[core] Improve LatLngBounds API

* Use "named constructors": empty, world, hull
* Make the two-argument constructor lenient (i.e., it is a hull operation)
* Add various accessors
* Enforce a single empty representation

5 files changed, 37 insertions, 43 deletions

diff --git a/platform/android/src/jni.cpp b/platform/android/src/jni.cpp
index 228d758f3b..4e76095a06 100755
--- a/platform/android/src/jni.cpp
+++ b/platform/android/src/jni.cpp
@@ -1182,10 +1182,9 @@ jlongArray JNICALL nativeGetAnnotationsInBounds(JNIEnv *env, jobject obj, jlong
         return nullptr;
     }
 
-    mbgl::LatLngBounds bounds({ swLat, swLon }, { neLat, neLon });
-
     // assume only points for now
-    std::vector<uint32_t> annotations = nativeMapView->getMap().getPointAnnotationsInBounds(bounds);
+    std::vector<uint32_t> annotations = nativeMapView->getMap().getPointAnnotationsInBounds(
+        mbgl::LatLngBounds::hull({ swLat, swLon }, { neLat, neLon }));
 
     return std_vector_uint_to_jobject(env, annotations);
 }
diff --git a/platform/darwin/MGLGeometry_Private.h b/platform/darwin/MGLGeometry_Private.h
index bf5bc4e0ff..72123827df 100644
--- a/platform/darwin/MGLGeometry_Private.h
+++ b/platform/darwin/MGLGeometry_Private.h
@@ -21,13 +21,13 @@ NS_INLINE CLLocationCoordinate2D MGLLocationCoordinate2DFromLatLng(mbgl::LatLng
 }
 
 NS_INLINE MGLCoordinateBounds MGLCoordinateBoundsFromLatLngBounds(mbgl::LatLngBounds latLngBounds) {
-    return MGLCoordinateBoundsMake(MGLLocationCoordinate2DFromLatLng(latLngBounds.sw),
-                                   MGLLocationCoordinate2DFromLatLng(latLngBounds.ne));
+    return MGLCoordinateBoundsMake(MGLLocationCoordinate2DFromLatLng(latLngBounds.southwest()),
+                                   MGLLocationCoordinate2DFromLatLng(latLngBounds.northeast()));
 }
 
 NS_INLINE mbgl::LatLngBounds MGLLatLngBoundsFromCoordinateBounds(MGLCoordinateBounds coordinateBounds) {
-    return mbgl::LatLngBounds(MGLLatLngFromLocationCoordinate2D(coordinateBounds.sw),
-                              MGLLatLngFromLocationCoordinate2D(coordinateBounds.ne));
+    return mbgl::LatLngBounds::hull(MGLLatLngFromLocationCoordinate2D(coordinateBounds.sw),
+                                    MGLLatLngFromLocationCoordinate2D(coordinateBounds.ne));
 }
 
 NS_INLINE BOOL MGLCoordinateInCoordinateBounds(CLLocationCoordinate2D coordinate, MGLCoordinateBounds coordinateBounds) {
diff --git a/platform/darwin/MGLMultiPoint.mm b/platform/darwin/MGLMultiPoint.mm
index fd27cf7819..3cd0f0c117 100644
--- a/platform/darwin/MGLMultiPoint.mm
+++ b/platform/darwin/MGLMultiPoint.mm
@@ -16,7 +16,7 @@ mbgl::Color MGLColorObjectFromCGColorRef(CGColorRef cgColor) {
 {
     CLLocationCoordinate2D *_coords;
     size_t _count;
-    mbgl::LatLngBounds _bounds;
+    MGLCoordinateBounds _bounds;
 }
 
 - (instancetype)initWithCoordinates:(CLLocationCoordinate2D *)coords
@@ -28,13 +28,16 @@ mbgl::Color MGLColorObjectFromCGColorRef(CGColorRef cgColor) {
     {
         _count = count;
         _coords = (CLLocationCoordinate2D *)malloc(_count * sizeof(CLLocationCoordinate2D));
-        _bounds = mbgl::LatLngBounds::getExtendable();
+
+        mbgl::LatLngBounds bounds = mbgl::LatLngBounds::empty();
 
         for (NSUInteger i = 0; i < _count; i++)
         {
             _coords[i] = coords[i];
-            _bounds.extend(mbgl::LatLng(coords[i].latitude, coords[i].longitude));
+            bounds.extend(mbgl::LatLng(coords[i].latitude, coords[i].longitude));
         }
+
+        _bounds = MGLCoordinateBoundsFromLatLngBounds(bounds);
     }
 
     return self;
@@ -93,20 +96,12 @@ mbgl::Color MGLColorObjectFromCGColorRef(CGColorRef cgColor) {
 
 - (MGLCoordinateBounds)overlayBounds
 {
-    return {
-        CLLocationCoordinate2DMake(_bounds.sw.latitude,  _bounds.sw.longitude),
-        CLLocationCoordinate2DMake(_bounds.ne.latitude, _bounds.ne.longitude)
-    };
+    return _bounds;
 }
 
 - (BOOL)intersectsOverlayBounds:(MGLCoordinateBounds)overlayBounds
 {
-    mbgl::LatLngBounds area(
-        mbgl::LatLng(overlayBounds.sw.latitude, overlayBounds.sw.longitude),
-        mbgl::LatLng(overlayBounds.ne.latitude, overlayBounds.ne.longitude)
-    );
-
-    return _bounds.intersects(area);
+    return MGLLatLngBoundsFromCoordinateBounds(_bounds).intersects(MGLLatLngBoundsFromCoordinateBounds(overlayBounds));
 }
 
 - (void)addShapeAnnotationObjectToCollection:(std::vector<mbgl::ShapeAnnotation> &)shapes withDelegate:(id <MGLMultiPointDelegate>)delegate {
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index c9d3145e2e..fdecf2b243 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -2177,8 +2177,8 @@ mbgl::Duration MGLDurationInSeconds(NSTimeInterval duration)
 /// Converts a geographic bounding box to a rectangle in the view’s coordinate
 /// system.
 - (CGRect)convertLatLngBounds:(mbgl::LatLngBounds)bounds toRectToView:(nullable UIView *)view {
-    CGRect rect = { [self convertLatLng:bounds.sw toPointToView:view], CGSizeZero };
-    rect = MGLExtendRect(rect, [self convertLatLng:bounds.ne toPointToView:view]);
+    CGRect rect = { [self convertLatLng:bounds.southwest() toPointToView:view], CGSizeZero };
+    rect = MGLExtendRect(rect, [self convertLatLng:bounds.northeast() toPointToView:view]);
     return rect;
 }
 
@@ -2186,7 +2186,7 @@ mbgl::Duration MGLDurationInSeconds(NSTimeInterval duration)
 /// bounding box.
 - (mbgl::LatLngBounds)convertRect:(CGRect)rect toLatLngBoundsFromView:(nullable UIView *)view
 {
-    mbgl::LatLngBounds bounds = mbgl::LatLngBounds::getExtendable();
+    mbgl::LatLngBounds bounds = mbgl::LatLngBounds::empty();
     bounds.extend([self convertPoint:rect.origin toLatLngFromView:view]);
     bounds.extend([self convertPoint:{ CGRectGetMaxX(rect), CGRectGetMinY(rect) } toLatLngFromView:view]);
     bounds.extend([self convertPoint:{ CGRectGetMaxX(rect), CGRectGetMaxY(rect) } toLatLngFromView:view]);
@@ -2195,26 +2195,26 @@ mbgl::Duration MGLDurationInSeconds(NSTimeInterval duration)
     // The world is wrapping if a point just outside the bounds is also within
     // the rect.
     mbgl::LatLng outsideLatLng;
-    if (bounds.sw.longitude > -180)
+    if (bounds.west() > -180)
     {
         outsideLatLng = {
-            (bounds.sw.latitude + bounds.ne.latitude) / 2,
-            bounds.sw.longitude - 1,
+            (bounds.south() + bounds.north()) / 2,
+            bounds.west() - 1,
         };
     }
-    else if (bounds.ne.longitude < 180)
+    else if (bounds.east() < 180)
     {
         outsideLatLng = {
-            (bounds.sw.latitude + bounds.ne.latitude) / 2,
-            bounds.ne.longitude + 1,
+            (bounds.south() + bounds.north()) / 2,
+            bounds.east() + 1,
         };
     }
     
     // If the world is wrapping, extend the bounds to cover all longitudes.
     if (CGRectContainsPoint(rect, [self convertLatLng:outsideLatLng toPointToView:view]))
     {
-        bounds.sw.longitude = -180;
-        bounds.ne.longitude = 180;
+        bounds.extend(mbgl::LatLng(bounds.south(), -180));
+        bounds.extend(mbgl::LatLng(bounds.south(),  180));
     }
     
     return bounds;
@@ -2965,7 +2965,7 @@ mbgl::Duration MGLDurationInSeconds(NSTimeInterval duration)
 {
     if ( ! annotations || ! annotations.count) return;
 
-    mbgl::LatLngBounds bounds = mbgl::LatLngBounds::getExtendable();
+    mbgl::LatLngBounds bounds = mbgl::LatLngBounds::empty();
 
     for (id <MGLAnnotation> annotation in annotations)
     {
diff --git a/platform/osx/src/MGLMapView.mm b/platform/osx/src/MGLMapView.mm
index 96144d964f..3a92c1901d 100644
--- a/platform/osx/src/MGLMapView.mm
+++ b/platform/osx/src/MGLMapView.mm
@@ -2180,8 +2180,8 @@ public:
 /// Converts a geographic bounding box to a rectangle in the view’s coordinate
 /// system.
 - (NSRect)convertLatLngBounds:(mbgl::LatLngBounds)bounds toRectToView:(nullable NSView *)view {
-    NSRect rect = { [self convertLatLng:bounds.sw toPointToView:view], NSZeroSize };
-    rect = MGLExtendRect(rect, [self convertLatLng:bounds.ne toPointToView:view]);
+    NSRect rect = { [self convertLatLng:bounds.southwest() toPointToView:view], NSZeroSize };
+    rect = MGLExtendRect(rect, [self convertLatLng:bounds.northeast() toPointToView:view]);
     return rect;
 }
 
@@ -2192,7 +2192,7 @@ public:
 /// Converts a rectangle in the given view’s coordinate system to a geographic
 /// bounding box.
 - (mbgl::LatLngBounds)convertRect:(NSRect)rect toLatLngBoundsFromView:(nullable NSView *)view {
-    mbgl::LatLngBounds bounds = mbgl::LatLngBounds::getExtendable();
+    mbgl::LatLngBounds bounds = mbgl::LatLngBounds::empty();
     bounds.extend([self convertPoint:rect.origin toLatLngFromView:view]);
     bounds.extend([self convertPoint:{ NSMaxX(rect), NSMinY(rect) } toLatLngFromView:view]);
     bounds.extend([self convertPoint:{ NSMaxX(rect), NSMaxY(rect) } toLatLngFromView:view]);
@@ -2201,22 +2201,22 @@ public:
     // The world is wrapping if a point just outside the bounds is also within
     // the rect.
     mbgl::LatLng outsideLatLng;
-    if (bounds.sw.longitude > -180) {
+    if (bounds.west() > -180) {
         outsideLatLng = {
-            (bounds.sw.latitude + bounds.ne.latitude) / 2,
-            bounds.sw.longitude - 1,
+            (bounds.south() + bounds.north()) / 2,
+            bounds.west() - 1,
         };
-    } else if (bounds.ne.longitude < 180) {
+    } else if (bounds.northeast().longitude < 180) {
         outsideLatLng = {
-            (bounds.sw.latitude + bounds.ne.latitude) / 2,
-            bounds.ne.longitude + 1,
+            (bounds.south() + bounds.north()) / 2,
+            bounds.east() + 1,
         };
     }
     
     // If the world is wrapping, extend the bounds to cover all longitudes.
     if (NSPointInRect([self convertLatLng:outsideLatLng toPointToView:view], rect)) {
-        bounds.sw.longitude = -180;
-        bounds.ne.longitude = 180;
+        bounds.extend(mbgl::LatLng(bounds.south(), -180));
+        bounds.extend(mbgl::LatLng(bounds.south(),  180));
     }
     
     return bounds;