popup随鼠标移动，OpenLayers.Control.Measure测量距离

之前需要做一个测量距离的工具，于是查了OpenLayers.Control.Measure，量算过程通过调用事件处理器 Handler 实现在 vector 图层上的距离或面积的量算。

这里做的是距离量算，点击之后会弹出popup（OpenLayers.Popup），效果是点击之后出现增加popup计算出之前几个点之间的距离，并删掉前面的popup（并没有做出向百度那样随鼠标移动变化距离的效果）。

调用方法MeasurePath();就可以查看效果啦

 1 var measurePopup = null;
 2 var messagelast = null;
 3
 4 //距离测量
 5 var measureControl = new OpenLayers.Control.Measure(OpenLayers.Handler.Path, {
 6     persist: true,
 7     eventListeners: {
 8         ‘measure‘: measureDistance,
 9         ‘measurepartial‘: measurepartial
10     }
11 });
12
13
14 function MeasurePath() {
15     measureControl.updateHandler(OpenLayers.Handler.Path, { persist: true });
16     map.addControl(measureControl);
17     measureControl.activate();
18 }
19 function measureDistance(event) {
20     messagelast = parseFloat(event.measure).toFixed(2) + "" + event.units;
21     if (event.order > 1) {
22         messagelast += "2";
23     }
24     //获取鼠标点击处的经纬度
25     var points = event.geometry.components;
26     var point = points[points.length - 1];
27     if (measurePopup != null)
28         map.removePopup(measurePopup);
29     measurePopup = new OpenLayers.Popup("chicken",
30     //弹出框位置
31                    new OpenLayers.LonLat(point.x, point.y),
32     //new OpenLayers.LonLat(position.x, position.y),
33                    null,
34                    messagelast,
35                    true,
36                    closeBoxCallback
37                    );
38     measurePopup.autoSize = true;
39     measurePopup.backgroundColor = "#06a09f";
40     measurePopup.opacity = 0.8;
41     map.addPopup(measurePopup);
42 }
43
44 function measurepartial(event) {
45     var message = parseFloat(event.measure).toFixed(2) + "" + event.units;
46     var points = event.geometry.components;
47     var point = points[points.length - 1];
48     if (measurePopup != null)
49         map.removePopup(measurePopup);
50     measurePopup = new OpenLayers.Popup("chicken",
51     //弹出框位置
52                    new OpenLayers.LonLat(point.x, point.y),
53                    null,
54                    message,
55                    true,
56                    closeBoxCallback
57                    );
58     measurePopup.autoSize = true;
59     measurePopup.backgroundColor = "#06a09f";
60     measurePopup.opacity = 0.8;
61     if (points.length > 2)
62         map.addPopup(measurePopup);
63 }
64
65 //function changeHandler(checked){
66 //        measureClick();
67 //    }
68
69 function closeBoxCallback() {
70     map.removePopup(measurePopup);
71     measureControl.deactivate();
72     map.removeControl(measureControl);
73     messagelast = null;
74 }  

popup有点丑，哈哈。双击结束一次测量，点击popup的关闭按钮（右上角的红叉叉），结束测量事件。