1.引言

　　由于Arcgis for javascript API不可以绘制Geojson，并且提供的Popup一般只可以弹出一个，在很多专题图制作中，会遇到不少的麻烦。因此本文结合了两个现有的Arcgis for javascript API扩充库，对其进行改造达到绘制Geojson并同时弹出多个Popup的目的。

目前已有的两个扩充库github地址（可供单独使用）：

1.绘制Geojson的扩充库：https://github.com/Esri/geojson-layer-js

2.多个Popup显示的扩充库：https://github.com/nickcam/PopupExtended

　　本文实现的效果图：

图1 上海5个地点的部分预报属性图2 上海某三条航线的部分预报属性

2. 各类依赖库引入及前端HTML

　　首先需要先载入需要用的常用js、Arcgis及两个扩充库的js及部分css（下载地址见其github）：

<!DOCTYPE html>

<html>

<head>

    <title>Add GeoJSON and Display Multiple Popup</title>

    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">

    <meta http-equiv="X-UA-Compatible" content="IE=7,IE=9">

    <meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">

    <!-- ArcGIS API for JavaScript CSS-->

    <link rel="stylesheet" href="http://js.arcgis.com/3.13/esri/css/esri.css">

    <link rel="stylesheet" href="http://js.arcgis.com/3.13/dijit/themes/claro/claro.css">

    <!-- Web Framework CSS - Bootstrap (getbootstrap.com) and Bootstrap-map-js (github.com/esri/bootstrap-map-js) -->

    <link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css" rel="stylesheet">

    <link rel="stylesheet" href="./css/bootstrap.min.css">

    <!-- PopExtendCss -->

    <link href="./vendor/ncam/PopupExtended.css" rel="stylesheet" />

    <!-- PopupExtended references -->

    <script>

        var dojoConfig = {

            parseOnLoad: false,

            async: true,

            tlmSiblingOfDojo: false,

            packages: [{

                name: "ncam",

                location: location.pathname.replace(/\/[^/]+$/, '') + "ncam"

            }]

        };

    </script>

    <!-- ArcGIS API for JavaScript library references -->

    <script src="//js.arcgis.com/3.10"></script>

    <!-- Terraformer reference -->

    <script src="./vendor/terraformer/terraformer.min.js"></script>

    <script src="./vendor/terraformer-arcgis-parser/terraformer-arcgis-parser.min.js"></script>

    <!-- other reference -->

    <script src="./vendor/jquery.js"></script>

</head>

<body>

</body>

</html>

　　加入底图所需要的div与图层切换的Button：

<body>

     <div id="mapDiv"></div>

     <button type="line" id="shanghaiPoint" class="btn btn-default buttonRight" style="top:20px;right:20px">上海区各点</button>

     <button type="point" id="threeLine" class="btn btn-default buttonRight" style="top:70px;right:20px">三条航线</button>

</body>

3.置入Popupextended并扩充geojsonlayer.js　　

　　然后从geojsonlayer.js源码入手，开始将PopupExtended扩展其中，让我们新构建的geojsonlayer直接可拥有多个Popup。在geojsonlayer.js的constructor中很容易可以找出infotemplate的set方法：

            // Default popup

            if (options.infoTemplate !== false) {

                this.setInfoTemplate(options.infoTemplate || new InfoTemplate("GeoJSON Data", "${*}"));

            }

　　很明显，geojsonlayer初始化时通过options传入参数进行判断并构造，所以实现本文目的的大致思路是将这里的setInfoTemplate替换成可以扩展的PopupExtended:

if (options.infoTemplate !== false) {

                //① create a PopupTemplate

                var template = new PopupTemplate({

                        title: "{name}",

                        fieldInfos: [

                            { fieldName: "Id", label: "Id", visible: true },

                            { fieldName: "publishdate", label: "观测日期", visible: true },

                            { fieldName: "waveheight", label: "浪高", visible: true },

                            { fieldName: "wavedirection", label: "浪向", visible: true },

                            { fieldName: "windspeed", label: "风速", visible: true },

                            { fieldName: "winddirection", label: "风向", visible: true },

                            { fieldName: "comfort", label: "等级", visible: true }

                        ],

                        extended: {

                            actions: [

                                { text: " IconText", className: "iconText", title: "Custom action with an icon and Text", click: function (feature) { alert("Icon Text clicked on " + "id: " + feature.attributes.id + " " + feature.attributes.name); } },

                                { text: "", className: "iconOnly", title: "Custom action only using an icon", click: function (feature) { alert("Icon action clicked on " + "id: " + feature.attributes.id + " " + feature.attributes.name); } }

                            ],

                         //uses a pretty bad custom theme defined in PopupExtended.css.

                             scaleSelected: 1.6

                        }

                    });

                //② create a extend for basemap

                var extendedPopup = new PopupExtended({

                        extended: {

                            themeClass: "light",

                            draggable: true,

                            defaultWidth: 250,

                            actions: [{

                                text: "其他", className: "defaultAction", title: "Default action added in extendedPopup properties.",

                                click: function (feature) { alert("clicked feature - " + feature.attributes); }

                            }],

                            hideOnOffClick: false,

                            multiple: true,

                        },

                        highlight: false,

                        //titleInBody: false,

                    }, dojo.create("div"));

                //③set the map to use the exteneded popup

                extendedPopup.setMap(options.baseMap);

                options.baseMap.infoWindow = extendedPopup;

                this.setInfoTemplate(options.infoTemplate || template);

            }

　　由上段代码可见，引入Popup给GeoJSON共分为三步：①实例化一个你需要的PopupTemplate（这里起名为template），可指定你需要展示的主题、数据项及扩展的一些交互action；②实例化一个PopupExtended并设置一些默认的Popup属性；③将实例化的PopupExtended——extendedPopup的Map设置为baseMap，并将baseMap的infowindow设置为extendedPopup，最后将geojsonlayer的infoTemplate设置为新构建的template。这样便可以实现对置入底图的geojsonlayer进行多个infoTemplate展示需求了。源代码见github:展示效果如图3：

图3 对geojsonlayer扩充Popupextended后的显示效果

　　如若只需增加多个Popup至geojsonlayer的话，以上部分足以实现了。

4.增加新的Attributes及调整Popup的样式　　

　　由于设计上的需求，笔者需要从其他地址获取观测点的部分观测值，并且笔者的老师觉得应该加一些icon给属性，美化展示效果，所以需要重新构造两部分：①获取并为graphics增加新的attributes；②重构geojsonlayer的infoTemplate的content。

4.1 获取并为graphics增加新的attributes：

　　通过在button上利用fetch及Promise.all来同时获取6个点或3条航线的数据，并传入至初始化geojsonlayer的函数内；

$("#shanghaiPoint").click(function(){

            // if first init geojsonlayer

            if(firstPointInit){

                var requestBZ = 'http://wx.dhybzx.org:18080/forecast/shanghai_sea_env/80';

                var requestWGQ = 'http://wx.dhybzx.org:18080/forecast/shanghai_sea_env/81';

                var requestHS = 'http://wx.dhybzx.org:18080/forecast/shanghai_sea_env/82';

                var requestLCG = 'http://wx.dhybzx.org:18080/forecast/shanghai_sea_env/83';

                var requestJHG = 'http://wx.dhybzx.org:18080/forecast/shanghai_sea_env/84';

                var requestJSW = 'http://wx.dhybzx.org:18080/forecast/shanghai_sea_env/85';

                var urls = [requestBZ, requestWGQ,requestHS,requestLCG,requestJHG,requestJSW]

                Promise.all(urls.map(url =>

                    fetch(url).then(resp => resp.json())

                )).then(results => {

                var tempJson = {

                     "堡镇":results[0][0],

                     "外高桥":results[1][0],

                     "横沙":results[2][0],

                     "芦潮港":results[3][0],

                     "金汇港":results[4][0],

                     "金山卫":results[5][0]

                }

                addGeoJsonToMap("./data/six_point.json",tempJson)

                });

            }else{

                //geojsonlayer has been initial

                 addGeoJsonToMap("./data/six_point.json")

            }

        })

　　这里的Promise.all采用了ES2015的箭头函数，兼容性问题需要自己考虑，也可以手动改成ES5支持的。将额外的attributes组装成tempJson后传入至初始化方法addGeoJsonToMap内。

4.2 重构geojsonlayer的infoTemplate的content：

　　在geojsonlayer.js内继续做一部分修改，注释掉实例化template中的fieldInfos属性及值，并且为geojsonlayer的infoTemplate设置新的content,代码如下：

               var template = new PopupTemplate({

                        title: "{name}",

                        // fieldInfos: [

                        //     { fieldName: "Id", label: "Id", visible: true },

                        //     { fieldName: "publishdate", label: "观测日期", visible: true },

                        //     { fieldName: "waveheight", label: "浪高", visible: true },

                        //     { fieldName: "wavedirection", label: "浪向", visible: true },

                        //     { fieldName: "windspeed", label: "风速", visible: true },

                        //     { fieldName: "winddirection", label: "风向", visible: true },

                        //     { fieldName: "comfort", label: "等级", visible: true }

                        // ],

                        extended: {

                            actions: [

                                { text: " IconText", className: "iconText", title: "Custom action with an icon and Text", click: function (feature) { alert("Icon Text clicked on " + "id: " + feature.attributes.id + " " + feature.attributes.name); } },

                                { text: "", className: "iconOnly", title: "Custom action only using an icon", click: function (feature) { alert("Icon action clicked on " + "id: " + feature.attributes.id + " " + feature.attributes.name); } }

                            ],

                         //uses a pretty bad custom theme defined in PopupExtended.css.

                             scaleSelected: 1.6

                        }

                    });

                //create a extend for basemap

                var extendedPopup = new PopupExtended({

                        extended: {

                            themeClass: "light",

                            draggable: true,

                            defaultWidth: 250,

                            actions: [{

                                text: "其他", className: "defaultAction", title: "Default action added in extendedPopup properties.",

                                click: function (feature) { alert("clicked feature - " + feature.attributes); }

                            }],

                            hideOnOffClick: false,

                            multiple: true,

                        },

                        highlight: false,

                        //titleInBody: false,

                    }, dojo.create("div"));

                //set the map to use the exteneded popup

                extendedPopup.setMap(options.baseMap);

                options.baseMap.infoWindow = extendedPopup;

                this.setInfoTemplate(options.infoTemplate || template);

                this.infoTemplate.setContent("<b class='popupTitle'>${name}</b>" +

                                "<div class='hzLine'></div>"+

                                "<div class='popupContent'>"+

                                "<i class='glyphicon glyphicon-calendar'></i><b>日期: </b> ${publishdate}<br/>"+

                                "<i class='glyphicon glyphicon-resize-vertical'></i><b>浪高: </b> ${waveheight}<br/>" +

                                "<i class='glyphicon glyphicon-random'></i><b>浪向: </b> ${wavedirection}<br/>"+

                                "<i class='glyphicon glyphicon-share'></i><b>风速: </b> ${windspeed}<br/>" +

                                "<i class='glyphicon glyphicon-transfer'></i><b>风向: </b> ${winddirection}<br/>"+

                                "<i class='glyphicon glyphicon-export'></i><b>等级: </b> ${comfort}<br/>"+

                                "</div>"

                    );

　　额外的属性和新的infoTemplate样式构造完成，但存在一个问题，即额外的attributes必须要在geojsonlayer绘制好后再进行设置并展示，arcgis提供了layer的layer-add及layer-add-result事件，但是无法监控到graphics是否已经增入至geojsonlayer内，所以必须要再做一些改进，使额外的属性能够在graphics绘制完毕后再添加进去。具体方法分为两步：1）初始化geojsonlayer时，将showAllPopup方法传入其构造函数内；2）在grahics添加至layer后，调用showAllPopup方法，显示所有的Popup。前端代码如下：

//add GeoJSON to baseMap , constuct show&hide popup method and add other attribute to graphics

        function addGeoJsonToMap(url,otherJson){

             require(["esri/map",

            "./src/geojsonlayer.js",

            "esri/geometry/Point", "esri/SpatialReference",

            "dojo/on",

            "dojo/dom",

            "dojo/domReady!"],

              function (Map, GeoJsonLayer, Point, SpatialReference,on, dom) {

                 var hasThisLayer=false;

                 otherJson=otherJson?otherJson:"";

                 hideAllPopup()

　　　　　　　　　　　//judge layer has been init

                   map.getLayersVisibleAtScale().forEach(function(item){

                       if(item._url==url&&item.dataType=="geojson"){

                           console.log(item)

                           item.show();

                           console.log("dd")

                           showAllPopup(item);

                           hasThisLayer=true;

                           // map.setExtent(item.extent)

                       }else if(item._url!=url&&item.dataType=="geojson"){

                           item.hide();

                       }

                   })

                   if(!hasThisLayer){

                       addGeoJsonLayer(url);

                   }

                   //show all popups

                   function showAllPopup(layer){

                      ......

                   }

                   //hide all popups

                   function hideAllPopup(){

                     .......

                   }

                   //add other attribute to grpahics for popup

                   function addAttrToGrpahics(item,type){

                     .......

                   }

                // Add the layer

                function addGeoJsonLayer(url) {

                    // Create the layer

                    var geoJsonLayer = new GeoJsonLayer({

                        baseMap:map,

                        url: url,

                        onLayerLoaded:function(layer){

                            showAllPopup(layer);

                        }

                    });

                    // Add to map

                    geoJsonLayer.dataType="geojson";

                    map.addLayer(geoJsonLayer);

                }

            });

        }

并且在geojsonlayer.js的constructor内加入：

this._onLayerLoaded = options.onLayerLoaded;

在最后的_addGraphics方法中onLoad方法后，加入：

if (this._onLayerLoaded) this._onLayerLoaded(this);

利用show/hide方法，控制popup显示及隐藏。

//open all popup

layer.graphics.forEach(function(item){

　　if(firstPointInit&&otherJson[item.attributes.name]){

   　　 addAttrToGrpahics(item,layer.graphics[0].geometry.type)

　　}

　　var loc = map.toScreen(item.geometry);

　　map.infoWindow.setFeatures([item]);

　　map.infoWindow.show(loc);

})

//hide all popup

var tempLength = map.infoWindow.openPopups.length;

for(var i=0;i<tempLength;i++){

　　map.infoWindow.openPopups[0].hide()

}

5. 结论　　

　　至此，本文已经完成了在Arcgis for javascript API中实现Geojson的绘制，并同时展示其多个Popup的需求。最终的展示效果如图1、2。源代码见笔者的github:https://github.com/EasonXu818/Add-GeoJSON-Multiple-Popups。

巴特西

利用Arcgis for javascript API绘制GeoJSON并同时弹出多个Popup