Openlayers write and save a KML based on your map

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时光说笑
时光说笑 2021-02-04 17:43

Is it possible to write and save a KML from OpenLayers? Anyone know of an example of exporting one?

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3条回答
  • 2021-02-04 18:02

    Here's some JQuery action to save:

    $('#saveKML').click(function() {
     var kmlFormat = new OpenLayers.Format.KML();
     var newWindow = window.open('', 
      'KML Export ' + (new Date()).getTime(), "width=300,height=300");
       newWindow.document.write('<textarea id="kml" style="width: 100%; height: 100%">' + 
       kmlFormat.write(features) + '</textarea>');
    });
    
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  • 2021-02-04 18:04

    IF you are using Openlayers 3 or 4, you will find that the syntax of previous (2012) answers does not work anymore.

    This does:

            function GetKMLFromFeatures(features) {
                var format = new ol.format.KML();
                var kml = format.writeFeatures(features, {featureProjection: 'EPSG:3857'});
                return kml;
            }
            function GetGeoJSONFromFeatures(features) {
                var format = new ol.format.GeoJSON();
                var geoJSON = format.writeFeatures(features, {featureProjection: 'EPSG:3857'});
                return geoJSON;
            }
            function GetFeaturesFromLayer(layer) {
                var source = layer.getSource();
                var features = source.getFeatures();
                return features;
            }
    
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  • 2021-02-04 18:08

    You can export only the vector features to KML.

    function GetKMLFromFeatures(features) {
        var format = new OpenLayers.Format.KML({
            'maxDepth':10,
            'extractStyles':true,
            'internalProjection': map.baseLayer.projection,
            'externalProjection': new OpenLayers.Projection("EPSG:4326")
        });
    
        return format.write(features);
    }
    

    UPDATE

    In order to force the browser to download the KML string as a KML file you need to send that string back to the server-side so it can be returned to the browser as a file to download.

    You haven't specified what language/platform/etc you are using on the server-side But this is what i did in C#.

    I created a handler which takes in a the filename from the querystring and the KML from a textarea form.

    KMLDownload.ashx:

    <%@ WebHandler Language="C#" Class="KMLDownload" %>
    
    using System;
    using System.Web;
    
    public class KMLDownload : IHttpHandler
    {
    
        public void ProcessRequest(HttpContext context)
        {
    
    
            HttpResponse response = context.Response;
    
            string kml = context.Request["kml"];
            string filename = context.Request.QueryString["filename"];
    
            if (String.IsNullOrEmpty(kml))
            {
                context.Response.ContentType = "text/plain";
                context.Response.Write("{\"error\":\"No files recevied\"}");
            }
            else
            {
    
                if (String.IsNullOrEmpty(filename)){
                    filename = "Features_KML.kml";
                }
    
                // force a download of the kml file.
                response.Clear();
                response.ContentType = "application/kml";
                response.AddHeader("Content-Disposition", "attachment; filename=" + filename);
                response.AddHeader("content-legth", kml.Length.ToString());
                response.Write(kml.ToString());
                response.End();
            }
    
        }
    
        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    
    }
    

    Then from my javascript side i simply call this to initiate the download:

    var filename = "NameofKMLfileI_WANT.kml";
    
    var url = "secure/KMLDownload.ashx";
    if (filename) {
        url += "?filename=" + filename;
    }
    
    var input = '<TEXTAREA name="kml">' + kml + '</TEXTAREA>';
    
    //send request
    jQuery('<form action="' + url + '" method="post">' + input + '</form>').appendTo('body').submit().remove();
    
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