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Google Maps API V3 for ASP.NET

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30 Dec 2011CPOL4 min read 613.1K   45.7K   267   65
The most frequently used tasks in Google Maps. The article includes an explanation of geocoding and reverse geocoding both in JavaScript and C#.

Introduction

Google Maps provides a flexible way to integrate maps to provide directions, location information, and any other kind of stuff provided by the Google Maps API in your web application. Although there are some articles in CP explaining about maps, in my article I am going to provide information about the latest Google Maps API V3 version. In this article, we will see some of the common techniques that are used with Google Maps. In order to work with the code sample explained below, you need to have some basic knowledge about JavaScript and C#.

Your First Google Maps Map

In the earlier versions of the Google Maps API, as a developer we need to register the web application with Google and we were supposed to get an API key. However with the release of the new version, key registration has been eliminated for a few days for now, but recently, Google has come up with some kind of traffic limitations and we are supposed to register the application with an API Key. You can get more information about the usage of the API and the terms at this link: http://code.google.com/apis/maps/documentation/javascript/usage.html#usage_limits. Now we will start our work and create a simple Google Maps map that can be integrated into our site. The following script is used to connect to the Google Maps API:

HTML
<script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?sensor=false">
</script>

In order to create a simple Google Map map, you can use the following JavaScript code:

JavaScript
function InitializeMap() 
{
    var latlng = new google.maps.LatLng(-34.397, 150.644);
    var myOptions = {
        zoom: 8,
        center: latlng,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };
    var map = new google.maps.Map(document.getElementById("map"), myOptions);
}
window.onload = InitializeMap;

FirstGoogleMap

Google Maps Options

In the above example, we used the Map class which takes options and an HTML ID as parameters. Now moving further, we will look at the map options:

JavaScript
function initialize() {
    var latlng = new google.maps.LatLng(-34.397, 150.644);
    var options =
    {
        zoom: 3,
        center: new google.maps.LatLng(37.09, -95.71),
        mapTypeId: google.maps.MapTypeId.ROADMAP,
        mapTypeControl: true,
        mapTypeControlOptions:
        {
            style: google.maps.MapTypeControlStyle.DROPDOWN_MENU,
            poistion: google.maps.ControlPosition.TOP_RIGHT,
            mapTypeIds: [google.maps.MapTypeId.ROADMAP, 
              google.maps.MapTypeId.TERRAIN, 
              google.maps.MapTypeId.HYBRID, 
              google.maps.MapTypeId.SATELLITE]
        },
        navigationControl: true,
        navigationControlOptions:
        {
            style: google.maps.NavigationControlStyle.ZOOM_PAN
        },
        scaleControl: true,
        disableDoubleClickZoom: true,
        draggable: false,
        streetViewControl: true,
        draggableCursor: 'move'
    };
    var map = new google.maps.Map(document.getElementById("map"), options);
}
window.onload = initialize;

In the above example, all the properties of Map have been used. You can set the map options depending on your requirements.

MapOptions

The properties of the Map class are summarized in the following table:

PropertyClass
MapTypeControl:true/falsemapTypeControlOptions
PropertyConstants/Values
style
DEFAULT<br />
HORIZONTAL_BAR<br />
DROPDOWN_MENU
position
BOTTOM<br />
BOTTOM_LEFT<br />
BOTTOM_RIGHT <br />
LEFT<br />
RIGHT<br />
TOP<br />
TOP_LEFT<br />
TOP_RIGHT
mapTypeIds
ROADMAP<br />
SATELLITE<br />
Hybrid<br />
Terrain
navigationControl:true/falsenavigationControlOptions
PropertyConstants/Values
Position
BOTTOM<br />
BOTTOM_LEFT<br />
BOTTOM_RIGHT<br />
LEFT<br />
RIGHT<br />
TOP<br />
TOP_LEFT<br />
TOP_RIGHT T
style
DEFAULT<br />
SMALL<br />
ANDROID
scaleControl:true/falsescaleControlOptions: scalecontroloptions has the same properties as navigation control options (position, style) and behavior is also the same.
disableDoubleClickZoom: true/false
scrollwheel: true/false
draggable: true/false
streetViewControl: true/false

Map Marker

The Marker class provides you with an option to display a marker to the user for a given location. Use of the marker is a very general task that we will use often in our application. The following example shows you how to create a simple marker.

JavaScript
var marker = new google.maps.Marker
(
    {
        position: new google.maps.LatLng(-34.397, 150.644),
        map: map,
        title: 'Click me'
    }
);

Marker

Info Window

With the marker displayed on the map, you create an onclick event which provides the user with a popup window showing the information about the place. You can create an info window as shown below:

JavaScript
var infowindow = new google.maps.InfoWindow({
    content: 'Location info:
    Country Name:
    LatLng:'
});
google.maps.event.addListener(marker, 'click', function () {
    // Calling the open method of the infoWindow 
    infowindow.open(map, marker);
});

Combining them:

JavaScript
var map;
function initialize() {
    var latlng = new google.maps.LatLng(-34.397, 150.644);
    var myOptions = {
        zoom: 8,
        center: latlng,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };
    map = new google.maps.Map(document.getElementById("map"), myOptions);
    var marker = new google.maps.Marker
    (
        {
            position: new google.maps.LatLng(-34.397, 150.644),
            map: map,
            title: 'Click me'
        }
    );
    var infowindow = new google.maps.InfoWindow({
        content: 'Location info:<br/>Country Name:<br/>LatLng:'
    });
    google.maps.event.addListener(marker, 'click', function () {
        // Calling the open method of the infoWindow 
        infowindow.open(map, marker);
    });
}
window.onload = initialize;

With this complete, you are going to create a map and then locate the region of the user, load the map with a marker and the info window.

InfoWindow

Multiple Markers

In some cases, if you want to handle multiple markers, you achieve this like the following:

JavaScript
function markicons() {
   InitializeMap();

        var ltlng = [];

        ltlng.push(new google.maps.LatLng(17.22, 78.28));
        ltlng.push(new google.maps.LatLng(13.5, 79.2));
        ltlng.push(new google.maps.LatLng(15.24, 77.16));

        map.setCenter(ltlng[0]);
        for (var i = 0; i <= ltlng.length; i++) {
            marker = new google.maps.Marker({
                map: map,
                position: ltlng[i]
            });

            (function (i, marker) {

                google.maps.event.addListener(marker, 'click', function () {

                    if (!infowindow) {
                        infowindow = new google.maps.InfoWindow();
                    }

                    infowindow.setContent("Message" + i);

                    infowindow.open(map, marker);

                });

            })(i, marker);

        }
}

mulitplemarkers

Directions

One of the most useful features of the Google Maps API is it can be used to provide directions for any given location(s). The following code is used to accomplish this task:

C#
var directionsDisplay;
var directionsService = new google.maps.DirectionsService();

function InitializeMap() {
    directionsDisplay = new google.maps.DirectionsRenderer();
    var latlng = new google.maps.LatLng(-34.397, 150.644);
    var myOptions =
    {
        zoom: 8,
        center: latlng,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };
    var map = new google.maps.Map(document.getElementById("map"), myOptions);

    directionsDisplay.setMap(map);
    directionsDisplay.setPanel(document.getElementById('directionpanel'));

    var control = document.getElementById('control');
    control.style.display = 'block';


}
    function calcRoute() {

    var start = document.getElementById('startvalue').value;
    var end = document.getElementById('endvalue').value;
    var request = {
        origin: start,
        destination: end,
        travelMode: google.maps.DirectionsTravelMode.DRIVING
    };
    directionsService.route(request, function (response, status) {
        if (status == google.maps.DirectionsStatus.OK) {
            directionsDisplay.setDirections(response);
        }
    });

}

function Button1_onclick() {
    calcRoute();
}

window.onload = InitializeMap;

Directions

Layers

The Google Maps API provides you with multiple layer options of which one is bicycle. By using the bicycle layer, you can show bicycle paths for a particular location on the map to users. The following code snippet allows you to add a bicycle layer to a map.

C#
var map 
function InitializeMap() {
    var latlng = new google.maps.LatLng(-34.397, 150.644);
    var myOptions = {
        zoom: 8,
        center: latlng,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };
   map = new google.maps.Map(document.getElementById("map"), myOptions);
}
window.onload = InitializeMap;
var bikeLayer = new google.maps.BicyclingLayer();
bikeLayer.setMap(map);

Gecoding

So far we have learned the basic concepts of creating Google maps and displaying information about a location to the user. Now we will see how we can calculate/find a location specified by the user. Geocoding is nothing but the process of finding out the latitude and longitude for a given region. The following API code shows you how to find the latitude and longitude for a location.

JavaScript
geocoder.geocode({ 'address': address }, function (results, status) {
    if (status == google.maps.GeocoderStatus.OK) {
        map.setCenter(results[0].geometry.location);
        var marker = new google.maps.Marker({
            map: map,
            position: results[0].geometry.location
        });

    }
    else {
        alert("Geocode was not successful for the following reason: " + status);
    }
});

Geocoding C#

The same calculation can also be performed by using C#:

C#
public static Coordinate GetCoordinates(string region)
{
    using (var client = new WebClient())
    {

        string uri = "http://maps.google.com/maps/geo?q='" + region + 
          "'&output=csv&key=ABQIAAAAzr2EBOXUKnm_jVnk0OJI7xSosDVG8KKPE1" + 
          "-m51RBrvYughuyMxQ-i1QfUnH94QxWIa6N4U6MouMmBA";

        string[] geocodeInfo = client.DownloadString(uri).Split(',');

        return new Coordinate(Convert.ToDouble(geocodeInfo[2]), 
                   Convert.ToDouble(geocodeInfo[3]));
    }
}

public struct Coordinate
{
    private double lat;
    private double lng;

    public Coordinate(double latitude, double longitude)
    {
        lat = latitude;
        lng = longitude;

    }

    public double Latitude { get { return lat; } set { lat = value; } }
    public double Longitude { get { return lng; } set { lng = value; } }

}

Reverse Geocoding

As the name indicates, it is the reverse process of geocoding; that is depending on the latitude and longitude, we can find the location name. This can be achieved using the following code:

JavaScript
var map;
var geocoder;
function InitializeMap() {

    var latlng = new google.maps.LatLng(-34.397, 150.644);
    var myOptions =
    {
        zoom: 8,
        center: latlng,
        mapTypeId: google.maps.MapTypeId.ROADMAP,
        disableDefaultUI: true
    };
    map = new google.maps.Map(document.getElementById("map"), myOptions);
}

function FindLocaiton() {
    geocoder = new google.maps.Geocoder();
    InitializeMap();

    var address = document.getElementById("addressinput").value;
    geocoder.geocode({ 'address': address }, function (results, status) {
        if (status == google.maps.GeocoderStatus.OK) {
            map.setCenter(results[0].geometry.location);
            var marker = new google.maps.Marker({
                map: map,
                position: results[0].geometry.location
            });
            if (results[0].formatted_address) {
                region = results[0].formatted_address + '<br/>';
            }
            var infowindow = new google.maps.InfoWindow({
                content: 'Location info:<br/>Country Name:' + region + 
                '<br/>LatLng:' + results[0].geometry.location + ''
            });
            google.maps.event.addListener(marker, 'click', function () {
                // Calling the open method of the infoWindow 
                infowindow.open(map, marker);
            });

        }
        else {
            alert("Geocode was not successful for the following reason: " + status);
        }
    });
}

Reverse Geocoding in C#

The following C# code shows you the reverse geocoding technique:

C#
static string baseUri = 
  "http://maps.googleapis.com/maps/api/geocode/xml?latlng={0},{1}&sensor=false";
string location = string.Empty;

public static void RetrieveFormatedAddress(string lat, string lng)
{
    string requestUri = string.Format(baseUri, lat, lng);

    using (WebClient wc = new WebClient())
    {
        string result = wc.DownloadString(requestUri);
        var xmlElm = XElement.Parse(result);
        var status = (from elm in xmlElm.Descendants() where 
            elm.Name == "status" select elm).FirstOrDefault();
        if (status.Value.ToLower() == "ok")
        {
            var res = (from elm in xmlElm.Descendants() where 
                elm.Name == "formatted_address" select elm).FirstOrDefault();
            requestUri = res.Value;
        }
    }
}

Conclusion

In this article, I have tried to explain some of the basic and most frequently used tasks of the Google Maps API V3. Hope this article will help you in completing your tasks. Further, there are lot more things in the API which I have not discussed and I would try to include them in my future updates of this article. Any comments and feedback are always welcome.

External Resources

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Software Developer Collabera
Singapore Singapore
S V Sai Chandra is a Software Engineer from Hyderabad Deccan. He started Embedded Programing in his college days and now he is a Web Developer by Profession. He Loves coding and his passion has always been towards Microsoft Technologies. Apart from coding his other hobbies include reading books, painting and hang out with friends is his most favorite past time hobby.
He blogs at
http://technowallet.blogspot.com
Technical Skills:
C#,Ado.Net,Asp.Net,Sql Server,JavaScript,XML,Web services.

Comments and Discussions

 
QuestionPricing for Google Maps API V3 Pin
Member 1088946013-Feb-19 1:28
Member 1088946013-Feb-19 1:28 
Questiongoogle map with web api 2 with markers, lines, polygons along with info window Pin
Member 1270266015-Mar-17 19:57
Member 1270266015-Mar-17 19:57 
QuestionMap flashes on to screen then disappears leaving grey box Pin
Member 206269226-Sep-16 11:10
Member 206269226-Sep-16 11:10 
GeneralGeocoding C# code is obsolete Pin
Michael Freidgeim18-Nov-15 18:14
Michael Freidgeim18-Nov-15 18:14 
QuestionWhat does this have to do with ASP.NET? Pin
Dave Voyles26-Oct-15 5:18
Dave Voyles26-Oct-15 5:18 
QuestionVisual Studio 2013 Error - main.js Pin
C Millard5-Oct-15 6:51
C Millard5-Oct-15 6:51 
QuestionQuestion: Google Maps API V3 for ASP.NET Pin
QtzAli21-Aug-15 23:02
QtzAli21-Aug-15 23:02 
BugNot showing accurate search results Pin
Tathagat Verma19-May-15 3:03
Tathagat Verma19-May-15 3:03 
QuestionThis doesn't show how GMap is integrated into ASP.NET Pin
EverythingIsTakenAlready16-May-15 12:13
EverythingIsTakenAlready16-May-15 12:13 
Buggetting errors Pin
sumanta p18-Jul-14 2:08
sumanta p18-Jul-14 2:08 
QuestionGreat article for understanding Google Maps API Pin
pmcm2-Jul-14 5:35
pmcm2-Jul-14 5:35 
QuestionNot a question... Pin
Kandido27-Feb-14 0:50
Kandido27-Feb-14 0:50 
QuestionZooming on google maps api Pin
meridian200012-Feb-14 3:33
meridian200012-Feb-14 3:33 
BugYou are confusing the codes for Geocoding and Reversing geocoding. Pin
LamYongXian20-Oct-13 23:45
professionalLamYongXian20-Oct-13 23:45 
GeneralMy vote of 5 Pin
pradiprenushe25-Sep-13 5:42
professionalpradiprenushe25-Sep-13 5:42 
GeneralMy vote of 5 Pin
Abhishek Pant8-Aug-13 1:52
professionalAbhishek Pant8-Aug-13 1:52 
QuestionGreat work Pin
umeshfaq1-Jul-13 22:34
umeshfaq1-Jul-13 22:34 
QuestionProblem while implementing Google Maps API Pin
Member 101011379-Jun-13 23:57
Member 101011379-Jun-13 23:57 
GeneralMy vote of 5 Pin
alcitect13-Feb-13 9:21
alcitect13-Feb-13 9:21 
QuestionQuestion on google map Pin
alcitect13-Feb-13 9:20
alcitect13-Feb-13 9:20 
QuestionHow to search Near by Places using Google API in .net Pin
Member 438680722-Jan-13 20:20
Member 438680722-Jan-13 20:20 
GeneralHow to search generic locations using Google with Marker Pin
Member 438680722-Jan-13 20:14
Member 438680722-Jan-13 20:14 
QuestionFAQ: Using Google Maps & Places API Licensing Pin
etechpulse8-Jan-13 19:47
etechpulse8-Jan-13 19:47 
GeneralMy vote of 5 Pin
Maks_At3-Dec-12 20:42
Maks_At3-Dec-12 20:42 
GeneralMy vote of 5 Pin
Mukul00322-Nov-12 1:10
professionalMukul00322-Nov-12 1:10 

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