如何在OpenLayers的矢量圖層上以編程方式選擇要素？

Question

我目前正在尋找一種解決方案來選擇（或突出顯示）OpenLayers.Layer.Vector中的矢量。

我已經構建了一個簡單的網格表，用戶可以選擇一個向量（以WKT格式化字符串給出），該向量應該高亮顯示圖層上的相應向量。當用戶訪問該網站時，網格表中的所有矢量都會繪製到地圖上的矢量圖層。

我發現我要麼需要OpenLayers.Control.ModifyFeature的selectFeature(feature)功能或OpenLayers.Control.SelectFeature（見dev.openlayers.org/apidocs/files/OpenLayers/Control/SelectFeature-js.html's選擇（功能）功能（這可能不存在或不再存在？）。從郵件列表中查看帖子：osgeo-org.1803224.n2.nabble.com/Programatically-Select-a-Feature-tt2192485.html#a2193928瞭解更多信息相關信息。

我嘗試沒有成功以下，所以我希望有人能抓住這個行代碼，並能告訴我一個工作代碼段;-)

// ... some initializing code 
this.vlayer = new OpenLayers.Layer.Vector("VectorLayer"); // VectorLayer 

// some controls 
this.openLayerControlPoint = new OpenLayers.Control.DrawFeature(this.vlayer, OpenLayers.Handler.Point); 
this.openLayerControlPolygon = new OpenLayers.Control.DrawFeature(this.vlayer, OpenLayers.Handler.Polygon); 
this.openLayerControlModify = new OpenLayers.Control.ModifyFeature(this.vlayer, { 
    mode: OpenLayers.Control.ModifyFeature.RESHAPE | OpenLayers.Control.ModifyFeature.DRAG, 
    standalone: false 
}); 

// just deactivate to make sure everything is really deactivated 
this.openLayerControlPoint.deactivate(); 
this.openLayerControlPolygon.deactivate(); 
this.openLayerControlModify.deactivate(); 

// add the just created layer to the map 
this.map.addLayer(this.vlayer); 

// add all (deactivated) controls to the map 
this.map.addControl(this.openLayerControlPoint); 
this.map.addControl(this.openLayerControlPolygon); 
this.map.addControl(this.openLayerControlModify); 

後來在代碼：

// ... another function doing the action 
selectVector: function(wktVector) { 
    this.openLayerControlModify.activate(); 

    // this is no elegant solution, this should only show how I would 
    // test the functionallity. 
    for (var i = 0; i < this.vlayer.features.length; ++i) { 
    // returns a WKT formatted string: 
    // 'POLYGON((xxxx.xxx xxxx.xxx), (xxxx.xxx xxxx.xxx))' 
    var wktVectorCurrent = this.vlayer.features[i].geometry.toString(); 
    if (wktVector == wktVectorCurrent) { 
     // \/ doesn't work :-(
     this.openLayerControlModify.selectFeature(this.vlayer.features[i]); 
     break; 
    } 
    } 
} 

Answer 1

我不明白，爲什麼你正在使用ModifyFeature選擇功能。 OpenLayers.Control.SelectFeature專門用來選擇功能，所以我建議你改用這個控件。

因此，創建SelectFeature控制：

var selectFeature = new OpenLayers.Control.SelectFeature(this.vlayer); 
selectFeature.activate(); 

你

然後if語句（我猜它的工作原理，找到您要比較的幾何形狀來選擇功能？）使用選擇方法：

if (wktVector == wktVectorCurrent) { 
    selectFeature.select(this.vlayer.features[i]); 
} 

根據文檔此方法選擇應當標註功能，並提高相應的事件：

* Method: select 
* Add feature to the layer's selectedFeature array, render the feature as 
* selected, and call the onSelect function. 

如果你想要做在地圖上的東西時，功能被選中（如顯示彈出窗口），你應該訂閱矢量圖層選擇事件，當你創建：

this.vlayer.events.on({'featureselected': function(){ 
    //Handle select event 
}});