Customize GPX export.

app/build.gradle.kts

@@ -26,8 +26,8 @@ android {
         }
     }
     compileOptions {
-        sourceCompatibility = JavaVersion.VERSION_1_8
+        sourceCompatibility = JavaVersion.VERSION_17
-        targetCompatibility = JavaVersion.VERSION_1_8
+        targetCompatibility = JavaVersion.VERSION_17
     }
 }
 
@@ -50,4 +50,9 @@ dependencies {
 
     // optional - Guava support for Room, including Optional and ListenableFuture
     implementation("androidx.room:room-guava:$room_version")
+
+    implementation("io.jenetics:jpx:3.1.0")
+    // https://mvnrepository.com/artifact/org.codehaus.woodstox/woodstox-core-asl
+    implementation("org.codehaus.woodstox:woodstox-core-asl:4.4.1")
+
 }

app/src/main/java/com/proculite/logmylocation/LocationDao.java

@@ -2,9 +2,15 @@ package com.proculite.logmylocation;
 
 import androidx.room.Dao;
 import androidx.room.Insert;
+import androidx.room.Query;
+
+import java.util.List;
 
 @Dao
 public interface LocationDao {
     @Insert
     void insert(LocationEntity location);
+
+    @Query("SELECT * FROM locationentity")
+    List<LocationEntity> getAll();
 }

app/src/main/java/com/proculite/logmylocation/LocationLoggingService.java

@@ -65,6 +65,10 @@ public class LocationLoggingService extends Service implements LocationListener
         return super.onStartCommand(intent, flags, startId);
     }
 
+    public List<LocationEntity> allLocations(){
+        return locationDao.getAll();
+    }
+
     @SuppressLint("MissingPermission")
     public void subscribeToLocationUpdates(LocationListener locationListener)
     {

app/src/main/java/com/proculite/logmylocation/LocationLoggingServiceBinder.java

@@ -3,6 +3,8 @@ package com.proculite.logmylocation;
 import android.location.LocationListener;
 import android.os.Binder;
 
+import java.util.List;
+
 public class LocationLoggingServiceBinder extends Binder {
     private final LocationLoggingService service;
 
@@ -17,4 +19,8 @@ public class LocationLoggingServiceBinder extends Binder {
     public void subscribeToLocationUpdates(LocationListener locationListener){
         this.service.subscribeToLocationUpdates(locationListener);
     }
+
+    public List<LocationEntity> allLocations(){
+        return this.service.allLocations();
+    }
 }

app/src/main/java/com/proculite/logmylocation/MainActivity.java

@@ -9,6 +9,7 @@ import android.location.LocationListener;
 import android.os.Bundle;
 import android.os.IBinder;
 import android.util.Log;
+import android.widget.Button;
 import android.widget.TextView;
 
 import androidx.activity.EdgeToEdge;
@@ -18,13 +19,29 @@ import androidx.core.graphics.Insets;
 import androidx.core.view.ViewCompat;
 import androidx.core.view.WindowInsetsCompat;
 
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.io.PipedInputStream;
+import java.io.PipedOutputStream;
+import java.io.Writer;
+
+import io.jenetics.jpx.GPX;
+import io.jenetics.jpx.WayPoint;
+
 public class MainActivity extends AppCompatActivity implements LocationListener, ServiceConnection {
     private final String TAG = MainActivity.class.getName();
+    private Button exportButton;
+    private WriteToFile writeToFile;
+    private static boolean includeComments = false;
+    private static Double accuracyThreshold = 2.0;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
+        writeToFile = new WriteToFile(this,"application/gpx");
+
         Intent serviceIntent = new Intent(this, LocationLoggingService.class);
         startForegroundService(serviceIntent);
 
@@ -35,6 +52,8 @@ public class MainActivity extends AppCompatActivity implements LocationListener,
             v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
             return insets;
         });
+
+        exportButton = findViewById(R.id.buttonExport);
     }
 
     @Override
@@ -69,6 +88,89 @@ public class MainActivity extends AppCompatActivity implements LocationListener,
 
         LocationLoggingServiceBinder binder = (LocationLoggingServiceBinder) iBinder;
         binder.subscribeToLocationUpdates(this);
+
+        if(exportButton != null){
+            exportButton.setOnClickListener(v -> {
+                Log.d(TAG, "Export button clicked.");
+                new Thread(() -> {
+                    GPX gpx = GPX.builder().addTrack(track -> track.addSegment(segment -> {
+                        for(LocationEntity location : binder.allLocations()){
+                            WayPoint wayPoint = locationToWayPoint(location);
+                            if(wayPoint != null) {
+                                segment.addPoint(wayPoint);
+                            }
+                        }
+                    })).build();
+                    Log.d(TAG, "Built GPX.");
+
+                    writeToFile.write("output.gpx", outputStream -> {
+                        try {
+                        GPX.Writer.of(GPX.Writer.Indent.SPACE4).write(gpx, outputStream);
+                        } catch (IOException e) {
+                            Log.e(TAG, "Failed to write.");
+                        }
+                    });
+                }).start();
+            });
+        }
+    }
+
+    private static WayPoint locationToWayPoint(LocationEntity location) {
+        if(accuracyThreshold != null)
+        {
+            if(location.accuracy == null) {
+                return null;
+            }
+
+            if(location.accuracy > accuracyThreshold) {
+                return null;
+            }
+        }
+
+        WayPoint.Builder builder = WayPoint.builder()
+                .lat(location.latitude)
+                .lon(location.longitude)
+                .time(location.unixTime);
+
+        if(location.speed != null){
+            builder.speed(location.speed);
+        }
+
+        if(location.bearing != null){
+            builder.course(location.bearing);
+        }
+
+        if(location.altitude != null){
+            builder.ele(location.altitude);
+        }
+
+        if(includeComments) {
+            StringBuilder commentBuilder = new StringBuilder();
+
+            if (location.isMock) {
+                commentBuilder.append("Location is mock.\n");
+            }
+
+            if (location.accuracy != null) {
+                commentBuilder.append(String.format("Accuracy is expected to be within %s meters.\n", location.accuracy));
+            }
+
+            if (location.altitudeAccuracy != null) {
+                commentBuilder.append(String.format("Altitude accuracy is expected to be within %s meters.\n", location.altitudeAccuracy));
+            }
+
+            if (location.bearingAccuracy != null) {
+                commentBuilder.append(String.format("Bearing accuracy is expected to be within %s degrees.\n", location.bearingAccuracy));
+            }
+
+            if (location.speedAccuracy != null) {
+                commentBuilder.append(String.format("Speed accuracy is expected to be within %s meters per second.\n", location.speedAccuracy));
+            }
+
+            builder.cmt(commentBuilder.toString());
+        }
+
+        return builder.build();
     }
 
     @Override

app/src/main/java/com/proculite/logmylocation/WriteToFile.java

@@ -0,0 +1,58 @@
+package com.proculite.logmylocation;
+
+import android.net.Uri;
+import android.os.ParcelFileDescriptor;
+import android.util.Log;
+
+import androidx.activity.result.ActivityResultCallback;
+import androidx.activity.result.ActivityResultLauncher;
+import androidx.activity.result.contract.ActivityResultContracts;
+import androidx.appcompat.app.AppCompatActivity;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.function.Consumer;
+
+public class WriteToFile implements ActivityResultCallback<Uri> {
+    private final String TAG = WriteToFile.class.getName();
+    private Consumer<OutputStream> fileConsumer;
+    private final AppCompatActivity activityCompat;
+    private final ActivityResultLauncher<String> launcher;
+
+    public WriteToFile(AppCompatActivity activity, String fileMimeType)
+    {
+        this.activityCompat = activity;
+        this.launcher = activity.registerForActivityResult(
+                new ActivityResultContracts.CreateDocument(fileMimeType), this);
+    }
+
+    @Override
+    public void onActivityResult(Uri o) {
+        if(o == null || o.getPath() == null)
+        {
+            Log.d(TAG, "Attempting to write to null path.");
+            return;
+        }
+
+        Log.d(TAG, String.format("Writing to file: %s", o.getPath()));
+
+        try {
+            try (ParcelFileDescriptor fileDescriptor = this.activityCompat.getContentResolver().openFileDescriptor(o, "w")) {
+                if (fileDescriptor == null) {
+                    Log.e(TAG, "Parcel file descriptor is null.");
+                    return;
+                }
+                try (FileOutputStream fileOutputStream = new FileOutputStream(fileDescriptor.getFileDescriptor())) {
+                    fileConsumer.accept(fileOutputStream);
+                }
+            }
+        }  catch (IOException e) {
+            Log.e(TAG, "Failed to write to file.");
+        }
+    }
+
+    public void write(String fileName, Consumer<OutputStream> fileConsumer){
+        this.fileConsumer = fileConsumer;
+        launcher.launch(fileName);
+    }
+}

app/src/main/res/layout/activity_main.xml

@@ -18,4 +18,13 @@
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 
+    <Button
+        android:id="@+id/buttonExport"
+        app:layout_constraintTop_toBottomOf="@+id/textViewMain"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        android:text="Export"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content" />
+
 </androidx.constraintlayout.widget.ConstraintLayout>