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ghuntley/get-all-markers-on-map-get-all-polygons-on-map-find-which-markers-are-within-a-polygon.js

Created February 26, 2013 05:29
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  1. ghuntley created this gist Feb 26, 2013.
    171 changes: 171 additions & 0 deletions get-all-markers-on-map-get-all-polygons-on-map-find-which-markers-are-within-a-polygon.js
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    // <summary>
    // Logging methods.
    // </summary>
    Log = {
    Dump: function (object)
    {
    if (object)
    {
    console.debug(object);
    }
    },
    Info: function (message, object)
    {
    console.info("### " + message)
    this.Dump(object);
    },
    Error: function (message, object)
    {
    console.error("+++ " + message);
    this.Dump(object);
    },
    }


    // <summary>
    // Return array of polygons, for each polygon
    // return the lat/longs which define the shape
    // of the object.
    // </sumary>
    // <returns>
    // [
    // Array[3]
    // 0: n.LatLng
    // 1: n.LatLng
    // 2: n.LatLng
    // length: 3
    // __proto__: Array[0]
    // ,
    // Array[3],
    // Array[3]
    // ]
    // </returns>
    function GetPolygons()
    {
    var items = window.drawnItems._layers;

    var collection = _.map(items, function(polygon)
    { return polygon._latlngs;
    });

    return collection;
    }

    // <summary>
    // Returns array of all markers (lat/long/description)
    // any markers found with invalid data are ignored.
    // </sumary>
    function GetMarkers()
    {
    var items = window.markers._map._layers;

    var collection = _.map(items, function(marker)
    {
    var description;
    var location;

    if (_.isEmpty(marker._popup))
    {
    Log.Info("marker found without description", marker);
    return;
    }

    description = marker._popup._content;

    if (_.isEmpty(marker._latlng))
    {
    Log.Info("marker found without latitude/longitude", marker);
    return;
    }

    location = marker._latlng;

    return {
    description: description,
    location: location
    };
    });

    var results = _.filter(collection, function(marker)
    {
    // exclude any markers that have empty/undefined
    // description or locations from the results
    if (_.isEmpty(marker)) return false;
    if (_.isEmpty(marker.description)) return false;
    if (_.isEmpty(marker.location)) return false;

    // marker has passed validation, allow it to exist.
    return true;
    });

    return results;
    }


    // <summary>
    // Checks if marker is within a polygon, algorithm
    // originally programmed in C, have ported it to JS.
    // disclaimer: no idea how or even why this algorithm
    // works. See the original implementation for a fantastic
    // explanation (with pictures) of the problem space/theory.
    // http://alienryderflex.com/polygon/
    // </summary>
    function IsMarkerInPolygon(marker, polygon)
    {
    if (_.isEmpty(polygon))
    {
    Log.Error("IsMarkerInPolygon: invalid polygon", polygon);
    return false;
    }

    if (_.isEmpty(marker))
    {
    Log.Error("IsMarkerInPolygon: invalid marker", marker);
    return false;
    }

    var j = 0;

    var sides = polygon.length;

    var x = marker.lng;
    var y = marker.lat;

    var inPoly = false;

    for (var i=0; i < sides; i++) {
    j++;
    if (j == sides) {j = 0;}
    if (((polygon[i].lat < y) && (polygon[j].lat >= y)) || ((polygon[j].lat < y) && (polygon[i].lat >= y)))
    {
    if (polygon[i].lng + (y - polygon[i].lat) / (polygon[j].lat-polygon[i].lat) * (polygon[j].lng - polygon[i].lng)<x )
    {
    inPoly = !inPoly
    }
    }
    }

    return inPoly;
    }

    // <summary>
    // Returns all markers found within a polygon.
    // </summary>
    function GetMarkersInPolygon(polygon)
    {
    if (_.isEmpty(polygon))
    {
    Log.Error("GetMarkersInPolygon: invalid polygon", polygon);
    return;
    }

    var markers = GetMarkers();


    var results = _.filter(markers, function(marker)
    {
    return IsMarkerInPolygon(marker.location, polygon);
    });

    return results;
    }
    41 changes: 41 additions & 0 deletions leafletjs.js
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    var map = L.map('map');

    window.drawnItems = new L.FeatureGroup();
    map.addLayer(drawnItems);

    var drawControl = new L.Control.Draw({
    draw: {
    position: 'topleft',
    polygon: {
    title: 'Draw a polygon',
    allowIntersection: false,
    drawError: {
    color: 'red',
    timeout: 1000
    },
    shapeOptions: {
    color: '#333333'
    }
    },
    circle: false,
    polyline: false,
    marker: false,
    rectangle: false
    },
    edit: {
    featureGroup: drawnItems,
    edit: {
    title: 'Edit a polygon'
    },
    remove: {
    title: 'Delete a polygon'
    }
    }
    });

    map.addControl(drawControl);

    window.markers = new L.KML("markers.kml", {async: true});
    markers.on("loaded", function(e) {
    map.addLayer(markers);
    });