1 files changed, 140 insertions, 0 deletions
diff --git a/platform/ios/test/MGLMapViewZoomTests.m b/platform/ios/test/MGLMapViewZoomTests.m
new file mode 100644
index 0000000000..bd617857fd
--- /dev/null
+++ b/platform/ios/test/MGLMapViewZoomTests.m
@@ -0,0 +1,140 @@
+#import <Mapbox/Mapbox.h>
+#import <XCTest/XCTest.h>
+
+@interface MGLMapView (MGLMapViewZoomTests)
+- (void)handlePinchGesture:(UIPinchGestureRecognizer *)pinch;
+@end
+
+@interface UIPinchGestureRecognizerMock : UIPinchGestureRecognizer
+@property (nonatomic) CGPoint locationInViewOverride;
+@end
+
+@implementation UIPinchGestureRecognizerMock
+- (CGPoint)locationInView:(nullable UIView *)view { return self.locationInViewOverride; }
+@end
+
+@interface MGLMapViewZoomTests : XCTestCase
+@property (nonatomic) MGLMapView *mapView;
+@end
+
+@implementation MGLMapViewZoomTests
+
+- (void)setUp {
+    [super setUp];
+
+    [MGLAccountManager setAccessToken:@"pk.feedcafedeadbeefbadebede"];
+    NSURL *styleURL = [[NSBundle bundleForClass:[self class]] URLForResource:@"one-liner" withExtension:@"json"];
+    self.mapView = [[MGLMapView alloc] initWithFrame:UIScreen.mainScreen.bounds styleURL:styleURL];
+}
+
+- (void)tearDown {
+    self.mapView = nil;
+    [MGLAccountManager setAccessToken:nil];
+    [super tearDown];
+}
+
+- (void)testZoom {
+    CLLocationCoordinate2D originalCenterCoordinate = self.mapView.centerCoordinate;
+
+    for (NSNumber *zoom in @[@1, @5, @10, @15, @22]) {
+        self.mapView.zoomLevel = [zoom doubleValue];
+        XCTAssertEqual(self.mapView.zoomLevel, [zoom doubleValue], @"Map zoom should match z%@.", zoom);
+
+        XCTAssertEqualWithAccuracy(originalCenterCoordinate.latitude, self.mapView.centerCoordinate.latitude, 0.0000001, "@Map center coordinate latitude should remain constant during zoom to z%@.", zoom);
+        XCTAssertEqualWithAccuracy(originalCenterCoordinate.longitude, self.mapView.centerCoordinate.longitude, 0.0000001, @"Map center coordinate longitude should remain constant during zoom to z%@.", zoom);
+    }
+}
+
+- (void)testZoomEnabled {
+    UIPinchGestureRecognizerMock *gesture = [[UIPinchGestureRecognizerMock alloc] initWithTarget:nil action:nil];
+    gesture.state = UIGestureRecognizerStateBegan;
+    gesture.scale = 10.f;
+    [self.mapView handlePinchGesture:gesture];
+    gesture.state = UIGestureRecognizerStateChanged;
+
+    // Disabled
+    {
+        self.mapView.zoomEnabled = NO;
+        XCTAssertEqual(self.mapView.allowsZooming, NO);
+
+        [self.mapView handlePinchGesture:gesture];
+        XCTAssertNotEqual(self.mapView.zoomLevel, log2(gesture.scale), @"Gestural zoom should not work when zoom is disabled.");
+
+        self.mapView.zoomLevel = 15.f;
+        XCTAssertEqualWithAccuracy(self.mapView.zoomLevel, 15, 0.001, @"Programmatic zoom is allowed when zoomEnabled = NO.");
+    }
+
+    // Enabled
+    {
+        // No need to reset the map zoom or gesture scale, since gesture scale hasn't been applied yet and the map zoom will be overriden when the gesture is handled.
+        self.mapView.zoomEnabled = YES;
+        XCTAssertEqual(self.mapView.allowsZooming, YES);
+
+        [self.mapView handlePinchGesture:gesture];
+        XCTAssertEqualWithAccuracy(self.mapView.zoomLevel, log2(gesture.scale), 0.001, @"Gestural zoom should work when zoom is enabled.");
+    }
+}
+
+- (void)testPinchGesture {
+    CLLocationCoordinate2D originalCenterCoordinate = self.mapView.centerCoordinate;
+
+    UIPinchGestureRecognizerMock *gesture = [[UIPinchGestureRecognizerMock alloc] initWithTarget:self.mapView action:nil];
+    gesture.state = UIGestureRecognizerStateBegan;
+    gesture.scale = 0;
+    gesture.locationInViewOverride = self.mapView.center;
+    [self.mapView handlePinchGesture:gesture];
+    XCTAssertEqual(self.mapView.zoomLevel, 0);
+
+    for (NSNumber *zoom in @[@1, @5, @10, @15, @22]) {
+        gesture.state = UIGestureRecognizerStateChanged;
+        gesture.scale = MGLScaleFromZoomLevel([zoom doubleValue]);
+        [self.mapView handlePinchGesture:gesture];
+        XCTAssertEqual(self.mapView.zoomLevel, [zoom doubleValue], @"Map zoom should match gesture to z%@.", zoom);
+
+        // Given a hypothetical zoom into the exact center of the map, the center coordinate should remain the same.
+        XCTAssertEqualWithAccuracy(originalCenterCoordinate.latitude, self.mapView.centerCoordinate.latitude, 0.0000001, "@Map center coordinate latitude should remain constant during zoom to z%@.", zoom);
+        XCTAssertEqualWithAccuracy(originalCenterCoordinate.longitude, self.mapView.centerCoordinate.longitude, 0.0000001, @"Map center coordinate longitude should remain constant during zoom to z%@.", zoom);
+    }
+}
+
+// Regression test for: https://github.com/mapbox/mapbox-gl-native/issues/14977
+- (void)testPinchGestureOffCenter {
+    self.mapView.zoomLevel = 15;
+
+    // Set up pinch gesture at z15 with an origin of 0,0.
+    UIPinchGestureRecognizerMock *gesture = [[UIPinchGestureRecognizerMock alloc] initWithTarget:self.mapView action:nil];
+    gesture.state = UIGestureRecognizerStateBegan;
+    gesture.scale = 0;
+    gesture.locationInViewOverride = CGPointMake(0, 0);
+    [self.mapView handlePinchGesture:gesture];
+    XCTAssertEqual(self.mapView.zoomLevel, 15);
+
+    // Set a map rotation so that we can later check if un-rotating happens around the correct center point.
+    self.mapView.direction = 45;
+
+    // Zoom to z18 at the off-center origin.
+    gesture.state = UIGestureRecognizerStateChanged;
+    gesture.scale = MGLScaleFromZoomLevel(3);
+    [self.mapView handlePinchGesture:gesture];
+    XCTAssertEqual(self.mapView.zoomLevel, 18, @"Map zoom should match original zoom plus gesture zoom.");
+
+    // Check that the center coordinate remains the same when direction is reset to north.
+    CLLocationCoordinate2D centerCoordinateBeforeReset = self.mapView.centerCoordinate;
+    CLLocationCoordinate2D manuallyDerivedCenterCoordinate = [self.mapView convertPoint:self.mapView.center toCoordinateFromView:nil];
+    XCTAssertEqualWithAccuracy(centerCoordinateBeforeReset.latitude, manuallyDerivedCenterCoordinate.latitude, 0.0000001, "@Map center latitude should be equal to manually derived latitude.");
+    XCTAssertEqualWithAccuracy(centerCoordinateBeforeReset.longitude, manuallyDerivedCenterCoordinate.longitude, 0.0000001, @"Map center longitude should be equal to manually derived longitude.");
+
+    self.mapView.direction = 0;
+    XCTAssertEqualWithAccuracy(centerCoordinateBeforeReset.latitude, self.mapView.centerCoordinate.latitude, 0.0000001, "@Map center coordinate latitude should remain constant after resetting to north.");
+    XCTAssertEqualWithAccuracy(centerCoordinateBeforeReset.longitude, self.mapView.centerCoordinate.longitude, 0.0000001, @"Map center coordinate longitude should remain constant after resetting to north.");
+}
+
+NS_INLINE CGFloat MGLScaleFromZoomLevel(double zoom) {
+    return pow(2, zoom);
+}
+
+__unused NS_INLINE double MGLZoomLevelFromScale(CGFloat scale) {
+    return log2(scale);
+}
+
+@end