From 28981611f1f929d2ccd66faf7afb9f3e78844298 Mon Sep 17 00:00:00 2001
From: Dennis Guse <dennis.guse@alumni.tu-berlin.de>
Date: Sun, 20 Aug 2023 19:38:37 +0200
Subject: [PATCH] GPX export: skip gain/loss if not present.

Part of #1671.
---
 src/androidTest/res/raw/gpx_timezone.gpx                  | 2 --
 .../opentracks/io/file/exporter/GPXTrackExporter.java     | 8 ++++++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/androidTest/res/raw/gpx_timezone.gpx b/src/androidTest/res/raw/gpx_timezone.gpx
index 82bcef041..23d754843 100644
--- a/src/androidTest/res/raw/gpx_timezone.gpx
+++ b/src/androidTest/res/raw/gpx_timezone.gpx
@@ -31,8 +31,6 @@ xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/
 <gpxtrkx:MovingTime>0</gpxtrkx:MovingTime>
 <gpxtrkx:StoppedTime>0</gpxtrkx:StoppedTime>
 <gpxtrkx:MaxSpeed>0.0</gpxtrkx:MaxSpeed>
-<gpxtrkx:Ascent>null</gpxtrkx:Ascent>
-<gpxtrkx:Descent>null</gpxtrkx:Descent>
 </gpxtrkx:TrackStatsExtension>
 </extensions>
 <trkseg>
diff --git a/src/main/java/de/dennisguse/opentracks/io/file/exporter/GPXTrackExporter.java b/src/main/java/de/dennisguse/opentracks/io/file/exporter/GPXTrackExporter.java
index a2354f861..a4de84eab 100644
--- a/src/main/java/de/dennisguse/opentracks/io/file/exporter/GPXTrackExporter.java
+++ b/src/main/java/de/dennisguse/opentracks/io/file/exporter/GPXTrackExporter.java
@@ -279,8 +279,12 @@ public class GPXTrackExporter implements TrackExporter {
         printWriter.println("<gpxtrkx:MovingTime>" + trackStatistics.getMovingTime().getSeconds() + "</gpxtrkx:MovingTime>");
         printWriter.println("<gpxtrkx:StoppedTime>" + trackStatistics.getStoppedTime().getSeconds() + "</gpxtrkx:StoppedTime>");
         printWriter.println("<gpxtrkx:MaxSpeed>" + trackStatistics.getMaxSpeed().toMPS() + "</gpxtrkx:MaxSpeed>");
-        printWriter.println("<gpxtrkx:Ascent>" + trackStatistics.getTotalAltitudeGain() + "</gpxtrkx:Ascent>");
-        printWriter.println("<gpxtrkx:Descent>" + trackStatistics.getTotalAltitudeLoss() + "</gpxtrkx:Descent>");
+        if (trackStatistics.hasTotalAltitudeGain()) {
+            printWriter.println("<gpxtrkx:Ascent>" + trackStatistics.getTotalAltitudeGain() + "</gpxtrkx:Ascent>");
+        }
+        if (trackStatistics.hasTotalAltitudeLoss()) {
+            printWriter.println("<gpxtrkx:Descent>" + trackStatistics.getTotalAltitudeLoss() + "</gpxtrkx:Descent>");
+        }
         printWriter.println("</gpxtrkx:TrackStatsExtension>");
 
         printWriter.println("</extensions>");