see what’s going on here.
It seems that when the keysym mappings were added to `QVTKRenderWindowInteractor.py`, these keys were skipped because there was uncertainty about how they were named.
I checked, and their names in Qt are `PageUp` and `PageDown` but their keysyms are actually `Prior` and `Next`.
So in `QVTKRenderWindowInteractor.py` at around line 720, you can change this:
```python
# Key.Key_Prior : 'Prior',
# Key.Key_Next : 'Next',
```
to this:
```python
Key.Key_PageUp : 'Prior',
Key.Key_PageDown: 'Next',
```
And then you can observe ‘Prior’ and ‘Next’ to see when those keys are pressed.
---
### Author:  [@Nam\_Le\_Hoang](https://discourse.vtk.org/u/Nam_Le_Hoang)
#### Post date: [February 12, 2026, 6:38am UTC](https://discourse.vtk.org/t/vtk-python-doesnt-support-get-key-pgup-pgdn/16284/3 "2026-02-12T06:38:05Z")
Thanks you. I can manage to make it works