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Creating an Interactive Map in ASP.NET 2.0 Using SharpMap

, 25 Nov 2005 CPOL 395.7K 7.6K 106
An article on how to create a web map application using SharpMap in ASP.NET 2.0.
SharpMap1_src.zip
App_Data
Bin
SharpMap.dll
using System;
using System.Data;
using System.Drawing;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class Default : System.Web.UI.Page
{
	private SharpMap.Map myMap;

	protected void Page_Load(object sender, EventArgs e)
	{
		//Set up the map
		myMap = InitializeMap(new System.Drawing.Size((int)imgMap.Width.Value,(int)imgMap.Height.Value));
		if (Page.IsPostBack) 
		{
			//Page is post back. Restore center and zoom-values from viewstate
			myMap.Center = (SharpMap.Geometries.Point)ViewState["mapCenter"];
			myMap.Zoom = (double)ViewState["mapZoom"];
		}
		else
		{
			//This is the initial view of the map. Zoom to the extents of the map:
			myMap.ZoomToExtents();
			//Save the current mapcenter and zoom in the viewstate
			ViewState.Add("mapCenter", myMap.Center);
			ViewState.Add("mapZoom", myMap.Zoom);
			//Create the map
			CreateMap();
		}
	}
  
	protected void imgMap_Click(object sender, ImageClickEventArgs e)
	{
		//Set center of the map to where the client clicked
		myMap.Center = SharpMap.Utilities.Transform.MapToWorld(new System.Drawing.Point(e.X, e.Y), myMap);
		//Set zoom value if any of the zoom tools were selected
		if (rblMapTools.SelectedValue == "0") //Zoom in
			myMap.Zoom = myMap.Zoom * 0.5;
		else if (rblMapTools.SelectedValue == "1") //Zoom out
			myMap.Zoom = myMap.Zoom * 2;
		//Save the new map's zoom and center in the viewstate
		ViewState.Add("mapCenter", myMap.Center);
		ViewState.Add("mapZoom", myMap.Zoom);
		//Create the map
		CreateMap();
	}
  
	/// <summary>
	/// Sets up the map, add layers and sets styles
	/// </summary>
	/// <param name="outputsize">Initiatial size of output image</param>
	/// <returns>Map object</returns>
	private SharpMap.Map InitializeMap(System.Drawing.Size outputsize)
	{
		//Initialize a new map of size 'imagesize'
		SharpMap.Map map = new SharpMap.Map(outputsize);
				
		//Set up the countries layer
		SharpMap.Layers.VectorLayer layCountries = new SharpMap.Layers.VectorLayer("Countries");
		//Set the datasource to a shapefile in the App_data folder
		layCountries.DataSource = new SharpMap.Providers.ShapeFile(Server.MapPath(@"~\App_data\countries.shp"), true);
		//Set fill-style to green
		layCountries.Style.Fill = new SolidBrush(Color.Green);
		//Set the polygons to have a black outline
		layCountries.Style.Outline = System.Drawing.Pens.Black;
		layCountries.Style.EnableOutline = true;

		//Set up a river layer
		SharpMap.Layers.VectorLayer layRivers = new SharpMap.Layers.VectorLayer("Rivers");
		//Set the datasource to a shapefile in the App_data folder
		layRivers.DataSource = new SharpMap.Providers.ShapeFile(Server.MapPath(@"~\App_data\rivers.shp"), true);
		//Define a blue 1px wide pen
		layRivers.Style.Line = new Pen(Color.Blue,1);

		//Add the layers to the map object.
		//The order we add them in are the order they are drawn, so we add the rivers last to put them on top
		map.Layers.Add(layCountries);
		map.Layers.Add(layRivers);
		
		return map;
	}

	/// <summary>
	/// Creates the map, inserts it into the cache and sets the ImageButton Url
	/// </summary>
	private void CreateMap()
	{
		System.Drawing.Image img = myMap.GetMap();
		string imgID = SharpMap.Web.Caching.InsertIntoCache(1, img);
		imgMap.ImageUrl = "getmap.aspx?ID=" + HttpUtility.UrlEncode(imgID);
	}
}

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

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About the Author

Morten on GIS
Web Developer
United States United States
Morten Nielsen holds a M.Sc. in Engineering and GeoInformatics, and works full time as a .NET software developer in California making the next generation GIS applications. He specializes in mapping, GeoInformatics and image processing, and is the creator of several open source projects such as Proj.NET, SharpGPS and SharpMap.

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