view.fit() using view.animate() in OpenLayers 3.20

Question

I have the following code, written for OpenLayers pre 3.20:

fitViewToFeature: function (viewer, feature) {
    var pan = ol.animation.pan({
      source: viewer.olView.getCenter(),
      duration: 1000
    })

    var zoom = ol.animation.zoom({
      resolution: viewer.olView.getResolution(),
      duration: 1000
    })

    viewer.olMap.beforeRender(pan, zoom)

    viewer.olView.fit(feature.getGeometry(), viewer.olMap.getSize(), {
      padding: [ 100, 100, 100, 100 ],
      constrainResolution: false,
      maxZoom: 4
    })
}

My question is how to translate this function into the new view.animate() syntax introduced in OpenLayers 3.20?

Or alternately, should I open a GitHub issue and request a new option to be added to view.animate?

Answer 1

You should be able to achieve the same animation in a much simpler way, with the duration option of ol.View#fit():

viewer.olView.fit(feature.getGeometry(), {
  duration: 1000
});

The above works in OpenLayers 4.x.

Answer 2

@zsero, I use the same function to zoom to the extent of a layer source. I use view.animate() for up to half of my route and at the callback function I use view.fit().

I need to setTimeout on the view.fit() otherwise I have an error message: Cannot read property 'length' of null at ol.View.updateAnimations_

var origine = view.getCenter();
var destination = ol.extent.getCenter(extent);
var middleDestination = [(origine[0] + destination[0]) / 2, (origine[1] + destination[1]) / 2];
var viewFit = function() {
    setTimeout( function() {
        view.fit(extent, map.getSize(), {
            duration: duration / 2,
            padding: [ 64, 10, 10, 328 ],
            constrainResolution: false
        })
    }, 0)
}
var animation = function() {
    view.animate({
        center: middleDestination,
        duration: duration / 2
    });
    view.animate({
        zoom: zoom - backZoom,
        duration: duration / 2
    }, viewFit);
}