Line chart disappears when zooming

[olelond]

Expected behavior

You should be able to zoom in as much as you want

Current behavior

When zooming closely in the line in the line chart disappears and only reappears again after zooming out again.

Reproducible sample

https://codepen.io/olelond/pen/QwEEvzd

Optional extra steps/info to reproduce

No response

Possible solution

No response

Context

No response

chart.js version

v4.5.1

Browser name and version

No response

Link to your project

No response

[Akshat-0001]

I’ve submitted a fix for this in #12176.

The issue occurs when zooming into a range with zero visible
data points; the line controller skipped rendering entirely.

The fix includes boundary points so line segments crossing
the viewport are still drawn.

[olelond]

@Akshat-0001 sorry for the late feedback
thank you for the quick reaction
I'm wondering if it actually fixes the issue. As I understand it you fix handles the situation with no visible data points. But in the codepen the graph seems to disapears long before that. At least in my browser (chrome on linux)

[Akshat-0001]

@olelond thanks for reviewing, I rechecked the codepen repro, the line vanished because the data are in descending x which made the dataset look 'sorted' to our binary search and it skipped drawing when zoomed in.

a quick workaround is either:

1. remove parsing:false
   or 2) sort the data ascending by x.

Here’s a CodePen using the patched build: https://codepen.io/akshat0603/pen/EayWwVq

Could you try it and confirm it fixes the disappearing line on your end? If it does then I'll follow up with the updated pr.

[Akshat-0001]

I have pushed a follow-up commit to #12176 so parsing-disabled datasets no longer get marked sorted when the x values are descending. This addresses the bug, Please recheck on your end; if it looks good, this should close the disappearing-line issue.

[olelond]

@Akshat-0001 I've tried your codepen with the patch and I can confirm that it indeed fixes the problem.
I've also tested the workaround removing parsing: false which also fixes the problem.
That's awsome. Thank you