//Fucntion: converting coordinates between state plane and geograohic
//          Converts from/to latitude/Longitude to/from Delaware State Plane Coordinates.
//          values for latitude of first standard parallel and latitude of second standard parallel
//          are predicted by John R. Collier from DelDOT GIS survey section, because those two values are not
//          required in the project for State of Delaware.
//          The formulae this program is based on are from "Map Projections,
//          A Working Manual" by John P. Snyder, U.S. Geological Survey
//          Professional Paper 1395, 1987, pages 295-298
//          code: // Code based on asp code from Gerry Daumiller, Montana State Library 8-23-02 email. 
//          ASP code on web at http://nris.state.mt.us/gis/projection/projection.html.  
//Modified by Li Luo


var a = 6378206.4;   		//major radius of ellipsoid, map units in meters (NAD 83)
var ec = 0.08181905782;  		//eccentricity of ellipsoid (NAD 83)
var angRad = 0.01745329252;  	//number of radians in a degree
var pi4 = Math.PI / 4.0;
var p0 = 38 * angRad; 	 	//latitude of origin (Delaware)
var p1 = 38.5 * angRad;  		//latitude of first standard parallel (predicted)
var p2 = 40 * angRad;  	        //latitude of second standard parallel (predicted)
var m0 = -75.41666667 * angRad;  	//central meridian (Delaware)
var x0 = 200000;                    //False easting of central meridian, map units (Delaware)

var dLat;
var mLat;
var sLat;
var dLon;
var mLon;
var sLon;
var latDD;
var lonDD;

function mapToLatLon(uX,uY) {
// Calculate the coordinate system constants.
with (Math) {
m1 = cos(p1) / sqrt(1 - (pow(ec,2)) * pow(sin(p1),2));  
m2 = cos(p2) / sqrt(1 - (pow(ec,2)) * pow(sin(p2),2));
t0 = tan(pi4 - (p0 / 2));
t1 = tan(pi4 - (p1 / 2));
t2 = tan(pi4 - (p2 / 2));
t0 = t0 / pow(((1 - (ec * (sin(p0)))) / (1 + (ec * (sin(p0))))),ec/2);  
t1 = t1 / pow(((1 - (ec * (sin(p1)))) / (1 + (ec * (sin(p1))))),ec/2);
t2 = t2 / pow(((1 - (ec * (sin(p2)))) / (1 + (ec * (sin(p2))))),ec/2);
n = log(m1 / m2) / log(t1 / t2);
f = m1 / (n * pow(t1,n)); 
rho0 = a * f * pow(t0,n);

// Convert the coordinate to Lat/Lon

// Calculate the Longitude.
uX = uX - x0;
pi2 = pi4 * 2;

rho = sqrt(pow(uX,2) + pow((rho0 - uY),2));  
theta = atan(uX / (rho0 - uY));
txy = pow((rho / (a * f)),(1 / n));
lon = (theta / n) + m0;
uX = uX + x0;

// Estimate the Latitude
lat0 = pi2 - (2 * atan(txy));

// Substitute the estimate into the iterative calculation that
// converges on the correct Latitude value.
part1 = (1 - (ec * sin(lat0))) / (1 + (ec * sin(lat0)));
lat1 = pi2 - (2 * atan(txy * pow(part1,(ec/2))));

while ((abs(lat1 - lat0)) > 0.000000002) {
  lat0 = lat1;
  part1 = (1 - (ec * sin(lat0))) / (1 + (ec * sin(lat0)));
  lat1 = pi2 - (2 * atan(txy * pow(part1,(ec/2))));
  }

// Convert from radians to degrees.
Lat = lat1 / angRad;
Lon = lon / angRad;
//window.status = "Lat: "+ddToDegree(Lat, true)+" Lon: "+ddToDegree(Lon, false);
return "<b> Lat: </b>"+Lat+"<b> Lon: </b>" + Lon; //+latlonToMap(Lat, Lon);
}
}

function mapToLatLonRaw(uX,uY) {
// Calculate the coordinate system constants.
with (Math) {
m1 = cos(p1) / sqrt(1 - (pow(ec,2)) * pow(sin(p1),2));  
m2 = cos(p2) / sqrt(1 - (pow(ec,2)) * pow(sin(p2),2));
t0 = tan(pi4 - (p0 / 2));
t1 = tan(pi4 - (p1 / 2));
t2 = tan(pi4 - (p2 / 2));
t0 = t0 / pow(((1 - (ec * (sin(p0)))) / (1 + (ec * (sin(p0))))),ec/2);  
t1 = t1 / pow(((1 - (ec * (sin(p1)))) / (1 + (ec * (sin(p1))))),ec/2);
t2 = t2 / pow(((1 - (ec * (sin(p2)))) / (1 + (ec * (sin(p2))))),ec/2);
n = log(m1 / m2) / log(t1 / t2);
f = m1 / (n * pow(t1,n)); 
rho0 = a * f * pow(t0,n);

// Convert the coordinate to Lat/Lon

// Calculate the Longitude.
uX = uX - x0;
pi2 = pi4 * 2;

rho = sqrt(pow(uX,2) + pow((rho0 - uY),2));  
theta = atan(uX / (rho0 - uY));
txy = pow((rho / (a * f)),(1 / n));
lon = (theta / n) + m0;
uX = uX + x0;

// Estimate the Latitude
lat0 = pi2 - (2 * atan(txy));

// Substitute the estimate into the iterative calculation that
// converges on the correct Latitude value.
part1 = (1 - (ec * sin(lat0))) / (1 + (ec * sin(lat0)));
lat1 = pi2 - (2 * atan(txy * pow(part1,(ec/2))));

while ((abs(lat1 - lat0)) > 0.000000002) {
  lat0 = lat1;
  part1 = (1 - (ec * sin(lat0))) / (1 + (ec * sin(lat0)));
  lat1 = pi2 - (2 * atan(txy * pow(part1,(ec/2))));
  }

// Convert from radians to degrees.
Lat = lat1 / angRad;
Lon = lon / angRad;
var coords = new Array();
coords[0] = Lat;
coords[1] = Lon;
return coords;
}
}

function latlonToMapRaw(x, y)
{
var lat=x;
var lon=y;
with (Math) {
m1 = cos(p1) / sqrt(1 - (pow(ec,2)) * pow(sin(p1),2));  
m2 = cos(p2) / sqrt(1 - (pow(ec,2)) * pow(sin(p2),2));
t0 = tan(pi4 - (p0 / 2));
t1 = tan(pi4 - (p1 / 2));
t2 = tan(pi4 - (p2 / 2));
t0 = t0 / pow(((1 - (ec * (sin(p0)))) / (1 + (ec * (sin(p0))))),ec/2);  
t1 = t1 / pow(((1 - (ec * (sin(p1)))) / (1 + (ec * (sin(p1))))),ec/2);
t2 = t2 / pow(((1 - (ec * (sin(p2)))) / (1 + (ec * (sin(p2))))),ec/2);
n = log(m1 / m2) / log(t1 / t2);
f = m1 / (n * pow(t1,n)); 
rho0 = a * f * pow(t0,n);

//Convert the latitude/longitude to a coordinate.
lat = lat * angRad;
lon = lon * angRad;
t = tan(pi4 - (lat / 2));
t = t / (pow(((1 - (ec * (sin(lat)))) / (1 + (ec * (sin(lat))))),(ec / 2)));
rho = a * f * pow(t,n);
theta = n * (lon - m0);
x = (rho * sin(theta)) + x0;
y = rho0 - (rho * cos(theta));

lat = lat / angRad;
lon = lon / angRad;

//Round the coordinates
x = (round(x * 100)) / 100;
y = (round(y * 100)) / 100;
lat = (round(lat * 100000)) / 100000;
lon = (round(lon * 100000)) / 100000;
latDD=x;
lonDD=y;
var coords = new Array();
coords[0] = y;
coords[1] = x;
return coords;
}
}

function latlonToMap(x, y)
{
var lat=x;
var lon=y;
with (Math) {
m1 = cos(p1) / sqrt(1 - (pow(ec,2)) * pow(sin(p1),2));  
m2 = cos(p2) / sqrt(1 - (pow(ec,2)) * pow(sin(p2),2));
t0 = tan(pi4 - (p0 / 2));
t1 = tan(pi4 - (p1 / 2));
t2 = tan(pi4 - (p2 / 2));
t0 = t0 / pow(((1 - (ec * (sin(p0)))) / (1 + (ec * (sin(p0))))),ec/2);  
t1 = t1 / pow(((1 - (ec * (sin(p1)))) / (1 + (ec * (sin(p1))))),ec/2);
t2 = t2 / pow(((1 - (ec * (sin(p2)))) / (1 + (ec * (sin(p2))))),ec/2);
n = log(m1 / m2) / log(t1 / t2);
f = m1 / (n * pow(t1,n)); 
rho0 = a * f * pow(t0,n);

//Convert the latitude/longitude to a coordinate.
lat = lat * angRad;
lon = lon * angRad;
t = tan(pi4 - (lat / 2));
t = t / (pow(((1 - (ec * (sin(lat)))) / (1 + (ec * (sin(lat))))),(ec / 2)));
rho = a * f * pow(t,n);
theta = n * (lon - m0);
x = (rho * sin(theta)) + x0;
y = rho0 - (rho * cos(theta));

lat = lat / angRad;
lon = lon / angRad;

//Round the coordinates
x = (round(x * 100)) / 100;
y = (round(y * 100)) / 100;
lat = (round(lat * 100000)) / 100000;
lon = (round(lon * 100000)) / 100000;
latDD=x;
lonDD=y;
return "<b>X:</b> " + x + "	<b>Y:</b> " + y;
}
}

//convert decimal degree format of lat/lon into degree, minutes, seconds
function ddToDegree(dd, isLat){
    if (isLat) {
        if (dd < 0)
            sDir = "S";
        else
            sDir = "N";
    } else {
        if (dd < 0)
            sDir = "W";
        else
            sDir = "E";
  }
    var d=getIntegerOnly(dd);
    var m = 60 * (dd - d);
    var s = 60 * (m - getIntegerOnly(m));
    return d+"\u00b0"+getIntegerOnly(Math.abs(m))+"' "+getIntegerOnly(Math.abs(s))+"\" "+sDir;
}
//convert degree, minutes, seconds format of lat/lon into decimal degree
function degreeToDD(){

    if(mLat == "") 
        mLat = 0;
    if(sLat == "")
        sLat = 0;
    latDD = parseFloat(dLat)+mLat/60+sLat/3600;
        
    if(dLon>0)
        dLon=0-dLon;
    if(mLon == "") 
        mLon = 0;
    if(sLon == "")
        sLon = 0;
    lonDD = dLon-mLon/60-sLon/3600;

}
//get the integer part of the decimal value for degree munites and seconds calculation
function getIntegerOnly(xy){
    //debugger;
    if(Math.abs(Math.round(xy))-Math.abs(xy)>0)
    {
        if(xy>0)
            return Math.round(xy)-1;
        else
            return Math.round(xy)+1;
    }
    else
    {
        return Math.round(xy);
    }
}

//convert degree values into map coordinates
function findLocation(source){
    //get the value from user's input
    dLat=document.all.dLat.value;
    mLat=document.all.mLat.value;
    sLat=document.all.sLat.value;
    dLon=document.all.dLon.value;
    mLon=document.all.mLon.value;
    sLon=document.all.sLon.value;
    latDD=document.all.latitudedd.value;
    lonDD=document.all.longitudedd.value;
    xm = document.all.x.value;
    ym = document.all.y.value;
    //convert degree minutes seconds into decimal values, 
    //then convert it to map coordinates through latlonToMap() function
    if(source=="dms")
    {
        if(dLat==""){
            alert("Please Enter the Correct Latitude Value!");
        }
        if(dLon==""){
            alert("Please Enter the Correct Longitude Value!");
        }
        else{
            //convert to decimal value first then calculate the map coordinates
            degreeToDD();
            latlonToMap(latDD, lonDD);
            //alert(latDD+"|"+lonDD);
            window.opener.zoomToGPS(latDD, lonDD);
        }
    }
    else if(source=="dd")
    {

        if(document.all.latitudedd.value=="")
        {
            alert("Please Enter the Correct Latitude Value!");
            
        }
        if(document.all.longitudedd.value=="")
        {
            alert("Please Enter the Correct Longitude Value!");
        }
        else{
            latlonToMap(latDD, lonDD);
            //alert(latDD+"|"+lonDD);
            window.opener.zoomToGPS(latDD, lonDD);
        }
    }
    else if(source == "meter")
    {
        if(document.all.x.value=="")
        {
            alert("Please Enter the Correct X Value!");
            
        }
        if(document.all.y.value=="")
        {
            alert("Please Enter the Correct Y Value!");
        }
        else{
            window.opener.zoomToGPS(xm, ym);
        }
    }else if(source == "utm")
    {
            var latlon = btnToGeographic_OnClick(document.all.utmX.value, document.all.utmY.value, document.all.zone.value);

            latlonToMap(latlon[0], latlon[1]);

            window.opener.zoomToGPS(latDD, lonDD);

    }
}
function mapToUTM(xCoord, yCoord)
{
	var coordWidth;					
	var coordHeight;
	if (newMaxx == 0){
		coordWidth = newMaxx - newMinx;						
		coordHeight = newMaxy - newMiny;
	}else{
		coordWidth = newMaxx - newMinx;						
		coordHeight = newMaxy - newMiny;
	}
			
		
		
	var imgWidthInMeters = (mapWidth) * 3779.52756;
	var imgHeightInMeters = (mapHeight) * 3779.52756;

	var imgCoordInMetersX = xCoord * 3779.52756;
	var imgCoordInMetersY =  imgHeightInMeters - (yCoord * 3779.52756);

	var mapX1 = (coordWidth * imgCoordInMetersX) / imgWidthInMeters;
	var mapY1 = (coordHeight * imgCoordInMetersY) / imgHeightInMeters;
																
	var ptX = newMinx + mapX1;
	var ptY = newMiny + mapY1;
	var pointCoords = new Array();
	pointCoords[0] = ptX;
	pointCoords[1] = ptY;
	return pointCoords;

}