parseGeoJson.js
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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
/**
* 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;
});
}