feat: line selection highlighting

[rich-b]

Description

Adds selection highlight support to Line charts

Related Issue

#374

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
96.7% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[marshallpete]

Do you mind adding a story that demonstrates this feature?

[rich-b]

@marshallpete the existing story already demonstrates this. the ChartPopover -> LineChart story has a UNSAFE_highlightBy control. It can be set to item(default), series, or dimension. This is the same as what we already have for the ChartPopover -> StackedBarChart story

[majornista]

I think "line highlighting" highlight the line, by drawing a stroke outline, rather than all the points in the line?

I'm thinking of the use case where there are hundreds of points in a condensed space, so that highlighted points would overlap.

[marshallpete]

Good callout @majornista . With spectrum 2 changes we will be re-evaluating all the hover, focus and select states. I think we can revisit then.