avoid altering annotation view transforms set by user

platform/ios/CHANGELOG.md

@@ -39,6 +39,7 @@ Mapbox welcomes participation and contributions from everyone. Please read [CONT
 * To make an MGLPolyline or MGLPolygon span the antimeridian, specify coordinates with longitudes greater than 180° or less than −180°. ([#6088](https://github.com/mapbox/mapbox-gl-native/pull/6088))
 * Improved the performance of relocating a non-view-backed point annotation by changing its `coordinate` property. ([#5385](https://github.com/mapbox/mapbox-gl-native/pull/5385))
 * Improved the precision of annotations at zoom levels greater than 18. ([#5517](https://github.com/mapbox/mapbox-gl-native/pull/5517))
+* Fixed an issue that could reset user-added transformations on annotation views. ([#6166](https://github.com/mapbox/mapbox-gl-native/pull/6166))
 
 ### Other changes
 

platform/ios/src/MGLAnnotationView.mm

@@ -11,6 +11,7 @@ @interface MGLAnnotationView () <UIGestureRecognizerDelegate>
 
 @property (nonatomic, readwrite, nullable) NSString *reuseIdentifier;
 @property (nonatomic, readwrite, nullable) id <MGLAnnotation> annotation;
+@property (nonatomic, readwrite) CATransform3D lastAppliedScaleTransform;
 @property (nonatomic, weak) UIPanGestureRecognizer *panGestureRecognizer;
 @property (nonatomic, weak) UILongPressGestureRecognizer *longPressRecognizer;
 @property (nonatomic, weak) MGLMapView *mapView;
@@ -24,6 +25,7 @@ - (instancetype)initWithReuseIdentifier:(NSString *)reuseIdentifier
  self = [self initWithFrame:CGRectZero];
  if (self)
  {
+ _lastAppliedScaleTransform = CATransform3DIdentity;
  _reuseIdentifier = [reuseIdentifier copy];
  _scalesWithViewingDistance = YES;
  _enabled = YES;
@@ -68,32 +70,22 @@ - (void)setCenter:(CGPoint)center
  center.y += _centerOffset.dy;
 
  super.center = center;
- [self updateTransform];
+ [self updateScaleTransformForViewingDistance];
 }
 
 - (void)setScalesWithViewingDistance:(BOOL)scalesWithViewingDistance
 {
  if (_scalesWithViewingDistance != scalesWithViewingDistance)
  {
  _scalesWithViewingDistance = scalesWithViewingDistance;
- [self updateTransform];
+ [self updateScaleTransformForViewingDistance];
  }
 }
 
-- (void)updateTransform
+- (void)updateScaleTransformForViewingDistance
 {
- // Omit applying a new transformation while the view is being dragged.
- if (self.dragState == MGLAnnotationViewDragStateDragging)
- {
- return;
- }
-
- self.layer.transform = CATransform3DIdentity;
- if ( ! self.scalesWithViewingDistance)
- {
- return;
- }
-
+ if (self.scalesWithViewingDistance == NO || self.dragState == MGLAnnotationViewDragStateDragging) return;
+
  CGFloat superviewHeight = CGRectGetHeight(self.superview.frame);
  if (superviewHeight > 0.0) {
  // Find the maximum amount of scale reduction to apply as the view's center moves from the top
@@ -115,9 +107,15 @@ - (void)updateTransform
  // map view is 50% pitched then the annotation view should be reduced by 37.5% (.75 * .5). The
  // reduction is then normalized for a scale of 1.0.
  CGFloat pitchAdjustedScale = 1.0 - maxScaleReduction * pitchIntensity;
-
- CATransform3D transform = CATransform3DIdentity;
- self.layer.transform = CATransform3DScale(transform, pitchAdjustedScale, pitchAdjustedScale, 1);
+
+ // We keep track of each viewing distance scale transform that we apply. Each iteration,
+ // we can account for it so that we don't get cumulative scaling every time we move.
+ // We also avoid clobbering any existing transform passed in by the client, too.
+ CATransform3D undoOfLastScaleTransform = CATransform3DInvert(_lastAppliedScaleTransform);
+ CATransform3D newScaleTransform = CATransform3DMakeScale(pitchAdjustedScale, pitchAdjustedScale, 1);
+ CATransform3D effectiveTransform = CATransform3DConcat(undoOfLastScaleTransform, newScaleTransform);
+ self.layer.transform = CATransform3DConcat(self.layer.transform, effectiveTransform);
+ _lastAppliedScaleTransform = newScaleTransform;
  }
 }