4 files changed, 26 insertions, 6 deletions
diff --git a/src/core/DataCollection.vala b/src/core/DataCollection.vala
index 83a216d..044f7b6 100644
--- a/src/core/DataCollection.vala
+++ b/src/core/DataCollection.vala
@@ -559,7 +559,7 @@ public class DataCollection {
         if (!properties.unset(name))
             return;
         
-        // only notify if the propery was unset (that is, was set to begin with)
+        // only notify if the property was unset (that is, was set to begin with)
         notify_property_cleared(name);
             
         // notify all items
diff --git a/src/core/DataSourceTypes.vala b/src/core/DataSourceTypes.vala
index a79264f..1baf387 100644
--- a/src/core/DataSourceTypes.vala
+++ b/src/core/DataSourceTypes.vala
@@ -72,9 +72,9 @@ public abstract class EventSource : ThumbnailSource {
         base (object_id);
     }
     
-    public abstract time_t get_start_time();
+    public abstract DateTime? get_start_time();
     
-    public abstract time_t get_end_time();
+    public abstract DateTime? get_end_time();
     
     public abstract uint64 get_total_filesize();
     
diff --git a/src/core/SourceInterfaces.vala b/src/core/SourceInterfaces.vala
index 91a8aca..6e0c149 100644
--- a/src/core/SourceInterfaces.vala
+++ b/src/core/SourceInterfaces.vala
@@ -42,3 +42,18 @@ public interface Indexable : DataSource {
     }
 }
 
+// Positionable DataSources provide a globally locatable point in longitude and latitude degrees
+
+public struct GpsCoords {
+    public int has_gps;
+    public double latitude;
+    public double longitude;
+    public bool equals(ref GpsCoords gps) {
+        return (has_gps == 0 && gps.has_gps == 0) || (latitude == gps.latitude && longitude == gps.longitude);
+    }
+}
+
+public interface Positionable : DataSource {
+    public abstract GpsCoords get_gps_coords();
+    public abstract void set_gps_coords(GpsCoords gps_coords);
+}
diff --git a/src/core/util.vala b/src/core/util.vala
index 9507895..461d2c0 100644
--- a/src/core/util.vala
+++ b/src/core/util.vala
@@ -190,7 +190,12 @@ public bool null_progress_monitor(uint64 count, uint64 total) {
     return true;
 }
 
+public static int64 nullsafe_date_time_comperator(DateTime? time_a, DateTime? time_b) {
+    if (time_a == null && time_b == null) return 0;
 
-double degrees_to_radians(double theta) {
-    return (theta * (GLib.Math.PI / 180.0));
-}
+    if (time_a == null && time_b != null) return -1;
+    if (time_a != null && time_b == null) return 1;
+
+    return time_a.compare(time_b);
+
+}
+\ No newline at end of file