Get current viewer

Get a reference to the current napari viewer.

Whilst this example is contrived, it can be useful to get a reference to the viewer when the viewer is out of scope.

Tags: gui

Python (.py)

Notebook (.ipynb)

/home/runner/work/docs/docs/.venv/lib/python3.12/site-packages/napari/_qt/qt_event_loop.py:50: UserWarning: System theme detection requires a Qt6 backend. Please switch to PyQt6 or PySide6 to use it.
  theme_type=get_system_theme(),
/home/runner/work/docs/docs/.venv/lib/python3.12/site-packages/napari/_qt/qt_event_loop.py:50: UserWarning: System theme detection requires a Qt6 backend. Please switch to PyQt6 or PySide6 to use it.
  theme_type=get_system_theme(),

import numpy as np

import napari

# create viewer
viewer = napari.Viewer()

# lose reference to viewer
viewer = 'oops no viewer here'

# get that reference again
viewer = napari.current_viewer()

# work with the viewer
x = np.arange(256)
y = np.arange(256).reshape((256, 1))
# from: https://botsin.space/@bitartbot/113553754823363986
image = (-(~((y - x) ^ (y + x)))) % 11
layer = viewer.add_image(image)
layer.contrast_limits = (8.5, 10)

if __name__ == '__main__':
    napari.run()