OpenLayers: How to Zoom Map to Fit Selected Features Efficiently

openlayers

In my openlayers based application, I need to trigger zoom when user selects features so that all the selected features fit within the map extent.

I make use of this code:

map.getView().fit([swLong, swLat, neLong, neLat], map.getSize());

(swLong, swLat) is the south-west corner and (neLong, neLat) is the north-east corner of bounding box containing the selected features. These are in degrees.

What I am not sure is whether I need to provide these in pixels or degrees is the correct way?

Best Answer

The extent should be in view coordinates. The way you have specified size is correct for OpenLayers 3. For OpenLayers 4 and 5 the size defaults to map size so you don't need to specify it, but if you do I've included the OL4/5 syntax

map.getView().fit(ol.proj.transformExtent([swLong, swLat, neLong, neLat], 'EPSG:4326', map.getView().getProjection()), { size: map.getSize() });

Related Solutions

[GIS] Convert bounding box for OL2 to extent for OL3

ol.Extent is simply an array of 4 numbers. But you can translate this extent to a polygon with the function ol.geom.Polygon.fromExtent. And this polygon can be used to create a feature, so that you can display the bounding-box.

var extent = [bb_left, bb_bottom, bb_right, bb_top];
var polygon = ol.geom.Polygon.fromExtent(extent);
var feature = new ol.Feature({
  geometry: polygon
});

[GIS] Find out if a bounding box is within a vector layer in openlayers 3

comparing extents should be enough, but instead of comparing the extent of the whole vector layer ( regions ) you'll have to compare the extents of each feature from it with you bbox:

regionsSource.forEachFeature(function(feature){
    var geom=feature.getGeometry();
    var regionExtent=geom.getExtent();
    var intersects= regionExtent.intersectsExtent(yourBBOXExtent); // boolean
});

now you can add it in a function and return intersects (boolean)

Best Answer

Related Solutions

[GIS] Convert bounding box for OL2 to extent for OL3

[GIS] Find out if a bounding box is within a vector layer in openlayers 3

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