Arcgis for Javascript之统计图的实现

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首先，截个图给大家看看效果：

初始化状态

放大后的状态

点击选中后的状态

如上图所示，一般的涉及到的地图的统计涉及到上述所展示的三个状态：1、初始化状态；2、缩放后的状态；3、点击选中显示详情状态。第一种状态下，加载统计图，一般来说，在地图上显示的统计图只是一个趋势或者示意，详细的还得去点击显示；第二种状态，随着地图的缩放，地图统计图随着地图的大小变化；第三种状态，点击选中，在信息框显示详细的统计图的信息。

首先，跟大家谈谈地图统计图几种实现方式。目前情况下，在Arcgis for Javascript下面，实现统计图有三种方式。

1、示意图方式

示意图方式是最简单的一种方式，什么意思呢，就是用一个静态的png图片的方式，示意图的数据不代表真实的数据，示意在该状态时是地图统计图，详细的统计信息在点击示意图的时候才会出现。

2、后台生成图片方式

后台生成图片的方式也是有很多人采取的一种解决方案，在这种方式下，地图上的统计图的数据代表真实的数据信息，地图上的统计图是在后台用java或者c#生成的，并在地图上展示出来，并通过点击获取详细统计信息，这种处理方式就是将压力交给服务器，减小客户端压力，但是显示的效果不好。

3、前台直接展示方式

前台直接展示是将统计数据传给前台，前台生成统计图的方式。这种方式对客户端的压力比较大，而且从技术上来说，也是最难的。

了解了上述三种统计图的生成方式，接下来了解一下统计图在地图中的展示方式。不论是上述那种方式，统计图在地图中的显示都是通过graphic和graphiclayer来展示的，只是前两种展示的是栅格图，后一种方式展示的是矢量图，每一个统计图是一个graphic对象，统计图在graphiclayer中显示。

下文将详细的讲述上述三种状态下的实现思路与方式。

第一，加载统计图。

在此，数据是json格式的，统计图的显示是通过X与Y去定位的，JSON的数据如下：

var CITY_DATA={ "total":34, "items":[{"id":1,"name":"乌鲁木齐","X":87.575829,"Y":43.782212}, {"id":2,"name":"拉萨","X":91.162998,"Y":29.71042}, {"id":3,"name":"西宁","X":101.797303,"Y":36.593642}, {"id":4,"name":"兰州","X":103.584297,"Y":36.119086}, {"id":5,"name":"成都","X":104.035508,"Y":30.714179}, {"id":6,"name":"重庆","X":106.519115,"Y":29.478925}, {"id":7,"name":"贵阳","X":106.668071,"Y":26.457312}, {"id":8,"name":"昆明","X":102.726775,"Y":24.969385}, {"id":9,"name":"银川","X":106.167225,"Y":38.598524}, {"id":10,"name":"西安","X":108.967128,"Y":34.276112}, {"id":11,"name":"南宁","X":108.233931,"Y":22.748296}, {"id":12,"name":"海口","X":110.346181,"Y":19.96992}, {"id":13,"name":"广州","X":113.226683,"Y":23.18307}, {"id":14,"name":"长沙","X":112.947928,"Y":28.169916}, {"id":15,"name":"南昌","X":115.893715,"Y":28.652363}, {"id":16,"name":"福州","X":119.246768,"Y":26.070765}, {"id":17,"name":"台北","X":121.503567,"Y":25.008274}, {"id":18,"name":"杭州","X":120.183046,"Y":30.330584}, {"id":19,"name":"上海","X":121.449707,"Y":31.253361}, {"id":20,"name":"武汉","X":114.216597,"Y":30.579253}, {"id":21,"name":"合肥","X":117.262302,"Y":31.838353}, {"id":22,"name":"南京","X":118.805692,"Y":32.085022}, {"id":23,"name":"郑州","X":113.6511,"Y":34.746308}, {"id":24,"name":"济南","X":117.048331,"Y":36.60841}, {"id":25,"name":"石家","X":114.478215,"Y":38.033276}, {"id":26,"name":"太原","X":112.483066,"Y":37.798404}, {"id":27,"name":"呼和浩特","X":111.842806,"Y":40.895751}, {"id":28,"name":"天津","X":117.351094,"Y":38.925719}, {"id":29,"name":"沈阳","X":123.296299,"Y":41.801604}, {"id":30,"name":"长春","X":125.26142,"Y":43.981984}, {"id":31,"name":"哈尔","X":126.567138,"Y":45.69381}, {"id":32,"name":"北京","X":116.068276,"Y":39.892225}, {"id":33,"name":"香港","X":114.093117,"Y":22.427852}, {"id":34,"name":"澳门","X":113.552482,"Y":22.184495} ] };

紧接着，就是显示统计图，代码如下：

通过X与Y，将每一个统计图通过graphic的方式添加到graphiclayer里。

第二，缩放时统计图大小的变化。

地图缩放时，统计图的大小也得随着地图的缩放发生相对应的变化，如下：

map.on("zoom-end",function(zoom){ var level=zoom.level; var symbol = new PictureMarkerSymbol("bar.png",20*(level-3),30*(level-3)); symbol.setOffset(-10*(level-3),18*(level-3)); var graphics = chartLayer.graphics; for(var i=0;i<graphics.length;i++){ graphics[i].symbol = symbol; chartLayer.redraw(); } });

这里，主要通过监听map的zoom-end事件，去重新绘制统计图。

第三，点击显示详细图。

点击是监听的graphiclayer的click事件，点击图通过infowindow的方式显示详细统计图信息，这里面就好做多了，如下：

通过以上几步，就基本上实现了地图统计图部分的功能。完整代码如下：

<!DOCTYPE html><html><head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no"/> <title>Simple Map</title> <link rel="stylesheet" href="http://localhost/arcgis_js_api/library/3.9/3.9/js/esri/css/esri.css"> <style> html, body, #map { height: 100%; margin: 0; padding: 0; } body { background-color: #FFF; overflow: hidden; font-family: "Trebuchet MS"; } </style> <script src="http://localhost/arcgis_js_api/library/3.9/3.9/init.js"></script> <script src="jquery-1.8.3.js"></script> <script> var CITY_DATA={ "total":34, "items":[{"id":1,"name":"乌鲁木齐","X":87.575829,"Y":43.782212}, {"id":2,"name":"拉萨","X":91.162998,"Y":29.71042}, {"id":3,"name":"西宁","X":101.797303,"Y":36.593642}, {"id":4,"name":"兰州","X":103.584297,"Y":36.119086}, {"id":5,"name":"成都","X":104.035508,"Y":30.714179}, {"id":6,"name":"重庆","X":106.519115,"Y":29.478925}, {"id":7,"name":"贵阳","X":106.668071,"Y":26.457312}, {"id":8,"name":"昆明","X":102.726775,"Y":24.969385}, {"id":9,"name":"银川","X":106.167225,"Y":38.598524}, {"id":10,"name":"西安","X":108.967128,"Y":34.276112}, {"id":11,"name":"南宁","X":108.233931,"Y":22.748296}, {"id":12,"name":"海口","X":110.346181,"Y":19.96992}, {"id":13,"name":"广州","X":113.226683,"Y":23.18307}, {"id":14,"name":"长沙","X":112.947928,"Y":28.169916}, {"id":15,"name":"南昌","X":115.893715,"Y":28.652363}, {"id":16,"name":"福州","X":119.246768,"Y":26.070765}, {"id":17,"name":"台北","X":121.503567,"Y":25.008274}, {"id":18,"name":"杭州","X":120.183046,"Y":30.330584}, {"id":19,"name":"上海","X":121.449707,"Y":31.253361}, {"id":20,"name":"武汉","X":114.216597,"Y":30.579253}, {"id":21,"name":"合肥","X":117.262302,"Y":31.838353}, {"id":22,"name":"南京","X":118.805692,"Y":32.085022}, {"id":23,"name":"郑州","X":113.6511,"Y":34.746308}, {"id":24,"name":"济南","X":117.048331,"Y":36.60841}, {"id":25,"name":"石家","X":114.478215,"Y":38.033276}, {"id":26,"name":"太原","X":112.483066,"Y":37.798404}, {"id":27,"name":"呼和浩特","X":111.842806,"Y":40.895751}, {"id":28,"name":"天津","X":117.351094,"Y":38.925719}, {"id":29,"name":"沈阳","X":123.296299,"Y":41.801604}, {"id":30,"name":"长春","X":125.26142,"Y":43.981984}, {"id":31,"name":"哈尔","X":126.567138,"Y":45.69381}, {"id":32,"name":"北京","X":116.068276,"Y":39.892225}, {"id":33,"name":"香港","X":114.093117,"Y":22.427852}, {"id":34,"name":"澳门","X":113.552482,"Y":22.184495} ] }; var map, mapCenter; require([ "esri/map", "esri/layers/ArcGISTiledMapServiceLayer", "esri/layers/FeatureLayer", "esri/layers/GraphicsLayer", "esri/geometry/Point", "esri/symbols/PictureMarkerSymbol", "esri/symbols/SimpleLineSymbol", "esri/renderers/SimpleRenderer", "dojo/_base/Color", "dojo/domReady!"], function(Map, Tiled, FeatureLayer, GraphicsLayer, Point, PictureMarkerSymbol, SimpleLineSymbol, SimpleRenderer, Color) { map = new Map("map", {logo:false,slider: true}); var tiled = new Tiled("http://localhost:6080/arcgis/rest/services/chinamap/MapServer"); map.addLayer(tiled,0); mapCenter = new Point(103.847, 36.0473, map.spatialReference); map.centerAndZoom(mapCenter,4); var chartLayer = new GraphicsLayer({"id":"chartLayer"}); map.addLayer(chartLayer,1); chartLayer.on("click",showDetailChart); addReadPopup(CITY_DATA); function addReadPopup(data){ var items= data.items; for(var i=0;i<data.total;i++){ var symbol = new PictureMarkerSymbol("bar.png",20,30); symbol.setOffset(-10,18); var pt=new Point(items[i].X,items[i].Y,map.spatialReference); var graphic = new esri.Graphic(pt,symbol,items[i]); chartLayer.add(graphic); } map.on("zoom-end",function(zoom){ var level=zoom.level; var symbol = new PictureMarkerSymbol("bar.png",20*(level-3),30*(level-3)); symbol.setOffset(-10*(level-3),18*(level-3)); var graphics = chartLayer.graphics; for(var i=0;i<graphics.length;i++){ graphics[i].symbol = symbol; chartLayer.redraw(); } }); }; function showDetailChart(evt){ var graphic = evt.graphic; graphic.symbol.url="bar_select.png"; chartLayer.redraw(); map.infoWindow.setTitle("<b>"+graphic.attributes.name+"</b>"); var content="<div style='text-align: center;'><img src='bar_detail.png'/></div>"; map.infoWindow.setContent(content); map.infoWindow.show(graphic.geometry); $(".maximize").hide(); $(".close").click(function(){ restoreChart(evt); }); }; function restoreChart(evt){ var graphic = evt.graphic; graphic.symbol.url="bar.png"; chartLayer.redraw(); }; }); </script></head><body><div id="map"></div></body></html>

最后，第三种方式的实现目前本人正在努力实现，实现后会第一时间与大家分享，如有不对，还望指正！

如有疑问，请联系QQ：1004740957或者e-mail：niujp08@qq.com，联系请说明来意，谢谢！