openlayer 獲取當前視圖窗口內的要素

//監聽分辨率變化
Map.map.getView().on('change:resolution', function(){
   var zoom = Map.map.getView().getZoom();
   if(zoom>=10){
      console.info("當前層級:"+zoom);
      var extent =Map.map.getView().calculateExtent(Map.map.getSize());
      console.info(extent);
      var features = parent.GlobalOLTOWER.tower_750.getSource().getFeaturesInExtent(extent); //先縮小feature的范圍
      console.info(features);
   }else{
      console.info("層級未達到")
   }
});

//監聽地圖實時的 extent
Map.map.on('moveend', function () {
   var zoom = Map.map.getView().getZoom();
   if(zoom>=10){
      console.info("當前層級:"+zoom);
      var extent =Map.map.getView().calculateExtent(Map.map.getSize());
      console.info(extent);
      var features = parent.GlobalOLTOWER.tower_750.getSource().getFeaturesInExtent(extent); //先縮小feature的范圍
      console.info(features);
   }else{
      console.info("層級未達到")
   }
});