Implements precision on Decode and Encode

[rodo]

Some tools like OSRM uses the same algorithm but with different precision,; this patch allows to indicate precision on function Decode and Encode.

[emcconville]

Hey rodo,

Thanks for the great work + test cases!

Precision control is a great idea & I'd love to integrate this library with OSRM, but I'm not satisfied with the design of this solution. The encoder & decoder must be in agreement of precision at all times, and shouldn't be passed as a optional parameter. Here's why

• Encoded string doesn't communicate the precision level.
• Mixing precision level at run time will introduce undefined behavior ( functional test will pass, but behavior ones will fail )
• Users may be given a false sense of assumption that they are free to adjust precision, yet Google, Bing, and others are pretty strict on rounding.

But Honestly

Controlling precision level is a good idea. I'd propose achieving this on a defined application layer, not within the user's run-time configuration. Keep the $number * pow(...) methods, but replace the local $precision variable to a late static binding. Also remove the second argument from the parameters.

class Polyline {
   static $precision = 5;
   // ...
   final public static function Encode($points) {
     // ...
     $number = floor($number * pow(10, static::$precision));
     // ... &tc

Anyone who wishes to customize, or use a vendor specific precision can simply extend the class, and overwrite the default level.

class PolylineOSRM extends Polyline {
  protected static $precision = 6;
} // done

Now the only challenge would be communicating how to implement precision level.

[RSully]

Sad to see this hasn't had any updates. Interested in what comes of this.