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 = this.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 < this.MCBAND.length; i++) {
        if (absLngLat.lat >= this.MCBAND[i]) {
            mc = this.MC2LL[i];
            break
        }
    }
    var lngLat = this.convertor(mLngLat, mc);
    var lngLat = {
        lng: lngLat.lng.toFixed(6),
        lat: lngLat.lat.toFixed(6)
    };
    return lngLat
}

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]]

MCBAND = [12890594.86, 8362377.87, 5591021, 3481989.83, 1678043.12, 0]