8

I am new to Leaflet as well as Javascript, and I'm looking for some advice on a basic topic.

Currently, I am trying to create a spatial index of library holdings for old topographic maps that people can access and download online. The source of the features is a GeoJSON file.

Sample Map

The problem is that the school library has multiple types of the same map over the years, but when I click on a map, only one popup shows up. I want the option to cycle through multiple maps, but I am unsure on how to approach the problem. Is there a special term in the local jargon for cycling through overlapping polygons, or is there a stronger approach to this problem?

Any advice on the direction I should take is appreciated. Thanks!

9

One option would be to use leaflet point in poly (leaflet.pip) which is available through Mapbox: https://www.mapbox.com/mapbox.js/example/v1.0.0/point-in-polygon/ Or as a leaflet plugin: https://github.com/mapbox/leaflet-pip

The fiddle here: http://jsfiddle.net/TnX96/136/ will show exactly how this would work. Or see the code below....

HTML be sure to include the PIP library:

<script src='https://api.tiles.mapbox.com/mapbox.js/plugins/leaflet-pip/v0.0.2/leaflet-pip.js'></script>

Javascript:

var map = new L.Map('map', {center: new L.LatLng(51, -100), zoom: 4});
var osm = new L.TileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png');
var ggl = new L.Google();
var ggl2 = new L.Google('TERRAIN');
map.addLayer(osm);
map.addControl(new L.Control.Layers( {'Street Maps':osm, 'Satellite':ggl, 'Terrain':ggl2}, {}));

function handleClick(e) {
    var html = '';
        var match = leafletPip.pointInLayer(
            // the clicked point
            e.latlng,
            // this layer
            streets,
            // whether to stop at first match
            false);
        if (match.length) {
            for (var i = 0; i < match.length; i++) { 
                html += "<br>"+"_____"+
                        "<br><b>" + match[i].feature.properties.title + ", " + match[i].feature.properties.subtitle + ":</b>" + 
                        "<br>Scale: " + match[i].feature.properties.Scale + 
                        "<br>Year Published: " + match[i].feature.properties.year + 
                        "<br><br><b>URL for map:</b> <a>" + match[i].feature.properties.location2 + "</a>"+
                        "<br><b>URL for cropped, georeferenced map:</b> <a>"+ match[i].feature.properties.location1 + "</a>"+
                        "<br><b>URL for KML:</b> <a>" + match[i].feature.properties.location3 +"</a>"

            }
        }
    if (html) {
        map.openPopup(html, e.latlng);
    }
}

var streets = new L.geoJson(histMap)
    .on('click', handleClick)
    .addTo(map);
  • Wow, and thank you! I was hoping for a term or two to google when I asked this. This, is quite a lot more. – brianbancroft Jun 7 '15 at 4:31

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