Allow a configurable title of the legend

[timroes]

To make timelion in Kibana use elastic-charts we'd need to be able to have the "header"/"title" of the legend be configurable. This currently shows the active hovered time when you hover over the chart. We'd need this either built into elastic-chart, or make the title configurable, so we can build this implementation on the Kibana side:

Kibana cross issue: elastic/kibana#79984

[markov00]

I've taken a deeper look at Timelion and I think we can live without that feature for the following reasons:

• when moving the mouse over the chart, Timelion doesn't show the tooltip, but the legend act as a tooltip: the header is the current cursor position along the x-axis + every series current value. Our tooltip works exactly in the same way at the moment.
• keep consistency with other tools using elastic-charts: I think it's preferable to use the same tooltip all over the place, instead of having Timelion charts with a Legend-Tooltip but Lens one having Legend + Tooltip
• in a near future, the tooltip and the legend can be designed as a unique and interchangeable component, and at that point, we can have a fixed legend/tooltip like today in Timelion. I prefer to work on this together with all the legend and tooltip redesign effort Legends #580 Tooltip redesign #615

@timroes are you ok if we change the way Timelion legend/tooltip works and align that to the available behavior of elastic-charts? The need to render the legend within the chart will remain and we will work on that
I don't think this is considered a breaking change because our tooltip provides exactly the same information provided by the Timelion legend

[markov00]

@stratoula could you please check if you are ok with my previous comment?

[stratoula]

@markov00 as this information appears on hover and works exactly as our tooltip I am fine with that and I agree, let's be consistent

[markov00]

Ok good, I'm closing this ticket as we are not going to implement the requested feature.
If required, please feel free to reopen it

[yannbolliger]

Would be awesome to have customisable legend titles.