Flatten the Interaction types down to a single Interaction protocol.

Summary:
This new protocol is abstract over the target type, T. This diff flattens ViewInteraction and PropertyInteraction into a single protocol, greatly simplifying the overall type system and also making it possible for interactions to support novel target types.

This change introduces a feature regression: interactions can no longer support multiple target types via overloads. In practice, I found that this actually cleaned up runtime.add call sites (e.g. springs can't be added to views anymore, they must be explicitly added to a property), so I'm not particularly concerned about this regression.

If we do find that it's important for an interaction to support multiple distinct target types, then we can introduce variant Interaction types, e.g. InteractionVariant1, InteractionVariant2, etc... with corresponding runtime APIs.

Reviewers: O2 Material Motion, O4 Material Apple platform reviewers, #material_motion, chuga

Reviewed By: O4 Material Apple platform reviewers, chuga

Subscribers: chuga

Tags: #material_motion

Differential Revision: http://codereview.cc/D2827

examples/ContextualTransitionExample.swift

@@ -333,15 +333,15 @@ private class PushBackTransition: Transition {
 
 // TODO: The need here is we want to hide a given view will the transition is active. This
 // implementation does not register a stream with the runtime.
-private class Hidden: ViewInteraction {
+private class Hidden: Interaction {
   deinit {
     for view in hiddenViews {
       view.isHidden = false
     }
   }
-  func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime) {
-    reactiveView.view.isHidden = true
-    hiddenViews.insert(reactiveView.view)
+  func add(to view: UIView, withRuntime runtime: MotionRuntime) {
+    view.isHidden = true
+    hiddenViews.insert(view)
   }
   var hiddenViews = Set<UIView>()
 }

examples/DragSourceExample.swift

@@ -56,6 +56,6 @@ public class DragSourceExampleViewController: UIViewController {
 
     let spring = Spring<CGPoint>(threshold: 1, system: coreAnimation)
     runtime.connect(tossable.spring.destination, to: spring.destination)
-    runtime.add(spring, to: square2)
+    runtime.add(spring, to: runtime.get(square2.layer).position)
   }
 }

examples/FabTransitionExample.swift

@@ -170,15 +170,15 @@ private class CircularRevealTransition: Transition {
 
 // TODO: The need here is we want to hide a given view will the transition is active. This
 // implementation does not register a stream with the runtime.
-private class Hidden: ViewInteraction {
+private class Hidden: Interaction {
   deinit {
     for view in hiddenViews {
       view.isHidden = false
     }
   }
-  func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime) {
-    reactiveView.view.isHidden = true
-    hiddenViews.insert(reactiveView.view)
+  func add(to view: UIView, withRuntime runtime: MotionRuntime) {
+    view.isHidden = true
+    hiddenViews.insert(view)
   }
   var hiddenViews = Set<UIView>()
 }

examples/SwipeExample.swift

@@ -23,7 +23,7 @@ enum TossDirection {
   case right
 }
 
-class TossableStackedCard: ViewInteraction {
+class TossableStackedCard: Interaction {
   public let tossDirection = createProperty("tossDirection", withInitialValue: TossDirection.none)
 
   init(relativeView: UIView, previousCard: TossableStackedCard? = nil, rotation: CGFloat) {
@@ -34,11 +34,11 @@ class TossableStackedCard: ViewInteraction {
     self.dragGesture = UIPanGestureRecognizer()
   }
 
-  func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime) {
+  func add(to view: UIView, withRuntime runtime: MotionRuntime) {
+    let reactiveView = runtime.get(view)
     let position = reactiveView.centerX
     self.position = position
 
-    let view = reactiveView.view
     view.addGestureRecognizer(dragGesture)
 
     let destination = createProperty("destination", withInitialValue: relativeView.bounds.midX)
@@ -145,7 +145,7 @@ public class SwipeExampleViewController: UIViewController {
                                    alpha: 1)
 
     let interaction = TossableStackedCard(relativeView: view, previousCard: queue.last, rotation: rotation)
-    runtime.add(interaction, to: runtime.get(card))
+    runtime.add(interaction, to: card)
 
     lastRotation = rotation
 

src/Interaction.swift

@@ -24,12 +24,7 @@ public protocol StatefulInteraction {
   var state: MotionObservable<MotionState> { get }
 }
 
-public protocol ViewInteraction {
-  /** Connect all streams with the provided runtime. */
-  func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime)
-}
-
-public protocol PropertyInteraction {
-  associatedtype T
-  func add(to property: ReactiveProperty<T>, withRuntime runtime: MotionRuntime)
+public protocol Interaction {
+  associatedtype Target
+  func add(to target: Target, withRuntime runtime: MotionRuntime)
 }

src/MotionRuntime.swift

@@ -33,17 +33,9 @@ public final class MotionRuntime {
     self.containerView = containerView
   }
 
-  public func add(_ interaction: ViewInteraction, to view: UIView) {
-    add(interaction, to: get(view))
-  }
-
-  public func add<I: PropertyInteraction, P: ReactivePropertyConvertible>(_ interaction: I, to property: P) where I.T == P.T {
-    interaction.add(to: property.asProperty(), withRuntime: self)
-  }
-
-  public func add(_ interaction: ViewInteraction, to reactiveView: ReactiveUIView) {
-    interaction.add(to: reactiveView, withRuntime: self)
-    viewInteractions.append(interaction)
+  public func add<I: Interaction>(_ interaction: I, to target: I.Target) {
+    interaction.add(to: target, withRuntime: self)
+    interactions.append(interaction)
   }
 
   public func connect<O: MotionObservableConvertible>(_ stream: O, to property: ReactiveProperty<O.T>) {
@@ -160,5 +152,5 @@ public final class MotionRuntime {
   }
 
   private var subscriptions: [Subscription] = []
-  private var viewInteractions: [ViewInteraction] = []
+  private var interactions: [Any] = []
 }

src/interactions/AdjustsAnchorPoint.swift

@@ -24,9 +24,8 @@ public class AdjustsAnchorPoint {
   }
 }
 
-extension AdjustsAnchorPoint: ViewInteraction {
-  public func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime) {
-    let view = reactiveView.view
+extension AdjustsAnchorPoint: Interaction {
+  public func add(to view: UIView, withRuntime runtime: MotionRuntime) {
     var anchorPointStreams = gestureRecognizers.map {
       runtime.get($0)
         .onRecognitionState(.began)
@@ -42,7 +41,7 @@ extension AdjustsAnchorPoint: ViewInteraction {
     })
 
     for stream in anchorPointStreams {
-      runtime.connect(stream, to: reactiveView.reactiveLayer.anchorPointAdjustment)
+      runtime.connect(stream, to: runtime.get(view.layer).anchorPointAdjustment)
     }
   }
 }

src/interactions/ArcMove.swift

@@ -33,13 +33,13 @@ public class ArcMove {
   fileprivate let system: PathTweenToStream<CGPoint>
 }
 
-extension ArcMove: ViewInteraction {
-  public func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime) {
+extension ArcMove: Interaction {
+  public func add(to view: UIView, withRuntime runtime: MotionRuntime) {
     let tween = PathTween(system: system, timeline: timeline)
     runtime.connect(arcMove(from: from, to: to), to: tween.path)
     runtime.connect(duration, to: tween.duration)
 
-    runtime.add(tween, to: reactiveView.reactiveLayer.position)
+    runtime.add(tween, to: runtime.get(view.layer).position)
   }
 }
 

src/interactions/DirectlyManipulable.swift

@@ -36,8 +36,8 @@ public class DirectlyManipulable: NSObject {
   }
 }
 
-extension DirectlyManipulable: ViewInteraction {
-  public func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime) {
+extension DirectlyManipulable: Interaction {
+  public func add(to view: UIView, withRuntime runtime: MotionRuntime) {
     for gestureRecognizer in [draggable.nextGestureRecognizer,
                               rotatable.nextGestureRecognizer,
                               scalable.nextGestureRecognizer] {
@@ -48,10 +48,10 @@ extension DirectlyManipulable: ViewInteraction {
 
     let adjustsAnchorPoint = AdjustsAnchorPoint(gestureRecognizers: [rotatable.nextGestureRecognizer,
                                                                      scalable.nextGestureRecognizer])
-    runtime.add(adjustsAnchorPoint, to: reactiveView)
-    runtime.add(draggable, to: reactiveView)
-    runtime.add(rotatable, to: reactiveView)
-    runtime.add(scalable, to: reactiveView)
+    runtime.add(adjustsAnchorPoint, to: view)
+    runtime.add(draggable, to: view)
+    runtime.add(rotatable, to: view)
+    runtime.add(scalable, to: view)
   }
 }
 

src/interactions/Draggable.swift

@@ -19,8 +19,9 @@ import Foundation
 public class Draggable: Gesturable<UIPanGestureRecognizer> {
 }
 
-extension Draggable: ViewInteraction {
-  public func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime) {
+extension Draggable: Interaction {
+  public func add(to view: UIView, withRuntime runtime: MotionRuntime) {
+    let reactiveView = runtime.get(view)
     let gestureRecognizer = dequeueGestureRecognizer(withReactiveView: reactiveView)
     let position = reactiveView.reactiveLayer.position
     runtime.connect(runtime.get(gestureRecognizer).translated(from: position), to: position)

src/interactions/PathTween.swift

@@ -62,7 +62,7 @@ public final class PathTween: TogglableInteraction, StatefulInteraction {
   fileprivate let _state = createProperty("PathTween._state", withInitialValue: MotionState.atRest)
 }
 
-extension PathTween: PropertyInteraction {
+extension PathTween: Interaction {
   public func add(to property: ReactiveProperty<CGPoint>, withRuntime runtime: MotionRuntime) {
     runtime.connect(asStream(), to: property)
   }

src/interactions/Rotatable.swift

@@ -19,8 +19,9 @@ import Foundation
 public class Rotatable: Gesturable<UIRotationGestureRecognizer> {
 }
 
-extension Rotatable: ViewInteraction {
-  public func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime) {
+extension Rotatable: Interaction {
+  public func add(to view: UIView, withRuntime runtime: MotionRuntime) {
+    let reactiveView = runtime.get(view)
     let gestureRecognizer = dequeueGestureRecognizer(withReactiveView: reactiveView)
     let rotation = reactiveView.reactiveLayer.rotation
     runtime.connect(runtime.get(gestureRecognizer).rotated(from: rotation), to: rotation)

src/interactions/Scalable.swift

@@ -19,8 +19,9 @@ import Foundation
 public class Scalable: Gesturable<UIPinchGestureRecognizer> {
 }
 
-extension Scalable: ViewInteraction {
-  public func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime) {
+extension Scalable: Interaction {
+  public func add(to view: UIView, withRuntime runtime: MotionRuntime) {
+    let reactiveView = runtime.get(view)
     let gestureRecognizer = dequeueGestureRecognizer(withReactiveView: reactiveView)
     let scale = reactiveView.reactiveLayer.scale
     runtime.connect(runtime.get(gestureRecognizer).scaled(from: scale), to: scale)

src/interactions/Spring.swift

@@ -22,7 +22,7 @@ import IndefiniteObservable
 
  This class defines the expected shape of a Spring for use in creating a Spring source.
  */
-public class Spring<T: Zeroable>: PropertyInteraction, ViewInteraction, TogglableInteraction, StatefulInteraction {
+public class Spring<T: Zeroable>: Interaction, TogglableInteraction, StatefulInteraction {
   /** Creates a spring with the provided properties and an initial velocity. */
   public init(threshold: CGFloat, system: @escaping SpringToStream<T>) {
     self.threshold = createProperty("Spring.threshold", withInitialValue: threshold)
@@ -67,12 +67,6 @@ public class Spring<T: Zeroable>: PropertyInteraction, ViewInteraction, Togglabl
   fileprivate let system: SpringToStream<T>
   fileprivate let _state = createProperty("Spring._state", withInitialValue: MotionState.atRest)
 
-  public func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime) {
-    if let castedSelf = self as? Spring<CGPoint> {
-      castedSelf.add(to: reactiveView.reactiveLayer.position, withRuntime: runtime)
-    }
-  }
-
   public func add(to property: ReactiveProperty<T>, withRuntime runtime: MotionRuntime) {
     let shadow = SpringShadow(of: self, initialValue: property)
     runtime.connect(shadow.state.dedupe(), to: ReactiveProperty(initialValue: .atRest) { state in

src/interactions/Tap.swift

@@ -36,7 +36,7 @@ public class Tap {
   }
 }
 
-extension Tap: PropertyInteraction {
+extension Tap: Interaction {
   public func add(to property: ReactiveProperty<CGPoint>, withRuntime runtime: MotionRuntime) {
     let gestureRecognizer: UITapGestureRecognizer
 

src/interactions/Tossable.swift

@@ -32,9 +32,9 @@ public class Tossable {
   }
 }
 
-extension Tossable: ViewInteraction {
-  public func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime) {
-    let position = reactiveView.reactiveLayer.position
+extension Tossable: Interaction {
+  public func add(to view: UIView, withRuntime runtime: MotionRuntime) {
+    let position = runtime.get(view.layer).position
 
     let gesture = runtime.get(draggable.nextGestureRecognizer)
 
@@ -48,6 +48,6 @@ extension Tossable: ViewInteraction {
     runtime.enable(spring, whenAtRest: gesture)
     runtime.add(spring, to: position)
 
-    runtime.add(draggable, to: reactiveView)
+    runtime.add(draggable, to: view)
   }
 }

src/interactions/Tween.swift

@@ -17,7 +17,7 @@
 import Foundation
 
 /** A tween describes a potential interpolation from one value to another. */
-public final class Tween<T>: PropertyInteraction, TogglableInteraction, StatefulInteraction {
+public final class Tween<T>: Interaction, TogglableInteraction, StatefulInteraction {
 
   /** The duration of the animation in seconds. */
   public let duration: ReactiveProperty<CGFloat>