Is there a 'getZoomForResolution' in OpenLayers 3?

问题

OpenLayers 2 used to have a getZoomForResolution method that would give you the zoom level (or closest zoom level) of a given resolution.

I don't see any such method in ol3, for the ol.View object that is. Is there a way to achieve this with what ol.view currently have ?

回答1:

This will give the next closest integer zoom for a give resolution:

function zoomForResolution(resolution) {
    var zoom = 0;
    var r = 156543.03390625; // resolution for zoom 0
    while (resolution < r) {
        r /= 2;
        zoom++;
        if (resolution > r) {
            return zoom;
        }
    }
    return zoom; // resolution was greater than 156543.03390625 so return 0
}

zoomForResolution(40); // 12

My brother suggested:

var zoom = Math.ceil( (Math.log(resolution) - Math.log(156543.03390625) ) / Math.log(0.5))

refining the logarithmic solution for browsers with Math.log2()

var zoom = Math.log2(156543.03390625) - Math.log2(resolution);

and for IE which does not have log2()

var zoom = Math.log(156543.03390625) * Math.LOG2E  - Math.log(resolution) * Math.LOG2E;

来源：https://stackoverflow.com/questions/29900520/is-there-a-getzoomforresolution-in-openlayers-3