How to make 'shape' track mouse motion?

plotly.js
10

Recently I struggled to to the same with geo plots, which have a different coordinate system. I wrote the following function to cover all (?) possibilities and also to clip events that occur outside of the plotting area:

function eventToCursor(event) {
    var layout = gd._fullLayout
    x = event.offsetX - layout.margin.l
    y = event.offsetY - layout.margin.t
    if (x < 0 || y < 0 || x > layout.width || y > layout.height) {
        return
    }
    
    if (layout.hasOwnProperty('xaxis')) {
        x = layout.xaxis.p2c(x)
        y = layout.yaxis.p2c(y)
        cursor = {cursor: {x: x, y: y}}
    } else {
        if (layout.hasOwnProperty('geo')) {
            geo = layout.geo
        } else if (layout.hasOwnProperty('mapbox')) {
            geo = layout.mapbox
        } else {
            return
        }
        x = geo._subplot.xaxis.p2c()
        y = geo._subplot.yaxis.p2c()
        cursor = {cursor: {lon: x, lat: y}}
    }
    return cursor
}