Arcgis for Javascript实现图

首先，截个图给大家看结果：

初始化状态

放大后的状态

点击选中后的状态

如上图所看到的，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，载入统计图。一般来说，在地图上显示的统计图仅仅是一个趋势或者示意，具体的还得去点击显示。另外一种状态。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，在信息框显示具体的统计图的信息。

首先，跟大家谈谈地图统计图几种实现方式。眼下情况下，在Arcgis for Javascript以下，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，具体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非常多人採取的一种解决方式，在这样的方式下，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，并通过点击获取具体统计信息，这样的处理方式就是将压力交给server，减小client压力。可是显示的效果不好。

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。这样的方式对client的压力比較大。并且从技术上来说，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，仅仅是前两种展示的是栅格图，后一种方式展示的是矢量图，每个统计图是一个graphic对象。统计图在graphiclayer中显示。

下文将具体的讲述上述三种状态下的实现思路与方式。

第一，载入统计图。

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的数据例如以下：

        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，代码例如以下：

            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);
                }
            };

通过X与Y。将每个统计图通过graphic的方式加入到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相应的变化，例如以下：

                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，去又一次绘制统计图。

第三，点击显示具体图。

点击是监听的graphiclayer的click事件，点击图通过infowindow的方式显示具体统计图信息，这里面就好做多了，例如以下：

            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();
            };

通过以上几步，就基本上实现了地图统计图部分的功能。完整代码例如以下：

<!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，第三种方式的实现眼下本人正在努力实现。实现后会第一时间与大家分享，如有不正确。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！

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