echart map 编辑 和 压缩

geojson在线编辑器：

https://mapshaper.org/

echartsmap压缩说明：https://blog.csdn.net/isea533/article/details/79194819

压缩方法：javascript版本

// 压缩文件===============================================
function convert2Echarts(rawStr,fileName,type){
    var results="";
    var json = JSON.parse(rawStr);
    // Meta tag
    json.UTF8Encoding = true;
    var features = json.features;
    if (!features) {
        return;
    }
    features.forEach(function (feature){
        var encodeOffsets = feature.geometry.encodeOffsets = [];
        var coordinates = feature.geometry.coordinates;
        if (feature.geometry.type === 'Polygon') {
            coordinates.forEach(function (coordinate, idx){
                coordinates[idx] = encodePolygon(
                    coordinate, encodeOffsets[idx] = []
                );
            });
        } else if(feature.geometry.type === 'MultiPolygon') {
            coordinates.forEach(function (polygon, idx1){
                encodeOffsets[idx1] = [];
                polygon.forEach(function (coordinate, idx2) {
                    coordinates[idx1][idx2] = encodePolygon(
                        coordinate, encodeOffsets[idx1][idx2] = []
                    );
                });
            });
        }
    });
    if(type==='json'){
        results=JSON.stringify(json);
    }else{
        results=addEchartsJsWrapper(JSON.stringify(json), fileName);
    }
    return results;
};
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 addAMDWrapper(jsonStr) {
    return ['define(function() {',
        '    return ' + jsonStr + ';',
        '});'].join('\n');
}

function addEchartsJsWrapper(jsonStr,fileName) {
    return ['(function (root, factory) {',
        "   if (typeof define === 'function' && define.amd) {",
        "       define(['exports', 'echarts'], factory);",
        "   } else if (typeof exports === 'object' && typeof exports.nodeName !== 'string') {",
        "       factory(exports, require('echarts'));",
        "   } else {",
        "       factory({}, root.echarts);",
        "   }",
        " }(this, function (exports, echarts) {",
        "       var log = function (msg) {",
        "           if (typeof console !== 'undefined') {",
        "               console && console.error && console.error(msg);",
        "           }",
        "       }",
        " if (!echarts) {",
        "       log('ECharts is not Loaded');",
        "           return;",
        "       }",
        " if (!echarts.registerMap) {",
        "       log('ECharts Map is not loaded')",
        "       return;",
        " }",
        "  echarts.registerMap('"+fileName+"',"+ jsonStr,
        '  )}));'].join('\n');
}

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);
}

压缩方法：

var _jsons=convert2Echarts(JSON.stringify(_SL.mapjson),'中国地图华北冀北','json');

console.log(_jsons);

 

解压缩：

在echart地图加载完成后，将整个mapjson stringify()后输出来，就是解压后的文件。