PointClusterService.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using SafeRoutes.Infrastructure.Storage.Domain;
namespace SafeRoutes.Infrastructure.Services
{
 
        /// <summary>
        /// Service that clusters ProjectPoints
        /// </summary>
        /// <remarks>could be generalized via interfaces</remarks>
        public static class PointClusterService
        {
            /// <remarks>Originally From James O'Brien's Clustering Sample</remarks>
            public static List<ProjectPoint> Cluster(List<ProjectPoint> pins, double resolution)
            {
                //sort pins - must be ordered correctly by x,y          
                pins.Sort();

                List<ProjectPoint> clusteredPoints = new List<ProjectPoint>();

                for (int index = 0; index < pins.Count; index++)
                {
                    if (!pins[index].c) //skip already clustered pins
                    {

                        ProjectPoint currentClusterPin = new ProjectPoint();

                        //create our cluster object and add the first pin
                        currentClusterPin.AddPoint(pins[index]);
                        //the pin will represent this first point...
                        
                        currentClusterPin.pid = pins[index].pid;
                        currentClusterPin.Amount = pins[index].Amount;
                        currentClusterPin.Name = pins[index].Name;
                        currentClusterPin.Src = pins[index].Src;
                        currentClusterPin.Year = pins[index].Year;
                        currentClusterPin.cs = pins[index].cs;
                        currentClusterPin.nsc = pins[index].nsc;
                        currentClusterPin.Location = pins[index].Location;                        


                        //Need to know what icon to show
                        if (pins[index].Src.ToLower() == "statewide")
                        {
                            currentClusterPin.st = true;
                        }
                        //If any pin the the cluster is positive,the entire cluster needs to know
                        if (pins[index].Src.ToLower() == "district")
                        {
                            currentClusterPin.sd =true;
                        }
                        
                        //look backwards in the list for any points within the range that are not already grouped, 
                        //as the points are in order we exit as soon as it exceeds the range.  
                        PointClusterService.AddPinsWithinRange(pins, index, -1, currentClusterPin, resolution);

                        //look forwards in the list for any points within the range, again we short out.  
                        PointClusterService.AddPinsWithinRange(pins, index, 1, currentClusterPin, resolution);

                        currentClusterPin.ico = GetPointIcon(currentClusterPin);
                        currentClusterPin.SortCluster();
                        clusteredPoints.Add(currentClusterPin);
                        
                    }
                }
                
                return clusteredPoints;
            }


            public static string GetPointIcon(ProjectPoint pt)
            {
                //assume it's just a school
                string icoName = "sa";                
                //check if the st flag has been set (i.e. this is a state-wide award)
                if (pt.st)
                {
                    //state award trumps everything...
                    icoName = "sta";
                }
                else if(pt.sd)
                {                    
                    icoName = "sda";
                }
                //if it's clustered...
                if (pt.c) { icoName += "-c"; }
                return icoName;
            }
            

            /// <summary>
            /// 
            /// </summary>
            /// <param name="pins"></param>
            /// <param name="index"></param>
            /// <param name="direction"></param>
            /// <param name="currentClusterPin"></param>
            /// <param name="zoomLevel"></param>
            /// <remarks>From James O'Brien's Clustering Sample</remarks>
            private static void AddPinsWithinRange(List<ProjectPoint> pins, int index, int direction, ProjectPoint currentClusterPin, double resolution)
            {
                //Cluster width & heigth are in pixels. So any point within 20 pixels at the zoom level will be clustered.
                int clusterwidth = 22; //Cluster region width, all pin within this area are clustered
                

                bool finished = false;
                int searchindex;
                searchindex = index + direction;
                while (!finished)
                {
                    if (searchindex >= pins.Count || searchindex < 0)
                    {
                        finished = true;
                    }
                    else
                    {
                        if (!pins[searchindex].c)
                        {
                            //find distance between two points at specified indexes
                            if (Math.Abs(pins[searchindex].Location.X - pins[index].Location.X) / resolution < clusterwidth) //within the same x range
                            {
                                if (Math.Abs(pins[searchindex].Location.Y - pins[index].Location.Y) / resolution < clusterwidth) //within the same y range = cluster needed
                                {
                                    //add to cluster
                                    currentClusterPin.AddPoint(pins[searchindex]);
                                  
                                    //this point represents a cluster...
                                    currentClusterPin.c = true;

                                    //=================================================================================
                                    // Need to update the parent when we find a higher ranking point in the cluster
                                    //basically transfer all the attributes "up"
                                    //=================================================================================
                                    if (currentClusterPin.Src.ToLower() == "school" && pins[searchindex].Src.ToLower() == "district")
                                    {
                                        //currently it's a school, and the new pin is a district... copy
                                        currentClusterPin.sd = true;
                                        currentClusterPin.pid = pins[searchindex].pid;
                                        currentClusterPin.Amount = pins[searchindex].Amount;
                                        currentClusterPin.Name = pins[searchindex].Name;
                                        currentClusterPin.Src = pins[searchindex].Src;
                                        currentClusterPin.Year = pins[searchindex].Year;
                                        currentClusterPin.cs = pins[searchindex].cs;
                                        currentClusterPin.nsc = pins[searchindex].nsc;
                                    }
                                    if (currentClusterPin.Src.ToLower() == "school" && pins[searchindex].Src.ToLower() == "statewide")
                                    {
                                        //clone up
                                        currentClusterPin.st = true;
                                        currentClusterPin.pid = pins[searchindex].pid;
                                        currentClusterPin.Amount = pins[searchindex].Amount;
                                        currentClusterPin.Name = pins[searchindex].Name;
                                        currentClusterPin.Src = pins[searchindex].Src;
                                        currentClusterPin.Year = pins[searchindex].Year;
                                        currentClusterPin.cs = pins[searchindex].cs;
                                        currentClusterPin.nsc = pins[searchindex].nsc;
                                    }

                                    if (currentClusterPin.Src.ToLower() == "district" && pins[searchindex].Src.ToLower() == "statewide")
                                    {
                                        //clone up
                                        currentClusterPin.st = true;
                                        currentClusterPin.pid = pins[searchindex].pid;
                                        currentClusterPin.Amount = pins[searchindex].Amount;
                                        currentClusterPin.Name = pins[searchindex].Name;
                                        currentClusterPin.Src = pins[searchindex].Src;
                                        currentClusterPin.Year = pins[searchindex].Year;
                                        currentClusterPin.cs = pins[searchindex].cs;
                                        currentClusterPin.nsc = pins[searchindex].nsc;
                                    }

                                    //stop any further clustering actions on the pin we are comparing
                                    //because it's already added to a cluster
                                    pins[searchindex].c = true;
                                }
                            }
                            else
                            {
                                finished = true;
                            }
                        }
                        searchindex += direction;
                    }
                }
            }


        }
    }