[GIS] Openlayers feature identification

openlayers

In OL4 (or, I guess, any version >=3.0), all features have an undefined id unless it is set by any mean. They do have, however, an ol_uid value (as far as I could understand, all ol objects have such property), that seems a "random" number set automatically by openlayers. In order to store feature styles in memory, it is safe to use this variable as a map index? I am doing it already, but want to be sure that there's "no chance" of collision.

Best Answer

As they said in the comment, there'll be no collision.

https://github.com/openlayers/openlayers/blob/4a2d711fb77703ef708c596452775f4d0eebaf11/src/ol/index.js#L112-L114

Unique IDs are generated as a strictly increasing sequence.

Related Solutions

[GIS] Remove selected feature Openlayers 3

Yes, you can remove selected feature.

var draw;
var featureID = 0;
var singleClick;
var selectedFeatureID;

// First some change in this function.

function addInteraction() {
   map.removeInteraction(singleClick);

      draw = new ol.interaction.Draw({
      source: source,
      type: ("LineString")
  });

 // Create drawend event of feature and set ID to feature

  draw.on('drawend', function (event) {
    featureID = featureID + 1;
    event.feature.setProperties({
        'id': featureID
    })
 })
   map.addInteraction(draw);
 }

Then Change in select Function as follow:

 function addSelect() {
    map.removeInteraction(draw);
    singleClick = new ol.interaction.Select();
    map.addInteraction(singleClick);

     singleClick .getFeatures().on('add', function (event) {
     var properties = event.element.getProperties();
     selectedFeatureID = properties.id;       
    });
 }

Then call this function on REMOVE button click

 function removeSelectedFeature() {
   var features = source.getFeatures();
     if (features != null && features.length > 0) {
         for (x in features) {
            var properties = features[x].getProperties();
            console.log(properties);
            var id = properties.id;
            if (id == selectedFeatureID) {
              source.removeFeature(features[x]);
               break;
            }
          }
        }
      }

With this code you can remove any selected feature. If it is Line,Point, Polygon etc.

[GIS] Openlayers 4 unselect a feature

You can simply add the following line within your closer click event:

select.getFeatures().clear();

select.getFeatures() will return the currently selected feature(s), and clear() will remove them from the selection.

Best Answer

Related Solutions

[GIS] Remove selected feature Openlayers 3

[GIS] Openlayers 4 unselect a feature

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