EXIF Data and the Map Object

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a JPEG image stores location information if the user allows that feature. Let’s look at an example in which the user can choose an image from the camera roll, read its location information, and display the corresponding map:

import com.google.maps.Map;
import com.google.maps.MapEvent;
import com.google.maps.LatLng;
import com.google.maps.MapType;
import com.google.maps.overlays.Marker;
import com.google.maps.overlays.MarkerOptions;
import flash.events.Event;
import flash.events.MediaEvent;
import flash.media.CameraRoll;
import flash.net.URLRequest;
import jp.shichiseki.exif.*;
public static KEY:String = YOUR_API_KEY;
public static SITE:String = YOUR_SITE;

var cameraRoll:CameraRoll;
var exifLoader:ExifLoader;
var map:Map;

Create your Map object as before:

map = new Map();
map.url = SITE;
map.key = KEY;
map.sensor = “false”;
map.setSize(new Point(stage.stageWidth, stage.stageHeight));
map.addEventListener(MapEvent.MAP_READY, onMapReady);
addChild(map);

Get an image from the device Gallery using the CameraRoll API:

function onMapReady(event:MapEvent):void {
map.setCenter
(new LatLng(40.736072, -73.992062), 14, MapType.NORMAL_MAP_TYPE);
if (CameraRoll.supportsBrowseForImage) {
var camera:CameraRoll = new CameraRoll();
camera.addEventListener(MediaEvent.SELECT, onImageSelected);
camera.browseForImage();
}
}

After the user selects an image, create an instance of the ExifLoader class and pass it the photo url. It will load the image and read its EXIF data:

function onImageSelected(event:MediaEvent):void {
exifLoader = new ExifLoader();
exifLoader.addEventListener(Event.COMPLETE, onExifRead);
exifLoader.load(new URLRequest(event.data.file.url));
}

If the image contains geolocation information, it is used to draw the map and a marker at the exact location:

function onImageLoaded(event:Event):void {
var exif:ExifInfo = reader.exif;
if (exif.ifds.gps) {
var gpsIfd:IFD = exif.ifds.gps;
var exifLat:Array = gpsIfd[“GPSLatitude”] as Array;
var latitude:Number = shorten(exifLat, gpsIfd[“GPSLatitudeRef”]);
var exifLon:Array = gpsIfd[“GPSLongitude”] as Array;
var longitude:Number = shorten(exifLon, gpsIfd[“GPSLongitudeRef”]);
var marker:Marker;
var parts:Array;
marker = new Marker(new LatLng(latitude, longitude));
map.addOverlay(marker);
map.setCenter(new LatLng(latitude, longitude));
}
}

function shorten(info:Array, reference:String):Number {
var degree:Number = info[0] + (info[1]/60) + (info[2]/3600);
// position from Greenwich and equator
if (reference == “S” || reference == “E”) {
degree * -1;
}
return degree;
}

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