[Bullet] Tooltips shouldn't appear on the entire canvas

[ghudgins]

Is your feature request related to a problem? Please describe.
Distracting to have the tooltip appear when you hover over white space in the chart canvas

Describe the solution you'd like
Consider only letting the "Actual" value show when hovering on the bullet

Kibana Cross Issues
Related to Lens integration of this visualization type elastic/kibana#89859 CC @flash1293

Checklist

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[monfera]

Documenting some design considerations here:

• It's possible, and sometimes desirable to style a horizontal or vertical bullet such that it's thin (eg. for a clean look) eg. this or thinner
• Fitts law prompts us to have a decent sized mouse capture zone for the tooltip to activate; while in Lens config, the bullet chart may be in a huge area with hundreds of pixels of empty space around it, in a dashboard the entire thing may be a few tens of pixels horizontally or vertically; so it's useful to take the maximum of the computed width/height and some value at which the tooltip-on-background is not disturbing (something like 100px CSS)
• In case of circly gauge/goal (should they become requested by customers) it'd be esp. annoying to have to precisely hit a potentially thin circle (or tick label)
• due to tick placement, other annotations, ticks etc. the chart has no definite area

So I'm planning with something like this:

The width of the capture zone would be the largest of

• 100 CSS pixels (Fitts law driven)
• 50% of the chart width (so a decent fraction of the full chart area is tooltip sensitive)
• the width of the bounding box of anything that gets rendered

Same for height.

@markov00 @ghudgins please bring up alternatives

[markov00]

@monfera I think this is a sensible selection of params, so I'm ok with your suggestion.
One alternative could be just the bounding box of the bullet chart without the label

[markov00]

or the background area of the quantitative scale independently from the size and weight of the bar

[ghudgins]

I agree with the concern (thinness) - great catch. I don't have any new suggestions: the bounding box idea sounds simplest but having a little bit of padding seems nice for usability. This is probably one of those things that needs to be quickly prototyped to zero in on the optimal balance between easy to activate and easy to NOT activate.