在前两节,讲到了两种不同方式的聚类,一种是基于距离的,一种是基于区域范围的,两种不同的聚类都是通过扩展esri/layers/GraphicsLayer方法来实现的。在本节,就详细的讲讲esri/layers/GraphicsLayer方法的扩展。
首先,在讲解扩展之前,先看看API中esri/layers/GraphicsLayer的一些参数和方法等。
1、创建一个GraphicLayer
在ESRI官方的API中,创建GraphicLayer有两种方式:
例如:
或者:
在第二种方式的options的参数包括:
2、GraphicLayer的属性
GraphicLayer的属性包括:
其中,有几个比较常见和重要的属性为:
a、graphics:数组,返回的参数是一个数组,为GraphicLayer中包含的Graphic对象。
b、visiable:布尔型,Graphiclayer是否可见。
c、visiableAtMapScale:布尔型,在特定比例尺下的可见性。
3、Graphiclayer的方法
图中,红框标出的是Graphiclayer最常用的方法,详细的介绍很清楚,在此不再做赘述了。
接下来,扩展Graphiclayer。
GraphicLayer藏得很深,位于library3.93.9jsesrilayersGraphicsLayer.js,虽然对参数变量代码做了混淆,但是有些东西还是没做变化。在做GraphicLayer扩展时,有几个是比较常用的:
a、_setMap
// 重构esri/layers/GraphicsLayer方法 _setMap: function(map, surface) { // GraphicsLayer will add its own listener here var div = this.inherited(arguments); return div; }
b、_unsetMap
_unsetMap: function() { this.inherited(arguments); }
c、_draw
_draw:function(graphic, redrawFlag, zoomFlag){ if (!this._map) { return; } }此外,还有一些地图控制的,如:_onPanStartHandler,_onZoomStartHandler,_onExtentChangeHandler等。扩展GraphicLayer的大概框架代码如下:
define([ "dojo/_base/declare", "esri/layers/GraphicsLayer" ], function ( declare, GraphicsLayer ) { return declare([GraphicsLayer], { constructor: function(options) { //参数设置 this._id = options.id || ""; this._divId = options.chartDiv || "chart"; }, // 重构esri/layers/GraphicsLayer方法 _setMap: function(map, surface) { // GraphicsLayer will add its own listener here var div = this.inherited(arguments); return div; }, _unsetMap: function() { this.inherited(arguments); }, //拖拽 _onPanStartHandler: function() { // }, //缩放 _onZoomStartHandler:function(){ // }, _onExtentChangeHandler: function(delta, extent, levelChange, lod) { // }, _draw:function(graphic){ if (!this._map) { return; } // } }); });
例子:添加统计图
统计图通过dojo chart实现,代码如下:
define([ "dojo/_base/declare", "esri/layers/GraphicsLayer", "esri/geometry/Point", "esri/graphic", "dojox/charting/Chart2D", "dojox/charting/themes/PlotKit/blue", "dojox/charting/action2d/Highlight", "dojox/charting/action2d/Tooltip" ], function ( declare, GraphicsLayer, Point, Graphic, Chart2D, theme, Highlight, Tooltip ) { return declare([GraphicsLayer], { constructor: function(options) { this._id = options.id || ""; this._divId = options.chartDiv || "chart"; this._charttype = options.chartType || "Pie"; this._chartSize = options.size || 50; }, // 重构esri/layers/GraphicsLayer方法 _setMap: function(map, surface) { // GraphicsLayer will add its own listener here var div = this.inherited(arguments); return div; }, _unsetMap: function() { this.inherited(arguments); }, hide: function() { dojo.style(dojo.byId(this._divId),{ "display": "none" }); }, show: function() { dojo.style(dojo.byId(this._divId),{ "display": "" }); }, //拖拽 _onPanStartHandler: function() { this.hide(); }, //缩放 _onZoomStartHandler:function(){ this.hide(); }, _onExtentChangeHandler: function() { this._refresh(true); }, _refresh: function(redraw) { var that=this; var gs = this.graphics, _draw = this._draw; for (i = 0; i < gs.length; i++) { _draw(gs[i], redraw); } this.show(); }, _draw:function(graphic, redraw){ if (!this._map) { return; } if(graphic instanceof Graphic)//判断graphic是否为MapChartGraphic类型 { this._drawChart(graphic,redraw); } }, _drawChart:function(graphic,redraw){ var showMapPt = graphic.geometry, attribute = graphic.attributes; var showPt = map.toScreen(showMapPt); var id=attribute.code, series = [attribute.male, attribute.female]; if(redraw){ dojo.byId(this._divId).removeChild(dojo.byId("div"+id)); } if(attribute){ var _chartDiv = dojo.doc.createElement("div"); _chartDiv.id ="div"+id; dojo.style(_chartDiv, { "left": (showPt.x-this._chartSize/4) + "px", "top": (showPt.y-this._chartSize/2) + "px", "position": "absolute", "width": this._chartSize + "px", "height": this._chartSize + "px" }); dojo.byId(this._divId).appendChild(_chartDiv); var _chart = new Chart2D(_chartDiv); var _themes = dojox.charting.themes.PlotKit.blue; _themes.chart.fill = "transparent"; _themes.chart.stroke = "transparent"; _themes.plotarea.fill = "transparent"; _chart.setTheme(_themes); switch(this._charttype){ case "Pie":{//饼状图 _chart.addPlot("default", { type: this._charttype, labels:false }); break; } case "StackedColumns":{//柱状堆积图 _chart.addPlot("default", { type: this._charttype, labels:false, markers: true, gap: 2 }); break; } case "Lines":{//柱状堆积图 _chart.addPlot("default", { type: this._charttype, labels:false, markers: true, radius: 1, tension:"X" }); break; } default:{//柱状图 _chart.addPlot("default", { type: this._charttype, labels:false, gap: 3 }); chart.addAxis("y", { vertical:true, fixLower: "major", fixUpper: "major" }); break; } } _chart.addSeries(id, series,{stroke: {1}}); //效果 new Highlight(_chart, "default", {highlight: "lightskyblue"}); new Tooltip(_chart, "default"); _chart.render(); } } }); });
实现后的效果如下:
源码下载地址:
链接:http://pan.baidu.com/s/1i3EbnF3 密码:cvbf
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