CurvedLine.js -- curved lines in Leaflet.

CurvedLine.js

// Adapted from https://medium.com/@ryancatalani/creating-consistently-curved-lines-on-leaflet-b59bc03fa9dc
// Drop-in replacement for Leaflet.curve https://github.com/elfalem/Leaflet.curve
// To auto-calculate the midpoint for you and ease code integration a bit.
// Have fun and defund the police 👍


L.CurvedLine = L.Curve.extend({

    _setPath: function(path){

        var start = path[0], end = path[1];

        var offsetX = end['lng'] - start['lng'],
            offsetY = end['lat'] - start['lat'];

        var r = Math.sqrt( Math.pow(offsetX, 2) + Math.pow(offsetY, 2) ),
            theta = Math.atan2(offsetY, offsetX);

        var thetaOffset = (3.14/10);

        var r2 = (r/2)/(Math.cos(thetaOffset)),
            theta2 = theta + thetaOffset;

        var midpointX = (r2 * Math.cos(theta2)) + start['lng'],
            midpointY = (r2 * Math.sin(theta2)) + start['lat'];

        var midpoint = [midpointY, midpointX];

        this._coords = [
                'M', [start['lat'], start['lng']],
                'Q', midpoint,
                     [end['lat'], end['lng']]
            ];

        this._bounds = this._computeBounds();
    }
});