【转】echarts地图数据和压缩、解码

ZigZag算法
亲测有用

/* 解码 */
function decodePolygon(coordinate, encodeOffsets) {
    var result = [];
    var prevX = encodeOffsets[0];
    var prevY = encodeOffsets[1];

    for (var i = 0; i < coordinate.length; i += 2) {
        var x = coordinate.charCodeAt(i) - 64;
        var y = coordinate.charCodeAt(i + 1) - 64;
        // ZigZag decoding
        x = (x >> 1) ^ ( - (x & 1));
        y = (y >> 1) ^ ( - (y & 1));
        // Delta deocding
        x += prevX;
        y += prevY;

        prevX = x;
        prevY = y;
        // Dequantize
        result.push([x / 1024, y / 1024]);
    }
    return result;
}
/* 压缩 */
// function encodePolygon(coordinate) {
// var prevX = 0,
// prevY = 0;
// var coorstr = "";
// var encodeOffsets = [];
// var result = {
// 'coordinate': coorstr,
// 'encodeOffsets': encodeOffsets
// };
// for (var i = coordinate.length - 1; i > 0; i--) {
// var x = coordinate[i][0];
// var y = coordinate[i][1];
// x = x * 1024;
// y = y * 1024;
// x -= coordinate[i - 1][0] * 1024;
// y -= coordinate[i - 1][1] * 1024;
// x = (x << 1) ^ (x >> 31);
// y = (y << 1) ^ (y >> 31);
// coorstr = String.fromCharCode(x + 64) + String.fromCharCode(y + 64) + coorstr;
// }
// result.coordinate = "@@" + coorstr;
// result.encodeOffsets = [coordinate[0][0] * 1024, coordinate[0][1] * 1024]
// return result;
// 
// }
function encodePolygon(coordinate, encodeOffsets) {
    var result = '';
    var prevX = quantize(coordinate[0][0]);
    var prevY = quantize(coordinate[0][1]);
    // Store the origin offset
    encodeOffsets[0] = prevX;
    encodeOffsets[1] = prevY;
    for (var i = 0; i < coordinate.length; i++) {
        var point = coordinate[i];
        result += encode(point[0], prevX);
        result += encode(point[1], prevY);
        prevX = quantize(point[0]);
        prevY = quantize(point[1]);
    }
    return result;
}
function encode(val, prev) {
    // Quantization
    val = quantize(val);
    // var tmp = val;
    // Delta
    val = val - prev;
    if (((val << 1) ^ (val >> 15)) + 64 === 8232) {
        //WTF, 8232 will get syntax error in js code
        val--;
    }
    // ZigZag
    val = (val << 1) ^ (val >> 15);
    // add offset and get unicode
    return String.fromCharCode(val + 64);
    // var tmp = {'tmp' : str};
    // try{
    // eval("(" + JSON.stringify(tmp) + ")");
    // }catch(e) {
    // console.log(val + 64);
    // }
}
function quantize(val) {
    return Math.ceil(val * 1024);
}

 

*注：每次压缩之后需要将编码中的 \ 更换为 \\

另外附上：
省市县地图json or js
geoJson在线生成工具
from：https://blog.csdn.net/qq_43476178/article/details/97266795