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Evangelism/Firefox3.5/35Days/Articles/geolocationDemo: Difference between revisions
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Evangelism/Firefox3.5/35Days/Articles/geolocationDemo (view source)
Revision as of 14:37, 8 June 2009
, 8 June 2009→Geolocation API and free data providers
| Line 13: | Line 13: | ||
var lat1 = aLatitude*Math.PI/180; | var lat1 = aLatitude*Math.PI/180; | ||
var lon1 = aLongitude*Math.PI/180; | var lon1 = aLongitude*Math.PI/180; | ||
// Point at 45° North East | // Point at 45° North East | ||
var brng = 45*Math.PI/180; | var brng = 45*Math.PI/180; | ||
| Line 24: | Line 23: | ||
lat2 =lat2*180/Math.PI; | lat2 =lat2*180/Math.PI; | ||
lon2 =lon2*180/Math.PI; | lon2 =lon2*180/Math.PI; | ||
// Point at 45° South West | |||
var brng = 225*Math.PI/180; | |||
var lat3 = Math.asin( Math.sin(lat1)*Math.cos(aAccuracy/R) + | |||
Math.cos(lat1)*Math.sin(aAccuracy/R)*Math.cos(brng) ); | |||
var lon3 = lon1 + | |||
Math.atan2( Math.sin(brng)*Math.sin(aAccuracy/R)*Math.cos(lat1), | |||
Math.cos(aAccuracy/R)-Math.sin(lat1)*Math.sin(lat3)); | |||
lon3 = (lon3+Math.PI)%(2*Math.PI) - Math.PI; | |||
lat3 =lat3*180/Math.PI; | |||
lon3 =lon3*180/Math.PI; | |||
// return the extent | |||
return {north:lat2,south:lat3,east:lon2,west:lon3}; | |||
} | } | ||
Une fois que nous connaissons cet extent, the map is zoom to extent (center to the position with a precision reflecting the accuracy) and we query GeoNames to know geolocalised wikipedia's article and places inside the accuracy extent. If the accuracy is less than 1000 meters, we used to query GeoNames an accuracy extent based on an accuracy of 1000 meters. | Une fois que nous connaissons cet extent, the map is zoom to extent (center to the position with a precision reflecting the accuracy) and we query GeoNames to know geolocalised wikipedia's article and places inside the accuracy extent. If the accuracy is less than 1000 meters, we used to query GeoNames an accuracy extent based on an accuracy of 1000 meters. | ||