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如何在OpenLayers中的矢量图层上以编程方式选择要素?

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我目前正在寻找一种解决方案来选择(或突出显示)OpenLayers.Layer.Vector中的向量 .

我已经构建了一个简单的网格表,用户可以在其中选择一个向量(以WKT格式的字符串给出),该向量应突出显示图层上的相应向量 . 当用户访问网站时,网格表中的所有向量都将绘制到 Map 上的矢量图层 .

我发现我需要OpenLayers.Control.ModifyFeatureselectFeature(feature)函数或OpenLayers.Control.SelectFeature(请参阅dev.openlayers.org/apidocs/files/OpenLayers/Control/SelectFeature-js.html 's select(feature) function (which probably does not exists or doesn't再存在?) . 如需更多信息,请参阅邮件列表中的帖子:osgeo-org.1803224.n2.nabble.com/Programatically-Select-a-Feature-tt2192485.html#a2193928 .

我尝试了以下但没有成功,所以我希望有人可以 grab 这些代码行,并可以向我展示一个有效的代码片段;-)

// ... 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);

后来的代码:

// ... 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;
    }
  }
}

1 回答

  • 20

    我不明白你为什么使用ModifyFeature来选择一个功能 . OpenLayers.Control.SelectFeature专门用于选择功能,所以我建议您使用此控件 .

    因此,创建SelectFeature控件:

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

    然后在你的if语句中(我想它可以通过比较几何来找到你想要选择的特征?)使用select方法:

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

    根据文档,此方法应将功能标记为已选择并引发适当的事件:

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

    如果您想在选择要素时在 Map 上执行某些操作(如显示弹出窗口),则应在创建时将矢量图层订阅为select-event:

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

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