Adding custom markers dynamically to map using OpenLayers

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 2  2014

I would like to let users add custom markers on a map with a description for each marker. Any tips, links to any tutorials would be really useful.

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佛祖请我去吃肉

2021-02-04 10:36

i tried @Fran 's solution but it didnt work for me. so i adapted this example from openlayers so that i could accomplish 2 things:

save latitude and longitude of marker position

place a marker by clicking on the openlayers map

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" debug="true">
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <title>MousePosition Control</title>
    <link rel="stylesheet" href="http://openlayers.org/dev/theme/default/style.css" type="text/css">
    <link rel="stylesheet" href="http://openlayers.org/dev/examples/style.css" type="text/css">
    <script src="../OpenLayers.js"></script>
    <script type="text/javascript">
        var map;
        function init(){
            var map = new OpenLayers.Map('map');
            var proj4326 = new OpenLayers.Projection("EPSG:4326");
            var projmerc = new OpenLayers.Projection("EPSG:900913");
            var layerOSM = new OpenLayers.Layer.OSM("Street Map");
            map.addLayers([layerOSM]);
            if (!map.getCenter()) map.zoomToMaxExtent();
            map.events.register("mousemove", map, function(e) { 
                var position = this.events.getMousePosition(e);
                OpenLayers.Util.getElement("coords").innerHTML = 'MOUSE POSITION '+position;
                var lonlat = map.getLonLatFromPixel( this.events.getMousePosition(e) );
                OpenLayers.Util.getElement("lonlatTG").innerHTML = 'lonlat => '+lonlat;
                var lonlatTransf = lonlat.transform(map.getProjectionObject(), proj4326);
                OpenLayers.Util.getElement("lonlatTrans").innerHTML = 'lonlatTransf => '+lonlatTransf;
                OpenLayers.Util.getElement("lonlatDouble").innerHTML = 'lonlat => '+lonlat;
            });

            map.events.register("click", map, function(e) {
                var position = this.events.getMousePosition(e);
                var icon = new OpenLayers.Icon('http://maps.google.com/mapfiles/ms/icons/red-pushpin.png');   
                var lonlat = map.getLonLatFromPixel(position);
                var lonlatTransf = lonlat.transform(map.getProjectionObject(), proj4326);
                alert ('lonlatTrans=> lat='+lonlatTransf.lat+' lon='+lonlatTransf.lon+'\nlonlat=>'+lonlat+'\nposition=>'+position);
                var lonlat = lonlatTransf.transform(proj4326, map.getProjectionObject());
                var markerslayer = new OpenLayers.Layer.Markers( "Markers" );
                markerslayer.addMarker(new OpenLayers.Marker(lonlat, icon));
                map.addLayer(markerslayer);
            });
            map.addControl(new OpenLayers.Control.LayerSwitcher());
        }
    </script>
  </head>  

  <body onload="init()">
    <h1 id="title">MousePosition Control</h1>
    <div id="tags">coordinate</div>
    <p>Click on map and create marker</p>
    <div id="map" class="smallmap"></div>
    <div id="coords"></div>
    <div id="lonlatTG"></div>
    <div id="lonlatTrans"></div><br/>
    <p>
    see how, even though we did NOT transform [lonlat],
    <br/>it was nevertheless transformed
    </p>
    <div id="lonlatDouble"></div>

  </body>
</html>

there is something that you need to be aware of regarding the TRANSFORM method for LonLat as used in this simple example: when you apply [ .transform(projection1, projection2) ] to any LonLat, ALL LonLat objects are transformed.

play around with the order of certain commands and you will see what i mean.

for draggable markers, this example has it all

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我在风中等你

2021-02-04 10:38

You can register a function to 'click' event on your map. When the user click on it, the mark is added automatically.

Try something like this:

// 'map' is your map created using new OpenLayers.Map(options)

markers = new OpenLayers.Layer.Markers( "Markers" );
markers.id = "Markers";
map.addLayer(markers);

map.events.register("click", map, function(e) {
      //var position = this.events.getMousePosition(e);
      var position = map.getLonLatFromPixel(e.xy);
      var size = new OpenLayers.Size(21,25);
   var offset = new OpenLayers.Pixel(-(size.w/2), -size.h);
   var icon = new OpenLayers.Icon('images/mark.png', size, offset);   
   var markerslayer = map.getLayer('Markers');

   markerslayer.addMarker(new OpenLayers.Marker(position,icon));

   });

Pretty simple, but I think that you can understand it :)

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