How can I get zoom levels to decode a polyline from Google Maps Directions API?

问题

Following this polyline decoder class from @Kenny:

int[] decodedZoomLevels = PolylineDecoder.decodeZoomLevels(levels);
GeoPoint[] gPts = PolylineDecoder.decodePoints(points, decodedZoomLevels.length);

I'm trying to draw the route from Barcelona to Madrid with Google Maps Directions API:

<DirectionsResponse>
  <status>OK</status>
  <route>
    <leg>
      ...
    </leg>
    <copyrights>Datos de mapa ©2012 Google, Tele Atlas</copyrights>
    <overview_polyline>
      <points>
        cjr{F_u(...)rw@bD~]ln@xo@fnB`M|iAxEvV
      </points>
    </overview_polyline>
  <route>
<DirectionsResponse>

I manage to read the XML response and get \DirectionsResponse\route\overview_polyline\points polyline string; but I cannot find the <levels> tag.

I'm trying to draw smoother line (route) when the users zooms in but freeing smartphone's CPU when the zoom is out.

Am I using wrong API? Or this class is outdated?

Thanks in advance...

回答1:

ZoomLevel is econded inside the polyline "string". In the Kenny's class just give as 2nd parameter to "decodePoints" method the size of the polyline string.

Look at the bottom of this 1 and I wonder you will understand more.

来源：https://stackoverflow.com/questions/9653483/how-can-i-get-zoom-levels-to-decode-a-polyline-from-google-maps-directions-api