[ios, macos] Short-circuit redundant camera changes

Avoid canceling transitions (and triggering preexisting completion handlers) until we get a chance to ensure that a new transition really does have to begin. Consistently avoid mbgl transitions for redundant camera changes. Upon bailing, schedule the completion handler to run asynchronously on a delay equivalent to the requested animation duration.

Added a “functional” equality method to MGLMapCamera that avoids trivial differences.

Fixed invocations of XCTAssertEqualWithAccuracy() that incorrectly expressed the accuracy as a number of digits rather than a scalar tolerance.

1 files changed, 27 insertions, 12 deletions

diff --git a/platform/macos/src/MGLMapView.mm b/platform/macos/src/MGLMapView.mm
index 9cbc923271..e4a0c364da 100644
--- a/platform/macos/src/MGLMapView.mm
+++ b/platform/macos/src/MGLMapView.mm
@@ -1116,12 +1116,6 @@ public:
 }
 
 - (void)setCamera:(MGLMapCamera *)camera withDuration:(NSTimeInterval)duration animationTimingFunction:(nullable CAMediaTimingFunction *)function completionHandler:(nullable void (^)(void))completion {
-    _mbglMap->cancelTransitions();
-    if ([self.camera isEqual:camera]) {
-        return;
-    }
-
-    mbgl::CameraOptions cameraOptions = [self cameraOptionsObjectForAnimatingToCamera:camera];
     mbgl::AnimationOptions animationOptions;
     if (duration > 0) {
         animationOptions.duration.emplace(MGLDurationInSeconds(duration));
@@ -1137,8 +1131,19 @@ public:
             });
         };
     }
+    
+    if ([self.camera isEqualToMapCamera:camera]) {
+        if (completion) {
+            dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(duration * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
+                completion();
+            });
+        }
+        return;
+    }
 
     [self willChangeValueForKey:@"camera"];
+    _mbglMap->cancelTransitions();
+    mbgl::CameraOptions cameraOptions = [self cameraOptionsObjectForAnimatingToCamera:camera];
     _mbglMap->easeTo(cameraOptions, animationOptions);
     [self didChangeValueForKey:@"camera"];
 }
@@ -1152,12 +1157,6 @@ public:
 }
 
 - (void)flyToCamera:(MGLMapCamera *)camera withDuration:(NSTimeInterval)duration peakAltitude:(CLLocationDistance)peakAltitude completionHandler:(nullable void (^)(void))completion {
-    _mbglMap->cancelTransitions();
-    if ([self.camera isEqual:camera]) {
-        return;
-    }
-
-    mbgl::CameraOptions cameraOptions = [self cameraOptionsObjectForAnimatingToCamera:camera];
     mbgl::AnimationOptions animationOptions;
     if (duration >= 0) {
         animationOptions.duration = MGLDurationInSeconds(duration);
@@ -1178,8 +1177,19 @@ public:
             });
         };
     }
+    
+    if ([self.camera isEqualToMapCamera:camera]) {
+        if (completion) {
+            dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(duration * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
+                completion();
+            });
+        }
+        return;
+    }
 
     [self willChangeValueForKey:@"camera"];
+    _mbglMap->cancelTransitions();
+    mbgl::CameraOptions cameraOptions = [self cameraOptionsObjectForAnimatingToCamera:camera];
     _mbglMap->flyTo(cameraOptions, animationOptions);
     [self didChangeValueForKey:@"camera"];
 }
@@ -1228,6 +1238,11 @@ public:
     if (animated) {
         animationOptions.duration = MGLDurationInSeconds(MGLAnimationDuration);
     }
+    
+    MGLMapCamera *camera = [self cameraForCameraOptions:cameraOptions];
+    if ([self.camera isEqualToMapCamera:camera]) {
+        return;
+    }
 
     [self willChangeValueForKey:@"visibleCoordinateBounds"];
     animationOptions.transitionFinishFn = ^() {