public List<P> GetClusterResult(Boundary grid)
{
// Collect used buckets and return the result
var clusterPoints = new List<P>();
// O(m*n)
foreach (var item in BucketsLookup)
{
var bucket = item.Value;
if (!bucket.IsUsed) continue;
if (bucket.Points.Count < GmcSettings.Get.MinClusterSize)
{
clusterPoints.AddRange(bucket.Points);
}
else
{
bucket.Centroid.C = bucket.Points.Count;
clusterPoints.Add(bucket.Centroid);
}
}
// var filtered = FilterDataset(clusterPoints, grid); // post filter data for client viewport
// return filtered; //not working properly when zoomed far out.
return clusterPoints; // return not post filtered
}
/// <summary>
/// todo use threads and threadData
/// </summary>
/// <param name="points"></param>
/// <param name="input"></param>
public GridCluster(IList<P> points, JsonGetMarkersReceive input)
: base(points)
{
this._jsonReceive = input;
double[] deltas = GetDelta(GmcSettings.Get.Gridx, GmcSettings.Get.Gridy, input.Zoomlevel);
DeltaX = deltas[0];
DeltaY = deltas[1];
Grid = GetBoundaryExtended(input);
}
public static Boundary GetBoundaryExtended(JsonGetMarkersReceive input)
{
var deltas = GetDelta(GmcSettings.Get.Gridx, GmcSettings.Get.Gridy, input.Zoomlevel);
var deltaX = deltas[0];
var deltaY = deltas[1];
// Grid with extended outer grid-area non-visible
var a = MathTool.FloorLatLon(input.Viewport.Minx, deltaX) - deltaX * GmcSettings.Get.OuterGridExtend;
var b = MathTool.FloorLatLon(input.Viewport.Miny, deltaY) - deltaY * GmcSettings.Get.OuterGridExtend;
var a2 = MathTool.FloorLatLon(input.Viewport.Maxx, deltaX) + deltaX * (1 + GmcSettings.Get.OuterGridExtend);
var b2 = MathTool.FloorLatLon(input.Viewport.Maxy, deltaY) + deltaY * (1 + GmcSettings.Get.OuterGridExtend);
// Latitude is special with Google Maps, they don't wrap around, then do constrain
b = MathTool.ConstrainLatitude(b);
b2 = MathTool.ConstrainLatitude(b2);
var grid = new Boundary { Minx = a, Miny = b, Maxx = a2, Maxy = b2 };
grid.Normalize();
return grid;
}
public JsonGetMarkersReceive(double nelat, double nelon, double swlat, double swlon, int zoomlevel, string filter)
{
Zoomlevel = zoomlevel;
Viewport = new Boundary { Minx = swlon, Maxx = nelon, Miny = swlat, Maxy = nelat };
// Parse filter
var typeFilter = new HashSet<int>();
if (string.IsNullOrWhiteSpace(filter))
{
// no filter used
IsClusteringEnabled = true;
IsDebugLinesEnabled = false;
}
else
{
int binarySum = 0;
int.TryParse(filter, out binarySum);
string binary = Convert.ToString(binarySum, 2);
binary = Reverse(binary); // more easy to take index of when reversed
// First two are reserved for cluster and debug lines flag
IsClusteringEnabled = binary.Length >= 1 && binary[0] == '1';
IsDebugLinesEnabled = binary.Length >= 2 && binary[1] == '1';
// Rest are marker type filter
var type1 = binary.Length >= 3 && binary[2] == '1';
var type2 = binary.Length >= 4 && binary[3] == '1';
var type3 = binary.Length >= 5 && binary[4] == '1';
if (!type1) typeFilter.Add(1);
if (!type2) typeFilter.Add(2);
if (!type3) typeFilter.Add(3);
}
TypeFilterExclude = typeFilter;
}
/// <summary>
/// For debugging purpose
/// Display the red grid lines on the map to show how the points are clustered
/// </summary>
/// <returns></returns>
public IList<Line> GetPolyLines()
{
if (!GmcSettings.Get.DoShowGridLinesInGoogleMap) return null; // server disabled it
if (!_jsonReceive.IsDebugLinesEnabled) return null; // client disabled it
// Make the red lines data to be drawn in Google map
var temp = new List<Rectangle>();
const int borderLinesAdding = 1;
var linesStepsX = (int)(Math.Round(Grid.AbsX / DeltaX) + borderLinesAdding);
var linesStepsY = (int)(Math.Round(Grid.AbsY / DeltaY) + borderLinesAdding);
var b = new Boundary(Grid);
const double restrictLat = 5.5; // heuristic value, Google maps related
b.Miny = MathTool.ConstrainLatitude(b.Miny, restrictLat); // Make sure it is visible on screen, restrict by some value
b.Maxy = MathTool.ConstrainLatitude(b.Maxy, restrictLat);
// Vertical lines
for (var i = 0; i < linesStepsX; i++)
{
var xx = b.Minx + i * DeltaX;
// Draw region
if (_jsonReceive.Zoomlevel > 3) // heuristic value, Google maps related
{
temp.Add(new Rectangle { Minx = xx, Miny = b.Miny, Maxx = xx, Maxy = b.Maxy });
}
// World wrap issue when same latlon area visible multiple times
// Make sure line is drawn from left to right on screen
else
{
temp.Add(new Rectangle { Minx = xx, Miny = LatLonInfo.MinLatValue + restrictLat, Maxx = xx, Maxy = 0 });
temp.Add(new Rectangle { Minx = xx, Miny = 0, Maxx = xx, Maxy = LatLonInfo.MaxLatValue - restrictLat });
}
}
// Horizontal lines
for (var i = 0; i < linesStepsY; i++)
{
var yy = b.Miny + i * DeltaY;
// Draw region
if (_jsonReceive.Zoomlevel > 3) // heuristic value
{
// Don't draw lines outsize the world
if (MathTool.IsLowerThanLatMin(yy) || MathTool.IsGreaterThanLatMax(yy)) continue;
temp.Add(new Rectangle { Minx = b.Minx, Miny = yy, Maxx = b.Maxx, Maxy = yy });
}
// World wrap issue when same latlon area visible multiple times
// Make sure line is drawn from left to right on screen
else
{
temp.Add(new Rectangle { Minx = LatLonInfo.MinLonValue, Miny = yy, Maxx = 0, Maxy = yy });
temp.Add(new Rectangle { Minx = 0, Miny = yy, Maxx = LatLonInfo.MaxLonValue, Maxy = yy });
}
}
var lines = new List<Line>();
// Normalize the lines and add as string
foreach (var line in temp)
{
var x = (line.Minx).NormalizeLongitude().DoubleToString();
var x2 = (line.Maxx).NormalizeLongitude().DoubleToString();
var y = (line.Miny).NormalizeLatitude().DoubleToString();
var y2 = (line.Maxy).NormalizeLatitude().DoubleToString();
lines.Add(new Line { X = x, Y = y, X2 = x2, Y2 = y2 });
}
return lines;
}
// To work properly it requires the p is already normalized
protected static int[] GetPointMappedIds(P p, Boundary grid, double deltax, double deltay)
{
#region Naive
// Naive version, lon points near 180 and lat points near 90 are not clustered together
//idx = (int)(relativeX / deltax);
//idy = (int)(relativeY / deltay);
//var relativeX = p.X - grid.Minx;
#endregion Naive
/*
You have to draw a line with longitude values 180, -180 on papir to understand this
e.g. _deltaX = 20
longitude 150 170 180 -170 -150
| | | |
idx = 7 8 9 -9 -8
-10
here we want idx 8, 9, -10 and -9 be equal to each other, we set them to idx=8
then the longitudes from 170 to -170 will be clustered together
*/
var relativeY = p.Y - grid.Miny;
var overlapMapMinX = (int)(LatLonInfo.MinLonValue / deltax) - 1;
var overlapMapMaxX = (int)(LatLonInfo.MaxLonValue / deltax);
// The deltaX = 20 example scenario, then set the value 9 to 8 and -10 to -9
// Similar to if (LatLonInfo.MaxLonValue % deltax == 0) without floating presicion issue
if (Math.Abs(LatLonInfo.MaxLonValue % deltax - 0) < Numbers.Epsilon)
{
overlapMapMaxX--;
overlapMapMinX++;
}
var idxx = (int)(p.X / deltax);
if (p.X < 0) idxx--;
if (Math.Abs(LatLonInfo.MaxLonValue % p.X - 0) < Numbers.Epsilon)
{
if (p.X < 0) idxx++;
else idxx--;
}
if (idxx == overlapMapMinX) idxx = overlapMapMaxX;
var idx = idxx;
// Latitude never wraps around with Google Maps, ignore 90, -90 wrap-around for latitude
var idy = (int)(relativeY / deltay);
return new[] { idx, idy };
}
public static bool IsInside(Boundary b, P p)
{
return IsInside(b.Minx, b.Miny, b.Maxx, b.Maxy, p.X, p.Y, false, false);
}
// O(n)
public static IList<P> FilterDataByViewport(IList<P> points, Boundary viewport)
{
return points
.Where(i => MathTool.IsInside(viewport, i))
.ToList();
}
