1. 1.       首先修改 OpenLayers Events.js

定位到下面代码段，添加右键菜单事件：

OpenLayers.Events = OpenLayers.Class({
    /**      * Constant: BROWSER_EVENTS      * {Array(String)} supported events */     BROWSER_EVENTS: [         "mouseover", "mouseout",         "mousedown", "mouseup", "mousemove",         "click", "dblclick", "rightclick", "dblrightclick",         "resize", "focus", "blur",         "touchstart", "touchmove", "touchend" //添加右键菜单事件2011 11 02         , "contextmenu" ], …… })

现在OpenLayers可以捕捉右键了，只是Handler还没有处理；

1. 2.       修改OpenLayers Handler Feature.js

修改Handler能够处理的事件：

OpenLayers.Handler.Feature = OpenLayers.Class(OpenLayers.Handler, {
    /**     * Property: EVENTMAP     * {Object} A object mapping the browser events to objects with callback     *     keys for in and out. */     EVENTMAP: {
            '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 },         'touchstart': { 'in': 'click', 'out': 'clickout' }, //添加Handler处理事件 2011 11 02         'contextmenu': {'in';'click','out':'clickout'} }, })

这里的in和out可以理解为选中和取消选中；到此Handler可以处理comntexmenu事件了，可是谁来处理我们的事件呢？添加contextmenu方法，将事件处理交给Handler，如下所示：

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

OpenLayers中触发选中默认操作方式为：左键单击和双击(touchstart暂没关注是什么操作)，我们需要添加右键单击操作类型：

var click = (type == "click" || type == "dblclick" || type == "touchstart"||type=="contextmenu");

另外，我们需要在触发的事件中添加一个参数，来区分是左键还是右键

if (this.geometryTypeMatches(this.feature)) {
    // in to a feature if (previouslyIn && inNew) {
    // out of last feature and in to another if (this.lastFeature) {
    this.triggerCallback(type, 'out', [this.lastFeature]);                     } //原始：this.triggerCallback(type, 'in', [this.feature]); this.triggerCallback(type, 'in', [this.feature,type]);                 } else if (!previouslyIn || click) {
    //原始: this.triggerCallback(type, 'in', [this.feature]); // in feature for the first time this.triggerCallback(type, 'in', [this.feature,type]);                 }

Handler只是为Control服务的，下面我们修改Control中的操作；

1. 3.       修改OpenLayers Control SelectFeature.js

原始：

clickFeature: function(feature) {
    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});                 } this.select(feature);             }         } },

修改（添加一个参数）后：

clickFeature: function(feature,triggertype) {
    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});                 } this.select(feature,triggertype);             }         }     },

原始： 

select: function(feature) {
    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.highlight(feature); // if the feature handler isn't involved in the feature // selection (because the box handler is used or the // feature is selected programatically) we fake the // feature handler to allow unselecting on click if(!this.handlers.feature.lastFeature) {
    this.handlers.feature.lastFeature = layer.selectedFeatures[0];                 }                 layer.events.triggerEvent("featureselected", {feature: feature}); this.onSelect.call(this.scope, feature);             }         } },

修改后：

select: function (feature, triggertype) {
    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.highlight(feature); // if the feature handler isn't involved in the feature // selection (because the box handler is used or the // feature is selected programatically) we fake the // feature handler to allow unselecting on click if (!this.handlers.feature.lastFeature) {
    this.handlers.feature.lastFeature = layer.selectedFeatures[0];                 }                 layer.events.triggerEvent("featureselected", { feature: feature }); //添加类型选择 2011 11 02 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);                 }             }         } },

提供一个调用的接口  

/**     * APIProperty: onRightSelect     * {Function} Optional function to be called when a feature is selected.     *     The function should expect to be called with a feature. */ onRightSelect: function () { },

示例：

selectFeatureControl=new OpenLayers.Control.SelectFeature([layer],

    {

       onSelect:onFeatureSelect,

       onUnSelect:onFeatureUnselect,

       onRightSelect:onFeatureRightSelect

}

);

map.addControl(selectFeatureControl);

selectFeatureControl.activate();

 

至此，右键扩展完成。