add elevationGain property

Author: jgillich

src/main/kotlin/be/yellowduck/gpx/Segment.kt

@@ -25,6 +25,23 @@ data class Segment(
             return Distance(distance)
         }
 
+    /**
+     * Returns the total elevation gain of the segment
+     */
+    val elevationGain: Double
+        get() {
+            var total = 0.0
+            points.forEachIndexed { index, point ->
+                if (index > 0) {
+                    val ele = points[index].ele - points[index - 1].ele
+                    if (ele > 0) {
+                        total += ele
+                    }
+                }
+            }
+            return total
+        }
+
     /**
      * Returns the segment as an encoded polyline string.
      *

src/main/kotlin/be/yellowduck/gpx/Track.kt

@@ -21,6 +21,14 @@ data class Track(
             return Distance(segments.sumOf { it.distance.meters })
         }
 
+    /**
+     * Returns the total elevation gain of the track
+     */
+    val elevationGain: Double
+        get() {
+            return segments.sumOf { it.elevationGain }
+        }
+
     /**
      * Returns the segment as an encoded polyline string.
      *

src/test/kotlin/be/yellowduck/gpx/TrackTests.kt

@@ -0,0 +1,13 @@
+package be.yellowduck.gpx
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+
+class TrackTests {
+    @Test
+    fun testElevationGain() {
+        val path = "src/test/resources/Gravelgrinders_Gent_4.gpx"
+        val gpx = GPX.parse(path)
+        assertThat(gpx.tracks.firstOrNull()?.elevationGain).isEqualTo(469.7999999999836)
+    }
+}