Getting relayout parameters from Plotly figures

[teristam]

Currently the on_relayout callback of Plotly figure doesn't return any argument, especially the current zoom-in axis coordinates. Plotly.js does remit these values as far as I know (https://plotly.com/javascript/plotlyjs-events/#update-data)
Having these information is important for efficiency reason, e.g. the backend may down-sample the data before sending it over to Plotly. I hope this feature can be added.

Thank you!

[linear]

ENG-4195 Getting relayout parameters from Plotly figures