Zoom focal point (#1122)

Co-authored-by: Andrew Hershberger <andrew.hershberger@mapbox.com>
mapbox · Feb 23, 2022 · 1c862c7 · 1c862c7
1 parent 7b9720b
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Showing 29 changed files with 234 additions and 46 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -14,6 +14,7 @@ Mapbox welcomes participation and contributions from everyone.
 * Exposed APIs to allow positioning of other views relative to the logoView, compassView, scaleBarView and attributionButton. ([#1130](https://github.com/mapbox/mapbox-maps-ios/pull/1130))
 * Add `GestureOptions.pinchPanEnabled` and `.pinchZoomEnabled`. ([#1092](https://github.com/mapbox/mapbox-maps-ios/pull/1092))
 * Fix an issue where pinch gesture emitted superfluous camera changed events. ([#1137](https://github.com/mapbox/mapbox-maps-ios/pull/1137))
+* Add focalPoint property to zoom and rotate gestures ([#1122](https://github.com/mapbox/mapbox-maps-ios/pull/1122))
 * Expose public initializers for `LayerInfo` and `SourceInfo`. ([#1144](https://github.com/mapbox/mapbox-maps-ios/pull/1144))
 
 ## 10.3.0 - February 10, 2022

diff --git a/Sources/MapboxMaps/Foundation/MapViewDependencyProvider.swift b/Sources/MapboxMaps/Foundation/MapViewDependencyProvider.swift
@@ -77,7 +77,7 @@ internal final class MapViewDependencyProvider: MapViewDependencyProviderProtoco
 
     func makeDoubleTapToZoomInGestureHandler(view: UIView,
                                              mapboxMap: MapboxMapProtocol,
-                                             cameraAnimationsManager: CameraAnimationsManagerProtocol) -> GestureHandler {
+                                             cameraAnimationsManager: CameraAnimationsManagerProtocol) -> FocusableGestureHandlerProtocol {
         let gestureRecognizer = UITapGestureRecognizer()
         view.addGestureRecognizer(gestureRecognizer)
         return DoubleTapToZoomInGestureHandler(
@@ -88,7 +88,7 @@ internal final class MapViewDependencyProvider: MapViewDependencyProviderProtoco
 
     func makeDoubleTouchToZoomOutGestureHandler(view: UIView,
                                                 mapboxMap: MapboxMapProtocol,
-                                                cameraAnimationsManager: CameraAnimationsManagerProtocol) -> GestureHandler {
+                                                cameraAnimationsManager: CameraAnimationsManagerProtocol) -> FocusableGestureHandlerProtocol {
         let gestureRecognizer = UITapGestureRecognizer()
         view.addGestureRecognizer(gestureRecognizer)
         return DoubleTouchToZoomOutGestureHandler(
@@ -97,8 +97,7 @@ internal final class MapViewDependencyProvider: MapViewDependencyProviderProtoco
             cameraAnimationsManager: cameraAnimationsManager)
     }
 
-    func makeQuickZoomGestureHandler(view: UIView,
-                                     mapboxMap: MapboxMapProtocol) -> GestureHandler {
+    func makeQuickZoomGestureHandler(view: UIView, mapboxMap: MapboxMapProtocol) -> FocusableGestureHandlerProtocol {
         let gestureRecognizer = UILongPressGestureRecognizer()
         view.addGestureRecognizer(gestureRecognizer)
         return QuickZoomGestureHandler(

diff --git a/Sources/MapboxMaps/Gestures/GestureHandlers/DoubleTapToZoomInGestureHandler.swift b/Sources/MapboxMaps/Gestures/GestureHandlers/DoubleTapToZoomInGestureHandler.swift
@@ -2,10 +2,10 @@ import UIKit
 
 /// `DoubleTapToZoomInGestureHandler` updates the map camera in response
 /// to double tap gestures with 1 touch
-internal final class DoubleTapToZoomInGestureHandler: GestureHandler {
+internal final class DoubleTapToZoomInGestureHandler: GestureHandler, FocusableGestureHandlerProtocol {
+    internal var focalPoint: CGPoint?
 
     private let mapboxMap: MapboxMapProtocol
-
     private let cameraAnimationsManager: CameraAnimationsManagerProtocol
 
     internal init(gestureRecognizer: UITapGestureRecognizer,
@@ -26,9 +26,9 @@ internal final class DoubleTapToZoomInGestureHandler: GestureHandler {
             delegate?.gestureBegan(for: .doubleTapToZoomIn)
             delegate?.gestureEnded(for: .doubleTapToZoomIn, willAnimate: true)
 
-            let tapLocation = gestureRecognizer.location(in: view)
+            let anchor = focalPoint ?? gestureRecognizer.location(in: view)
             cameraAnimationsManager.internalEase(
-                to: CameraOptions(anchor: tapLocation, zoom: mapboxMap.cameraState.zoom + 1),
+                to: CameraOptions(anchor: anchor, zoom: mapboxMap.cameraState.zoom + 1),
                 duration: 0.3,
                 curve: .easeOut) { _ in
                     self.delegate?.animationEnded(for: .doubleTapToZoomIn)

diff --git a/Sources/MapboxMaps/Gestures/GestureHandlers/DoubleTouchToZoomOutGestureHandler.swift b/Sources/MapboxMaps/Gestures/GestureHandlers/DoubleTouchToZoomOutGestureHandler.swift
@@ -2,10 +2,10 @@ import UIKit
 
 /// `DoubleTouchToZoomOutGestureHandler` updates the map camera in response
 /// to single tap gestures with 2 touches
-internal final class DoubleTouchToZoomOutGestureHandler: GestureHandler {
+internal final class DoubleTouchToZoomOutGestureHandler: GestureHandler, FocusableGestureHandlerProtocol {
+    internal var focalPoint: CGPoint?
 
     private let mapboxMap: MapboxMapProtocol
-
     private let cameraAnimationsManager: CameraAnimationsManagerProtocol
 
     internal init(gestureRecognizer: UITapGestureRecognizer,
@@ -26,9 +26,9 @@ internal final class DoubleTouchToZoomOutGestureHandler: GestureHandler {
             delegate?.gestureBegan(for: .doubleTouchToZoomOut)
             delegate?.gestureEnded(for: .doubleTouchToZoomOut, willAnimate: true)
 
-            let tapLocation = gestureRecognizer.location(in: view)
+            let anchor = focalPoint ?? gestureRecognizer.location(in: view)
             cameraAnimationsManager.internalEase(
-                to: CameraOptions(anchor: tapLocation, zoom: mapboxMap.cameraState.zoom - 1),
+                to: CameraOptions(anchor: anchor, zoom: mapboxMap.cameraState.zoom - 1),
                 duration: 0.3,
                 curve: .easeOut) { _ in
                     self.delegate?.animationEnded(for: .doubleTouchToZoomOut)

diff --git a/Sources/MapboxMaps/Gestures/GestureHandlers/FocusableGestureHandlerProtocol.swift b/Sources/MapboxMaps/Gestures/GestureHandlers/FocusableGestureHandlerProtocol.swift
@@ -0,0 +1,5 @@
+import Foundation
+
+internal protocol FocusableGestureHandlerProtocol: GestureHandler {
+    var focalPoint: CGPoint? { get set }
+}
diff --git a/Sources/MapboxMaps/Gestures/GestureHandlers/PinchBehaviors/PanRotatePinchBehavior.swift b/Sources/MapboxMaps/Gestures/GestureHandlers/PinchBehaviors/PanRotatePinchBehavior.swift
@@ -1,3 +1,5 @@
+import CoreGraphics
+
 internal final class PanRotatePinchBehavior: PinchBehavior {
     private let initialCameraState: CameraState
     private let initialPinchMidpoint: CGPoint

diff --git a/Sources/MapboxMaps/Gestures/GestureHandlers/PinchBehaviors/PanZoomPinchBehavior.swift b/Sources/MapboxMaps/Gestures/GestureHandlers/PinchBehaviors/PanZoomPinchBehavior.swift
@@ -1,3 +1,5 @@
+import CoreGraphics
+
 internal final class PanZoomPinchBehavior: PinchBehavior {
     private let initialCameraState: CameraState
     private let initialPinchMidpoint: CGPoint

diff --git a/Sources/MapboxMaps/Gestures/GestureHandlers/PinchBehaviors/PinchBehaviorProvider.swift b/Sources/MapboxMaps/Gestures/GestureHandlers/PinchBehaviors/PinchBehaviorProvider.swift
@@ -1,3 +1,4 @@
+import CoreFoundation
 import CoreLocation
 
 internal protocol PinchBehaviorProviderProtocol: AnyObject {
@@ -7,7 +8,8 @@ internal protocol PinchBehaviorProviderProtocol: AnyObject {
                            rotateEnabled: Bool,
                            initialCameraState: CameraState,
                            initialPinchMidpoint: CGPoint,
-                           initialPinchAngle: CGFloat) -> PinchBehavior
+                           initialPinchAngle: CGFloat,
+                           focalPoint: CGPoint?) -> PinchBehavior
 }
 
 internal final class PinchBehaviorProvider: PinchBehaviorProviderProtocol {
@@ -24,7 +26,8 @@ internal final class PinchBehaviorProvider: PinchBehaviorProviderProtocol {
                                     rotateEnabled: Bool,
                                     initialCameraState: CameraState,
                                     initialPinchMidpoint: CGPoint,
-                                    initialPinchAngle: CGFloat) -> PinchBehavior {
+                                    initialPinchAngle: CGFloat,
+                                    focalPoint: CGPoint?) -> PinchBehavior {
         switch (panEnabled, zoomEnabled, rotateEnabled) {
         case (true, true, true):
             return PanZoomRotatePinchBehavior(
@@ -53,17 +56,20 @@ internal final class PinchBehaviorProvider: PinchBehaviorProviderProtocol {
                 initialCameraState: initialCameraState,
                 initialPinchMidpoint: initialPinchMidpoint,
                 initialPinchAngle: initialPinchAngle,
+                focalPoint: focalPoint,
                 mapboxMap: mapboxMap)
         case (false, true, false):
             return ZoomPinchBehavior(
                 initialCameraState: initialCameraState,
                 initialPinchMidpoint: initialPinchMidpoint,
+                focalPoint: focalPoint,
                 mapboxMap: mapboxMap)
         case (false, false, true):
             return RotatePinchBehavior(
                 initialCameraState: initialCameraState,
                 initialPinchMidpoint: initialPinchMidpoint,
                 initialPinchAngle: initialPinchAngle,
+                focalPoint: focalPoint,
                 mapboxMap: mapboxMap)
         case (false, false, false):
             return EmptyPinchBehavior()

diff --git a/Sources/MapboxMaps/Gestures/GestureHandlers/PinchBehaviors/RotatePinchBehavior.swift b/Sources/MapboxMaps/Gestures/GestureHandlers/PinchBehaviors/RotatePinchBehavior.swift
@@ -1,16 +1,20 @@
+import CoreGraphics
 internal final class RotatePinchBehavior: PinchBehavior {
     private let initialCameraState: CameraState
     private let initialPinchMidpoint: CGPoint
     private let initialPinchAngle: CGFloat
     private let mapboxMap: MapboxMapProtocol
+    private let focalPoint: CGPoint?
 
     internal init(initialCameraState: CameraState,
                   initialPinchMidpoint: CGPoint,
                   initialPinchAngle: CGFloat,
+                  focalPoint: CGPoint?,
                   mapboxMap: MapboxMapProtocol) {
         self.initialCameraState = initialCameraState
         self.initialPinchMidpoint = initialPinchMidpoint
         self.initialPinchAngle = initialPinchAngle
+        self.focalPoint = focalPoint
         self.mapboxMap = mapboxMap
     }
 
@@ -23,7 +27,7 @@ internal final class RotatePinchBehavior: PinchBehavior {
             .wrappedAngle(to: pinchAngle)
             .toDegrees()
         mapboxMap.setCamera(to: CameraOptions(
-            anchor: initialPinchMidpoint,
+            anchor: focalPoint ?? initialPinchMidpoint,
             bearing: initialCameraState.bearing + CLLocationDirection(bearingIncrement)))
     }
 }
diff --git a/Sources/MapboxMaps/Gestures/GestureHandlers/PinchBehaviors/ZoomPinchBehavior.swift b/Sources/MapboxMaps/Gestures/GestureHandlers/PinchBehaviors/ZoomPinchBehavior.swift
@@ -2,12 +2,15 @@ internal final class ZoomPinchBehavior: PinchBehavior {
     private let initialCameraState: CameraState
     private let initialPinchMidpoint: CGPoint
     private let mapboxMap: MapboxMapProtocol
+    private let focalPoint: CGPoint?
 
     internal init(initialCameraState: CameraState,
                   initialPinchMidpoint: CGPoint,
+                  focalPoint: CGPoint?,
                   mapboxMap: MapboxMapProtocol) {
         self.initialCameraState = initialCameraState
         self.initialPinchMidpoint = initialPinchMidpoint
+        self.focalPoint = focalPoint
         self.mapboxMap = mapboxMap
     }
 
@@ -16,7 +19,7 @@ internal final class ZoomPinchBehavior: PinchBehavior {
                          pinchAngle: CGFloat) {
         let zoomIncrement = log2(pinchScale)
         mapboxMap.setCamera(to: CameraOptions(
-            anchor: initialPinchMidpoint,
+            anchor: focalPoint ?? initialPinchMidpoint,
             zoom: initialCameraState.zoom + zoomIncrement))
     }
 }
diff --git a/Sources/MapboxMaps/Gestures/GestureHandlers/PinchBehaviors/ZoomRotatePinchBehavior.swift b/Sources/MapboxMaps/Gestures/GestureHandlers/PinchBehaviors/ZoomRotatePinchBehavior.swift
@@ -3,14 +3,17 @@ internal final class ZoomRotatePinchBehavior: PinchBehavior {
     private let initialPinchMidpoint: CGPoint
     private let initialPinchAngle: CGFloat
     private let mapboxMap: MapboxMapProtocol
+    private let focalPoint: CGPoint?
 
     internal init(initialCameraState: CameraState,
                   initialPinchMidpoint: CGPoint,
                   initialPinchAngle: CGFloat,
+                  focalPoint: CGPoint?,
                   mapboxMap: MapboxMapProtocol) {
         self.initialCameraState = initialCameraState
         self.initialPinchMidpoint = initialPinchMidpoint
         self.initialPinchAngle = initialPinchAngle
+        self.focalPoint = focalPoint
         self.mapboxMap = mapboxMap
     }
 
@@ -25,7 +28,7 @@ internal final class ZoomRotatePinchBehavior: PinchBehavior {
             .wrappedAngle(to: pinchAngle)
             .toDegrees()
         mapboxMap.setCamera(to: CameraOptions(
-            anchor: initialPinchMidpoint,
+            anchor: focalPoint ?? initialPinchMidpoint,
             zoom: initialCameraState.zoom + zoomIncrement,
             bearing: initialCameraState.bearing + CLLocationDirection(bearingIncrement)))
     }

diff --git a/Sources/MapboxMaps/Gestures/GestureHandlers/PinchGestureHandler.swift b/Sources/MapboxMaps/Gestures/GestureHandlers/PinchGestureHandler.swift
@@ -1,9 +1,11 @@
 import UIKit
+@_implementationOnly import MapboxCommon_Private
 
-internal protocol PinchGestureHandlerProtocol: GestureHandler {
+internal protocol PinchGestureHandlerProtocol: FocusableGestureHandlerProtocol {
     var rotateEnabled: Bool { get set }
     var zoomEnabled: Bool { get set }
     var panEnabled: Bool { get set }
+    var focalPoint: CGPoint? { get set }
 }
 
 /// `PinchGestureHandler` updates the map camera in response to a 2-touch
@@ -18,6 +20,9 @@ internal final class PinchGestureHandler: GestureHandler, PinchGestureHandlerPro
     /// Whether pinch gesture can pan map or not
     internal var panEnabled: Bool = true
 
+    /// Anchor point for rotating and zooming
+    internal var focalPoint: CGPoint?
+
     /// The behavior for the current gesture, based on the initial state of the \*Enabled flags.
     private var pinchBehavior: PinchBehavior?
 
@@ -86,13 +91,21 @@ internal final class PinchGestureHandler: GestureHandler, PinchGestureHandlerPro
         guard let view = gestureRecognizer.view else {
             return
         }
+
+        if panEnabled, focalPoint != nil {
+            Log.warning(
+                forMessage: "Possible pinch gesture recognizer misconfiguration: the specified focal point will be ignored when pinching. In order for the focal point to work, pinch pan has to be disabled.",
+                category: "Gestures")
+        }
+
         pinchBehavior = pinchBehaviorProvider.makePinchBehavior(
             panEnabled: panEnabled,
             zoomEnabled: zoomEnabled,
             rotateEnabled: rotateEnabled,
             initialCameraState: mapboxMap.cameraState,
             initialPinchMidpoint: gestureRecognizer.location(in: view),
-            initialPinchAngle: pinchAngle(with: gestureRecognizer))
+            initialPinchAngle: pinchAngle(with: gestureRecognizer),
+            focalPoint: focalPoint)
         // if this is the first time we started handling the gesture, inform
         // the delegate.
         if !invokedGestureBegan {

diff --git a/Sources/MapboxMaps/Gestures/GestureHandlers/QuickZoomGestureHandler.swift b/Sources/MapboxMaps/Gestures/GestureHandlers/QuickZoomGestureHandler.swift
@@ -1,10 +1,12 @@
 import UIKit
 
 /// `QuickZoomGestureHandler` updates the map camera in response to double tap and drag gestures
-internal final class QuickZoomGestureHandler: GestureHandler {
+internal final class QuickZoomGestureHandler: GestureHandler, FocusableGestureHandlerProtocol {
     private var initialLocation: CGPoint?
     private var initialZoom: CGFloat?
+    internal var focalPoint: CGPoint?
     private let mapboxMap: MapboxMapProtocol
+    private var initialFocalPoint: CGPoint?
 
     internal init(gestureRecognizer: UILongPressGestureRecognizer,
                   mapboxMap: MapboxMapProtocol) {
@@ -25,6 +27,7 @@ internal final class QuickZoomGestureHandler: GestureHandler {
             delegate?.gestureBegan(for: .quickZoom)
             initialLocation = location
             initialZoom = mapboxMap.cameraState.zoom
+            initialFocalPoint = focalPoint
         case .changed:
             guard let initialLocation = initialLocation,
                   let initialZoom = initialZoom else {
@@ -33,10 +36,12 @@ internal final class QuickZoomGestureHandler: GestureHandler {
             let distance = location.y - initialLocation.y
             // change by 1 zoom level per 75 points of translation
             let newZoom = initialZoom + distance / 75
-            mapboxMap.setCamera(to: CameraOptions(anchor: initialLocation, zoom: newZoom))
+            let anchor = initialFocalPoint ?? initialLocation
+            mapboxMap.setCamera(to: CameraOptions(anchor: anchor, zoom: newZoom))
         case .ended, .cancelled:
             initialLocation = nil
             initialZoom = nil
+            initialFocalPoint = nil
             delegate?.gestureEnded(for: .quickZoom, willAnimate: false)
         default:
             break

diff --git a/Sources/MapboxMaps/Gestures/GestureManager.swift b/Sources/MapboxMaps/Gestures/GestureManager.swift
@@ -29,6 +29,10 @@ public final class GestureManager: GestureHandlerDelegate {
             quickZoomGestureRecognizer.isEnabled = newValue.quickZoomEnabled
             panGestureHandler.panMode = newValue.panMode
             panGestureHandler.decelerationFactor = newValue.panDecelerationFactor
+            doubleTapToZoomInGestureHandler.focalPoint = newValue.focalPoint
+            doubleTouchToZoomOutGestureHandler.focalPoint = newValue.focalPoint
+            quickZoomGestureHandler.focalPoint = newValue.focalPoint
+            pinchGestureHandler.focalPoint = newValue.focalPoint
         }
         get {
             var gestureOptions = GestureOptions()
@@ -43,6 +47,7 @@ public final class GestureManager: GestureHandlerDelegate {
             gestureOptions.quickZoomEnabled = quickZoomGestureRecognizer.isEnabled
             gestureOptions.panMode = panGestureHandler.panMode
             gestureOptions.panDecelerationFactor = panGestureHandler.decelerationFactor
+            gestureOptions.focalPoint = doubleTapToZoomInGestureHandler.focalPoint
             return gestureOptions
         }
     }
@@ -95,19 +100,19 @@ public final class GestureManager: GestureHandlerDelegate {
     private let panGestureHandler: PanGestureHandlerProtocol
     private let pinchGestureHandler: PinchGestureHandlerProtocol
     private let pitchGestureHandler: GestureHandler
-    private let doubleTapToZoomInGestureHandler: GestureHandler
-    private let doubleTouchToZoomOutGestureHandler: GestureHandler
-    private let quickZoomGestureHandler: GestureHandler
+    private let doubleTapToZoomInGestureHandler: FocusableGestureHandlerProtocol
+    private let doubleTouchToZoomOutGestureHandler: FocusableGestureHandlerProtocol
+    private let quickZoomGestureHandler: FocusableGestureHandlerProtocol
     private let singleTapGestureHandler: GestureHandler
     private let anyTouchGestureHandler: GestureHandler
     private let mapboxMap: MapboxMapProtocol
 
     internal init(panGestureHandler: PanGestureHandlerProtocol,
                   pinchGestureHandler: PinchGestureHandlerProtocol,
                   pitchGestureHandler: GestureHandler,
-                  doubleTapToZoomInGestureHandler: GestureHandler,
-                  doubleTouchToZoomOutGestureHandler: GestureHandler,
-                  quickZoomGestureHandler: GestureHandler,
+                  doubleTapToZoomInGestureHandler: FocusableGestureHandlerProtocol,
+                  doubleTouchToZoomOutGestureHandler: FocusableGestureHandlerProtocol,
+                  quickZoomGestureHandler: FocusableGestureHandlerProtocol,
                   singleTapGestureHandler: GestureHandler,
                   anyTouchGestureHandler: GestureHandler,
                   mapboxMap: MapboxMapProtocol) {

diff --git a/Sources/MapboxMaps/Gestures/GestureOptions.swift b/Sources/MapboxMaps/Gestures/GestureOptions.swift
@@ -60,5 +60,10 @@ public struct GestureOptions: Equatable {
     /// Defaults to `UIScrollView.DecelerationRate.normal.rawValue`
     public var panDecelerationFactor: CGFloat = UIScrollView.DecelerationRate.normal.rawValue
 
+    /// By default, gestures rotate and zoom around the center of the gesture. Set this property to rotate and zoom around a fixed point instead.
+    ///
+    /// This property will be ignored by the pinch gesture if ``GestureOptions/pinchPanEnabled`` is set to `true`.
+    public var focalPoint: CGPoint?
+
     public init() {}
 }
diff --git a/Tests/MapboxMapsTests/Foundation/Mocks/MockMapViewDependencyProvider.swift b/Tests/MapboxMapsTests/Foundation/Mocks/MockMapViewDependencyProvider.swift
@@ -53,9 +53,11 @@ final class MockMapViewDependencyProvider: MapViewDependencyProviderProtocol {
                 gestureRecognizer: UIGestureRecognizer()),
             pinchGestureHandler: MockPinchGestureHandler(gestureRecognizer: UIGestureRecognizer()),
             pitchGestureHandler: makeGestureHandler(),
-            doubleTapToZoomInGestureHandler: makeGestureHandler(),
-            doubleTouchToZoomOutGestureHandler: makeGestureHandler(),
-            quickZoomGestureHandler: makeGestureHandler(),
+            doubleTapToZoomInGestureHandler: MockFocusableGestureHandler(
+                gestureRecognizer: UIGestureRecognizer()),
+            doubleTouchToZoomOutGestureHandler: MockFocusableGestureHandler(
+                gestureRecognizer: UIGestureRecognizer()),
+            quickZoomGestureHandler: MockFocusableGestureHandler(gestureRecognizer: UIGestureRecognizer()),
             singleTapGestureHandler: makeGestureHandler(),
             anyTouchGestureHandler: makeGestureHandler(),
             mapboxMap: mapboxMap)