1 files changed, 65 insertions, 0 deletions
diff --git a/platform/darwin/src/MGLPolyline.mm b/platform/darwin/src/MGLPolyline.mm
index ae4fbe61de..fd75dc2795 100644
--- a/platform/darwin/src/MGLPolyline.mm
+++ b/platform/darwin/src/MGLPolyline.mm
@@ -6,6 +6,7 @@
 #import "MGLPolyline+MGLAdditions.h"
 
 #import <mbgl/util/geojson.hpp>
+#import <mapbox/polylabel.hpp>
 
 @implementation MGLPolyline
 
@@ -52,6 +53,61 @@
     return self == other || ([other isKindOfClass:[MGLPolyline class]] && [super isEqual:other]);
 }
 
+- (CLLocationCoordinate2D)coordinate {
+    NSUInteger count = self.pointCount;
+    NSAssert(count > 0, @"Polyline must have coordinates");
+
+    CLLocationCoordinate2D *coordinates = self.coordinates;
+    CLLocationDistance middle = [self length] / 2.0;
+    CLLocationDistance traveled = 0.0;
+    
+    if (count > 1 || middle > traveled) {
+        for (NSUInteger i = 0; i < count; i++) {
+            
+            MGLRadianCoordinate2D from = MGLRadianCoordinateFromLocationCoordinate(coordinates[i]);
+            MGLRadianCoordinate2D to = MGLRadianCoordinateFromLocationCoordinate(coordinates[i + 1]);
+            
+            if (traveled >= middle) {
+                double overshoot = middle - traveled;
+                if (overshoot == 0) {
+                    return coordinates[i];
+                }
+                to = MGLRadianCoordinateFromLocationCoordinate(coordinates[i - 1]);
+                CLLocationDirection direction = [self direction:from to:to] - 180;
+                MGLRadianCoordinate2D otherCoordinate = MGLRadianCoordinateAtDistanceFacingDirection(from,
+                                                                                                     overshoot/mbgl::util::EARTH_RADIUS_M,
+                                                                                                     MGLRadiansFromDegrees(direction));
+                return CLLocationCoordinate2DMake(MGLDegreesFromRadians(otherCoordinate.latitude),
+                                                  MGLDegreesFromRadians(otherCoordinate.longitude));
+            }
+            
+            traveled += (MGLDistanceBetweenRadianCoordinates(from, to) * mbgl::util::EARTH_RADIUS_M);
+            
+        }
+    }
+
+    return coordinates[count - 1];
+}
+
+- (CLLocationDistance)length
+{
+    CLLocationDistance length = 0.0;
+    
+    NSUInteger count = self.pointCount;
+    CLLocationCoordinate2D *coordinates = self.coordinates;
+    
+    for (NSUInteger i = 0; i < count - 1; i++) {        
+        length += (MGLDistanceBetweenRadianCoordinates(MGLRadianCoordinateFromLocationCoordinate(coordinates[i]),                                                  MGLRadianCoordinateFromLocationCoordinate(coordinates[i + 1])) * mbgl::util::EARTH_RADIUS_M);
+    }
+    
+    return length;
+}
+
+- (CLLocationDirection)direction:(MGLRadianCoordinate2D)from to:(MGLRadianCoordinate2D)to
+{
+    return MGLDegreesFromRadians(MGLRadianCoordinatesDirection(from, to));
+}
+
 @end
 
 @interface MGLMultiPolyline ()
@@ -114,6 +170,15 @@
     return hash;
 }
 
+- (CLLocationCoordinate2D)coordinate {
+    MGLPolyline *polyline = self.polylines.firstObject;
+    CLLocationCoordinate2D *coordinates = polyline.coordinates;
+    NSAssert([polyline pointCount] > 0, @"Polyline must have coordinates");
+    CLLocationCoordinate2D firstCoordinate = coordinates[0];
+
+    return firstCoordinate;
+}
+
 - (BOOL)intersectsOverlayBounds:(MGLCoordinateBounds)overlayBounds {
     return MGLCoordinateBoundsIntersectsCoordinateBounds(_overlayBounds, overlayBounds);
 }