13,400,804 members (37,768 online)
Tip/Trick
alternative version

Stats

29.8K views
9 bookmarked
Posted 9 Jan 2012

Google Directions API Polyline Points Decoder in C#

, 9 Jan 2012
Google Directions API Polyline Points Decoder in C#
I have an algorithm for Google Directions API Polyline Points Decoder in C#. It may save you some development time.

Assuming that you have collected encoded point string from the Google Direction API Call.

```private List<Location> DecodePolylinePoints(string encodedPoints)
{
if (encodedPoints == null || encodedPoints == "") return null;
List<Location> poly = new List<Location>();
char[] polylinechars = encodedPoints.ToCharArray();
int index = 0;

int currentLat = 0;
int currentLng = 0;
int next5bits;
int sum;
int shifter;

try
{
while (index < polylinechars.Length)
{
// calculate next latitude
sum = 0;
shifter = 0;
do
{
next5bits = (int)polylinechars[index++] - 63;
sum |= (next5bits & 31) << shifter;
shifter += 5;
} while (next5bits >= 32 && index < polylinechars.Length);

if (index >= polylinechars.Length)
break;

currentLat += (sum & 1) == 1 ? ~(sum >> 1) : (sum >> 1);

//calculate next longitude
sum = 0;
shifter = 0;
do
{
next5bits = (int)polylinechars[index++] - 63;
sum |= (next5bits & 31) << shifter;
shifter += 5;
} while (next5bits >= 32 && index < polylinechars.Length);

if (index >= polylinechars.Length && next5bits >= 32)
break;

currentLng += (sum & 1) == 1 ? ~(sum >> 1) : (sum >> 1);
Location p = new Location();
p.Latitude = Convert.ToDouble(currentLat) / 100000.0;
p.Longitude = Convert.ToDouble(currentLng) / 100000.0;
}
}
catch (Exception ex)
{
// logo it
}
return poly;
}```

Here `Location `is simply a class with Latitude and Longitude attributes.

Share

 Software Developer (Senior) Pakistan
Expertise on Enterprise solutions, Mobile Apps & Services based applications on .NET platform. As Sr. Software Engineer, I have worked on variety of technologies like ASP.NET MVC, MS Windows Phone 7, WCF, and MS SharePoint 2010, MS Dynamics CRM.

You may also be interested in...

 Pro

 First Prev Next
 Thanks, saves me some coding time. toy4fun9-Feb-14 6:57 toy4fun 9-Feb-14 6:57
 Message Closed 24-Sep-13 0:26 Ravi.Kumar021 24-Sep-13 0:26
 Last Visit: 31-Dec-99 19:00     Last Update: 19-Feb-18 12:27 Refresh 1