Additional line segments drawn when gaps and min/max

[jledentu]

Hi, I've some issues when I apply min/max on X scale: on some datasets, additional line segments are drawn. I think this bug appears when there are "gaps" in the line, making the line split into several segments.

Expected Behavior

Given this chart if no min/max:

If I set min: 1, max: 3, I'd expect this:

Current Behavior

What I get:

Steps to Reproduce

https://codepen.io/jledentu/pen/GRrGWPg

Environment

• Chart.js version: v3.1.0
• Browser name and version: Firefox, Chrome...

[kurkle]

This probably comes form #8844

No, same behavior with 3.0.2, so its older.

[jledentu]

@kurkle I reproduced the bug with #7808 but not #7793, so I presume that #7808 introduced the bug.

Note that the issue then happens on animated charts. On un-animated charts (options.animation: false), the bug appeared later, on #8703.

So it seems to be related to this check in controller.line.js:

if (scaleRangesChanged(meta)) {
      start = 0;
      count = points.length;
}

where start and count (computed above with getStartAndCountOfVisiblePoints) are overridden. If I comment the 2 reassignments, it fixes the issue in my test. I don't know how to fix the bug by myself but I hope that these infos will help you.