天津投入产出系统后端
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/**
* echarts地图投射算法
*
* @desc echarts基于Canvas,纯Javascript图表库,提供直观,生动,可交互,可个性化定制的数据统计图表。
* @author Kener (@Kener-林峰, kener.linfeng@gmail.com)
*
*/
define(function() {
// Derived from Tom Carden's Albers implementation for Protovis.
// http://gist.github.com/476238
// http://mathworld.wolfram.com/AlbersEqual-AreaConicProjection.html
function _albers() {
var radians = Math.PI / 180;
var origin = [0, 0]; //[-98, 38],
var parallels = [29.5, 45.5];
var scale = 1000;
var translate = [0, 0]; //[480, 250],
var lng0; // radians * origin[0]
var n;
var C;
var p0;
function albers(coordinates) {
var t = n * (radians * coordinates[0] - lng0);
var p = Math.sqrt(
C - 2 * n * Math.sin(radians * coordinates[1])
) / n;
return [
scale * p * Math.sin(t) + translate[0],
scale * (p * Math.cos(t) - p0) + translate[1]
];
}
albers.invert = function (coordinates) {
var x = (coordinates[0] - translate[0]) / scale;
var y = (coordinates[1] - translate[1]) / scale;
var p0y = p0 + y;
var t = Math.atan2(x, p0y);
var p = Math.sqrt(x * x + p0y * p0y);
return [
(lng0 + t / n) / radians,
Math.asin((C - p * p * n * n) / (2 * n)) / radians
];
};
function reload() {
var phi1 = radians * parallels[0];
var phi2 = radians * parallels[1];
var lat0 = radians * origin[1];
var s = Math.sin(phi1);
var c = Math.cos(phi1);
lng0 = radians * origin[0];
n = 0.5 * (s + Math.sin(phi2));
C = c * c + 2 * n * s;
p0 = Math.sqrt(C - 2 * n * Math.sin(lat0)) / n;
return albers;
}
albers.origin = function (x) {
if (!arguments.length) {
return origin;
}
origin = [+x[0], +x[1]];
return reload();
};
albers.parallels = function (x) {
if (!arguments.length) {
return parallels;
}
parallels = [+x[0], +x[1]];
return reload();
};
albers.scale = function (x) {
if (!arguments.length) {
return scale;
}
scale = +x;
return albers;
};
albers.translate = function (x) {
if (!arguments.length) {
return translate;
}
translate = [+x[0], +x[1]];
return albers;
};
return reload();
}
return _albers;
});