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Google Maps Control for ASP.Net - Part I

Posted by Shabdar Ghata Articles | Visual C# March 27, 2008
This is a user control for ASP.Net. You can use this control to insert google map in your aspx pages.
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Features

  • Enables you to draw google map. No javascript knowledge required. Just drag and drop control on your page.
  • Uses Ajax calls to retrieve server side data.
  • Enables you to change pushpin postions on the fly. No need to refresh full map.
  • Enables you to change pushpin icons on the fly.
  • Optimized to give you best performance. i.e. only those pushpin data will be retrieved from server that are changed.
  • Allows you to draw polylines and polygons

How to use

In this part of article, I don't want you to explain how I created this control. Instead I want you to start using it.

Requirements

  • Visual Studio 2005 or higher
  • Microsot ASP.Net Ajax framework. You can download it from here.
  • Internet Explorer 7.0 or Mozilla Firefox 2.x.

    (Note: It may work on other browsers. I have tested on IE and Firefox only.)

Follow below steps in order to use it in your ASP.Net website.

  • Download source from link provided on top of the page. Extract it somewhere on your harddrive.
  • Open extracted folder as a website in Visual Studio and run it. When you run this website, you will be able to navigate few samples pages.
  • To use this control in your application, copy following files to your ASP.Net application in same structure as shown below.

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Now we will add reference to Ajax library. If you are already using Ajax controls in your application, you can skip following 4 steps.

Adding Ajax Framework to your website

  • Right click on your website in solution explorer and click add reference. 

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  • In Add Reference window, select System.Web and System.Web.Extensions libraries and click OK. Note library versions (in below picture 1.0.61025.0. You may have another version. You can use any version).

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  • Go to your web.config file and add following lines between <System.Web></System.Web> element.  

<httpHandlers>

      <remove path="*.asmx" verb="*"/>

 

      <add path="*.asmx" verb="*"

      type="System.Web.Script.Services.ScriptHandlerFactory,

       System.Web.Extensions,  Version=1.0.61025.0,

       Culture=neutral,

       PublicKeyToken=31BF3856AD364E35"

      validate="false"/>

 

      <add path="*_AppService.axd" verb="*"

      type="System.Web.Script.Services.ScriptHandlerFactory,

       System.Web.Extensions, Version=1.0.61025.0,

       Culture=neutral,

       PublicKeyToken=31BF3856AD364E35"

      validate="false"/>

 

      <add path="ScriptResource.axd" verb="GET,HEAD"

      type="System.Web.Handlers.ScriptResourceHandler,

       System.Web.Extensions, Version=1.0.61025.0,

       Culture=neutral,

       PublicKeyToken=31BF3856AD364E35"

      validate="false"/>

 

    </httpHandlers>

 

    <httpModules>

      <add name="ScriptModule"

      type="System.Web.Handlers.ScriptModule,

       System.Web.Extensions,

       Version=1.0.61025.0, Culture=neutral,

       PublicKeyToken=31BF3856AD364E35"/>
    </httpModules>   

Note: Make sure that version of System.Web.Extension library is same as what you have selected when you added reference.

Adding Google Map control to your webpage

  • Open page where you want to insert Google Map.
  • Drag GoogleMapForASPNet.ascx control to your page.

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You won't be able to see Google Map in design view. Instead, you should see Script Manager as part of this control.

  • At this point you can run your application and you should be able to see a blank Google Map on your page as shown below.

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Let's add few pushpins on this map. For that you will have to add some code in Page_Load() event of your page.

Passing parameters to Google Map control

  • You must specify Google Map API Key for this component. You can obtain this key from http://code.google.com/apis/maps/signup.html.
  • if (!IsPostBack)
    {
        GoogleMapForASPNet1.GoogleMapObject.APIKey = "<YourGoogleMapKey>";
    Note that inialization code for map should go inside if (!IsPostBack) block.
  • Optionally you can specify which version of Google maps API to use. You can get more information about Google Maps API version here.
  • GoogleMapForASPNet1.GoogleMapObject.APIVersion = "2";
  • Specify width and height for map. You can specify either in pixels or in percentage relative to it's container.
  • GoogleMapForASPNet1.GoogleMapObject.Width = "800px";
  • GoogleMapForASPNet1.GoogleMapObject.Height = "600px";
  • Specify zoom level. Default is 3.
  • GoogleMapForASPNet1.GoogleMapObject.ZoomLevel = 14;
  • Specify Center Point for map. Map will be centered on this point.
  • GoogleMapForASPNet1.GoogleMapObject.CenterPoint = new GooglePoint("CenterPoint", 43.66619, -79.44268);
  • Add pushpins for map. This can be done by initializing GooglePoint type object. In constructor of GooglePoint, First argument is ID of this pushpin. It must be unique for each pin. Second and third arguments are latitude and longitude.
  • GoogleMapForASPNet1.GoogleMapObject.Points.Add(new GooglePoint("1", 43.65669, -79.45278));
    Alternatively you can also do it like below,
    GooglePoint GP = new GooglePoint();
    GP.ID = "1";
    GP.Latitude = 43.65669;
    GP.Longitude = -79.43270;
    GoogleMapForASPNet1.GoogleMapObject.Points.Add(GP);

You can add as many pushpins as you wish. Now run website again and you should see pushpins on map.

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Assigning custom icon to pushpins

  • You can assign your own icons with google map control. For that first copy your icons in some directory under root directory of your website. You can assign icon to a pushpin as below,
  • GP.IconImage = "icons/pushpin-blue.png";
    Note that path to image is relative to root folder. You should have icons (or whichever) directory in root folder of your website.
  • You can add description of a pushpin which will pop up when user clicks a pushpin.
    GP.InfoHTML = "This is Pushpin-1";

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  • You can format InfoHTML property using standard HTML tags.
    example: GP.InfoHTML = "This is <font color='red'><b>Pushpin-1</b></font>";

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Up to this point, I have explained you basics of using Google Map control. Now let's implement some advanced functionality.

Let's say we want to move pushpins when user do some action. For example when a user clicks on a button. For that, follow below steps.

Creating Interactive Map

You can create interactive map using Google Map control. You can move pushpins when user clicks on a button. Here is how you can do it.

  • Insert standard asp.net button on your web page. Write following code in click event of this button.

protected void Button1_Click(object sender, EventArgs e)

{

   GoogleMapForASPNet1.GoogleMapObject.Points["1"].Latitude += 0.003;

   GoogleMapForASPNet1.GoogleMapObject.Points["1"].Longitude += 0.003;

}

We are incrementing Latitude and Longitude value for Pushpin-1 here. Note that I am using ID(In above code "1") of pushpin to set new Latitude and Longitude.

  • Run your application and click on Button. You will note that whole page get's refreshed (or postback). To stop it from posting back, you need to wrap this button with an Ajax Update panel. Go to Visual Studio toolbox and drag Ajax Updatepanel control on your page.

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  • Move your button inside this update panel.

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  • Now run website again and click on button. You should notice that now page is not posting back and Pushpin moves on map.

Auto refreshing map and GPS Navigation

You can use Ajax Framewor's timer control in similar way as button control (I have explained above). On Timer_Tick() event you can specify new latitude longitude for all pushpins. This way Map will move all pushpins automatically after specified time delay. You can hook up any GPS service with this control to create GPS Navigation system.

Creating Polylines with Google Map control

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Create points for polyline 


GooglePoint GP1 = new GooglePoint();

GP1.ID = "GP1";

GP1.Latitude = 43.65669;

GP1.Longitude = -79.44268;

GP1.InfoHTML = "This is point 1";

GoogleMapForASPNet1.GoogleMapObject.Points.Add(GP1);

 

GooglePoint GP2 = new GooglePoint();

GP2.ID = "GP2";

GP2.Latitude = 43.66619;

GP2.Longitude = -79.44268;

GP2.InfoHTML = "This is point 2";

GoogleMapForASPNet1.GoogleMapObject.Points.Add(GP2);

 

GooglePoint GP3 = new GooglePoint();

GP3.ID = "GP3";

GP3.Latitude = 43.67689;

GP3.Longitude = -79.43270;

GP3.InfoHTML = "This is point 3";

GoogleMapForASPNet1.GoogleMapObject.Points.Add(GP3);

Create polyline between points GP1, GP2 and GP3

//Define polyline

GooglePolyline PL1 = new GooglePolyline();

PL1.ID = "PL1";

//Give Hex code for line color

PL1.ColorCode = "#0000FF";

//Specify width for line

PL1.Width = 5;

 

//Add points

PL1.Points.Add(GP1);

PL1.Points.Add(GP2);

PL1.Points.Add(GP3);

Add Polyline to Google Map control,

GoogleMapForASPNet1.GoogleMapObject.Polylines.Add(PL1);Creating Polygons with Google Map control

Creating Polygons with Google Map control

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Create points for polyline,

//Define Points for polygon

GooglePoint GP1 = new GooglePoint();

GP1.ID = "GP1";

GP1.Latitude = 43.66675;

GP1.Longitude = -79.4042;

 

GooglePoint GP2 = new GooglePoint();

GP2.ID = "GP2";

GP2.Latitude = 43.67072;

GP2.Longitude = -79.38677;

 

//Define GP3,GP4,GP5,GP6 and GP7 in similar way

GooglePoint GP7 = new GooglePoint();

GP7.ID = "GP7";

GP7.Latitude = 43.66656;

GP7.Longitude = -79.40445;

 

//Create Polygon using above points

GooglePolygon PG1 = new GooglePolygon();

PG1.ID = "PG1";


//Give Hex code for line color

PG1.FillColor = "#0000FF";

PG1.FillOpacity = 0.4;


//Stroke is outer border of polygon.

PG1.StrokeColor = "#0000FF";

PG1.StrokeOpacity = 1;

PG1.StrokeWeight = 2;


//Add points to polygon

PG1.Points.Add(GP1);

PG1.Points.Add(GP2);

PG1.Points.Add(GP3);

PG1.Points.Add(GP4);

PG1.Points.Add(GP5);

PG1.Points.Add(GP6);

PG1.Points.Add(GP7);


//Add polygon to google map control,

GoogleMapForASPNet1.GoogleMapObject.Polygons.Add(PG1);

Go through samples provided in download. I have explained all sort of circumtances in which you may want to use google map control. If you have any questions, feel free to ask.

In Part 2, I will explain you souce code of Google Map user control and how to customize it for your own use.

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