Blazor World Utility
The resource topic provides implementation of utility that helps with generating Blazor geographic data.
Code Snippet
export default class WorldUtils {
// calculate geo-paths between two locations using great circle formula
public static calcPaths(origin: any, dest: any): any[] {
let interval = 200;
let paths: any[] = [[]];
let pathID = 0;
let distance = this.calcDistance(origin, dest);
if (distance <= interval) {
paths[pathID].push({ x: origin.lon, y: origin.lat });
paths[pathID].push({ x: dest.lon, y: dest.lat });
} else {
let current = origin;
let previous = origin;
for (let dist = interval; dist <= distance; dist += interval)
{
previous = current
paths[pathID].push({ x: current.lon, y: current.lat });
let bearing = this.calcBearing(current, dest);
current = this.calcDestination(current, bearing, interval);
// ensure geo-path wrap around the world through the new date-line
if (previous.lon > 150 && current.lon < -150) {
paths[pathID].push({ x: 180, y: current.lat });
paths.push([]);
pathID++
current = { lon: -180, lat: current.lat }
} else if (previous.lon < -150 && current.lon > 150) {
paths[pathID].push({ x: -180, y: current.lat });
paths.push([]);
pathID++
current = { lon: 180, lat: current.lat }
}
}
paths[pathID].push({ x: dest.lon, y: dest.lat });
}
return paths;
}
// calculate bearing angle between two locations
public static calcBearing(origin: any, dest: any) : number
{
origin = this.toRadianLocation(origin);
dest = this.toRadianLocation(dest);
let range = (dest.lon - origin.lon);
let y = Math.sin(range) * Math.cos(dest.lat);
let x = Math.cos(origin.lat) * Math.sin(dest.lat) -
Math.sin(origin.lat) * Math.cos(dest.lat) * Math.cos(range);
let angle = Math.atan2(y, x);
return this.toDegreesNormalized(angle);
}
// calculate destination for origin location and travel distance
public static calcDestination(origin: any, bearing: number, distance: number): any {
let radius = 6371.0;
origin = this.toRadianLocation(origin);
bearing = this.toRadians(bearing);
distance = distance / radius; // angular distance in radians
let lat = Math.asin(Math.sin(origin.lat) * Math.cos(distance) +
Math.cos(origin.lat) * Math.sin(distance) * Math.cos(bearing));
let x = Math.sin(bearing) * Math.sin(distance) * Math.cos(origin.lat);
let y = Math.cos(distance) - Math.sin(origin.lat) * Math.sin(origin.lat);
let lon = origin.lon + Math.atan2(x, y);
// normalize lon to coordinate between -180º and +180º
lon = (lon + 3 * Math.PI) % (2 * Math.PI) - Math.PI;
lon = this.toDegrees(lon);
lat = this.toDegrees(lat);
return { lon: lon, lat: lat };
}
// calculate distance between two locations
public static calcDistance(origin: any, dest: any) : number {
origin = this.toRadianLocation(origin);
dest = this.toRadianLocation(dest);
let sinProd = Math.sin(origin.lat) * Math.sin(dest.lat);
let cosProd = Math.cos(origin.lat) * Math.cos(dest.lat);
let lonDelta = (dest.lon - origin.lon);
let angle = Math.acos(sinProd + cosProd * Math.cos(lonDelta));
let distance = angle * 6371.0;
return distance; // * 6371.0; // in km
}
public static toRadianLocation(geoPoint: any) : any {
let x = this.toRadians(geoPoint.lon);
let y = this.toRadians(geoPoint.lat);
return { lon: x, lat: y };
}
public static toRadians(degrees: number) : number
{
return degrees * Math.PI / 180;
}
public static toDegrees(radians: number) : number {
return (radians * 180.0 / Math.PI);
}
public static toDegreesNormalized(radians: number) : number
{
let degrees = this.toDegrees(radians);
degrees = (degrees + 360) % 360;
return degrees;
}
// converts latitude coordinate to a string
public static toStringLat(latitude: number) : string {
let str = Math.abs(latitude).toFixed(1) + "°";
return latitude > 0 ? str + "N" : str + "S";
}
// converts longitude coordinate to a string
public static toStringLon(coordinate: number) : string {
let val = Math.abs(coordinate);
let str = val < 100 ? val.toFixed(1) : val.toFixed(0);
return coordinate > 0 ? str + "°E" : str + "°W";
}
public static toStringAbbr(value: number) : string {
if (value > 1000000000000) {
return (value / 1000000000000).toFixed(1) + " T"
} else if (value > 1000000000) {
return (value / 1000000000).toFixed(1) + " B"
} else if (value > 1000000) {
return (value / 1000000).toFixed(1) + " M"
} else if (value > 1000) {
return (value / 1000).toFixed(1) + " K"
}
return value.toFixed(0);
}
public static getLongitude(location: any) : number {
if (location.x) return location.x;
if (location.lon) return location.lon;
if (location.longitude) return location.longitude;
return Number.NaN;
}
public static getLatitude(location: any) : number {
if (location.y) return location.y;
if (location.lat) return location.lat;
if (location.latitude) return location.latitude;
return Number.NaN;
}
public static getBounds(locations: any[]) : any {
let minLat = 90;
let maxLat = -90;
let minLon = 180;
let maxLon = -180;
for (const location of locations) {
const crrLon = this.getLongitude(location);
if (!Number.isNaN(crrLon)) {
minLon = Math.min(minLon, crrLon);
maxLon = Math.max(maxLon, crrLon);
}
const crrLat = this.getLatitude(location);
if (!Number.isNaN(crrLat)) {
minLat = Math.min(minLat, crrLat);
maxLat = Math.max(maxLat, crrLat);
}
}
const geoBounds = {
left: minLon,
top: minLat,
width: Math.abs(maxLon - minLon),
height: Math.abs(maxLat - minLat)
};
return geoBounds;
}
} public static class WorldUtils
{
public static List<List<Point>> CalcPaths(GeoLocation origin, GeoLocation dest)
{
int interval = 200;
List<List<Point>> paths = new List<List<Point>>() { new List<Point>() };
int pathID = 0;
double distance = WorldUtils.CalcDistance(origin, dest);
if (distance <= interval)
{
Console.WriteLine("Distance Less Than Equal To Interval!");
paths[pathID].Add(new Point() { X = dest.Lon, Y = dest.Lat });
}
else
{
Console.WriteLine("Distance Greater Than Interval!");
GeoLocation current = origin;
GeoLocation previous = origin;
for (int dist = interval; dist <= distance; dist += interval)
{
previous = current;
paths[pathID].Add(new Point() { X = current.Lon, Y = current.Lat });
double bearing = WorldUtils.CalcBearing(current, dest);
current = WorldUtils.CalcDestination(current, bearing, interval);
if (previous.Lon > 150 && current.Lon < -150)
{
paths[pathID].Add(new Point() { X = 180, Y = current.Lat });
paths.Add(new List<Point>());
pathID++;
current = new GeoLocation() { Lon = -180, Lat = current.Lat };
}
else if (previous.Lon < -150 && current.Lon > 150)
{
paths[pathID].Add(new Point() { X = -180, Y = current.Lat });
paths.Add(new List<Point>());
pathID++;
current = new GeoLocation() { Lon = 180, Lat = current.Lat };
}
}
paths[pathID].Add(new Point() { X = dest.Lon, Y = dest.Lat });
}
return paths;
}
public static double CalcBearing(GeoLocation origin, GeoLocation dest)
{
origin = WorldUtils.ToRadianLocation(origin);
dest = WorldUtils.ToRadianLocation(dest);
double range = (dest.Lon - origin.Lon);
double y = Math.Sin(range) * Math.Cos(dest.Lat);
double x = Math.Cos(origin.Lat) * Math.Sin(dest.Lat) - Math.Sin(origin.Lat) * Math.Cos(dest.Lat) * Math.Cos(range);
double angle = Math.Atan2(y, x);
return WorldUtils.ToDegreesNormalized(angle);
}
public static GeoLocation CalcDestination(GeoLocation origin, double bearing, double distance)
{
double radius = 6371.0;
origin = WorldUtils.ToRadianLocation(origin);
bearing = WorldUtils.ToRadians(bearing);
distance = distance / radius;
double lat = Math.Asin(Math.Sin(origin.Lat) * Math.Cos(distance) +
Math.Cos(origin.Lat) * Math.Sin(distance) * Math.Cos(bearing));
double x = Math.Sin(bearing) * Math.Sin(distance) * Math.Cos(origin.Lat);
double y = Math.Cos(distance) - Math.Sin(origin.Lat) * Math.Sin(origin.Lat);
double lon = origin.Lon + Math.Atan2(x, y);
// normalize lon to coordinate between -180º and +180º
lon = (lon + 3 * Math.PI) % (2 * Math.PI) - Math.PI;
lon = WorldUtils.ToDegrees(lon);
lat = WorldUtils.ToDegrees(lat);
return new GeoLocation() { Lat = lat, Lon = lon };
}
public static double CalcDistance(GeoLocation origin, GeoLocation dest)
{
origin = WorldUtils.ToRadianLocation(origin);
dest = WorldUtils.ToRadianLocation(dest);
double sinProd = Math.Sin(origin.Lat) * Math.Sin(dest.Lat);
double cosProd = Math.Cos(origin.Lat) * Math.Cos(dest.Lat);
double lonDelta = (dest.Lon - origin.Lon);
double angle = Math.Acos(sinProd + cosProd * Math.Cos(lonDelta));
double distance = angle * 6371.0;
return distance;
}
public static GeoLocation ToRadianLocation(GeoLocation geoPoint)
{
double x = WorldUtils.ToRadians(geoPoint.Lon);
double y = WorldUtils.ToRadians(geoPoint.Lat);
return new GeoLocation() { Lon = x, Lat = y };
}
public static double ToRadians(double degrees)
{
return degrees * Math.PI / 180;
}
public static double ToDegrees(double radians)
{
return (radians * 180.0 / Math.PI);
}
public static double ToDegreesNormalized(double radians)
{
double degrees = WorldUtils.ToDegrees(radians);
degrees = (degrees + 360) % 360;
return degrees;
}
public static string ToStringLat(double latitude)
{
string str = Math.Abs(latitude) + "°";
return latitude > 0 ? str + "N" : str + "S";
}
public static string ToStringLon(double coordinate)
{
double val = Math.Abs(coordinate);
string str = val.ToString();
return coordinate > 0 ? str + "°E" : str + "°W";
}
public static string ToStringAbbr(double value)
{
if (value > 1000000000000)
{
return (value / 1000000000000).ToString("N1") + " T";
}
else if (value > 1000000000)
{
return (value / 1000000000).ToString("N1") + " B";
}
else if (value > 1000000)
{
return (value / 1000000).ToString("N1") + " M";
}
else if (value > 1000)
{
return (value / 1000).ToString("N1") + " K";
}
return value.ToString("N0");
}
public static double GetLongitude(GeoLocation location)
{
return location.Lon;
}
public static double GetLatitude(GeoLocation location)
{
return location.Lat;
}
public static Rect GetBounds(List<GeoLocation> locations)
{
double minLat = 90;
double maxLat = -90;
double minLon = 180;
double maxLon = -180;
foreach (GeoLocation gl in locations)
{
double curLon = WorldUtils.GetLongitude(gl);
double curLat = WorldUtils.GetLatitude(gl);
if (!double.IsNaN(curLon))
{
minLon = Math.Min(minLon, curLon);
maxLon = Math.Max(maxLon, curLon);
}
if (!double.IsNaN(curLat))
{
minLat = Math.Min(minLat, curLat);
maxLat = Math.Min(maxLat, curLat);
}
}
Rect geoBounds = new Rect(minLon, minLat, Math.Abs(maxLon - minLon), Math.Abs(maxLat - minLat));
return geoBounds;
}
public static List<Point> GetNightShapes()
{
List<Point> line = new List<Point>();
for (int lon = -180; lon <= 180; lon += 1)
{
double x = lon;
double y = 75 * Math.Cos(lon * Math.PI / 180);
line.Add(new Point(x, y));
}
return line;
}
}