bug: ZeroDivisionError when altering clims for uniform image.

[gselzer]

• ndv version: 0.0.5.dev8...
• Python version: 3.12.3
• Operating System: Windows 11
• BACKEND: vispy

Description

It would seem that SceneCanvas.elements_at (naturally) throws a ZeroDivisionError, crashing python, when the contrast range is zero. This can happen when the dataset only contains a single value (example below). As this method is called from data interrogation (during hovering), this can cause unexpected crashes.

I'm not sure whether this is a vispy bug, or whether it's something we should handle here. I lean towards the former but would appreciate others' opinions.

What I Did

Here's the code for a minimal example:

import ndv
import numpy as np

img = np.ones((256, 256)) * 128
ndv.imshow(img)

Steps to reproduce the crash:

1. Set the contrast limits to the same value.
2. Hover over a part of the image.

[tlambert03]

This actually will be fixed in the next vispy release... see vispy/vispy#2621

(Maybe? Is your error on that same line?)

[gselzer]

Heh, you beat me to it! Great! 💨