en/builder/src/echarts3/coord/geo/parseGeoJson.js

/**
 * Parse and decode geo json
 * @module echarts/coord/geo/parseGeoJson
 */
import * as zrUtil from 'zrender/src/core/util';
import Region from './Region';

function decode(json) {
  if (!json.UTF8Encoding) {
    return json;
  }

  var encodeScale = json.UTF8Scale;

  if (encodeScale == null) {
    encodeScale = 1024;
  }

  var features = json.features;

  for (var f = 0; f < features.length; f++) {
    var feature = features[f];
    var geometry = feature.geometry;
    var coordinates = geometry.coordinates;
    var encodeOffsets = geometry.encodeOffsets;

    for (var c = 0; c < coordinates.length; c++) {
      var coordinate = coordinates[c];

      if (geometry.type === 'Polygon') {
        coordinates[c] = decodePolygon(coordinate, encodeOffsets[c], encodeScale);
      } else if (geometry.type === 'MultiPolygon') {
        for (var c2 = 0; c2 < coordinate.length; c2++) {
          var polygon = coordinate[c2];
          coordinate[c2] = decodePolygon(polygon, encodeOffsets[c][c2], encodeScale);
        }
      }
    }
  } // Has been decoded


  json.UTF8Encoding = false;
  return json;
}

function decodePolygon(coordinate, encodeOffsets, encodeScale) {
  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 / encodeScale, y / encodeScale]);
  }

  return result;
}
/**
 * @alias module:echarts/coord/geo/parseGeoJson
 * @param {Object} geoJson
 * @return {module:zrender/container/Group}
 */


export default function (geoJson) {
  decode(geoJson);
  return zrUtil.map(zrUtil.filter(geoJson.features, function (featureObj) {
    // Output of mapshaper may have geometry null
    return featureObj.geometry && featureObj.properties && featureObj.geometry.coordinates.length > 0;
  }), function (featureObj) {
    var properties = featureObj.properties;
    var geo = featureObj.geometry;
    var coordinates = geo.coordinates;
    var geometries = [];

    if (geo.type === 'Polygon') {
      geometries.push({
        type: 'polygon',
        // According to the GeoJSON specification.
        // First must be exterior, and the rest are all interior(holes).
        exterior: coordinates[0],
        interiors: coordinates.slice(1)
      });
    }

    if (geo.type === 'MultiPolygon') {
      zrUtil.each(coordinates, function (item) {
        if (item[0]) {
          geometries.push({
            type: 'polygon',
            exterior: item[0],
            interiors: item.slice(1)
          });
        }
      });
    }

    var region = new Region(properties.name, geometries, properties.cp);
    region.properties = properties;
    return region;
  });
}