Merge pull request #2 from Free2MoveApp/fix-polyline-on-small-negativ…

…e-delta

Fix polyline encoding for cases with very small negative delta

polyline/src/main/scala/com/free2move/geoscala/polyline.scala

@@ -48,7 +48,7 @@ object polyline {
 
   private def num2Poly(num: Double): String = {
     val scaled = Math.round(num * 1e5).toInt
-    val bits = if (num < 0.0) ~(scaled << 1) else scaled << 1
+    val bits = if (scaled < 0.0) ~(scaled << 1) else scaled << 1
     chunkMasks
       .map {
         case (mask, idx) =>

polyline/src/test/scala/com/free2move/geoscala/PolylineTest.scala

@@ -16,6 +16,7 @@
 package com.free2move.geoscala
 
 import org.scalacheck._
+import org.scalactic.{Equality, TolerantNumerics}
 import org.scalatest._
 import org.scalatestplus.scalacheck.ScalaCheckDrivenPropertyChecks
 
@@ -41,6 +42,17 @@ class PolylineTest extends FlatSpec with Matchers with OptionValues with TryValu
     polyline.encode(decoded) shouldBe poly
   }
 
+  it should "handle cases where coordinate delta is slightly negative (< 10^-5)" in {
+    val ls = LineString(List(Coordinate(13.39336395263672,52.52311483252328), Coordinate(13.39332,52.52311)))
+    val encoded = polyline.encode(ls)
+    val decoded = polyline.decode(encoded).success.value
+    implicit val doubleEquality: Equality[Double] = TolerantNumerics.tolerantDoubleEquality(0.00001) // 10^-5
+    decoded.coordinates.head.latitude should ===(ls.coordinates.head.latitude)
+    decoded.coordinates.head.longitude should ===(ls.coordinates.head.longitude)
+    decoded.coordinates.tail.head.latitude should ===(ls.coordinates.tail.head.latitude)
+    decoded.coordinates.tail.head.longitude should ===(ls.coordinates.tail.head.longitude)
+  }
+
   implicit val coordGen: Gen[Coordinate] = for {
     lat <- Gen.chooseNum[Double](-90.0, +90.0)
     lng <- Gen.chooseNum[Double](-180.0, +180.0)