[ios] Sort accessibility elements by screen distance from center

Sort annotation accessibility elements by screen distance, not the hypotenuse of coordinates, which can yield incorrect results when the map is rotated or tilted or when the user is located at high latitudes. Sort place feature accessibility elements by screen distance as well.

1 files changed, 18 insertions, 10 deletions

diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index c59eff6569..0622802502 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -2428,24 +2428,24 @@ public:
         return self.userLocationAnnotationView;
     }
     
+    CGPoint centerPoint = self.contentCenter;
+    if (self.userTrackingMode != MGLUserTrackingModeNone)
+    {
+        centerPoint = self.userLocationAnnotationViewCenter;
+    }
+    
     // Visible annotations
     NSRange visibleAnnotationRange = NSMakeRange(NSMaxRange(userLocationAnnotationRange), visibleAnnotations.size());
     if (NSLocationInRange(index, visibleAnnotationRange))
     {
         std::sort(visibleAnnotations.begin(), visibleAnnotations.end());
-        CGPoint centerPoint = self.contentCenter;
-        if (self.userTrackingMode != MGLUserTrackingModeNone)
-        {
-            centerPoint = self.userLocationAnnotationViewCenter;
-        }
-        CLLocationCoordinate2D currentCoordinate = [self convertPoint:centerPoint toCoordinateFromView:self];
         std::sort(visibleAnnotations.begin(), visibleAnnotations.end(), [&](const MGLAnnotationTag tagA, const MGLAnnotationTag tagB) {
             CLLocationCoordinate2D coordinateA = [[self annotationWithTag:tagA] coordinate];
             CLLocationCoordinate2D coordinateB = [[self annotationWithTag:tagB] coordinate];
-            CLLocationDegrees deltaA = hypot(coordinateA.latitude - currentCoordinate.latitude,
-                                             coordinateA.longitude - currentCoordinate.longitude);
-            CLLocationDegrees deltaB = hypot(coordinateB.latitude - currentCoordinate.latitude,
-                                             coordinateB.longitude - currentCoordinate.longitude);
+            CGPoint pointA = [self convertCoordinate:coordinateA toPointToView:self];
+            CGPoint pointB = [self convertCoordinate:coordinateB toPointToView:self];
+            CGFloat deltaA = hypot(pointA.x - centerPoint.x, pointA.y - centerPoint.y);
+            CGFloat deltaB = hypot(pointB.x - centerPoint.x, pointB.y - centerPoint.y);
             return deltaA < deltaB;
         });
         
@@ -2459,6 +2459,14 @@ public:
     NSRange visiblePlaceFeatureRange = NSMakeRange(NSMaxRange(visibleAnnotationRange), visiblePlaceFeatures.count);
     if (NSLocationInRange(index, visiblePlaceFeatureRange))
     {
+        visiblePlaceFeatures = [visiblePlaceFeatures sortedArrayUsingComparator:^NSComparisonResult(id <MGLFeature> _Nonnull featureA, id <MGLFeature> _Nonnull featureB) {
+            CGPoint pointA = [self convertCoordinate:featureA.coordinate toPointToView:self];
+            CGPoint pointB = [self convertCoordinate:featureB.coordinate toPointToView:self];
+            CGFloat deltaA = hypot(pointA.x - centerPoint.x, pointA.y - centerPoint.y);
+            CGFloat deltaB = hypot(pointB.x - centerPoint.x, pointB.y - centerPoint.y);
+            return [@(deltaA) compare:@(deltaB)];
+        }];
+        
         id <MGLFeature> feature = visiblePlaceFeatures[index - visiblePlaceFeatureRange.location];
         return [self accessibilityElementForFeature:feature withIdentifier:feature.identifier];
     }