openlayers 如何添加多个标注
1、一、多标注显示
1、多标注显示：通过Feature和Marker实现多点标注。
我对openlayers例子提供的代码做了一些改动，添加单个标注函数如下:
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/**
* Function: addMarker
* Add a new marker to the markers layer given the following lonlat,
* popupClass, and popup contents HTML. Also allow specifying
* whether or not to give the popup a close box.
*
* Parameters:
* ll - {<OpenLayers.LonLat>} Where to place the marker
* popupClass - {<OpenLayers.Class>} Which class of popup to bring up
* when the marker is clicked.
* popupContentHTML - {String} What to put in the popup
* closeBox - {Boolean} Should popup have a close box?
* overflow - {Boolean} Let the popup overflow scrollbars?
*/
function addMarker(markerName,icon,ll, popupClass, popupContentHTML, closeBox, overflow) {
var feature = new OpenLayers.Feature(markerName,ll,{icon:icon.clone()});
feature.closeBox = closeBox;
feature.popupClass = popupClass;
feature.data.popupContentHTML = popupContentHTML;
feature.data.overflow = (overflow) ? "auto" : "hidden";
var marker = feature.createMarker();
var markerClick = function (evt) {
if (this.popup == null) {
this.popup = this.createPopup(this.closeBox);
this.popup.setBackgroundColor("#E2E7EB");
this.popup.setBorder("1px #0066ff solid");
map.addPopup(this.popup);
this.popup.show();
} else {
this.popup.toggle();
}
currentPopup = this.popup;
OpenLayers.Event.stop(evt);
};
marker.events.register("mousedown", feature, markerClick);
markerName.addMarker(marker);
}
上诉函数中
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if (this.popup == null) {
this.popup = this.createPopup(this.closeBox);
this.popup.setBackgroundColor("#E2E7EB");
this.popup.setBorder("1px #0066ff solid");
map.addPopup(this.popup);
this.popup.show();
} else {
this.popup.toggle();
}
currentPopup = this.popup;
同时也实现了点击弹出框的效果，显示内容见下面。
2、调用上面函数实现多点标注，核心代码如下：
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var url = 'gis/img/cctv.gif';
var sz = new OpenLayers.Size(20, 20); //尺寸大小
var calculateOffset = function(size) {
return new OpenLayers.Pixel(-(size.w/2), -size.h);
};
var icon = new OpenLayers.Icon(url, sz, null, calculateOffset);
var lonLat,popupContentHTML,popupClass;
if(cctvList == null){
return;
}
//遍历显示
for(var i=0;i<cctvList.length;i++){
lonLat = new OpenLayers.LonLat(cctvList[i].gis_x,cctvList[i].gis_y);
//google地图需要转换坐标
lonLat.transform(map.displayProjection, map.getProjectionObject());
device_name = cctvList[i].device_name;
//popupContentHTML = "<b> 治安监控<br> "+device_name+"</b>";
popupContentHTML = createPopupContentHTML('治安监控',cctvList[i]);
popupClass = OpenLayers.Popup.Anchored;
addMarker(cctvMarkers,icon,lonLat, popupClass, popupContentHTML,true);
}
其中cctvList是从数据库获取设备列表json格式；
createPopupContentHTML函数实现点击GIS标注弹出框显示内容；
cctvMarkers是定义的全局图层变量，用于多图层显示控制；
用户通过遍历将多个点在GIS上显示；
2、二、图层控制
通过定义全局Markers变量实现不同图层的显示控制。
预先定义几个变量，如：var cctvMarkers,tgsMarkers,epsMarkers; 每个变量表示一个图层，每个图层上的标注通过方法一实现添加即可；
在页面加载时把各图层的标注全部加载完毕，需要隐藏某一个图层则通过调用Markers.clearMarkers()方法清理掉该图层数据即可，待需要显示时再重新加载，即调用方法一即可。
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//隐藏图层
function hiddenMarker(markerName){
if(markerName == 'cctv'){
cctvMarkers.clearMarkers();
}else if(markerName == 'tgs'){
tgsMarkers.clearMarkers();
}else{
epsMarkers.clearMarkers();
}
}
3、三、搜索定位
搜索定位其实首先是从数据库中根据关键字查找出符合的结果项，然后再将这些结果根据坐标在GIS上进行渲染标注，当点击某一结果是进行定位；
我这里定位的实现是通过marker标注的定位图片的方式实现，这样做有个问题就是定位marker会覆盖方法一中设备的点击弹出事件，我这里用了最笨的方法就是定位标注时重新注册点击弹出事件。关键代码如下：
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//gis定位并居中
function deviceLocate(data){
//alert(data);
var url = 'jsp/gis/img/location.gif';
var sz = new OpenLayers.Size(25, 30); //尺寸大小
var calculateOffset = function(size) {
return new OpenLayers.Pixel(-(size.w/2), -size.h);
};
var icon = new OpenLayers.Icon(url, sz, null, calculateOffset);
var lonLat = new OpenLayers.LonLat(locationDataList[data].gis_x,locationDataList[data].gis_y);
//google地图需要转换坐标
lonLat.transform(map.displayProjection, map.getProjectionObject());
locateMarkers.clearMarkers();
//
var popupContentHTML,popupClass;
var title = '设备信息';
if(locationDataList[data].device_type == '10'){
title = '卡口';
}else if(locationDataList[data].device_type == '11'){
title = '电警';
}else if(locationDataList[data].device_type == '12'){
title = '治安监控';
}
popupContentHTML = createPopupContentHTML(title,locationDataList[data]);
popupClass = OpenLayers.Popup.Anchored;
addMarker(locateMarkers,icon,lonLat, popupClass, popupContentHTML,true);
//locateMarkers.addMarker(new OpenLayers.Marker(lonLat, icon));
//居中显示
map.setCenter(lonLat, 4);
}
4、四、新增标注
在GIS上添加新标注只需获取相应的经纬度坐标，保存志数据库即可。
init方法里增加
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//单击事件
var click = new OpenLayers.Control.Click();
map.addControl(click);
click.activate();
单机获取坐标函数
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//单击事件响应
OpenLayers.Control.Click = OpenLayers.Class(OpenLayers.Control, {
defaultHandlerOptions: {
'single': true,
'double': false,
'pixelTolerance': 0,
'stopSingle': false,
'stopDouble': false
},
initialize: function(options) {
this.handlerOptions = OpenLayers.Util.extend(
{}, this.defaultHandlerOptions
);
OpenLayers.Control.prototype.initialize.apply(
this, arguments
);
this.handler = new OpenLayers.Handler.Click(
this, {
'click': this.trigger
}, this.handlerOptions
);
},
trigger: function(e) {
markers.clearMarkers();
var url = 'gis/img/biaozhu.png';
var sz = new OpenLayers.Size(30, 30); //尺寸大小
var calculateOffset = function(size) {
return new OpenLayers.Pixel(-(size.w/2), -size.h);
};
var icon = new OpenLayers.Icon(url, sz, null, calculateOffset);
var lonlat = map.getLonLatFromPixel(e.xy);
marker = new OpenLayers.Marker(lonlat, icon);
markers.addMarker(marker);
//将墨卡托坐标转换成经纬坐标
lonlat.transform(new OpenLayers.Projection("EPSG:900913"),
new OpenLayers.Projection("EPSG:4326"));
//坐标传回给父页面变量
parent.gisx = lonlat.lon.toFixed(5);
parent.gisy = lonlat.lat.toFixed(5);
}
});
以上几个功能对付简单GIS应用已经足够。
典型界面如下：
