feat(xy)!: change timeAxisLayerCount the default from 0 to 2

[walterra]

Summary

timeAxisLayerCount: 2 is now the default to render multiple layers for time based axes. This feature was originally added in 2021 and now just a small set of consumers are using the legacy time axis.

BREAKING CHANGE

The timeAxisLayerCount options now defaults to 2 instead of 0.

Details

• This includes some tricky changes: Because timeAxisLayerCount defaulted to 0, code in some places assumed that a change to 2 was only done by users when the x axis was then time based. Thus changing the default to 2 changed the calculated padding for all axis types.
• On top of that this surfaced a limitation of this setting: When timeAxisLayerCount is set to 2, there was no check for axes if they were actually time based. This means this also affected vertical axes so the left and right margin would change. I think that's the reason why we see so many baseline changes in the playwright e2e image assertions.

Issues

This PR is part of elastic/kibana#193683

Checklist

• The proper chart type label has been added (e.g. :xy, :partition)
• The proper feature labels have been added (e.g. :interactions, :axis)
• All related issues have been linked (i.e. closes #123, fixes #123)
• New public API exports have been added to packages/charts/src/index.ts
• Unit tests have been added or updated to match the most common scenarios
• The proper documentation and/or storybook story has been added or updated
• The code has been checked for cross-browser compatibility (Chrome, Firefox, Safari, Edge)
• Visual changes have been tested with light and dark themes

[nickofthyme]

@walterra FYI, to update any playwright snapshots you can comment on the PR with..

buildkite update screenshots

This will run the ci in update mode and push a commit to your branch with the updated e2e screenshots, if any. The reason we need to run this in the CI is due to slight differences in the browser binaries between MacOS and linux ci agents. So to avoid this we only store screenshots generated from ci.

And to just trigger a re-run of the ci you can comment...

buildkite test this

[walterra]

This still causes a baseline change, right padding in the lowest chart:

[walterra]

This reason for this regression: We now have to check for both timeAxisLayerCount > 0 and if the scale type is time, however, the lowest chart uses ordinal.

[walterra]

If I change the xScaleType of the BarSeries of the last chart to ScaleType.Time it looks correct:

[walterra]

Posting this here for reference to start a thread, because the affected example file has not been touched.

There's a baseline change for stories with custom markers. Previously the axis ticks and markers would render overlapping, now they render with additional offset. Is the new version ok? I'm not sure the original overlapping was intentional or a bug?

https://ech-e2e-ci--pr-2582-n5t2yfqp.web.app/e2e-report/#?testId=9cb55a84df16c692f1c3-042343d23333860efb20

[elastic-datavis]

✅ Successful Deployment (build#4404) - abddedc

• Docs
• Storybook
• e2e server
• Playwright report