codehead / leaflet.curve

A Leaflet plugin for drawing Bézier curves and other complex shapes.

Leaflet.curve

A Leaflet plugin for drawing Bézier curves and other complex shapes. (DEMO)

Usage

If using directly, include the plugin after Leaflet:

<script src="leaflet.js"></script>
<script src="leaflet.curve.js"></script>

(If rendering using canvas AND using animations, include tween.js as well.)

If using Node.js, install and import:

yarn add @elfalem/leaflet-curve

import L from 'leaflet'
import '@elfalem/leaflet-curve'

Add a path that includes a Bézier curve and straight lines:

var path = L.curve(['M',[50.54136296522163,28.520507812500004],
					'C',[52.214338608258224,28.564453125000004],
						[48.45835188280866,33.57421875000001],
						[50.680797145321655,33.83789062500001],
					'V',[48.40003249610685],
					'L',[47.45839225859763,31.201171875],
						[48.40003249610685,28.564453125000004],'Z'],
					{color:'red',fill:true}).addTo(map);

Notes

• This plugin is based on Leaflet version 1.1.0.
• SVG rendering is best supported. Canvas rendering is also possible.
• Browser and device compatibility testing is very limited.

API

The first argument to L.curve() is an array of path data. This is composed of commands and coordinates. The commands are a subset of the SVG path specification.

Command	Parameters	Description
M	[lat,lng]+	move to [lat,lng]
L	[lat,lng]+	line to [lat,lng]
H	[lng]+	horizontal line to [lng]
V	[lat]+	vertical line to [lat]
C	([lat1,lng1],[lat2,lng2],[lat,lng])+	cubic Bézier curve to [lat,lng] with control points at [lat1,lng1] and [lat2,lng2]
S	([lat2,lng2],[lat,lng])+	cubic bézier curve to [lat,lng] with control points at reflection of second control point of previous curve [lat1,lng1] and [lat2,lng2]
Q	([lat1,lng1],[lat,lng])+	quadratic Bézier curve to [lat,lng] with control point at [lat1,lng1]
T	([lat,lng])+	quadratic Bézier curve to [lat,lng] with control point at reflection of control point of previous curve [lat1,lng1]
Z		close path (line to M)

Note that only absolute commands (uppercase) are implemented. It's possible to approximate elliptical arcs (command 'A') with Bézier curves (the elliptical-arc branch implements this command if you're interested).

The L.Curve class extends L.Path so options, events, and methods inherited from L.Path are available. The following new option and methods are introduced by L.Curve.

Options

Option	Type	Default	Description
animate	Integer or animate options object	undefined	Animates the curve. It takes a parameter which is the same one provided to the options parameter of Element.animate() method. Note: Web Animations API support varies across browsers.

Methods

Method	Returns	Description
setPath(pathData[])	this	Replaces the current path with the given array of commands and coordinates.
getPath()	pathData[]	Returns array of the commands and coordinates in the path.
trace(samplingDistance[])	latLng[]	Returns array of points that lie on the curve at the given distances. Sampling distance is a decimal value between 0 and 1 inclusive and is applied to each segment (i.e. command) of the curve. See DEMO for example.

License

MIT

Contributions

• Bug reports and pull requests are welcome!