How do I get a decimal latitude / longitude from the Nokia Maps API?

Question

I have the following code which will update a textbox with latitude / longitude of a location when I drag a marker on the map to its location:

var listener = function (evt) {
    /* We check if this drag listener is called while the marker is being
        * dragged using the default behavior component
        */
    var mapDragType = evt.dataTransfer.getData("application/map-drag-type");

    if (mapDragType === "marker") {
        // Get the marker itself.
        var marker = evt.dataTransfer.getData("application/map-drag-object");

        // Get the offset of the mouse relative to the top-left corner of the marker.
        var offset = evt.dataTransfer.getData("application/map-drag-object-offset");

        /* Calculate the current coordinate of the marker, so substract the offset from the 
            * current displayX/Y position to get the top-left position of the marker and then
            * add the anchor to get the pixel position of the anchor of the marker and then 
            * query for the coordinate of that pixel position
            */
        var coordinate = map.pixelToGeo(evt.displayX - offset.x + marker.anchor.x, evt.displayY - offset.y + marker.anchor.y);

        // If the marker is dragged above a zone where it may not be dropped
        if (evt.dataTransfer.dropEffect === "none") {
            // If this is the end of the drag
            if (evt.type === "dragend") {
                // then the marker will jump back to where it was; 
                updateInputValue(marker, marker.coordinate.toString());
            }
            else {
                // otherwise it is currently (while being dragged) above an invalid drop zone
                updateInputValue(marker, "Invalid drop zone!");
            }
        }
        else {
            // If the marker is somewhere above the map, update info text with the new coordinate.
                updateInputValue(marker, coordinate.toString());
        }
    }
};

/* Create a helper method that updates the text fields associated with the 
    * marker passed as argument
    */
var updateInputValue = function (draggedMarker, text) {
    if (draggedMarker === marker)
        $("input[name*='txtGeoLocation']").val(text);
    //markerPosUiElt.innerHTML = text;
};

The problem I'm having is that the latitude / longitude outputs in long format when I need it in decimal format.

I've tried changing the following lines:

updateInputValue(marker, marker.coordinate.toString());

To the following:

updateInputValue(marker, marker.coordinate.latitude.ToString() + ', ' + marker.coordinate.longitude.ToString());

But then my text box stops populating (I imagine an error is throwing which isn't bubbling up). I've even tried just retrieving the latitude with the following:

updateInputValue(marker, marker.coordinate.latitude.ToString());

But I still receive no output.

How can I accomplish this? I definitely don't want a long format latitude / longitude and only wish to write the decimal version on this to my textbox.

Jason Fox · Accepted Answer · 2013-05-03T11:12:43.467

The coordinate of a marker is only updated during the dragend event, so if you want to track the intermediate locations, you'll have to a re-calculate the current target location during the drag event using the map.pixelToGeo() method. You can reference the moving marker as the target of the current event i.e. evt.target

The evt.target.coordinate of the Marker i.e. the coordinate property returns a formatted latitude/longitude.
The evt.target.coordinate.latitude and evt.target.coordinate.longitude give the coordinates in decimal degrees.

Here is a working example - you'll need to substitute in your own app id and token to get it to work of course.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
    <head>
        <meta http-equiv="X-UA-Compatible" content="IE=7; IE=EmulateIE9; IE=EmulateIE10;"/>
        <base href="http://developer.here.com/apiexplorer/examples/api-for-js/events/map-object-events-displayed.html" />
        <meta http-equiv="content-type" content="text/html; charset=UTF-8"/>
        <title>Nokia Maps API for JavaScript Example: Map Object events</title>
        <meta name="description" content="Adding event listeners to objects on the map"/>
        <meta name="keywords" content="mapobjectevents, map, display, object, events"/>
        <!-- For scaling content for mobile devices, setting the viewport to the width of the device-->
        <meta name=viewport content="initial-scale=1.0, maximum-scale=1.0, user-scalable=no"/>

        <!-- By default we add ?with=all to load every package available, it's better to change this parameter to your use case. Options ?with=maps|positioning|places|placesdata|directions|datarendering|all -->
        <script type="text/javascript" charset="UTF-8" src="http://api.maps.nokia.com/2.2.4/jsl.js?with=all"></script>


    </head>
    <body>
        <div id="mapContainer" style="width:70%; height:70%; left:0; top:50; position: absolute;"></div>
        <div id="uiContainer" style="left:0; top:0; position: absolute;" >HELLO</div>
        <script type="text/javascript" id="exampleJsSource">
// <![CDATA[    
/////////////////////////////////////////////////////////////////////////////////////
// Don't forget to set your API credentials
//
// Replace with your appId and token which you can obtain when you 
// register on http://api.developer.nokia.com/ 
//
            nokia.Settings.set( "appId", "YOUR APP ID GOES HERE"); 
            nokia.Settings.set( "authenticationToken", "YOUR AUTHENTICATION TOKEN GOES HERE");

/////////////////////////////////////////////////////////////////////////////////////   

// Get the DOM node to which we will append the map
var mapContainer = document.getElementById("mapContainer");
// Create a map inside the map container DOM node
var map = new nokia.maps.map.Display(mapContainer, {
    // Initial center and zoom level of the map
    center: [52.51, 13.4],
    zoomLevel: 7,
    // We add the behavior component to allow panning / zooming of the map
    components:[new nokia.maps.map.component.Behavior()]
});



// Create a default listener for events that will just log a message.
var defaultHandler = function (evt) {

    if (evt.target instanceof nokia.maps.map.Marker) {

        //console.log(evt);

        var div = document.getElementById("uiContainer");
        if (evt.type = "dragend"){
            div.innerHTML = evt.type + " Formated: " + evt.target.coordinate  + " Decimal: " + evt.target.coordinate.latitude + ", " + evt.target.coordinate.longitude;
        }
        if (evt.type = "drag"){
            var coordinate = map.pixelToGeo(evt.displayX + evt.target.anchor.x, evt.displayY + evt.target.anchor.y);
            div.innerHTML = evt.type + " Formated: " + coordinate  + " Decimal: " + coordinate.latitude + ", " + coordinate.longitude;
        }
    }

    if (evt.target instanceof nokia.maps.map.Spatial) {
        /* Prevent other event listeners from being triggered
         * For more details see  nokia.maps.dom.Event
         */
        evt.stopImmediatePropagation();
    }
};

/* Adding event listeners one by one to a map object is not very
 * efficient therefore we have created a shortcut method 
 * to add multiple eventlisteners to an object using the "eventListener" property
 */

// Template with all listeners to be registered.
var listeners = {
    // type: [(listener, useCapture, namespaceURI)(, listener, useCapture, namespaceURI)(, ...)]
    "dragstart": [defaultHandler, false, null],
    "drag": [defaultHandler, false, null],
    "dragend": [defaultHandler, false, null]
}; 

// Create image marker object
var imageMarker = new nokia.maps.map.Marker(
    [52.88745, 13.43246],
    {
        $name: "Image Marker",
        eventListener: listeners,
        icon: "../../res/markerHouse.png",
        anchor: new nokia.maps.util.Point(35, 89),
        draggable: true
    }
);

// Add event listeners to the marker
imageMarker.addListeners(listeners);
map.objects.add(imageMarker);


// ]]>
        </script>
    </body>
</html>

How do I get a decimal latitude / longitude from the Nokia Maps API?

1 Answers1