[GIS] Getting zoom-in previous/next in OpenLayers 3

openlayerszoom

How to get Zoom-in, Zoom-out for previous or next in OpenLayers 3. There are controls for Zoom in or Zoom out for levels and area wise. They are as follows:

    Area zoom:
    var dragzoomin = new ol.interaction.DragZoom({
                condition: ol.events.condition.always
                });
    map.addInteraction(dragzoomin);     

Zoom in for levels

    var view = map.getView();
            view.setZoom(view.getZoom() + 1);

We can get zoom out if it is level wise.
But if it is area wise how to get zoom out and how to store these zoom in and zoom out events for entire session.

Best Answer

You can easily hook it up to the browser's history's buttons. See: http://openlayers.org/en/latest/examples/permalink.html for an example of how to do this.

Related Solutions

[GIS] OpenLayers 3: Zoom and center at map startup

From this discussion, it seems there is no event when the map is "ready" (at least for openlayers3).

A solution is to add a map.setView() function to your geolocalisation layer:

  // Layout map
  var layer = new ol.layer.Vector({
    map: map,
    source: new ol.source.Vector({
      features: [accuracyFeature, positionFeature]
    })
  });

  layer.once("change", function(){
    map.setView(new ol.View({
      center: geolocation.getPosition(),
      zoom: 15
    }));
  });

[GIS] Openlayers 4 and View Extent

extent is the extent of for the view's center constraint, not the extent of the viewable map. You could set an extent on the layer, but that would result in white space inside the view. To maintain a 2km x 2km constraint on the view's edges as could be done in OpenLayers 2 you would need to change the view as the resolution changes (ignoring very small changes to avoid performance issues):

    var extent = map.getView().calculateExtent(); // opening coverage
//    var extent = [529449 - 1000, 189252 - 1000, 529449 + 1000, 189252 + 1000]; // 2km box
    var resolution = 0;
    
    function resChange() {
        var newResolution = map.getView().getResolution();
        if (resolution == 0 || Math.abs((newResolution-resolution)/resolution) > 0.01) {
            resolution = newResolution;
            var width = map.getSize()[0] * resolution;
            var height = map.getSize()[1] * resolution;
            var view = new ol.View({
                projection: map.getView().getProjection(),
                extent: [extent[0]+(width/2), extent[1]+(height/2), extent[2]-(width/2), extent[3]-(height/2)],
                center: map.getView().getCenter(),
                resolution: resolution,
                maxZoom: map.getView().getMaxZoom(),
                minZoom: map.getView().getMinZoom()
            });
            view.on('change:resolution', resChange);
            map.setView(view);
        }
    }
    
    resChange();

UPDATE: The answer applies OpenLayers 3, 4 and 5. In OpenLayers 6 extent does define the view extent (as in did in Openlayers 2).

Best Answer

Related Solutions

[GIS] OpenLayers 3: Zoom and center at map startup

[GIS] Openlayers 4 and View Extent

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