javascript - Center a boundary of polygons in Google Maps - Stack Overflow

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I am trying to find a better way to center my google map.

I've already written code to add in Markers to Outline and area squarely of which is being store in an array: Coords[i], in-which when returning to the map after save, it centers the map window based on the "first marker" lat/lng coordinates Coords[0].

I am trying to figure out a better way to center the map where there is adequate space around my outline area.

I've try doing it on Dragend, which works somewhat:

google.maps.event.addListener(this.map, 'dragend', function(mapEvent) {
var lat = mapEvent.getCenter() .lat(),
lng = mapEvent.getCenter() .lng(),

console.log(lat + " " + lng + " " + this);

});

But it keeps throwing an error saying: "Unable to get property 'getCenter' of undefined or null reference"

Can someone tell me what I am doing wrong OR tell be a better way to achieve what I'm trying to do?

As, another option

It would be nice if possible if I can keep the first marker [0] the centering marker as it is already, But don't allow it to outline... just the markers 1 + and on .... But I don't know how to modify my code to do that.

Just looking for a solution that works.

My plete Code is here:

I am trying to find a better way to center my google map.

I've already written code to add in Markers to Outline and area squarely of which is being store in an array: Coords[i], in-which when returning to the map after save, it centers the map window based on the "first marker" lat/lng coordinates Coords[0].

I am trying to figure out a better way to center the map where there is adequate space around my outline area.

I've try doing it on Dragend, which works somewhat:

google.maps.event.addListener(this.map, 'dragend', function(mapEvent) {
var lat = mapEvent.getCenter() .lat(),
lng = mapEvent.getCenter() .lng(),

console.log(lat + " " + lng + " " + this);

});

But it keeps throwing an error saying: "Unable to get property 'getCenter' of undefined or null reference"

Can someone tell me what I am doing wrong OR tell be a better way to achieve what I'm trying to do?

As, another option

It would be nice if possible if I can keep the first marker [0] the centering marker as it is already, But don't allow it to outline... just the markers 1 + and on .... But I don't know how to modify my code to do that.

Just looking for a solution that works.

My plete Code is here: http://pastiebin./embed/593d6d809e2f0

• javascript
• google-maps
• google-maps-api-3

Share Improve this question Follow edited Dec 30, 2020 at 8:07 samjco- asked Jun 11, 2017 at 16:12 samjco-samjco- 40966 silver badges1414 bronze badges 3

• Update my question with pics and link to full code – samjco- Commented Jun 11, 2017 at 16:44
• 1 Are you trying to center on one Polygon? Multiple Polygons? Why do you want to center on dragend? Your question is unclear about what you are trying to achieve. – MrUpsidown Commented Jun 12, 2017 at 10:28
• possible duplicate of Google Maps get the center of coordinates (place label at center of polygon) – geocodezip Commented Jun 12, 2017 at 11:04

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2 Answers 2

Sorted by: Reset to default 8

You can use a LatLngBounds object. Loop through your Polygons if you have more than one and extend your bounds object with each path coordinates.

LatLngBounds

You can then make your map fit the bounds object so it will zoom and center accordingly by using map.fitBounds().

fitBounds

If you use multi-paths Polygon, make sure you use getPaths method instead of getPath as in the code below.

function initialize() {

    var mapOptions = {
        zoom: 4,
        center: new google.maps.LatLng(0, 0),
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };

    var map = new google.maps.Map(document.getElementById("map-canvas"), mapOptions);

    var polygon = new google.maps.Polygon({
        editable: true,
        strokeOpacity: 0,
        strokeWeight: 0,
        fillColor: '#00FF00',
        fillOpacity: .6,
        paths: [
        new google.maps.LatLng(39, 4),
        new google.maps.LatLng(34, 24),
        new google.maps.LatLng(43, 24),
        new google.maps.LatLng(39, 4)],
        map: map
    });
    
    // Create the bounds object
    var bounds = new google.maps.LatLngBounds();

    // Get paths from polygon and set event listeners for each path separately
    polygon.getPath().forEach(function (path, index) {
    
        bounds.extend(path);
    });
    
    // Fit Polygon path bounds
    map.fitBounds(bounds);
}

initialize();

#map-canvas {
  height: 200px;
}

<div id="map-canvas"></div>

<script src="https://maps.googleapis./maps/api/js"></script>

Ok I just figured out a way! I simply grabbed the lat/lng coordinates of the center of the polygon drawn and centered my whole map with that.

var bounds = new google.maps.LatLngBounds();
var i;

//Get Center of Saved Coordinates of the drawn polygons
for (var i = 0; i < values["coords"].length; i++) {

bounds.extend(values["coords"][i]);

}

var movemaplat = bounds.getCenter().lat();
var movemaplng= bounds.getCenter().lng();

console.log("MY MAP CENTER " + movemaplat + ", " + movemaplng);

Thanks to @Daniel Vassallo's answer here: How to get the center of a polygon in google maps v3?

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