让OpenLayers的SelectFeature控件支持鼠标右键事件

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OpenLayers上的一个Feature对象单击出现一个气泡很容易实现，但是右键出现点菜单什么的就不容易了，关键在于SelectFeature控件不支持右键事件，所以我就改之。。
修改的源文件是基于OpenLayers2.7+changeset9116
changeset9116修复了SelectFeature不能选取两个以上图层的bug，具体参见http://trac.openlayers.org/changeset/9116
所以有些源代码和官网上下的OpenLayers2.7有点不一样
代码太多了，显得文章比较长，懒得看的就直接下载修改后的用就行了：

OpenLayers2.7 lei3389修改版下载地址:
http://files.cnblogs.com/lei3389/OpenLayers27_ModedBy_lei3389.rar
使用方法本文最后有个例子的

1.首先修改【OpenLayers\Events.js】
修改OL能够捕获的鼠标事件,添加右键事件“contextmenu”

BROWSER_EVENTS: [
 "mouseover", "mouseout",
 "mousedown", "mouseup", "mousemove",
 "click", "dblclick", "rightclick", "dblrightclick",
 "resize", "focus", "blur"
 //added by lei3389
 ,"contextmenu"
 //added end
 ],

现在OL已经可以截获鼠标右键了，只是handler没有去处理，下面我们再继续
2.进入【OpenLayers\Handler\Feature.js】
修改这个handler能够处理的事件表

EVENTMAP: {
 //added by lei
 'contextmenu': {'in': 'click', 'out': 'clickout'},
 //added end

 'click': {'in': 'click', 'out': 'clickout'},
 'mousemove': {'in': 'over', 'out': 'out'},
 'dblclick': {'in': 'dblclick', 'out': null},
 'mousedown': {'in': null, 'out': null},
 'mouseup': {'in': null, 'out': null}
 },

这里的in和out可以理解为选中和取消选中
这样,这个handler就能够处理contextmenu事件了，但是谁去处理你的事件呢？只能自己添加了：

/**
 *added by lei3389!!!
 * Method: contextmenu
 * Handle contextmenu. Call the "contextmenu" callback if contextmenu on a feature,
 * or the "clickout" callback if rightclick outside any feature.
 *
 * Parameters:
 * evt - {Event}
 *
 * Returns:
 * {Boolean}
 */
 contextmenu:function(evt) {
 return this.handle(evt) ? !this.stopClick : true;
 },

这样就交给handle去处理了
触发选中的本来是左键单击和左键双击，现在我们添加上右击

handle:
 {

        // var click = (type == "click" || type == "dblclick");
       //moded by lei
       //for right click on feature
        var click = (type == "click" || type == "dblclick"|| type == "contextmenu");
        //moded end

}

我们添加右键点击只是利用左键点击触发的事件，所以我们要在触发的事件中添加一个参数，以区分是左键还是右键

if(previouslyIn && inNew) {
 // out of last feature and in to another
 this.triggerCallback(type, 'out', [this.lastFeature]);

 // this.triggerCallback(type, 'in', [this.feature]);
 //moded by lei3389
 //for add a param
 this.triggerCallback(type, 'in', [this.feature,type]);
 //end
 } else if(!previouslyIn || click) {
 // in feature for the first time
 // this.triggerCallback(type, 'in', [this.feature]);
 //moded by lei3389
 //for add a param
 this.triggerCallback(type, 'in', [this.feature,type]);
 //end
 }

3.进入【OpenLayers\Control\SelectFeature.js】
handler只是为control服务的，我们让handler处理了右键事件也是为control处理的
刚刚添加的参数就要有用了：

/**
 * Method: clickFeature
 * Called on click in a feature
 * Only responds if this.hover is false.
 *
 * Parameters:
 * feature - {<OpenLayers.Feature.Vector>}
 */
 //clickFeature: function(feature)
 //moded by lei3389
 //for add a param
 clickFeature: function(feature,triggertype) {
 //end
 if(!this.hover) {
 var selected = (OpenLayers.Util.indexOf(
 feature.layer.selectedFeatures, feature) > -1);
 if(selected) {
 if(this.toggleSelect()) {
 this.unselect(feature);
 } else if(!this.multipleSelect()) {
 this.unselectAll({except: feature});
 }
 } else {
 if(!this.multipleSelect()) {
 this.unselectAll({except: feature});
 }
 //moded by lei3389
 // this.select(feature);
 this.select(feature,triggertype);

 //end
 }
 }
 },

然后这里也得添加一个参数:

/**
 * Method: select
 * Add feature to the layer's selectedFeature array, render the feature as
 * selected, and call the onSelect function.
 *
 * Parameters:
 * feature - {<OpenLayers.Feature.Vector>}
 */
 //moded by lei3389
 //for add a param ---triggertype

 // select: function(feature)
 select: function(feature,triggertype){
 //end
 var cont = this.onBeforeSelect.call(this.scope, feature);
 var layer = feature.layer;
 if(cont !== false) {
 cont = layer.events.triggerEvent("beforefeatureselected", {
 feature: feature
 });
 if(cont !== false) {
 layer.selectedFeatures.push(feature);
 this.layerData = {};

 var selectStyle = this.selectStyle || this.renderIntent;

 layer.drawFeature(feature, selectStyle);
 layer.events.triggerEvent("featureselected", {feature: feature});

 //moded by lei3389
 //for add another "handler"
 //this.onSelect.call(this.scope, feature);
 switch(triggertype){
 case "click":
 this.onSelect.call(this.scope, feature);
 break;
 case "contextmenu":
 this.onRightSelect.call(this.scope, feature);
 break;
 default:
 this.onSelect.call(this.scope, feature);
 }

 //end

 }
 }
 },

当然还得添加一个属性，为使用我们刚才修改的成果提供一个调用的接口

Code

4.现在对OL库的修改已经over了,我们自己使用的时候就可以用了
到自己的代码中来
首先屏蔽掉默认的右键：
//forbid the mouse's default rightclick
map.div.oncontextmenu = function () { return false;}
然后就可以像定义左键一样来定义鼠标右键了：
sample:

//add selectStationControl
 selectFeatureControl = new OpenLayers.Control.SelectFeature([VectorLayer1,VectorLayer2,VectorLayer3],
 {onSelect: onFeatureSelect,
 onUnselect: onFeatureUnselect,
 onRightSelect: onFeatureRightSelect
 });
 map.addControl(selectFeatureControl);
 selectFeatureControl.activate();

5.应该这样就对右键的修改就over了吧，我把我自己用的OL上传了.

其中包括了SelectFeature控件对多层选择的支持+右键支持
另外还有和本文不相干的一点修改:
是关于ol解析GML v3.0的posList节点的问题，也可能是esri生成gml的时候esri本身的问题，但是arcgis的源代码我改不了。。只能对OL动手了~~
【OpenLayers.Format.GML】

linestring: function(node, ring) {
 /**
 * Two coordinate variations to consider:
 * 1) <gml:posList dimension="d">x0 y0 z0 x1 y1 z1</gml:posList>
 * 2) <gml:coordinates>x0, y0, z0 x1, y1, z1</gml:coordinates>
 */

 var dim = parseInt(nodeList[0].getAttribute("dimension"));
 /**
 * added by lei3389
 *dim will be 'NAN' for esri didnot give GML V3 the dimension attribute!
 */
 if(dim='NAN')dim=2;
 /**
 * end
 */

6.终于完了，好长啊
OpenLayers2.7 lei3389修改版下载地址:
http://files.cnblogs.com/lei3389/OpenLayers27_ModedBy_lei3389.rar

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