Created
November 13, 2012 03:11
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Handling for Google encoded polygons inside GeoJSON in Leaflet
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| // extend GeoJSON to handle google-encoded linestrings | |
| // assumes that any array of coordinates that make up a linestring are replaced with the google encoded line string | |
| L.extend(L.GeoJSON, { | |
| // This function is from Google's polyline utility. | |
| // Borrowed from: http://facstaff.unca.edu/mcmcclur/GoogleMaps/EncodePolyline/decode.js | |
| // Changed to return lng/lats instead of lat/lngs | |
| decodeLine: function (encoded) { | |
| var len = encoded.length; | |
| var index = 0; | |
| var array = []; | |
| var lat = 0; | |
| var lng = 0; | |
| while (index < len) { | |
| var b; | |
| var shift = 0; | |
| var result = 0; | |
| do { | |
| b = encoded.charCodeAt(index++) - 63; | |
| result |= (b & 0x1f) << shift; | |
| shift += 5; | |
| } while (b >= 0x20); | |
| var dlat = ((result & 1) ? ~(result >> 1) : (result >> 1)); | |
| lat += dlat; | |
| shift = 0; | |
| result = 0; | |
| do { | |
| b = encoded.charCodeAt(index++) - 63; | |
| result |= (b & 0x1f) << shift; | |
| shift += 5; | |
| } while (b >= 0x20); | |
| var dlng = ((result & 1) ? ~(result >> 1) : (result >> 1)); | |
| lng += dlng; | |
| array.push([lng * 1e-5, lat * 1e-5]); | |
| } | |
| return array; | |
| }, | |
| coordsToLatLngs: function (coords, levelsDeep, reverse) { // (Array, Number, Boolean) -> Array | |
| var latlng, | |
| latlngs = [], | |
| i, len; | |
| for (i = 0, len = coords.length; i < len; i++) { | |
| if (levelsDeep === 1 && typeof coords[i] === 'string') { | |
| coords[i] = this.decodeLine(coords[i]); | |
| } | |
| latlng = levelsDeep ? | |
| this.coordsToLatLngs(coords[i], levelsDeep - 1, reverse) : | |
| this.coordsToLatLng(coords[i], reverse); | |
| latlngs.push(latlng); | |
| } | |
| return latlngs; | |
| } | |
| }); |
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