sirithink / geojson-google-maps

Just a simple utility to convert GeoJSON objects to Google Maps vector objects (Marker, Polyline, Polygon)

GeoJSON to Google Maps

version 1.0

Jason Sanford

Overview

GeoJSON is used to create Google Maps API v3 vectors (Marker, Polyline, Polygon) from GeoJSON objects (Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon, Feature, GeometryCollection, FeatureCollection). Specifically, I'm translating some GeoJSON types to arrays of Google Maps vectors as there aren't really Google Maps equivalents of MultiPoint, MultiLineString, etc.

Constructor Parameters

@param {Object} geojson A valid GeoJSON object. One of Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon, Feature, GeometryCollection, FeatureCollection. See the official GeoJSON spec for more details. GeoJSON examples below.

@param? {Object} options - Optional Options for the specific type of Google Maps vector (Marker, Polyline, Polygon). If none specified, boring black vectors and red markers will be created - Optional. Samples Below.

GeoJSON -> Google Maps equivalents

GeoJSON Type	Output
Point	google.maps.Point
LineString	google.maps.Polyline
Polygon	google.maps.Polygon
MultiPoint	Array of google.maps.Point
MultiLineString	Array of google.maps.Polyline
MultiPolygon	Array of google.maps.Polygon
Feature	google.maps.[Point,Polyline,Polygon] (depends on Feature geometry type)
FeatureCollection	Array of google.maps.[Point,Polyline,Polygon] (depends on Feature geometry type)
GeometryCollection	Array of google.maps.[Point,Polyline,Polygon] (depends on geometry type)

GeoJSON Examples

// GeoJSON Point
{
	"type": "Point",
	"coordinates": [
		-80.66252,
		35.04267
	]
}

// GeoJSON LineString
{
	"type": "LineString",
	"coordinates": [
		[-80.661983228058659, 35.042968081213758],
		[-80.662076494242413, 35.042749414542243],
		[-80.662196794397431, 35.042626481357232],
		[-80.664238981504525, 35.041175532632963]
	]
}

// GeoJSON Polygon
{
	"type": "Polygon",
	"coordinates": [
		[
			[-80.662120612605904, 35.042875219905184],
			[-80.662141716053014, 35.042832740965068],
			[-80.662171938563816, 35.042789546962993],
			[-80.662209174653029, 35.042750233165179],
			[-80.662250709107454, 35.042716920859959],
			[-80.662627586829899, 35.043072078075667],
			[-80.662595574310288, 35.043162322407341],
			[-80.662142312824884, 35.043015448098977],
			[-80.662145396323511, 35.042970839922489],
			[-80.662117972448982, 35.042908385949438],
			[-80.662120612605904, 35.042875219905184]
		]
	]
}

// GeoJSON Feature
{
	"type": "Feature",
	"id": 9876,
	"geometry": {
		"type": "Point",
		"coordinates": [
			-80.66252,
			35.04267
		]
	},
	"properties": {
		"condition": "Satisfactory",
		"has_garage": false,
		"number_of_bedrooms": 3
	}
}

// GeoJSON FeatureCollection
{
	"type": "FeatureCollection",
	"features": [
		{
			"type": "Feature",
			"id": 9876,
			"geometry": {
				"type": "Point",
				"coordinates": [
					-80.66252,
					35.04267
				]
			},
			"properties": {
				"condition": "Satisfactory",
				"has_garage": false,
				"number_of_bedrooms": 3
			}
		},{
			"type": "Feature",
			"id": 9875,
			"geometry": {
				"type": "Point",
				"coordinates": [
					-80.66262,
					35.04277
				]
			},
			"properties": {
				"condition": "Excellent",
				"has_garage": true,
				"number_of_bedrooms": 4
			}
		}
	]
}

Sample Google Maps Vector Options

// google.maps.Polyline
{
	"strokeColor": "#FFFF00",
	"strokeWeight": 7,
	"strokeOpacity": 0.75
}

// google.maps.Polygon
{
	"strokeColor": "#FF7800",
	"strokeOpacity": 1,
	"strokeWeight": 2,
	"fillColor": "#46461F",
	"fillOpacity": 0.25
}

// google.maps.Marker
{
	"icon": "img/marker-house.png"
}

Error Handling (Invalid GeoJSON)

I've made an attempt to check for properly formatted GeoJSON. If something doesn't look quite right I return a very simple error object.

{
	"error": true,
	"message": "Invalid GeoJSON object: Feature object missing \"properties\" or \"geometry\" member."
}

It would be in your best interest to first check the returned object to see if it's error free.

var myGoogleVector = new GeoJSON(myGeoJSON, options);

if (myGoogleVector.error){
	// Handle the error.
}else{
	myGoogleVector.setMap(myMap);
}