CODEWITHSUNDEEP
javascriptgoogle-mapsgoogle-maps-api-3
angry kiwi
angry kiwi

Reputation: 11445

Google Maps API v3 save and reuse shape from drawingManager

I'm using one of the example of google map api provided by google. In this example, we can draw some lines on the map using the drawing library.

Lets say I've drawn something. Then how can I share this drawing? or save it for later reference?

Below is the code 

function initMap() {

    var map = new google.maps.Map(document.getElementById('map'), {
        center: {
            lat: -34.397,
            lng: 150.644
        },
        zoom: 11,
        // only show roadmap type of map, and disable ability to switch to other type
        mapTypeId: google.maps.MapTypeId.ROADMAP,
        mapTypeControl: false
    });

    var drawingManager = new google.maps.drawing.DrawingManager({
        drawingControl: true,
        drawingControlOptions: {
            position: google.maps.ControlPosition.TOP_CENTER,
            drawingModes: [
            google.maps.drawing.OverlayType.POLYGON, ],
            clickable: true,
            draggable: true
        },
        polygonOtions: {
            clickable: true,
            draggable: true
        }
    });

    drawingManager.setMap(map);
}

Updated:

I'm trying Vadim's solution, but it seems there's a bug. Draw something then refresh you will see

Here's the code that produce the bug:

<!DOCTYPE html>
<html>
    <head>

        <style>
            html, body {
                margin: 0;
                padding: 0;
                height:100%;
            }
            #map {
                height: 100%;
            }
            .btn {
                position:absolute;
                width:50px;
                height:60px;
                top:5%;
                left: 50%;
                z-index:9999;
                color:black;
            }
        </style>

        <script src="http://maps.googleapis.com/maps/api/js?sensor=false&libraries=drawing,geometry,places"></script>
    </head>
    <body>
        <div class="btn" onclick="clearall(map);">delete</div>
        <div id="map"></div>
        <script>
        var map;
        function initMap() {
            map = new google.maps.Map(document.getElementById('map'), {
                center: { lat: -34.397, lng: 150.644 },
                zoom: 4,
                // only show roadmap type of map, and disable ability to switch to other type
                mapTypeId: google.maps.MapTypeId.ROADMAP,
                mapTypeControl: false
            });

            map.data.setControls(['Polygon']);
            map.data.setStyle({
                editable: true,
                draggable: true
            });

            map.data.addListener('addfeature', savePolygon);
            map.data.addListener('removefeature', savePolygon);
            map.data.addListener('setgeometry', savePolygon);

            //load saved data
            loadPolygons(map);
        }

        function loadPolygons(map) {
            var data = JSON.parse(sessionStorage.getItem('geoData'));
            // map.data.forEach(function (f) {
            //     map.data.remove(f);
            // });
            map.data.addGeoJson(data)
        }

        function savePolygon() {
            map.data.toGeoJson(function (json) {
                // console.log(JSON.stringify(json));
                sessionStorage.setItem('geoData', JSON.stringify(json));
            });
        }
        function clearall(map){
            map.data.forEach(function (f) {
                map.data.remove(f);
            });
        }

        initMap();

        </script>

    </body>
</html>

Upvotes: 1

Views: 6259

Answers (2)

Vadim Gremyachev
Vadim Gremyachev

Reputation: 59328

You could utilize Google Maps Data layer for that purpose. The below example demonstrates how to export and import polygons as GeoJSON data using google.maps.Data class. localStorage is used for storing GeoJSON data.

var map;
function initMap() {
    map = new google.maps.Map(document.getElementById('map'), {
        center: { lat: -34.397, lng: 150.644 },
        zoom: 4,
        // only show roadmap type of map, and disable ability to switch to other type
        mapTypeId: google.maps.MapTypeId.ROADMAP,
        mapTypeControl: false
    });

    map.data.setControls(['Polygon']);
    map.data.setStyle({
        editable: true,
        draggable: true
    });
    bindDataLayerListeners(map.data);

    //load saved data
    loadPolygons(map);
}


// Apply listeners to refresh the GeoJson display on a given data layer.
function bindDataLayerListeners(dataLayer) {
    dataLayer.addListener('addfeature', savePolygon);
    dataLayer.addListener('removefeature', savePolygon);
    dataLayer.addListener('setgeometry', savePolygon);
}

function loadPolygons(map) {
    var data = JSON.parse(localStorage.getItem('geoData'));
    map.data.forEach(function (f) {
        map.data.remove(f);
    });
    map.data.addGeoJson(data)
}



function savePolygon() {
    map.data.toGeoJson(function (json) {
        localStorage.setItem('geoData', JSON.stringify(json));
    });
}

Demo

Update

The following demo demonstrates how to delete polygons.

Upvotes: 5

MrUpsidown
MrUpsidown

Reputation: 22490

You can use the overlaycomplete event to retrieve the paths from your drawn polygon:

google.maps.event.addListener(drawingManager, 'overlaycomplete', function (event) {

    // Get overlay paths
    var paths = event.overlay.getPaths(); 
});

The paths object can be reused to create a Polygon from scratch. See the below demo. When the overlaycomplete event is triggered, get the paths from the overlay and create a new Polygon with it.

JSFiddle demo

Upvotes: 1

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