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Revision as of 19:27, 21 November 2011 by Maveric (Talk | contribs)

HERE Maps API - How to check the Date Border Crossing

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Created: Maveric (16 Nov 2011)
Last edited: Maveric (21 Nov 2011)

This article explains how to check the Date Border Crossing.


Contents

Introduction

The isCDBA flag of the BoundingBox in Nokia Maps API has been added since v2 to indicate that the bounding box is crossing the date border. A bounding box which is spanned from -180° (left) to +180° (right) is NOT crossing the date border. Default value is false.

The API reference link: http://api.maps.nokia.com/2.0.0/apireference/symbols/nokia.maps.geo.BoundingBox.html?s=isCDB#isCDB

The International Date Line (IDL) Definition by WikiPedia.org

IDL is a generally north-south imaginary line on the surface of the Earth, passing through the middle of the Pacific Ocean, that designates the place where each calendar day begins. It is roughly along 180° longitude, opposite the Prime Meridian, but it is drawn with diversions to pass around some territories and island groups.Crossing the IDL travelling east results in a day or 24 hours being subtracted, so that the traveller repeats the date to the west of the line. Full description here: http://en.wikipedia.org/wiki/International_Date_Line

Example code

This example first adds two Markers for which the BoundingBox is not crossing the International Date Line. A third Marker is then randomly added to coordinates that will cause the check to produce the BoundingBox to have crossed the IDL.

<html>
<head>
<script type="text/javascript" charset="UTF-8" src="http://api.maps.nokia.com/2.0.0/jsl.js"></script>
</head>
<body>
<div id="map" style="width:100%; height:100%;"></div>
<script type="text/javascript">
 
var map = new nokia.maps.map.Display(document.getElementById("map"),
{ components: [ new nokia.maps.map.component.Behavior()],
{
'zoomLevel': 10,
'center':[-1.366667, 176.466667]
}
);
 
var markerContainer = new nokia.maps.map.Container()
markerContainer.objects.add(
new nokia.maps.map.StandardMarker
(
[-1.366667, 176.466667],
{
text: "-1.366667, 176.466667",
draggable: false
}));
 
markerContainer.objects.add(
new nokia.maps.map.StandardMarker(
[-1.366667, 180.000000],
{
text: "-1.366667, 180.000000",
draggable: false,
}));
 
map.objects.add(markerContainer);
map.zoomTo(markerContainer.getBoundingBox(),false,true);
 
// Check for Date Border Crossing
checkDateBorder();
 
// Add new Marker randomly
markerContainer.objects.add(
new nokia.maps.map.StandardMarker(
[Math.random() * 180 - 90, -176.000],
{ text: "-176.000, 179.000",
draggable: false,
}));
 
map.zoomTo(markerContainer.getBoundingBox(),false,true);
 
// Check for Date Border Crossing
 
checkDateBorder();
 
function checkDateBorder()
{
var CDB = markerContainer.getBoundingBox().isCDB;
if (CDB == false)
{
alert("False - The Bounding box is not crossing the date border");
} else if(CDB == true)
{
alert("True - The Bounding box crosses the date border");
}
}
 
</script>
</body>
</html>

Tested with

FireFox 7.0.1


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