Added additional test for interrupting a transition, and associated fix.

Added failing (currently disabled) test, where the interruption still triggers an infinite loop.

5 files changed, 109 insertions, 16 deletions

diff --git a/platform/ios/Integration Tests/MGLCameraTransitionTests.mm b/platform/ios/Integration Tests/MGLCameraTransitionTests.mm
index c895f47983..b95ac6613f 100644
--- a/platform/ios/Integration Tests/MGLCameraTransitionTests.mm
+++ b/platform/ios/Integration Tests/MGLCameraTransitionTests.mm
@@ -64,6 +64,84 @@
     [self waitForExpectations:@[expectation] timeout:1.5];
 }
 
+- (void)testInterruptingAndResetNorthOnlyOnceInIsChanging {
+
+    // Reset to non-zero, prior to testing
+    [self.mapView setDirection:45 animated:NO];
+
+    XCTestExpectation *expectation = [self expectationWithDescription:@"regionDidChange expectation"];
+    expectation.expectedFulfillmentCount = 1;
+    expectation.assertForOverFulfill = YES;
+
+    __weak typeof(self) weakself = self;
+    __block BOOL startedReset = NO;
+    __block BOOL finishedReset = NO;
+
+    self.regionIsChanging = ^(MGLMapView *mapView) {
+        MBCameraTransitionTests *strongSelf = weakself;
+        if (!strongSelf) return;
+
+        if (!startedReset) {
+            NSLog(@"Reset to north, interrupting the previous transition");
+            startedReset = YES;
+            [mapView resetNorth];
+            finishedReset = YES;
+        }
+    };
+
+    self.regionDidChange = ^(MGLMapView *mapView, MGLCameraChangeReason reason, BOOL animated) {
+        MBCameraTransitionTests *strongSelf = weakself;
+        if (!strongSelf) return;
+
+        MGLTestAssert(strongSelf, startedReset);
+
+        if (finishedReset) {
+            MGLTestAssert(strongSelf, !(reason & MGLCameraChangeReasonTransitionCancelled));
+            [expectation fulfill];
+        }
+        else {
+            MGLTestAssert(strongSelf, reason & MGLCameraChangeReasonTransitionCancelled);
+        }
+    };
+
+    [self.mapView setDirection:90 animated:YES];
+    [self waitForExpectations:@[expectation] timeout:1.5];
+
+    XCTAssertEqualWithAccuracy(self.mapView.direction, 0.0, 0.001, @"Camera should have reset to north. %0.3f", self.mapView.direction);
+}
+
+- (void)testContinuallyResettingNorthInIsChanging {
+
+    // Reset to non-zero, prior to testing
+    [self.mapView setDirection:45 animated:NO];
+
+    XCTestExpectation *expectation = [self expectationWithDescription:@"regionDidChange expectation"];
+    expectation.expectedFulfillmentCount = 1;
+    expectation.assertForOverFulfill = YES;
+
+    __weak typeof(self) weakself = self;
+
+    self.regionIsChanging = ^(MGLMapView *mapView) {
+        MBCameraTransitionTests *strongSelf = weakself;
+        if (!strongSelf) return;
+
+        [mapView resetNorth];
+    };
+
+    self.regionDidChange = ^(MGLMapView *mapView, MGLCameraChangeReason reason, BOOL animated) {
+        MBCameraTransitionTests *strongSelf = weakself;
+        if (!strongSelf) return;
+
+        MGLTestAssert(strongSelf, reason & MGLCameraChangeReasonTransitionCancelled);
+    };
+
+    [self.mapView setDirection:90 animated:YES];
+    [self waitForExpectations:@[expectation] timeout:1.5];
+
+    XCTAssertEqualWithAccuracy(self.mapView.direction, 0.0, 0.001, @"Camera should have reset to north. %0.3f", self.mapView.direction);
+}
+
+
 
 - (void)testSetCenterCancelsTransitions {
     XCTestExpectation *cameraIsInDCExpectation = [self expectationWithDescription:@"camera reset to DC"];
diff --git a/platform/ios/ios.xcodeproj/xcshareddata/xcschemes/Integration Test Harness.xcscheme b/platform/ios/ios.xcodeproj/xcshareddata/xcschemes/Integration Test Harness.xcscheme
index 1638592557..2a37b73caa 100644
--- a/platform/ios/ios.xcodeproj/xcshareddata/xcschemes/Integration Test Harness.xcscheme
+++ b/platform/ios/ios.xcodeproj/xcshareddata/xcschemes/Integration Test Harness.xcscheme
@@ -37,6 +37,11 @@
                BlueprintName = "integration"
                ReferencedContainer = "container:ios.xcodeproj">
             </BuildableReference>
+            <SkippedTests>
+               <Test
+                  Identifier = "MBCameraTransitionTests/testContinuallyResettingNorthInIsChanging">
+               </Test>
+            </SkippedTests>
          </TestableReference>
       </Testables>
       <MacroExpansion>
diff --git a/platform/ios/src/MGLCameraChangeReason.h b/platform/ios/src/MGLCameraChangeReason.h
index 6c6b3636ba..f439d3e7ea 100644
--- a/platform/ios/src/MGLCameraChangeReason.h
+++ b/platform/ios/src/MGLCameraChangeReason.h
@@ -57,5 +57,9 @@ typedef NS_OPTIONS(NSUInteger, MGLCameraChangeReason)
     MGLCameraChangeReasonGestureOneFingerZoom = 1 << 7,
 
     // :nodoc: The user panned with two fingers to tilt the map (two finger drag).
-    MGLCameraChangeReasonGestureTilt = 1 << 8
+    MGLCameraChangeReasonGestureTilt = 1 << 8,
+
+    // :nodoc: Cancelled
+    MGLCameraChangeReasonTransitionCancelled = 1 << 16
+
 };
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index 26b23abb4e..e16411f2c5 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -1271,7 +1271,7 @@ public:
     {
         [self setUserTrackingMode:MGLUserTrackingModeNone animated:NO];
     }
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 }
 
 - (void)notifyGestureDidBegin {
@@ -1321,7 +1321,7 @@ public:
 {
     if ( ! self.isScrollEnabled) return;
 
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 
     MGLMapCamera *oldCamera = self.camera;
 
@@ -1390,7 +1390,7 @@ public:
 {
     if ( ! self.isZoomEnabled) return;
 
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 
     CGPoint centerPoint = [self anchorPointForGesture:pinch];
     MGLMapCamera *oldCamera = self.camera;
@@ -1491,7 +1491,7 @@ public:
 {
     if ( ! self.isRotateEnabled) return;
 
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 
     CGPoint centerPoint = [self anchorPointForGesture:rotate];
     MGLMapCamera *oldCamera = self.camera;
@@ -1696,7 +1696,7 @@ public:
 {
     if ( ! self.isZoomEnabled) return;
 
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 
     if (doubleTap.state == UIGestureRecognizerStateEnded)
     {
@@ -1737,7 +1737,7 @@ public:
 
     if (_mbglMap->getZoom() == _mbglMap->getMinZoom()) return;
 
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 
     self.cameraChangeReasonBitmask |= MGLCameraChangeReasonGestureZoomOut;
 
@@ -1776,7 +1776,7 @@ public:
 {
     if ( ! self.isZoomEnabled) return;
 
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 
     self.cameraChangeReasonBitmask |= MGLCameraChangeReasonGestureOneFingerZoom;
 
@@ -1821,7 +1821,7 @@ public:
 {
     if ( ! self.isPitchEnabled) return;
 
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 
     self.cameraChangeReasonBitmask |= MGLCameraChangeReasonGestureTilt;
 
@@ -2981,7 +2981,7 @@ public:
         return;
     }
     
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 
     self.cameraChangeReasonBitmask |= MGLCameraChangeReasonProgrammatic;
 
@@ -3006,7 +3006,7 @@ public:
 - (void)setZoomLevel:(double)zoomLevel animated:(BOOL)animated
 {
     if (zoomLevel == self.zoomLevel) return;
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 
     self.cameraChangeReasonBitmask |= MGLCameraChangeReasonProgrammatic;
 
@@ -3149,7 +3149,7 @@ public:
     }
     
     [self willChangeValueForKey:@"visibleCoordinateBounds"];
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 
     self.cameraChangeReasonBitmask |= MGLCameraChangeReasonProgrammatic;
 
@@ -3182,7 +3182,7 @@ public:
 - (void)_setDirection:(CLLocationDirection)direction animated:(BOOL)animated
 {
     if (direction == self.direction) return;
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 
     CGFloat duration = animated ? MGLAnimationDuration : 0;
 
@@ -3271,7 +3271,7 @@ public:
     }
 
     [self willChangeValueForKey:@"camera"];
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 
     self.cameraChangeReasonBitmask |= MGLCameraChangeReasonProgrammatic;
 
@@ -3330,7 +3330,7 @@ public:
     }
 
     [self willChangeValueForKey:@"camera"];
-    _mbglMap->cancelTransitions();
+    [self cancelTransitions];
 
     self.cameraChangeReasonBitmask |= MGLCameraChangeReasonProgrammatic;
 
@@ -3339,6 +3339,12 @@ public:
     [self didChangeValueForKey:@"camera"];
 }
 
+- (void)cancelTransitions {
+    self.cameraChangeReasonBitmask |= MGLCameraChangeReasonTransitionCancelled;
+    _mbglMap->cancelTransitions();
+    self.cameraChangeReasonBitmask &= ~MGLCameraChangeReasonTransitionCancelled;
+}
+
 - (MGLMapCamera *)cameraThatFitsCoordinateBounds:(MGLCoordinateBounds)bounds
 {
     return [self cameraThatFitsCoordinateBounds:bounds edgePadding:UIEdgeInsetsZero];
diff --git a/src/mbgl/map/transform.cpp b/src/mbgl/map/transform.cpp
index 79815d9398..77dcd69972 100644
--- a/src/mbgl/map/transform.cpp
+++ b/src/mbgl/map/transform.cpp
@@ -655,7 +655,7 @@ void Transform::updateTransitions(const TimePoint& now) {
             finish();
         }
     }
-    else {
+    else if (!transitionFrameFn) {
         transitionFrameFn = std::move(transition);
     }
 }