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mercator.js
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mercator.js
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(function(root, factory) {
if (typeof exports !== 'undefined') {
if (typeof module !== 'undefined' && module.exports) {
exports = module.exports = factory(root, exports);
}
exports = factory(root, exports);
} else if (typeof define === 'function' && define.amd) {
define(['exports'], function(exports) {
root.mercator = factory(root, exports);
return root.mercator;
});
} else {
root.mercator = factory(root, {});
}
}(typeof window === "object"? window: this, function(root, mercator) {
var MCBAND = [12890594.86, 8362377.87, 5591021, 3481989.83, 1678043.12, 0];
var LLBAND = [75, 60, 45, 30, 15, 0];
var MC2LL = [
[1.410526172116255e-8, 0.00000898305509648872, -1.9939833816331, 200.9824383106796, -187.2403703815547, 91.6087516669843, -23.38765649603339, 2.57121317296198, -0.03801003308653, 17337981.2],
[-7.435856389565537e-9, 0.000008983055097726239, -0.78625201886289, 96.32687599759846, -1.85204757529826, -59.36935905485877, 47.40033549296737, -16.50741931063887, 2.28786674699375, 10260144.86],
[-3.030883460898826e-8, 0.00000898305509983578, 0.30071316287616, 59.74293618442277, 7.357984074871, -25.38371002664745, 13.45380521110908, -3.29883767235584, 0.32710905363475, 6856817.37],
[-1.981981304930552e-8, 0.000008983055099779535, 0.03278182852591, 40.31678527705744, 0.65659298677277, -4.44255534477492, 0.85341911805263, 0.12923347998204, -0.04625736007561, 4482777.06],
[3.09191371068437e-9, 0.000008983055096812155, 0.00006995724062, 23.10934304144901, -0.00023663490511, -0.6321817810242, -0.00663494467273, 0.03430082397953, -0.00466043876332, 2555164.4],
[2.890871144776878e-9, 0.000008983055095805407, -3.068298e-8, 7.47137025468032, -0.00000353937994, -0.02145144861037, -0.00001234426596, 0.00010322952773, -0.00000323890364, 826088.5]
];
var LL2MC = [
[-0.0015702102444, 111320.7020616939, 1704480524535203, -10338987376042340, 26112667856603880, -35149669176653700, 26595700718403920, -10725012454188240, 1800819912950474, 82.5],
[0.0008277824516172526, 111320.7020463578, 647795574.6671607, -4082003173.641316, 10774905663.51142, -15171875531.51559, 12053065338.62167, -5124939663.577472, 913311935.9512032, 67.5],
[0.00337398766765, 111320.7020202162, 4481351.045890365, -23393751.19931662, 79682215.47186455, -115964993.2797253, 97236711.15602145, -43661946.33752821, 8477230.501135234, 52.5],
[0.00220636496208, 111320.7020209128, 51751.86112841131, 3796837.749470245, 992013.7397791013, -1221952.21711287, 1340652.697009075, -620943.6990984312, 144416.9293806241, 37.5],
[-0.0003441963504368392, 111320.7020576856, 278.2353980772752, 2485758.690035394, 6070.750963243378, 54821.18345352118, 9540.606633304236, -2710.55326746645, 1405.483844121726, 22.5],
[-0.0003218135878613132, 111320.7020701615, 0.00369383431289, 823725.6402795718, 0.46104986909093, 2351.343141331292, 1.58060784298199, 8.77738589078284, 0.37238884252424, 7.45]
];
var mercator = {
pixelToPoint: function (point, zoom, center, bounds) {
// 像素到坐标
if (!point) {
return
}
var zoomUnits = getZoomUnits(zoom);
var mercatorLng = center.lng + zoomUnits * (point.x - bounds.width / 2);
var mercatorLat = center.lat - zoomUnits * (point.y - bounds.height / 2);
var mercatorLngLat = {lng: mercatorLng, lat: mercatorLat};
return mercatorToLngLat(mercatorLngLat)
},
pointToPixel: function (point, zoom, mCenter, bounds) {
// 坐标到像素
if (!point) {
return
}
point = lngLatToMercator(point);
var units = getZoomUnits(zoom);
var x = Math.round((point.lng - mCenter.lng) / units + bounds.width / 2);
var y = Math.round((mCenter.lat - point.lat) / units + bounds.height / 2);
return {x: x, y: y}
},
getZoomUnits: function (zoom) {
return Math.pow(2, (18 - zoom))
},
mercatorToLngLat: function (mLngLat) {
var absLngLat, mc;
absLngLat = {
lng: Math.abs(mLngLat.lng),
lat: Math.abs(mLngLat.lat)
};
for (var i = 0; i < MCBAND.length; i++) {
if (absLngLat.lat >= MCBAND[i]) {
mc = MC2LL[i];
break
}
}
var lngLat = convertor(mLngLat, mc);
var lngLat = {
lng: lngLat.lng.toFixed(6),
lat: lngLat.lat.toFixed(6)
};
return lngLat
},
lngLatToMercator: function (point) {
var lng_lat, mc;
point.lng = wrap(point.lng, -180, 180);
point.lat = clamp(point.lat, -74, 74);
lng_lat = {
lng: point.lng,
lat: point.lat
};
for (var i = 0; i < LLBAND.length; i++) {
if (lng_lat.lat >= LLBAND[i]) {
mc = LL2MC[i];
break
}
}
if (!mc) {
for (var i = LLBAND.length - 1; i >= 0; i--) {
if (lng_lat.lat <= -LLBAND[i]) {
mc = LL2MC[i];
break
}
}
}
var cE = convertor(point, mc);
var lng_lat = {
lng: cE.lng.toFixed(2),
lat: cE.lat.toFixed(2)
};
return lng_lat
},
wrap: function (a, min, max) {
var d = max - min
var b = a - min
var fq = b / d
var r = (Math.floor(fq) - fq) * d
return min + r
},
clamp: function (a, min, max) {
if (min != null) {
a = Math.max(a, min)
}
if (max != null) {
a = Math.min(a, max)
}
return a
},
convertor: function (point, mc) {
if (!point || !mc) {
return
}
var lng = mc[0] + mc[1] * Math.abs(point.lng);
var c = Math.abs(point.lat) / mc[9];
var lat = mc[2] + mc[3] * c + mc[4] * c * c + mc[5] * c * c * c + mc[6] * c * c * c * c + mc[7] * c * c * c * c * c + mc[8] * c * c * c * c * c * c;
lng *= (point.lng < 0 ? -1 : 1);
lat *= (point.lat < 0 ? -1 : 1);
return {lng: lng, lat: lat}
}
};
return mercator;
}));