How do Bounds work in OpenLayers 3?

Question

Does the concept of OpenLayers.Bounds from OpenLayers 2.x still exist in OpenLayers 3? How has it changed, and what is its new name?

var mapExtent = map.getView().calculateExtent(map.getSize()); — pstanton, Jun 23 '16 at 07:41

Christophe Roussy · Accepted Answer · 2017-08-17T10:01:20.253

8

UPDATE: OL4: https://openlayers.org/en/latest/apidoc/ol.html#.Extent

It seems that the new word for 'bounds' or 'bounding box' (BBOX) is 'extent'. See:

One way to find out things at the moment is to run searches in the OL3 repo, for example: https://github.com/openlayers/ol3/search?p=3&q=BBOX&type=Code

edited Aug 17 '17 at 10:01

answered Mar 11 '14 at 15:10

Christophe Roussy

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I can give you some rep for those questions :), that new tag will prove quite useful as OL3 is not compatible with OL3, for the moment both must be used otherwise no one will see those questions. – Christophe Roussy Mar 12 '14 at 09:02
I mean 'as OL3 is not compatible with OL2' – Christophe Roussy Dec 04 '15 at 15:18

Bastien Ho · Answer 2 · 2015-10-07T16:04:30.600

Did'nt found any documentation about this feature but Extent seems to work :

var vectorSources = new ol.source.Vector();
var map = new ol.Map({
  target: map_id,
  layers: [
    new ol.layer.Tile({
      source: ol.source.OSM()
    }),
    new ol.layer.Vector({
      source: vectorSources
    })
  ],
  view: new ol.View({
    center: [0, 0],
    zoom: 12
  })
});

var feature1 = new ol.Feature({
  geometry: new ol.geom.Point(coords)
});
vectorSources.addFeature(feature1);
var feature2 = new ol.Feature({
  geometry: new ol.geom.Point(coords)
});
vectorSources.addFeature(feature2);
map.getView().fitExtent(vectorSources.getExtent(), map.getSize());

The method vectorSources.getExtent() can also be replaced by any Extent object, like this :

~~map.getView().fitExtent([1,43,8,45], map.getSize());~~

Since OpenLayer 3.9, the method has changed :

map.getView().fit(vectorSources.getExtent(), map.getSize());

Thanks. This seems to be the **extent** of the documentation right now: http://openlayers.org/en/v3.0.0/apidoc/ol.extent.html — colllin, Oct 19 '14 at 16:15

Grmpfhmbl · Answer 3 · 2015-08-14T09:46:43.477

5

Just to add a little example to the answer: Bounds is now called "extent" and it's not a sophisticated Object/Class anymore, but merely an array of four numbers. There're a bunch of helper functions for transformation and so on in "ol.extent". Just a little example on how to to a transformation:

var tfn = ol.proj.getTransform('EPSG:4326', 'EPSG:3857');
var textent = ol.extent.applyTransform([6, 43, 16, 50], tfn);

var textent = ol.proj.transformExtent([6, 43, 16, 50], 'EPSG:4326', 'EPSG:3857');

~~I could not find an API-Doc so far in http://ol3js.org/en/master/apidoc so you have to read the source to get information.~~

~~The API-Docs have been completed since the BETA. So you'll find it now.~~

As mentioned in the comments, the correct API-function is ol.proj.transformExtent() now.

edited Aug 14 '15 at 09:46

answered Apr 02 '14 at 08:26

Grmpfhmbl

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I think ol.extent.transform has been renamed to ol.extent.applyTransform – Peter Oct 24 '14 at 19:30
The function to use for transforming an extent is `ol.proj.transformExtent`. – erilem Nov 26 '14 at 19:35
Thank you. At the time of writing this function did not exist. :-) – Grmpfhmbl Nov 27 '14 at 12:05

score 2 · Answer 4 · edited May 23 '17 at 12:00

On OpenLayers 3.17.1 and after trying various thing I was able to set the bounds in two different ways:

A) As @Grmpfhmbl mentioned, using ol.proj.transformExtent function like below:

var extent = ol.proj.transformExtent(
    [-0.6860987, 50.9395474, -0.2833177, 50.7948214],
    "EPSG:4326", "EPSG:3857"
);

map.getView().fit( extent, map.getSize() );

B) A little bit unusual, using ol.geom.Polygon like this:

// EPSG:3857 is optional as it is the default value
var a = ol.proj.fromLonLat( [-0.6860987, 50.9395474], "EPSG:3857" ),
    b = ol.proj.fromLonLat( [-0.2833177, 50.7948214], "EPSG:3857" ),
    extent = new ol.geom.Polygon([[a, b]]);

map.getView().fit( extent, map.getSize() );

How do Bounds work in OpenLayers 3?

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