leaflet 结合 Echarts4 实现散点图(附源码下载)

# 前言

leaflet 入门开发系列环境知识点了解：

# 内容概览

leaflet 结合 Echarts4 实现散点图

• 从官网下载 Echarts4 源码，通过 _theme进行定位，定位到 function Echarts(){ } 里面的 this._theme = theme1;添加一行代码： this._geo = Geo;
echarts.js 修改之处：

• 对 leaflet Layer 类进行扩展，新建 js 文件 leaflet-echarts.js，核心是 Echarts 的散点图其实也是在一个 Div 上画的，只要把这个 div 给拿到 map-pane 里面的 overlay-pane 。关于点的位置，因为 Echarts 内部自己有个把地理坐标转为像素坐标的方法，要重写 Echarts 内部方法 dataToPoint，完整的源码见文章尾部 demo 下载

  initECharts: function(){
if(this._echart === null || this._echart === undefined){
this._initECharts();
}else {
this._echart.dispose();
this._initECharts();
}
},
_initECharts: function() {
if (this._echart = echarts.init(this._echartsContainer),
"3.0" <= echarts.version) {
var me = this;
console.log(echarts.version);
console.log(me._echart);
me._echart._geo.prototype.dataToPoint = function(lnglat) {
//重写Echarts内部方法,Ecahrts内部有一套将经纬度转为像素坐标的方法，这里要换成与Leaflet相匹配的
var latlng = new L.latLng(lnglat[1],lnglat[0])
, pixel = me._map.latLngToContainerPoint(latlng);
return [pixel.x, pixel.y];  //给定地理坐标，返回相对于地图container容器的相应像素坐标。
}
}
this._unbindEvent();//屏蔽Echarts相关事件
},
• 地图页面 html，引用js以及css
  <link rel="stylesheet" href="lib/leaflet/leaflet.css">
<style>
html, body, #map {
height: 100%;
margin: 0;
}
</style>
<script src="lib/leaflet/leaflet.js"></script>
<script src="lib/echarts.js"></script>
<script src="lib/leaflet/leaflet-echarts.js"></script>
• 散点图初始化调用
`
//Echarts相关options配置
var geoCoordMap = {
"海门":[121.15,31.89],
"鄂尔多斯":[109.781327,39.608266],
"招远":[120.38,37.35],
"舟山":[122.207216,29.985295],
"齐齐哈尔":[123.97,47.33],
"盐城":[120.13,33.38],
"赤峰":[118.87,42.28],
"青岛":[120.33,36.07],
"乳山":[121.52,36.89],
"金昌":[102.188043,38.520089],
"泉州":[118.58,24.93],
"莱西":[120.53,36.86],
"日照":[119.46,35.42],
"胶南":[119.97,35.88],
"南通":[121.05,32.08],
"拉萨":[91.11,29.97],
"云浮":[112.02,22.93],
"梅州":[116.1,24.55],
"文登":[122.05,37.2],
"上海":[121.48,31.22],
"攀枝花":[101.718637,26.582347],
"威海":[122.1,37.5],
"承德":[117.93,40.97],
"厦门":[118.1,24.46],
"汕尾":[115.375279,22.786211],
"潮州":[116.63,23.68],
"丹东":[124.37,40.13],
"太仓":[121.1,31.45],
"曲靖":[103.79,25.51],
"烟台":[121.39,37.52],
"福州":[119.3,26.08],
"瓦房店":[121.979603,39.627114],
"即墨":[120.45,36.38],
"抚顺":[123.97,41.97],
"玉溪":[102.52,24.35],
"张家口":[114.87,40.82],
"阳泉":[113.57,37.85],
"莱州":[119.942327,37.177017],
"湖州":[120.1,30.86],
"汕头":[116.69,23.39],
"昆山":[120.95,31.39],
"宁波":[121.56,29.86],
"湛江":[110.359377,21.270708],
"揭阳":[116.35,23.55],
"荣成":[122.41,37.16],
"连云港":[119.16,34.59],
"葫芦岛":[120.836932,40.711052],
"常熟":[120.74,31.64],
"东莞":[113.75,23.04],
"河源":[114.68,23.73],
"淮安":[119.15,33.5],
"泰州":[119.9,32.49],
"南宁":[108.33,22.84],
"营口":[122.18,40.65],
"惠州":[114.4,23.09],
"江阴":[120.26,31.91],
"蓬莱":[120.75,37.8],
"韶关":[113.62,24.84],
"嘉峪关":[98.289152,39.77313],
"广州":[113.23,23.16],
"延安":[109.47,36.6],
"太原":[112.53,37.87],
"清远":[113.01,23.7],
"中山":[113.38,22.52],
"昆明":[102.73,25.04],
"寿光":[118.73,36.86],
"盘锦":[122.070714,41.119997],
"长治":[113.08,36.18],
"深圳":[114.07,22.62],
"珠海":[113.52,22.3],
"宿迁":[118.3,33.96],
"咸阳":[108.72,34.36],
"铜川":[109.11,35.09],
"平度":[119.97,36.77],
"佛山":[113.11,23.05],
"海口":[110.35,20.02],
"江门":[113.06,22.61],
"章丘":[117.53,36.72],
"肇庆":[112.44,23.05],
"大连":[121.62,38.92],
"临汾":[111.5,36.08],
"吴江":[120.63,31.16],
"石嘴山":[106.39,39.04],
"沈阳":[123.38,41.8],
"苏州":[120.62,31.32],
"茂名":[110.88,21.68],
"嘉兴":[120.76,30.77],
"长春":[125.35,43.88],
"胶州":[120.03336,36.264622],
"银川":[106.27,38.47],
"张家港":[120.555821,31.875428],
"三门峡":[111.19,34.76],
"锦州":[121.15,41.13],
"南昌":[115.89,28.68],
"柳州":[109.4,24.33],
"三亚":[109.511909,18.252847],
"自贡":[104.778442,29.33903],
"吉林":[126.57,43.87],
"阳江":[111.95,21.85],
"泸州":[105.39,28.91],
"西宁":[101.74,36.56],
"宜宾":[104.56,29.77],
"呼和浩特":[111.65,40.82],
"成都":[104.06,30.67],
"大同":[113.3,40.12],
"镇江":[119.44,32.2],
"桂林":[110.28,25.29],
"张家界":[110.479191,29.117096],
"宜兴":[119.82,31.36],
"北海":[109.12,21.49],
"西安":[108.95,34.27],
"金坛":[119.56,31.74],
"东营":[118.49,37.46],
"牡丹江":[129.58,44.6],
"遵义":[106.9,27.7],
"绍兴":[120.58,30.01],
"扬州":[119.42,32.39],
"常州":[119.95,31.79],
"潍坊":[119.1,36.62],
"重庆":[106.54,29.59],
"台州":[121.420757,28.656386],
"南京":[118.78,32.04],
"滨州":[118.03,37.36],
"贵阳":[106.71,26.57],
"无锡":[120.29,31.59],
"本溪":[123.73,41.3],
"克拉玛依":[84.77,45.59],
"渭南":[109.5,34.52],
"马鞍山":[118.48,31.56],
"宝鸡":[107.15,34.38],
"焦作":[113.21,35.24],
"句容":[119.16,31.95],
"北京":[116.46,39.92],
"徐州":[117.2,34.26],
"衡水":[115.72,37.72],
"包头":[110,40.58],
"绵阳":[104.73,31.48],
"乌鲁木齐":[87.68,43.77],
"枣庄":[117.57,34.86],
"杭州":[120.19,30.26],
"淄博":[118.05,36.78],
"鞍山":[122.85,41.12],
"溧阳":[119.48,31.43],
"库尔勒":[86.06,41.68],
"安阳":[114.35,36.1],
"开封":[114.35,34.79],
"济南":[117,36.65],
"德阳":[104.37,31.13],
"温州":[120.65,28.01],
"九江":[115.97,29.71],
"邯郸":[114.47,36.6],
"临安":[119.72,30.23],
"兰州":[103.73,36.03],
"沧州":[116.83,38.33],
"临沂":[118.35,35.05],
"南充":[106.110698,30.837793],
"天津":[117.2,39.13],
"富阳":[119.95,30.07],
"泰安":[117.13,36.18],
"诸暨":[120.23,29.71],
"郑州":[113.65,34.76],
"哈尔滨":[126.63,45.75],
"聊城":[115.97,36.45],
"芜湖":[118.38,31.33],
"唐山":[118.02,39.63],
"平顶山":[113.29,33.75],
"邢台":[114.48,37.05],
"德州":[116.29,37.45],
"济宁":[116.59,35.38],
"荆州":[112.239741,30.335165],
"宜昌":[111.3,30.7],
"义乌":[120.06,29.32],
"丽水":[119.92,28.45],
"洛阳":[112.44,34.7],
"秦皇岛":[119.57,39.95],
"株洲":[113.16,27.83],
"石家庄":[114.48,38.03],
"莱芜":[117.67,36.19],
"常德":[111.69,29.05],
"保定":[115.48,38.85],
"湘潭":[112.91,27.87],
"金华":[119.64,29.12],
"岳阳":[113.09,29.37],
"长沙":[113,28.21],
"衢州":[118.88,28.97],
"廊坊":[116.7,39.53],
"菏泽":[115.480656,35.23375],
"合肥":[117.27,31.86],
"武汉":[114.31,30.52],
"大庆":[125.03,46.58]
};

var convertData = function (data) {
var res = [];
for (var i = 0; i < data.length; i++) {
var geoCoord = geoCoordMap[data[i].name];
if (geoCoord) {
res.push({
name: data[i].name,
value: geoCoord.concat(data[i].value)
});
}
}
return res;
};

var option = {
//backgroundColor: '#404a59',
title: {
text: '全国主要城市空气质量',
subtext: '',