[ios, macos] Unwrap coordinate bounds

Updated coordinate bounds conversion methods to use the beyond-±180 method to indicate that the bounds extends beyond the antimeridian. Also copyedited conversion documentation.

2 files changed, 44 insertions, 40 deletions

diff --git a/platform/ios/src/MGLMapView.h b/platform/ios/src/MGLMapView.h
index a4dcc4cdbf..9c18965b09 100644
--- a/platform/ios/src/MGLMapView.h
+++ b/platform/ios/src/MGLMapView.h
@@ -659,11 +659,10 @@ MGL_EXPORT IB_DESIGNABLE
  want to animate the change, call `-setVisibleCoordinateBounds:animated:`
  instead.
  
- If a longitude is less than −180 degrees or greater than 180 degrees, the visible
- bounds straddles the antimeridian or international date line.
- 
- For example, a visible bounds that stretches from Tokyo to San Francisco would have
- coordinates of (35.68476, -220.24257) and (37.78428, -122.41310).
+ If a longitude is less than −180 degrees or greater than 180 degrees, the
+ visible bounds straddles the antimeridian or international date line. For
+ example, if both Tokyo and San Francisco are visible, the visible bounds might
+ extend from (35.68476, −220.24257) to (37.78428, −122.41310).
  */
 @property (nonatomic) MGLCoordinateBounds visibleCoordinateBounds;
 
@@ -671,11 +670,10 @@ MGL_EXPORT IB_DESIGNABLE
  Changes the receiver’s viewport to fit the given coordinate bounds,
  optionally animating the change.
  
- To make the visible bounds go across the antimeridian or international date line,
- specify some longitudes less than −180 degrees or greater than 180 degrees.
- 
- For example, a visible bounds that stretches from Tokyo to San Francisco would have
- coordinates of (35.68476, -220.24257) and (37.78428, -122.41310).
+ To bring both sides of the antimeridian or international date line into view,
+ specify some longitudes less than −180 degrees or greater than 180 degrees. For
+ example, to show both Tokyo and San Francisco simultaneously, you could set the
+ visible bounds to extend from (35.68476, −220.24257) to (37.78428, −122.41310).
 
  @param bounds The bounds that the viewport will show in its entirety.
  @param animated Specify `YES` to animate the change by smoothly scrolling
@@ -686,6 +684,11 @@ MGL_EXPORT IB_DESIGNABLE
 /**
  Changes the receiver’s viewport to fit the given coordinate bounds and
  optionally some additional padding on each side.
+ 
+ To bring both sides of the antimeridian or international date line into view,
+ specify some longitudes less than −180 degrees or greater than 180 degrees. For
+ example, to show both Tokyo and San Francisco simultaneously, you could set the
+ visible bounds to extend from (35.68476, −220.24257) to (37.78428, −122.41310).
 
  @param bounds The bounds that the viewport will show in its entirety.
  @param insets The minimum padding (in screen points) that will be visible
@@ -698,6 +701,11 @@ MGL_EXPORT IB_DESIGNABLE
 /**
  Changes the receiver’s viewport to fit all of the given coordinates and
  optionally some additional padding on each side.
+ 
+ To bring both sides of the antimeridian or international date line into view,
+ specify some longitudes less than −180 degrees or greater than 180 degrees. For
+ example, to show both Tokyo and San Francisco simultaneously, you could set the
+ visible coordinates to (35.68476, −220.24257) and (37.78428, −122.41310).
 
  @param coordinates The coordinates that the viewport will show.
  @param count The number of coordinates. This number must not be greater than
@@ -712,6 +720,11 @@ MGL_EXPORT IB_DESIGNABLE
 /**
  Changes the receiver’s viewport to fit all of the given coordinates and
  optionally some additional padding on each side.
+ 
+ To bring both sides of the antimeridian or international date line into view,
+ specify some longitudes less than −180 degrees or greater than 180 degrees. For
+ example, to show both Tokyo and San Francisco simultaneously, you could set the
+ visible coordinates to (35.68476, −220.24257) and (37.78428, −122.41310).
 
  @param coordinates The coordinates that the viewport will show.
  @param count The number of coordinates. This number must not be greater than
@@ -994,6 +1007,9 @@ MGL_EXPORT IB_DESIGNABLE
 /**
  Converts a rectangle in the given view’s coordinate system to a geographic
  bounding box.
+ 
+ If a longitude is less than −180 degrees or greater than 180 degrees, the
+ bounding box straddles the antimeridian or international date line.
 
  @param rect The rectangle to convert.
  @param view The view in whose coordinate system the rectangle is expressed.
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index c8e084795e..1cb4779555 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -3423,36 +3423,24 @@ public:
 /// bounding box.
 - (mbgl::LatLngBounds)convertRect:(CGRect)rect toLatLngBoundsFromView:(nullable UIView *)view
 {
-    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]);
-    bounds.extend([self convertPoint:{ CGRectGetMinX(rect), CGRectGetMaxY(rect) } toLatLngFromView:view]);
-
-    // The world is wrapping if a point just outside the bounds is also within
-    // the rect.
-    mbgl::LatLng outsideLatLng;
-    if (bounds.west() > -180)
-    {
-        outsideLatLng = {
-            (bounds.south() + bounds.north()) / 2,
-            bounds.west() - 1,
-        };
-    }
-    else if (bounds.east() < 180)
-    {
-        outsideLatLng = {
-            (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.extend(mbgl::LatLng(bounds.south(), -180));
-        bounds.extend(mbgl::LatLng(bounds.south(),  180));
-    }
+    auto bounds = mbgl::LatLngBounds::empty();
+    auto topLeft = [self convertPoint:{ CGRectGetMinX(rect), CGRectGetMinY(rect) } toLatLngFromView:view];
+    auto topRight = [self convertPoint:{ CGRectGetMaxX(rect), CGRectGetMinY(rect) } toLatLngFromView:view];
+    auto bottomRight = [self convertPoint:{ CGRectGetMaxX(rect), CGRectGetMaxY(rect) } toLatLngFromView:view];
+    auto bottomLeft = [self convertPoint:{ CGRectGetMinX(rect), CGRectGetMaxY(rect) } toLatLngFromView:view];
+    
+    // If the bounds straddles the antimeridian, unwrap it so that one side
+    // extends beyond ±180° longitude.
+    auto center = [self convertPoint:{ CGRectGetMidX(rect), CGRectGetMidY(rect) } toLatLngFromView:view];
+    topLeft.unwrapForShortestPath(center);
+    topRight.unwrapForShortestPath(center);
+    bottomRight.unwrapForShortestPath(center);
+    bottomLeft.unwrapForShortestPath(center);
+    
+    bounds.extend(topLeft);
+    bounds.extend(topRight);
+    bounds.extend(bottomRight);
+    bounds.extend(bottomLeft);
 
     return bounds;
 }