[android] union should take date line into considerationupstream/osana-latlngbounds-union-dateline

3 files changed, 54 insertions, 4 deletions

diff --git a/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/geometry/LatLngBounds.java b/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/geometry/LatLngBounds.java
index df8f764f44..fb12a76b55 100644
--- a/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/geometry/LatLngBounds.java
+++ b/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/geometry/LatLngBounds.java
@@ -444,10 +444,21 @@ public class LatLngBounds implements Parcelable {
    * @return BoundingBox
    */
   public LatLngBounds union(final double latNorth, final double lonEast, final double latSouth, final double lonWest) {
-    return new LatLngBounds((this.latitudeNorth < latNorth) ? latNorth : this.latitudeNorth,
-      (this.longitudeEast < lonEast) ? lonEast : this.longitudeEast,
-      (this.latitudeSouth > latSouth) ? latSouth : this.latitudeSouth,
-      (this.longitudeWest > lonWest) ? lonWest : this.longitudeWest);
+    double north = (this.latitudeNorth < latNorth) ? latNorth : this.latitudeNorth;
+    double south = (this.latitudeSouth > latSouth) ? latSouth : this.latitudeSouth;
+
+    if (LatLngSpan.getLongitudeSpan(lonEast, this.longitudeWest)
+      < LatLngSpan.getLongitudeSpan(this.longitudeEast, lonWest)) {
+      return new LatLngBounds(north,
+        lonEast,
+        south,
+        this.longitudeWest);
+    }
+
+    return new LatLngBounds(north,
+      this.longitudeEast,
+      south,
+      lonWest);
   }
 
   /**
diff --git a/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/geometry/LatLngSpan.java b/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/geometry/LatLngSpan.java
index 322c7dfb74..133949f743 100644
--- a/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/geometry/LatLngSpan.java
+++ b/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/geometry/LatLngSpan.java
@@ -4,6 +4,8 @@ import android.os.Parcel;
 import android.os.Parcelable;
 import android.support.annotation.NonNull;
 
+import com.mapbox.mapboxsdk.constants.GeometryConstants;
+
 /**
  * A geographical span defined by its latitude and longitude span.
  */
@@ -136,4 +138,20 @@ public class LatLngSpan implements Parcelable {
     result = 31 * result + (int) (temp ^ (temp >>> 32));
     return result;
   }
+
+  /**
+   * Get the absolute distance, in degrees, between the west and
+   * east boundaries of this LatLngBounds
+   *
+   * @return Span distance
+   */
+  static double getLongitudeSpan(double east, double west) {
+    double longSpan = Math.abs(east - west);
+    if (east > west) {
+      return longSpan;
+    }
+
+    // shortest span contains antimeridian
+    return GeometryConstants.LONGITUDE_SPAN - longSpan;
+  }
 }
diff --git a/platform/android/MapboxGLAndroidSDK/src/test/java/com/mapbox/mapboxsdk/geometry/LatLngBoundsTest.java b/platform/android/MapboxGLAndroidSDK/src/test/java/com/mapbox/mapboxsdk/geometry/LatLngBoundsTest.java
index 29ffd6bbbe..940fde1257 100644
--- a/platform/android/MapboxGLAndroidSDK/src/test/java/com/mapbox/mapboxsdk/geometry/LatLngBoundsTest.java
+++ b/platform/android/MapboxGLAndroidSDK/src/test/java/com/mapbox/mapboxsdk/geometry/LatLngBoundsTest.java
@@ -338,6 +338,27 @@ public class LatLngBoundsTest {
   }
 
   @Test
+  public void unionOverDateLine() {
+    LatLngBounds latLngBounds1 = new LatLngBounds.Builder()
+      .include(new LatLng(10, 170))
+      .include(new LatLng(0, 160))
+      .build();
+
+    LatLngBounds latLngBounds2 = new LatLngBounds.Builder()
+      .include(new LatLng(0, -170))
+      .include(new LatLng(-10, -160))
+      .build();
+
+    assertEquals("outer union should match",
+      latLngBounds1.union(latLngBounds2),
+      new LatLngBounds.Builder()
+        .include(new LatLng(10, 160))
+        .include(new LatLng(-10, -160))
+        .build());
+  }
+
+
+  @Test
   public void northWest() {
     double minLat = 5;
     double minLon = 6;