adding animation sequence of logic to transitions

65aef2c1 · Daniel Dahan · 45cd5276 · 65aef2c1 · 65aef2c1 · 65aef2c1
Commit 65aef2c1 authored May 30, 2017 by Daniel Dahan
8 changed files
--- a/Motion.xcodeproj/project.pbxproj
+++ b/Motion.xcodeproj/project.pbxproj
@@ -13,7 +13,7 @@
 		964C153D1EDCF6EA00F0869D /* Motion.swift in Sources */ = {isa = PBXBuildFile; fileRef = 964C153C1EDCF6EA00F0869D /* Motion.swift */; };
 		964C15471EDD001A00F0869D /* MotionTransitionAnimation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 964C15461EDD001A00F0869D /* MotionTransitionAnimation.swift */; };
 		9657A6AC1EDA1601004461DE /* MotionObserver.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9657A6AB1EDA1601004461DE /* MotionObserver.swift */; };
-		9657A6AE1EDA19D8004461DE /* MotionAnimator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9657A6AD1EDA19D8004461DE /* MotionAnimator.swift */; };
+		9657A6AE1EDA19D8004461DE /* MotionTransitionAnimator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9657A6AD1EDA19D8004461DE /* MotionTransitionAnimator.swift */; };
 		9657A6B31EDA63FC004461DE /* MotionContext.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9657A6B21EDA63FC004461DE /* MotionContext.swift */; };
 		966C539E1EDD207800A82A57 /* Motion+UIView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 966C539D1EDD207800A82A57 /* Motion+UIView.swift */; };
 		966C53A01EDD20DA00A82A57 /* Motion+UIViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 966C539F1EDD20DA00A82A57 /* Motion+UIViewController.swift */; };
@@ -23,7 +23,7 @@
 		966C53B51EDD327D00A82A57 /* MotionCascadeDirection.swift in Sources */ = {isa = PBXBuildFile; fileRef = 966C53B41EDD327D00A82A57 /* MotionCascadeDirection.swift */; };
 		966C53B71EDD328F00A82A57 /* MotionCoordinateSpace.swift in Sources */ = {isa = PBXBuildFile; fileRef = 966C53B61EDD328F00A82A57 /* MotionCoordinateSpace.swift */; };
 		966C53B91EDD366800A82A57 /* MotionTransitionPreprocessor.swift in Sources */ = {isa = PBXBuildFile; fileRef = 966C53B81EDD366800A82A57 /* MotionTransitionPreprocessor.swift */; };
-		966C53BB1EDD381E00A82A57 /* MotionCaptureSubviewPreprocessor.swift in Sources */ = {isa = PBXBuildFile; fileRef = 966C53BA1EDD381E00A82A57 /* MotionCaptureSubviewPreprocessor.swift */; };
+		966C53BB1EDD381E00A82A57 /* MotionSubviewPreprocessor.swift in Sources */ = {isa = PBXBuildFile; fileRef = 966C53BA1EDD381E00A82A57 /* MotionSubviewPreprocessor.swift */; };
 		966C53BD1EDD396800A82A57 /* MotionAnimationFillMode.swift in Sources */ = {isa = PBXBuildFile; fileRef = 966C53BC1EDD396800A82A57 /* MotionAnimationFillMode.swift */; };
 		966C53BF1EDD399400A82A57 /* MotionAnimationTimingFunction.swift in Sources */ = {isa = PBXBuildFile; fileRef = 966C53BE1EDD399400A82A57 /* MotionAnimationTimingFunction.swift */; };
 		96BFC1701E63C3460075DE1F /* MotionController.swift in Headers */ = {isa = PBXBuildFile; fileRef = 96C98DE31E4382B100B22906 /* MotionController.swift */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -37,7 +37,7 @@
 		964C153C1EDCF6EA00F0869D /* Motion.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Motion.swift; sourceTree = "<group>"; };
 		964C15461EDD001A00F0869D /* MotionTransitionAnimation.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionTransitionAnimation.swift; sourceTree = "<group>"; };
 		9657A6AB1EDA1601004461DE /* MotionObserver.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionObserver.swift; sourceTree = "<group>"; };
-		9657A6AD1EDA19D8004461DE /* MotionAnimator.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionAnimator.swift; sourceTree = "<group>"; };
+		9657A6AD1EDA19D8004461DE /* MotionTransitionAnimator.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionTransitionAnimator.swift; sourceTree = "<group>"; };
 		9657A6B21EDA63FC004461DE /* MotionContext.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionContext.swift; sourceTree = "<group>"; };
 		966C539D1EDD207800A82A57 /* Motion+UIView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "Motion+UIView.swift"; sourceTree = "<group>"; };
 		966C539F1EDD20DA00A82A57 /* Motion+UIViewController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "Motion+UIViewController.swift"; sourceTree = "<group>"; };
@@ -47,7 +47,7 @@
 		966C53B41EDD327D00A82A57 /* MotionCascadeDirection.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionCascadeDirection.swift; sourceTree = "<group>"; };
 		966C53B61EDD328F00A82A57 /* MotionCoordinateSpace.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionCoordinateSpace.swift; sourceTree = "<group>"; };
 		966C53B81EDD366800A82A57 /* MotionTransitionPreprocessor.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionTransitionPreprocessor.swift; sourceTree = "<group>"; };
-		966C53BA1EDD381E00A82A57 /* MotionCaptureSubviewPreprocessor.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionCaptureSubviewPreprocessor.swift; sourceTree = "<group>"; };
+		966C53BA1EDD381E00A82A57 /* MotionSubviewPreprocessor.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionSubviewPreprocessor.swift; sourceTree = "<group>"; };
 		966C53BC1EDD396800A82A57 /* MotionAnimationFillMode.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionAnimationFillMode.swift; sourceTree = "<group>"; };
 		966C53BE1EDD399400A82A57 /* MotionAnimationTimingFunction.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionAnimationTimingFunction.swift; sourceTree = "<group>"; };
 		96C98DD11E424AB000B22906 /* Motion.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Motion.framework; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -91,29 +91,53 @@
 				96C98DE21E43809D00B22906 /* LICENSE */,
 				96C98DDD1E424B9000B22906 /* Info.plist */,
 				96C98DED1E438A5700B22906 /* Motion.h */,
-				961409A91E43CF1B00E7BA99 /* Motion+Obj-C.swift */,
-				966C539D1EDD207800A82A57 /* Motion+UIView.swift */,
-				966C539F1EDD20DA00A82A57 /* Motion+UIViewController.swift */,
-				966C53AE1EDD2F8B00A82A57 /* Motion+CALayer.swift */,
-				966C53B01EDD2FE600A82A57 /* Motion+CABasicAnimation.swift */,
 				964C153C1EDCF6EA00F0869D /* Motion.swift */,
 				96C98DE31E4382B100B22906 /* MotionController.swift */,
 				9657A6AB1EDA1601004461DE /* MotionObserver.swift */,
 				9657A6B21EDA63FC004461DE /* MotionContext.swift */,
-				9657A6AD1EDA19D8004461DE /* MotionAnimator.swift */,
 				96C98DE51E43848500B22906 /* MotionAnimation.swift */,
 				964C15461EDD001A00F0869D /* MotionTransitionAnimation.swift */,
 				966C53B21EDD325B00A82A57 /* MotionSnapshot.swift */,
 				966C53B41EDD327D00A82A57 /* MotionCascadeDirection.swift */,
 				966C53B61EDD328F00A82A57 /* MotionCoordinateSpace.swift */,
-				966C53B81EDD366800A82A57 /* MotionTransitionPreprocessor.swift */,
-				966C53BA1EDD381E00A82A57 /* MotionCaptureSubviewPreprocessor.swift */,
 				966C53BC1EDD396800A82A57 /* MotionAnimationFillMode.swift */,
 				966C53BE1EDD399400A82A57 /* MotionAnimationTimingFunction.swift */,
+				96E846EB1EDD4FCF0005F32F /* Animator */,
+				96E846EC1EDD4FE40005F32F /* Extension */,
+				96E846EA1EDD4FB30005F32F /* Preprocessor */,
 			);
 			path = Sources;
 			sourceTree = "<group>";
 		};
+		96E846EA1EDD4FB30005F32F /* Preprocessor */ = {
+			isa = PBXGroup;
+			children = (
+				966C53B81EDD366800A82A57 /* MotionTransitionPreprocessor.swift */,
+				966C53BA1EDD381E00A82A57 /* MotionSubviewPreprocessor.swift */,
+			);
+			name = Preprocessor;
+			sourceTree = "<group>";
+		};
+		96E846EB1EDD4FCF0005F32F /* Animator */ = {
+			isa = PBXGroup;
+			children = (
+				9657A6AD1EDA19D8004461DE /* MotionTransitionAnimator.swift */,
+			);
+			name = Animator;
+			sourceTree = "<group>";
+		};
+		96E846EC1EDD4FE40005F32F /* Extension */ = {
+			isa = PBXGroup;
+			children = (
+				961409A91E43CF1B00E7BA99 /* Motion+Obj-C.swift */,
+				966C539D1EDD207800A82A57 /* Motion+UIView.swift */,
+				966C539F1EDD20DA00A82A57 /* Motion+UIViewController.swift */,
+				966C53AE1EDD2F8B00A82A57 /* Motion+CALayer.swift */,
+				966C53B01EDD2FE600A82A57 /* Motion+CABasicAnimation.swift */,
+			);
+			name = Extension;
+			sourceTree = "<group>";
+		};
 /* End PBXGroup section */
 /* Begin PBXHeadersBuildPhase section */
@@ -203,7 +227,7 @@
 				966C539E1EDD207800A82A57 /* Motion+UIView.swift in Sources */,
 				966C53B31EDD325B00A82A57 /* MotionSnapshot.swift in Sources */,
 				96C98DE61E43848500B22906 /* MotionAnimation.swift in Sources */,
-				9657A6AE1EDA19D8004461DE /* MotionAnimator.swift in Sources */,
+				9657A6AE1EDA19D8004461DE /* MotionTransitionAnimator.swift in Sources */,
 				9657A6AC1EDA1601004461DE /* MotionObserver.swift in Sources */,
 				9657A6B31EDA63FC004461DE /* MotionContext.swift in Sources */,
 				966C53B51EDD327D00A82A57 /* MotionCascadeDirection.swift in Sources */,
@@ -215,7 +239,7 @@
 				966C53A01EDD20DA00A82A57 /* Motion+UIViewController.swift in Sources */,
 				96C98DE41E4382B100B22906 /* MotionController.swift in Sources */,
 				966C53BF1EDD399400A82A57 /* MotionAnimationTimingFunction.swift in Sources */,
-				966C53BB1EDD381E00A82A57 /* MotionCaptureSubviewPreprocessor.swift in Sources */,
+				966C53BB1EDD381E00A82A57 /* MotionSubviewPreprocessor.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

--- a/Sources/Motion+CALayer.swift
+++ b/Sources/Motion+CALayer.swift
@@ -34,13 +34,12 @@ import UIKit
 extension CALayer: CAAnimationDelegate {}
 extension CALayer {
    /**
     A function that accepts CAAnimation objects and executes them on the
     view's backing layer.
     - Parameter animation: A CAAnimation instance.
     */
-    open func animate(_ animations: CAAnimation...) {
+    public func animate(_ animations: CAAnimation...) {
        animate(animations)
    }
@@ -49,7 +48,7 @@ extension CALayer {
     view's backing layer.
     - Parameter animation: A CAAnimation instance.
     */
-    open func animate(_ animations: [CAAnimation]) {
+    public func animate(_ animations: [CAAnimation]) {
        for animation in animations {
            if nil == animation.delegate {
                animation.delegate = self
@@ -69,7 +68,7 @@ extension CALayer {
        }
    }
-    open func animationDidStart(_ anim: CAAnimation) {}
+    public func animationDidStart(_ anim: CAAnimation) {}
    /**
     A delegation function that is executed when the backing layer stops
@@ -79,7 +78,7 @@ extension CALayer {
     because it was completed or interrupted. True if completed, false
     if interrupted.
     */
-    open func animationDidStop(_ anim: CAAnimation, finished flag: Bool) {
+    public func animationDidStop(_ anim: CAAnimation, finished flag: Bool) {
        guard let a = anim as? CAPropertyAnimation else {
            if let a = (anim as? CAAnimationGroup)?.animations {
                for x in a {
@@ -109,7 +108,7 @@ extension CALayer {
     A function that accepts a list of MotionAnimation values and executes them.
     - Parameter animations: A list of MotionAnimation values.
     */
-    open func motion(_ animations: MotionAnimation...) {
+    public func motion(_ animations: MotionAnimation...) {
        motion(animations)
    }
@@ -118,7 +117,7 @@ extension CALayer {
     - Parameter animations: An Array of MotionAnimation values.
     - Parameter completion: An optional completion block.
     */
-    open func motion(_ animations: [MotionAnimation], completion: (() -> Void)? = nil) {
+    public func motion(_ animations: [MotionAnimation], completion: (() -> Void)? = nil) {
        motion(delay: 0, duration: 0.35, timingFunction: .easeInEaseOut, animations: animations, completion: completion)
    }
@@ -137,6 +136,7 @@ extension CALayer {
            switch v {
            case let .delay(time):
                t = time
            default:break
            }
        }
@@ -157,11 +157,14 @@ extension CALayer {
                switch v {
                case let .width(width):
                    w = width
                case let .height(height):
                    h = height
                case let .size(width, height):
                    w = width
                    h = height
                default:break
                }
            }
@@ -173,11 +176,14 @@ extension CALayer {
                switch v {
                case let .x(x):
                    px = x + w / 2
                case let .y(y):
                    py = y + h / 2
                case let .point(x, y):
                    px = x + w / 2
                    py = y + h / 2
                default:break
                }
            }
@@ -186,86 +192,120 @@ extension CALayer {
                switch v {
                case let .timingFunction(timingFunction):
                    tf = timingFunction
                case let .duration(duration):
                    d = duration
                case let .custom(animation):
                    a.append(animation)
                case let .backgroundColor(color):
                    a.append(MotionBasicAnimation.background(color: color))
                case let .barTintColor(color):
                    a.append(MotionBasicAnimation.barTint(color: color))
                case let .borderColor(color):
                    a.append(MotionBasicAnimation.border(color: color))
                case let .borderWidth(width):
                    a.append(MotionBasicAnimation.border(width: width))
                case let .cornerRadius(radius):
                    a.append(MotionBasicAnimation.corner(radius: radius))
                case let .transform(transform):
                    a.append(MotionBasicAnimation.transform(transform: transform))
                case let .rotationAngle(angle):
                    let rotate = MotionBasicAnimation.rotation(angle: angle)
                    a.append(rotate)
                case let .rotationAngleX(angle):
                    a.append(MotionBasicAnimation.rotationX(angle: angle))
                case let .rotationAngleY(angle):
                    a.append(MotionBasicAnimation.rotationY(angle: angle))
                case let .rotationAngleZ(angle):
                    a.append(MotionBasicAnimation.rotationZ(angle: angle))
                case let .spin(rotations):
                    a.append(MotionBasicAnimation.spin(rotations: rotations))
                case let .spinX(rotations):
                    a.append(MotionBasicAnimation.spinX(rotations: rotations))
                case let .spinY(rotations):
                    a.append(MotionBasicAnimation.spinY(rotations: rotations))
                case let .spinZ(rotations):
                    a.append(MotionBasicAnimation.spinZ(rotations: rotations))
                case let .scale(to):
                    a.append(MotionBasicAnimation.scale(to: to))
                case let .scaleX(to):
                    a.append(MotionBasicAnimation.scaleX(to: to))
                case let .scaleY(to):
                    a.append(MotionBasicAnimation.scaleY(to: to))
                case let .scaleZ(to):
                    a.append(MotionBasicAnimation.scaleZ(to: to))
                case let .translate(x, y):
                    a.append(MotionBasicAnimation.translate(to: CGPoint(x: x, y: y)))
                case let .translateX(to):
                    a.append(MotionBasicAnimation.translateX(to: to))
                case let .translateY(to):
                    a.append(MotionBasicAnimation.translateY(to: to))
                case let .translateZ(to):
                    a.append(MotionBasicAnimation.translateZ(to: to))
                case .x(_), .y(_), .point(_, _):
                    let position = MotionBasicAnimation.position(to: CGPoint(x: px, y: py))
                    a.append(position)
                case let .position(x, y):
                    a.append(MotionBasicAnimation.position(to: CGPoint(x: x, y: y)))
                case let .fade(opacity):
                    let fade = MotionBasicAnimation.fade(opacity: opacity)
                    fade.fromValue = s.value(forKey: MotionAnimationKeyPath.opacity.rawValue) ?? NSNumber(floatLiteral: 1)
                    a.append(fade)
                case let .zPosition(index):
                    let zPosition = MotionBasicAnimation.zPosition(index: index)
                    zPosition.fromValue = s.value(forKey: MotionAnimationKeyPath.zPosition.rawValue) ?? NSNumber(integerLiteral: 0)
                    a.append(zPosition)
                case .width(_), .height(_), .size(_, _):
                    a.append(MotionBasicAnimation.size(CGSize(width: w, height: h)))
                case let .shadowPath(path):
                    let shadowPath = MotionBasicAnimation.shadow(path: path)
                    shadowPath.fromValue = s.shadowPath
                    a.append(shadowPath)
                case let .shadowOffset(offset):
                    let shadowOffset = MotionBasicAnimation.shadow(offset: offset)
                    shadowOffset.fromValue = s.shadowOffset
                    a.append(shadowOffset)
                case let .shadowOpacity(opacity):
                    let shadowOpacity = MotionBasicAnimation.shadow(opacity: opacity)
                    shadowOpacity.fromValue = s.shadowOpacity
                    a.append(shadowOpacity)
                case let .shadowRadius(radius):
                    let shadowRadius = MotionBasicAnimation.shadow(radius: radius)
                    shadowRadius.fromValue = s.shadowRadius
                    a.append(shadowRadius)
                case let .depth(offset, opacity, radius):
                    if let path = s.shadowPath {
                        let shadowPath = MotionBasicAnimation.shadow(path: path)
@@ -284,6 +324,7 @@ extension CALayer {
                    let shadowRadius = MotionBasicAnimation.shadow(radius: radius)
                    shadowRadius.fromValue = s.shadowRadius
                    a.append(shadowRadius)
                default:break
                }
            }

--- a/Sources/Motion+UIViewController.swift
+++ b/Sources/Motion+UIViewController.swift
@@ -34,7 +34,10 @@ fileprivate var MotionInstanceControllerKey: UInt8 = 0
 fileprivate struct MotionInstanceController {
    /// A boolean indicating whether Motion is enabled.
-    fileprivate var isMotionEnabled: Bool
+    fileprivate var isEnabled: Bool
+    /// An optional reference to the current snapshot.
+    fileprivate var snapshot: UIView?
 }
 extension UIViewController {
@@ -42,7 +45,7 @@ extension UIViewController {
    fileprivate var motionControllerInstance: MotionInstanceController {
        get {
            return AssociatedObject.get(base: self, key: &MotionInstanceControllerKey) {
-                return MotionInstanceController(isMotionEnabled: false)
+                return MotionInstanceController(isEnabled: false, snapshot: nil)
            }
        }
        set(value) {
@@ -50,13 +53,23 @@ extension UIViewController {
        }
    }
+    /// An optional reference to the current snapshot.
+    internal var motionSnapshot: UIView? {
+        get {
+            return motionControllerInstance.snapshot
+        }
+        set(value) {
+            motionControllerInstance.snapshot = value
+        }
+    }
    /// A boolean that indicates whether motion is enabled.
-    open var isMotionEnabled: Bool {
+    public var isMotionEnabled: Bool {
        get {
-            return motionControllerInstance.isMotionEnabled
+            return motionControllerInstance.isEnabled
        }
        set(value) {
-            motionControllerInstance.isMotionEnabled = value
+            motionControllerInstance.isEnabled = value
        }
    }
 }
--- a/Sources/Motion.swift
+++ b/Sources/Motion.swift
@@ -32,9 +32,76 @@ import UIKit
 public typealias MotionDelayCancelBlock = (Bool) -> Void
-open class Motion {
+public class Motion: MotionController {
+    /// A reference to an optional transitioning context provided by UIKit.
+    fileprivate weak var transitionContext: UIViewControllerContextTransitioning?
+    /**
+     A boolean indicating if the transition view controller is a
+     UINavigationController.
+     */
+    fileprivate var isNavigationController = false
+    /**
+     A boolean indicating if the transition view controller is a
+     UITabBarController.
+     */
+    fileprivate var isTabBarController = false
+    /**
+     A boolean indicating if the transition view controller is a
+     UINavigationController or UITabBarController.
+     */
+    fileprivate var isContainerController: Bool {
+        return isNavigationController || isTabBarController
+    }
+    /// A boolean indicating if the toView is at full screen.
+    fileprivate var isToViewFullScreen: Bool {
+        return !isContainerController && (.overFullScreen == toViewController!.modalPresentationStyle || .overCurrentContext == toViewController!.modalPresentationStyle)
+    }
+    fileprivate var isFromViewFullScreen: Bool {
+        return !isContainerController && (.overFullScreen == fromViewController!.modalPresentationStyle || .overCurrentContext == fromViewController!.modalPresentationStyle)
+    }
+    /// A reference to the fromViewController.view.
+    fileprivate var fromView: UIView {
+        return fromViewController!.view
+    }
+    /// A reference to the toViewController.view.
+    fileprivate var toView: UIView {
+        return toViewController!.view
+    }
+    /// A reference to the screen snapshot.
+    fileprivate var screenSnapshot: UIView!
+    /**
+     A reference to a shared Motion instance to control interactive
+     transitions.
+     */
+    public static let shared = Motion()
+    /// A reference to the source view controller.
+    public fileprivate(set) var fromViewController: UIViewController?
+    /// A reference to the destination view controller.
+    public fileprivate(set) var toViewController: UIViewController?
+    /// A boolean indicating if the view controller is presenting.
+    public fileprivate(set) var isPresenting = true
+    /// A reference to the animation elapsed time.
+    public override var elapsedTime: TimeInterval {
+        didSet {
+            guard isTransitioning else {
+                return
+            }
+            transitionContext?.updateInteractiveTransition(CGFloat(elapsedTime))
+        }
+    }
 }
 extension Motion {
@@ -46,13 +113,14 @@ extension Motion {
     the animations have completed.
     */
    @discardableResult
-    open class func delay(_ time: TimeInterval, execute block: @escaping () -> Void) -> MotionDelayCancelBlock? {
+    public class func delay(_ time: TimeInterval, execute block: @escaping () -> Void) -> MotionDelayCancelBlock? {
        var cancelable: MotionDelayCancelBlock?
        let delayed: MotionDelayCancelBlock = {
            if !$0 {
                DispatchQueue.main.async(execute: block)
            }
            cancelable = nil
        }
@@ -69,7 +137,7 @@ extension Motion {
     Cancels the delayed MotionDelayCancelBlock.
     - Parameter delayed completion: An MotionDelayCancelBlock.
     */
-    open class func cancel(delayed completion: MotionDelayCancelBlock) {
+    public class func cancel(delayed completion: MotionDelayCancelBlock) {
        completion(true)
    }
@@ -77,7 +145,7 @@ extension Motion {
     Disables the default animations set on CALayers.
     - Parameter animations: A callback that wraps the animations to disable.
     */
-    open class func disable(_ animations: (() -> Void)) {
+    public class func disable(_ animations: (() -> Void)) {
        animate(duration: 0, animations: animations)
    }
@@ -89,7 +157,7 @@ extension Motion {
     - Parameter completion: A completion block that is executed once
     the animations have completed.
     */
-    open class func animate(duration: CFTimeInterval, timingFunction: MotionAnimationTimingFunction = .easeInEaseOut, animations: (() -> Void), completion: (() -> Void)? = nil) {
+    public class func animate(duration: CFTimeInterval, timingFunction: MotionAnimationTimingFunction = .easeInEaseOut, animations: (() -> Void), completion: (() -> Void)? = nil) {
        CATransaction.begin()
        CATransaction.setAnimationDuration(duration)
        CATransaction.setCompletionBlock(completion)
@@ -105,7 +173,7 @@ extension Motion {
     - Parameter duration: An animation duration time for the group.
     - Returns: A CAAnimationGroup.
     */
-    open class func animate(group animations: [CAAnimation], timingFunction: MotionAnimationTimingFunction = .easeInEaseOut, duration: CFTimeInterval = 0.5) -> CAAnimationGroup {
+    public class func animate(group animations: [CAAnimation], timingFunction: MotionAnimationTimingFunction = .easeInEaseOut, duration: CFTimeInterval = 0.5) -> CAAnimationGroup {
        let group = CAAnimationGroup()
        group.fillMode = MotionAnimationFillModeToValue(mode: .both)
        group.isRemovedOnCompletion = false
@@ -115,3 +183,86 @@ extension Motion {
        return group
    }
 }
+extension Motion {
+    /// Prepares the screen snapshot.
+    fileprivate func prepareScreenSnapshot() {
+        screenSnapshot?.removeFromSuperview()
+        screenSnapshot = (transitionContainer.window ?? fromView).snapshotView(afterScreenUpdates: true)
+        (transitionContainer.window ?? transitionContainer)?.addSubview(screenSnapshot)
+    }
+    /// Prepares the preprocessors.
+    fileprivate func preparePreprocessors() {
+        preprocessors = [MotionSubviewPreprocessor()]
+    }
+    /// Prepares the animators.
+    fileprivate func prepareAnimators() {
+        animators = []
+    }
+    /// Prepares the transitionContainer.
+    fileprivate func prepareTransitionContainer() {
+        transitionContainer.isUserInteractionEnabled = false
+    }
+    /// Prepares the container.
+    fileprivate func prepareContainer() {
+        container = UIView(frame: transitionContainer.bounds)
+        transitionContainer.addSubview(container)
+    }
+    /// Prepares the context.
+    fileprivate func prepareContext() {
+        context = MotionContext(container: container)
+        container.addSubview(toView)
+        container.addSubview(fromView)
+        context.set(fromViews: subviews(of: fromView), toViews: subviews(of: toView))
+    }
+    /// Prepares the toView.
+    fileprivate func prepareToView() {
+        toView.frame = fromView.frame
+        toView.updateConstraints()
+        toView.setNeedsLayout()
+        toView.layoutIfNeeded()
+    }
+}
+extension Motion {
+    /**
+     Removes a snapshot from a given view controller.
+     - Parameter for viewController: A UIViewController.
+     */
+    fileprivate func removeSnapshot(for viewController: UIViewController?) {
+        guard let v = viewController?.motionSnapshot else {
+            return
+        }
+        v.removeFromSuperview()
+        viewController?.motionSnapshot = nil
+    }
+}
+extension Motion {
+    /// Starts the transition.
+    fileprivate func start() {
+        guard isTransitioning else {
+            return
+        }
+        removeSnapshot(for: fromViewController)
+        removeSnapshot(for: toViewController)
+        prepareScreenSnapshot()
+        preparePreprocessors()
+        prepareAnimators()
+        prepareTransitionContainer()
+        prepareContainer()
+        prepareToView()
+        prepareContext()
+    }
+}
--- a/Sources/MotionContext.swift
+++ b/Sources/MotionContext.swift
@@ -87,7 +87,7 @@ extension MotionContext {
     - Parameter fromViews: An Array of UIViews.
     - Parameter toViews: An Array of UIViews.
     */
-    fileprivate func set(fromViews: [UIView], toViews: [UIView]) {
+    internal func set(fromViews: [UIView], toViews: [UIView]) {
        self.fromViews = fromViews
        self.toViews = toViews
        prepare(views: fromViews, identifierIndex: &sourceIdentifierToView)

--- a/Sources/MotionController.swift
+++ b/Sources/MotionController.swift
@@ -30,7 +30,7 @@
 import UIKit
-open class MotionController: NSObject, MotionSubscriber {
+public class MotionController: NSObject, MotionSubscriber {
    /// An optional reference to the animation display link.
    fileprivate var displayLink: CADisplayLink? {
        willSet {
@@ -52,18 +52,18 @@ open class MotionController: NSObject, MotionSubscriber {
    }
    /// A reference to the animation duration.
-    fileprivate var transitionDuration: TimeInterval = 0
+    fileprivate var duration: TimeInterval = 0
    /**
     A reference to the animation total duration,
     which is the total running animation time.
     */
-    fileprivate var transitionTotalDuration: TimeInterval = 0
+    fileprivate var totalDuration: TimeInterval = 0
    /// A reference to the animation start time.
-    fileprivate var transitionStartTime: TimeInterval? {
+    fileprivate var startTime: TimeInterval? {
        didSet {
-            guard nil != transitionStartTime else {
+            guard nil != startTime else {
                displayLink = nil
                return
            }
@@ -77,7 +77,7 @@ open class MotionController: NSObject, MotionSubscriber {
    }
    /// A reference to the animation elapsed time.
-    open fileprivate(set) var transitionElapsedTime: TimeInterval = 0 {
+    public internal(set) var elapsedTime: TimeInterval = 0 {
        didSet {
            guard isTransitioning else {
                return
@@ -88,48 +88,46 @@ open class MotionController: NSObject, MotionSubscriber {
        }
    }
+    /// A reference to a MotionContext.
+    public internal(set) var context: MotionContext!
    /// A reference to an Array of MotionObservers.
-    open fileprivate(set) var observers = [MotionObserver]()
+    public internal(set) var observers = [MotionObserver]()
-    /// A reference to an Array of MotionAnimators.
+    /// A reference to an Array of MotionTransitionAnimator.
-    open fileprivate(set) var animators = [MotionAnimator]()
+    public internal(set) var animators = [MotionTransitionAnimator]()
    /// A reference to the preprocessors.
-    open fileprivate(set) var processors = [MotionTransitionPreprocessor]()
+    public internal(set) var preprocessors = [MotionTransitionPreprocessor]()
    /// A boolean indicating if a transition is in progress.
-    open var isTransitioning: Bool {
+    public var isTransitioning: Bool {
        return nil == transitionContainer
    }
    /// A boolean indicating if the animation is finished.
-    open fileprivate(set) var isFinished = false
+    public fileprivate(set) var isFinished = false
    /// A boolean indicating if the animation is interactive.
-    open var isInteractive: Bool {
+    public var isInteractive: Bool {
        return nil == displayLink
    }
+    /**
+     An animation container used within the transitionContainer
+     during a transition.
+     */
+    public internal(set) var container: UIView!
    /// Transition container.
-    open fileprivate(set) var transitionContainer: UIView!
+    public fileprivate(set) var transitionContainer: UIView!
    /// An Array of from and to view paris to be animated.
-    open fileprivate(set) var transitionParis = [(fromViews: [UIView], toViews: [UIView])]()
+    public fileprivate(set) var transitionParis = [(fromViews: [UIView], toViews: [UIView])]()
 }
 extension MotionController {
    /**
-     Retrieves all the subviews of a given view.
-     - Parameter of view: A UIView.
-     - Returns: An Array of UIViews.
-     */
-    fileprivate func subviews(of view: UIView) -> [UIView] {
-        var views: [UIView] = []
-        subviews(of: view, views: &views)
-        return views
-    }
-    /**
     Populates an Array of UIViews with the subviews of a given view.
     - Parameter of view: A UIView.
     - Returns: An Array of UIViews.
@@ -142,6 +140,17 @@ extension MotionController {
            subviews(of: v, views: &views)
        }
    }
+    /**
+     Retrieves all the subviews of a given view.
+     - Parameter of view: A UIView.
+     - Returns: An Array of UIViews.
+     */
+    internal func subviews(of view: UIView) -> [UIView] {
+        var views: [UIView] = []
+        subviews(of: view, views: &views)
+        return views
+    }
 }
 extension MotionController {
@@ -162,28 +171,28 @@ extension MotionController {
            return
        }
-        guard 0 < transitionDuration else {
+        guard 0 < duration else {
            return
        }
-        guard let v = transitionStartTime else {
+        guard let v = startTime else {
            return
        }
-        var elapsedTime = CACurrentMediaTime() - v
+        var t = CACurrentMediaTime() - v
-        if elapsedTime > transitionDuration {
+        if t > duration {
-            transitionElapsedTime = isFinished ? 1 : 0
+            elapsedTime = isFinished ? 1 : 0
            completeTransition()
        } else {
-            elapsedTime = elapsedTime / transitionDuration
+            t = t / duration
            if !isFinished {
-                elapsedTime = 1 - elapsedTime
+                t = 1 - t
            }
-            transitionElapsedTime = max(0, min(1, elapsedTime))
+            elapsedTime = max(0, min(1, t))
        }
    }
 }
@@ -191,16 +200,16 @@ extension MotionController {
 extension MotionController {
    fileprivate func updateMotionObservers() {
        for v in observers {
-            v.update(elapsedTime: transitionElapsedTime)
+            v.update(elapsedTime: elapsedTime)
        }
    }
    /// Updates the motion animators.
    fileprivate func updateMotionAnimators() {
-        let elapsedTime = transitionElapsedTime * transitionTotalDuration
+        let t = elapsedTime * totalDuration
        for v in animators {
-            v.seekTo(elapsedTime: elapsedTime)
+            v.seekTo(elapsedTime: t)
        }
    }
 }
@@ -221,8 +230,8 @@ extension MotionController {
    /// Cleans the transition values.
    fileprivate func cleanTransitionValues() {
-        transitionStartTime = nil
+        startTime = nil
-        transitionElapsedTime = 0
+        elapsedTime = 0
-        transitionTotalDuration = 0
+        totalDuration = 0
    }
 }
--- a/Sources/MotionCaptureSubviewPreprocessor.swift
+++ b/Sources/MotionCaptureSubviewPreprocessor.swift
@@ -30,7 +30,7 @@
 import UIKit
-public class MotionCaptureSubviewPreprocessor: MotionTransitionPreprocessor {
+public class MotionSubviewPreprocessor: MotionTransitionPreprocessor {
    /// A reference to a MotionContext.
    public weak var context: MotionContext!

--- a/Sources/MotionAnimator.swift
+++ b/Sources/MotionAnimator.swift
@@ -30,7 +30,7 @@
 import UIKit
-public protocol MotionAnimator {
+public protocol MotionTransitionAnimator {
    /// A reference to a MotionContext.
    weak var context: MotionContext! { get set }