mirror of https://github.com/espruino/BangleApps
203 lines
6.7 KiB
JavaScript
203 lines
6.7 KiB
JavaScript
(() => {
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function getFace(){
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var nofix = 0;
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function formatTime(now) {
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var fd = now.toUTCString().split(" ");
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return fd[4];
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}
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function timeSince(t) {
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var hms = t.split(":");
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var now = new Date();
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var sn = 3600*(now.getHours()) + 60*(now.getMinutes()) + 1*(now.getSeconds());
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var st = 3600*(hms[0]) + 60*(hms[1]) + 1*(hms[2]);
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return (sn - st);
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}
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Number.prototype.toRad = function() { return this*Math.PI/180; };
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/* Ordnance Survey Grid Reference functions (c) Chris Veness 2005-2014 */
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/* - www.movable-type.co.uk/scripts/gridref.js */
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/* - www.movable-type.co.uk/scripts/latlon-gridref.html */
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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function OsGridRef(easting, northing) {
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this.easting = 0|easting;
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this.northing = 0|northing;
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}
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OsGridRef.latLongToOsGrid = function(point) {
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var lat = point.lat.toRad();
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var lon = point.lon.toRad();
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var a = 6377563.396, b = 6356256.909; // Airy 1830 major & minor semi-axes
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var F0 = 0.9996012717; // NatGrid scale factor on central meridian
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var lat0 = (49).toRad(), lon0 = (-2).toRad(); // NatGrid true origin is 49�N,2�W
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var N0 = -100000, E0 = 400000; // northing & easting of true origin, metres
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var e2 = 1 - (b*b)/(a*a); // eccentricity squared
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var n = (a-b)/(a+b), n2 = n*n, n3 = n*n*n;
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var cosLat = Math.cos(lat), sinLat = Math.sin(lat);
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var nu = a*F0/Math.sqrt(1-e2*sinLat*sinLat); // transverse radius of curvature
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var rho = a*F0*(1-e2)/Math.pow(1-e2*sinLat*sinLat, 1.5); // meridional radius of curvature
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var eta2 = nu/rho-1;
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var Ma = (1 + n + (5/4)*n2 + (5/4)*n3) * (lat-lat0);
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var Mb = (3*n + 3*n*n + (21/8)*n3) * Math.sin(lat-lat0) * Math.cos(lat+lat0);
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var Mc = ((15/8)*n2 + (15/8)*n3) * Math.sin(2*(lat-lat0)) * Math.cos(2*(lat+lat0));
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var Md = (35/24)*n3 * Math.sin(3*(lat-lat0)) * Math.cos(3*(lat+lat0));
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var M = b * F0 * (Ma - Mb + Mc - Md); // meridional arc
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var cos3lat = cosLat*cosLat*cosLat;
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var cos5lat = cos3lat*cosLat*cosLat;
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var tan2lat = Math.tan(lat)*Math.tan(lat);
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var tan4lat = tan2lat*tan2lat;
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var I = M + N0;
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var II = (nu/2)*sinLat*cosLat;
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var III = (nu/24)*sinLat*cos3lat*(5-tan2lat+9*eta2);
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var IIIA = (nu/720)*sinLat*cos5lat*(61-58*tan2lat+tan4lat);
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var IV = nu*cosLat;
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var V = (nu/6)*cos3lat*(nu/rho-tan2lat);
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var VI = (nu/120) * cos5lat * (5 - 18*tan2lat + tan4lat + 14*eta2 - 58*tan2lat*eta2);
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var dLon = lon-lon0;
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var dLon2 = dLon*dLon, dLon3 = dLon2*dLon, dLon4 = dLon3*dLon, dLon5 = dLon4*dLon, dLon6 = dLon5*dLon;
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var N = I + II*dLon2 + III*dLon4 + IIIA*dLon6;
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var E = E0 + IV*dLon + V*dLon3 + VI*dLon5;
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return new OsGridRef(E, N);
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};
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/*
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* converts northing, easting to standard OS grid reference.
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*
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* [digits=10] - precision (10 digits = metres)
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* to_map_ref(8, 651409, 313177); => 'TG 5140 1317'
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* to_map_ref(0, 651409, 313177); => '651409,313177'
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*
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*/
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function to_map_ref(digits, easting, northing) {
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if (![ 0,2,4,6,8,10,12,14,16 ].includes(Number(digits))) throw new RangeError(`invalid precision '${digits}'`); // eslint-disable-line comma-spacing
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let e = easting;
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let n = northing;
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// use digits = 0 to return numeric format (in metres) - note northing may be >= 1e7
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if (digits == 0) {
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const format = { useGrouping: false, minimumIntegerDigits: 6, maximumFractionDigits: 3 };
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const ePad = e.toLocaleString('en', format);
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const nPad = n.toLocaleString('en', format);
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return `${ePad},${nPad}`;
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}
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// get the 100km-grid indices
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const e100km = Math.floor(e / 100000), n100km = Math.floor(n / 100000);
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// translate those into numeric equivalents of the grid letters
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let l1 = (19 - n100km) - (19 - n100km) % 5 + Math.floor((e100km + 10) / 5);
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let l2 = (19 - n100km) * 5 % 25 + e100km % 5;
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// compensate for skipped 'I' and build grid letter-pairs
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if (l1 > 7) l1++;
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if (l2 > 7) l2++;
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const letterPair = String.fromCharCode(l1 + 'A'.charCodeAt(0), l2 + 'A'.charCodeAt(0));
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// strip 100km-grid indices from easting & northing, and reduce precision
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e = Math.floor((e % 100000) / Math.pow(10, 5 - digits / 2));
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n = Math.floor((n % 100000) / Math.pow(10, 5 - digits / 2));
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// pad eastings & northings with leading zeros
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e = e.toString().padStart(digits/2, '0');
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n = n.toString().padStart(digits/2, '0');
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return `${letterPair} ${e} ${n}`;
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}
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function draw() {
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var gps_on = false;
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var fix = {
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fix: 0,
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alt: 0,
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lat: 0,
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lon: 0,
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speed: 0,
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time: 0,
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satellites: 0
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};
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var y_line = 26;
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var y_start = 46;
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var x_start = 10;
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// only attempt to get gps fix if gpsservuce is loaded
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if (WIDGETS.gpsservice !== undefined) {
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fix = WIDGETS.gpsservice.gps_get_fix();
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gps_on = WIDGETS.gpsservice.gps_get_status();
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}
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g.reset();
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g.clearRect(0,24,239,239);
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if (fix.fix) {
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var time = formatTime(fix.time);
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var age = timeSince(time);
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var os = OsGridRef.latLongToOsGrid(fix);
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var ref = to_map_ref(6, os.easting, os.northing);
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age = age >=0 ? age : 0; // avoid -1 etc
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g.reset();
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g.clearRect(0,24,239,239);
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g.setFontAlign(0,0);
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g.setFont("Vector");
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g.setColor(1,1,1);
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g.setFontVector(40);
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g.drawString(time, 120, 80);
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g.setFontVector(40);
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g.setColor(0xFFC0);
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g.drawString(ref, 120,140, true);
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g.setFont("6x8",2);
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g.setColor(1,1,1);
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g.drawString(age, 120, 194);
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} else if (gps_on) {
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g.setFontAlign(0, 1);
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g.setFont("6x8", 2);
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g.drawString("Gridref Watch", 120, 60);
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g.drawString("Waiting for GPS", 120, 80);
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nofix = (nofix+1) % 4;
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g.drawString(".".repeat(nofix) + " ".repeat(4-nofix), 120, 120);
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g.setFontAlign(0,0);
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g.drawString(fix.satellites + " satellites", 120, 100);
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} else if (!gps_on) {
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g.setFontAlign(0, 0);
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g.setFont("6x8", 3);
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g.drawString("Gridref Watch", 120, 80);
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g.drawString("GPS is off", 120, 160);
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}
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}
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function onSecond(){
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var t = new Date();
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if ((t.getSeconds() % 5) === 0) draw();
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}
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return {init:draw, tick:onSecond};
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}
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return getFace;
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})();
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