components/MaskedTransition/src/private/MDCMaskedTransition.m - external/github.com/material-components/material-components-ios - Git at Google

 // Copyright 2017-present the Material Components for iOS authors. All Rights Reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 // http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 #import <CoreGraphics/CoreGraphics.h>
 #import <QuartzCore/QuartzCore.h>

 #import "MDCMaskedTransition.h"

 #import <MotionAnimator/MotionAnimator.h>

 #import "MDCMaskedPresentationController.h"
 #import "MDCMaskedTransitionMotionForContext.h"
 #import "MDCMaskedTransitionMotionSpecs.h"

 // Math utilities

 static inline CGPoint CenterOfFrame(CGRect frame) {
   return CGPointMake(CGRectGetMidX(frame), CGRectGetMidY(frame));
 }

 static inline CGPoint AnchorPointFromPosition(CGPoint position, CGRect bounds) {
   return CGPointMake(position.x / CGRectGetWidth(bounds), position.y / CGRectGetHeight(bounds));
 }

 static inline CGRect FrameCenteredAround(CGPoint position, CGSize size) {
   return CGRectMake(position.x - size.width / 2, position.y - size.height / 2, size.width,
                     size.height);
 }

 static inline CGFloat LengthOfVector(CGVector vector) {
   return (CGFloat)hypot(vector.dx, vector.dy);
 }

 // TODO: Pull this out to MotionTransitioning.
 static void PrepareTransitionWithContext(id<UIViewControllerContextTransitioning> transitionContext,
                                          MDMTransitionDirection direction) {
   UIViewController *fromViewController =
       [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
   UIView *fromView = [transitionContext viewForKey:UITransitionContextFromViewKey];
   if (fromView == nil) {
     fromView = fromViewController.view;
   }
   if (fromView != nil && fromView == fromViewController.view) {
     CGRect finalFrame = [transitionContext finalFrameForViewController:fromViewController];
     if (!CGRectIsEmpty(finalFrame)) {
       fromView.frame = finalFrame;
     }
   }

   UIViewController *toViewController =
       [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
   UIView *toView = [transitionContext viewForKey:UITransitionContextToViewKey];
   if (toView == nil) {
     toView = toViewController.view;
   }
   if (toView != nil && toView == toViewController.view) {
     CGRect finalFrame = [transitionContext finalFrameForViewController:toViewController];
     if (!CGRectIsEmpty(finalFrame)) {
       toView.frame = finalFrame;
     }

     if (toView.superview == nil) {
       switch (direction) {
         case MDMTransitionDirectionForward:
           [transitionContext.containerView addSubview:toView];
           break;

         case MDMTransitionDirectionBackward:
           [transitionContext.containerView insertSubview:toView atIndex:0];
           break;
       }
     }
   }
 }

 // TODO: Pull this out to MotionTransitioning.
 static NSArray<UIViewController *> *OrderedViewControllersWithTransitionContext(
     id<UIViewControllerContextTransitioning> transitionContext, MDMTransitionDirection direction) {
   UIViewController *fromViewController =
       [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
   UIViewController *toViewController =
       [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

   if (direction == MDMTransitionDirectionForward) {
     return @[ fromViewController, toViewController ];
   } else {
     return @[ toViewController, fromViewController ];
   }
 }

 @implementation MDCMaskedTransition {
   UIView *_sourceView;
   CGFloat _initialSourceViewAlpha;
   MDMTransitionDirection _direction;
 }

 - (instancetype)initWithSourceView:(UIView *)sourceView
                          direction:(MDMTransitionDirection)direction {
   self = [super init];
   if (self) {
     _sourceView = sourceView;
     _direction = direction;
   }
   return self;
 }

 #pragma mark - UIViewControllerAnimatedTransitioning

 - (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext {
   NSArray<UIViewController *> *viewControllers =
       OrderedViewControllersWithTransitionContext(transitionContext, _direction);
   NSAssert([viewControllers count] == 2,
            @"Expected two view controllers to be involved in a transition.");
   if ([viewControllers count] != 2) {
     return 0;
   }
   UIViewController *presentedViewController = viewControllers[1];
   MDCMaskedTransitionMotionSpec motionSpecification = MDCMaskedTransitionMotionSpecForContext(
       transitionContext.containerView, presentedViewController);

   MDCMaskedTransitionMotionTiming motion =
       ((_direction == MDMTransitionDirectionForward) ? motionSpecification.expansion
                                                      : motionSpecification.collapse);

   return motion.overallDuration;
 }

 - (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext {
   PrepareTransitionWithContext(transitionContext, _direction);
   NSArray<UIViewController *> *viewControllers =
       OrderedViewControllersWithTransitionContext(transitionContext, _direction);
   NSAssert([viewControllers count] == 2,
            @"Expected two view controllers to be involved in a transition.");
   if ([viewControllers count] != 2) {
     [transitionContext completeTransition:YES];
     return;
   }
   UIViewController *presentedViewController = viewControllers[1];

   MDCMaskedTransitionMotionSpec motionSpecification = MDCMaskedTransitionMotionSpecForContext(
       transitionContext.containerView, presentedViewController);

   // Cache original state.
   // We're going to reparent the fore view, so keep this information for later.
   UIView *originalSuperview = presentedViewController.view.superview;
   const CGRect originalFrame = presentedViewController.view.frame;
   UIView *originalSourceSuperview = _sourceView.superview;
   const CGRect originalSourceFrame = _sourceView.frame;
   UIColor *originalSourceBackgroundColor = _sourceView.backgroundColor;

   // Reparent the fore view into a masked view.
   UIView *maskedView = [[UIView alloc] initWithFrame:presentedViewController.view.frame];
   {
     CGRect reparentedFrame = presentedViewController.view.frame;
     reparentedFrame.origin = CGPointZero;
     presentedViewController.view.frame = reparentedFrame;

     maskedView.layer.cornerRadius = presentedViewController.view.layer.cornerRadius;
     maskedView.clipsToBounds = presentedViewController.view.clipsToBounds;
   }
   [transitionContext.containerView addSubview:maskedView];

   UIView *floodFillView = [[UIView alloc] initWithFrame:presentedViewController.view.bounds];
   floodFillView.backgroundColor = _sourceView.backgroundColor;

   // TODO(featherless): Profile whether it's more performant to fade the flood fill out or to
   // fade the fore view in (what we're currently doing).
   [maskedView addSubview:floodFillView];
   [maskedView addSubview:presentedViewController.view];

   // All frames are assumed to be relative to the container view unless named otherwise.
   const CGRect initialSourceFrame = [_sourceView convertRect:_sourceView.bounds
                                                       toView:transitionContext.containerView];
   const CGRect finalMaskedFrame = originalFrame;
   CGRect initialMaskedFrame;
   CGPoint corner;
   const CGPoint initialSourceCenter = CenterOfFrame(initialSourceFrame);
   if (motionSpecification.isCentered) {
     initialMaskedFrame = FrameCenteredAround(initialSourceCenter, originalFrame.size);
     // Bottom right
     corner = CGPointMake(CGRectGetMaxX(initialMaskedFrame), CGRectGetMaxY(initialMaskedFrame));

   } else {
     initialMaskedFrame = CGRectMake(CGRectGetMinX(transitionContext.containerView.bounds),
                                     CGRectGetMinY(initialSourceFrame) - 20,
                                     CGRectGetWidth(originalFrame), CGRectGetHeight(originalFrame));
     if (CGRectGetMidX(initialSourceFrame) < CGRectGetMidX(initialMaskedFrame)) {
       // Middle-right
       corner = CGPointMake(CGRectGetMaxX(initialMaskedFrame), CGRectGetMidY(initialMaskedFrame));
     } else {
       // Middle-left
       corner = CGPointMake(CGRectGetMinX(initialMaskedFrame), CGRectGetMidY(initialMaskedFrame));
     }
   }

   maskedView.frame = initialMaskedFrame;
   const CGRect initialSourceFrameInMask = [maskedView convertRect:initialSourceFrame
                                                          fromView:transitionContext.containerView];

   const CGFloat initialRadius = CGRectGetWidth(_sourceView.bounds) / 2;
   const CGFloat finalRadius = LengthOfVector(
       CGVectorMake(initialSourceCenter.x - corner.x, initialSourceCenter.y - corner.y));
   const CGFloat finalScale = finalRadius / initialRadius;

   CAShapeLayer *shapeLayer = [[CAShapeLayer alloc] init];
   {
     // Ensures that we transform from the center of the source view's frame.
     shapeLayer.anchorPoint =
         AnchorPointFromPosition(CenterOfFrame(initialSourceFrameInMask), maskedView.layer.bounds);
     shapeLayer.frame = maskedView.layer.bounds;
     shapeLayer.path = [[UIBezierPath bezierPathWithOvalInRect:initialSourceFrameInMask] CGPath];
   }
   maskedView.layer.mask = shapeLayer;

   _sourceView.frame = initialSourceFrameInMask;
   _sourceView.backgroundColor = nil;
   [maskedView addSubview:_sourceView];

   [CATransaction begin];
   [CATransaction setCompletionBlock:^{
     presentedViewController.view.frame = originalFrame;
     [originalSuperview addSubview:presentedViewController.view];

     self->_sourceView.frame = originalSourceFrame;
     self->_sourceView.backgroundColor = originalSourceBackgroundColor;
     if (motionSpecification.shouldSlideWhenCollapsed &&
         transitionContext.presentationStyle != UIModalPresentationCustom) {
       // If we're going to slide when collapsed then this transition won't be invoked. If we also
       // don't have a presentation controller (because of the presentation style) then we need to
       // restore the source view's visibility somehow. This is the only place I could think of to
       // do so, but it unfortunately means if the presented view controller is somehow presented
       // such that the source view is still visible then the source view will appear to flash back
       // into existence at the end of the transition, breaking the illusion of continuity.
       self->_sourceView.alpha = 1;
     }
     [originalSourceSuperview addSubview:self->_sourceView];

     [maskedView removeFromSuperview];

     [transitionContext completeTransition:YES];  // Hand off back to UIKit
   }];

   MDCMaskedTransitionMotionTiming motion =
       ((_direction == MDMTransitionDirectionForward) ? motionSpecification.expansion
                                                      : motionSpecification.collapse);

   MDMMotionAnimator *animator = [[MDMMotionAnimator alloc] init];
   animator.shouldReverseValues = _direction == MDMTransitionDirectionBackward;

   if (_direction == MDMTransitionDirectionForward) {
     _initialSourceViewAlpha = _sourceView.alpha;
   }

   [animator animateWithTiming:motion.iconFade
                       toLayer:_sourceView.layer
                    withValues:@[ @(_initialSourceViewAlpha), @0 ]
                       keyPath:MDMKeyPathOpacity];

   [animator animateWithTiming:motion.contentFade
                       toLayer:presentedViewController.view.layer
                    withValues:@[ @0, @1 ]
                       keyPath:MDMKeyPathOpacity];

   // TODO(featherless): Support shadow + elevation changes. May need companion transition for this?

   {
     UIColor *initialColor = floodFillView.backgroundColor;
     if (!initialColor) {
       initialColor = [UIColor clearColor];
     }
     UIColor *finalColor = presentedViewController.view.backgroundColor;
     if (!finalColor) {
       finalColor = [UIColor whiteColor];
     }
     [animator animateWithTiming:motion.floodBackgroundColor
                         toLayer:floodFillView.layer
                      withValues:@[ initialColor, finalColor ]
                         keyPath:MDMKeyPathBackgroundColor];
   }

   {
     void (^completion)(void) = nil;
     if (_direction == MDMTransitionDirectionForward) {
       completion = ^{
         // Upon completion of the animation we want all of the content to be visible, so we jump
         // to a full bounds mask.
         shapeLayer.transform = CATransform3DIdentity;
         shapeLayer.path =
             [[UIBezierPath bezierPathWithRect:presentedViewController.view.bounds] CGPath];
       };
     }
     [animator animateWithTiming:motion.maskTransformation
                         toLayer:shapeLayer
                      withValues:@[ @1, @(finalScale) ]
                         keyPath:MDMKeyPathScale
                      completion:completion];
   }

   [animator animateWithTiming:motion.horizontalMovement
                       toLayer:maskedView.layer
                    withValues:@[
                      @(CGRectGetMidX(initialMaskedFrame)), @(CGRectGetMidX(finalMaskedFrame))
                    ]
                       keyPath:MDMKeyPathX];

   [animator animateWithTiming:motion.verticalMovement
                       toLayer:maskedView.layer
                    withValues:@[
                      @(CGRectGetMidY(initialMaskedFrame)), @(CGRectGetMidY(finalMaskedFrame))
                    ]
                       keyPath:MDMKeyPathY];

   [CATransaction commit];
 }

 @end
	// Copyright 2017-present the Material Components for iOS authors. All Rights Reserved.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	#import <CoreGraphics/CoreGraphics.h>
	#import <QuartzCore/QuartzCore.h>

	#import "MDCMaskedTransition.h"

	#import <MotionAnimator/MotionAnimator.h>

	#import "MDCMaskedPresentationController.h"
	#import "MDCMaskedTransitionMotionForContext.h"
	#import "MDCMaskedTransitionMotionSpecs.h"

	// Math utilities

	static inline CGPoint CenterOfFrame(CGRect frame) {
	return CGPointMake(CGRectGetMidX(frame), CGRectGetMidY(frame));
	}

	static inline CGPoint AnchorPointFromPosition(CGPoint position, CGRect bounds) {
	return CGPointMake(position.x / CGRectGetWidth(bounds), position.y / CGRectGetHeight(bounds));
	}

	static inline CGRect FrameCenteredAround(CGPoint position, CGSize size) {
	return CGRectMake(position.x - size.width / 2, position.y - size.height / 2, size.width,
	size.height);
	}

	static inline CGFloat LengthOfVector(CGVector vector) {
	return (CGFloat)hypot(vector.dx, vector.dy);
	}

	// TODO: Pull this out to MotionTransitioning.
	static void PrepareTransitionWithContext(id<UIViewControllerContextTransitioning> transitionContext,
	MDMTransitionDirection direction) {
	UIViewController *fromViewController =
	[transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
	UIView *fromView = [transitionContext viewForKey:UITransitionContextFromViewKey];
	if (fromView == nil) {
	fromView = fromViewController.view;
	}
	if (fromView != nil && fromView == fromViewController.view) {
	CGRect finalFrame = [transitionContext finalFrameForViewController:fromViewController];
	if (!CGRectIsEmpty(finalFrame)) {
	fromView.frame = finalFrame;
	}
	}

	UIViewController *toViewController =
	[transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
	UIView *toView = [transitionContext viewForKey:UITransitionContextToViewKey];
	if (toView == nil) {
	toView = toViewController.view;
	}
	if (toView != nil && toView == toViewController.view) {
	CGRect finalFrame = [transitionContext finalFrameForViewController:toViewController];
	if (!CGRectIsEmpty(finalFrame)) {
	toView.frame = finalFrame;
	}

	if (toView.superview == nil) {
	switch (direction) {
	case MDMTransitionDirectionForward:
	[transitionContext.containerView addSubview:toView];
	break;

	case MDMTransitionDirectionBackward:
	[transitionContext.containerView insertSubview:toView atIndex:0];
	break;
	}
	}
	}
	}

	// TODO: Pull this out to MotionTransitioning.
	static NSArray<UIViewController > OrderedViewControllersWithTransitionContext(
	id<UIViewControllerContextTransitioning> transitionContext, MDMTransitionDirection direction) {
	UIViewController *fromViewController =
	[transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
	UIViewController *toViewController =
	[transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

	if (direction == MDMTransitionDirectionForward) {
	return @[ fromViewController, toViewController ];
	} else {
	return @[ toViewController, fromViewController ];
	}
	}

	@implementation MDCMaskedTransition {
	UIView *_sourceView;
	CGFloat _initialSourceViewAlpha;
	MDMTransitionDirection _direction;
	}

	- (instancetype)initWithSourceView:(UIView *)sourceView
	direction:(MDMTransitionDirection)direction {
	self = [super init];
	if (self) {
	_sourceView = sourceView;
	_direction = direction;
	}
	return self;
	}

	#pragma mark - UIViewControllerAnimatedTransitioning

	- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext {
	NSArray<UIViewController > viewControllers =
	OrderedViewControllersWithTransitionContext(transitionContext, _direction);
	NSAssert([viewControllers count] == 2,
	@"Expected two view controllers to be involved in a transition.");
	if ([viewControllers count] != 2) {
	return 0;
	}
	UIViewController *presentedViewController = viewControllers[1];
	MDCMaskedTransitionMotionSpec motionSpecification = MDCMaskedTransitionMotionSpecForContext(
	transitionContext.containerView, presentedViewController);

	MDCMaskedTransitionMotionTiming motion =
	((_direction == MDMTransitionDirectionForward) ? motionSpecification.expansion
	: motionSpecification.collapse);

	return motion.overallDuration;
	}

	- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext {
	PrepareTransitionWithContext(transitionContext, _direction);
	NSArray<UIViewController > viewControllers =
	OrderedViewControllersWithTransitionContext(transitionContext, _direction);
	NSAssert([viewControllers count] == 2,
	@"Expected two view controllers to be involved in a transition.");
	if ([viewControllers count] != 2) {
	[transitionContext completeTransition:YES];
	return;
	}
	UIViewController *presentedViewController = viewControllers[1];

	MDCMaskedTransitionMotionSpec motionSpecification = MDCMaskedTransitionMotionSpecForContext(
	transitionContext.containerView, presentedViewController);

	// Cache original state.
	// We're going to reparent the fore view, so keep this information for later.
	UIView *originalSuperview = presentedViewController.view.superview;
	const CGRect originalFrame = presentedViewController.view.frame;
	UIView *originalSourceSuperview = _sourceView.superview;
	const CGRect originalSourceFrame = _sourceView.frame;
	UIColor *originalSourceBackgroundColor = _sourceView.backgroundColor;

	// Reparent the fore view into a masked view.
	UIView *maskedView = [[UIView alloc] initWithFrame:presentedViewController.view.frame];
	{
	CGRect reparentedFrame = presentedViewController.view.frame;
	reparentedFrame.origin = CGPointZero;
	presentedViewController.view.frame = reparentedFrame;

	maskedView.layer.cornerRadius = presentedViewController.view.layer.cornerRadius;
	maskedView.clipsToBounds = presentedViewController.view.clipsToBounds;
	}
	[transitionContext.containerView addSubview:maskedView];

	UIView *floodFillView = [[UIView alloc] initWithFrame:presentedViewController.view.bounds];
	floodFillView.backgroundColor = _sourceView.backgroundColor;

	// TODO(featherless): Profile whether it's more performant to fade the flood fill out or to
	// fade the fore view in (what we're currently doing).
	[maskedView addSubview:floodFillView];
	[maskedView addSubview:presentedViewController.view];

	// All frames are assumed to be relative to the container view unless named otherwise.
	const CGRect initialSourceFrame = [_sourceView convertRect:_sourceView.bounds
	toView:transitionContext.containerView];
	const CGRect finalMaskedFrame = originalFrame;
	CGRect initialMaskedFrame;
	CGPoint corner;
	const CGPoint initialSourceCenter = CenterOfFrame(initialSourceFrame);
	if (motionSpecification.isCentered) {
	initialMaskedFrame = FrameCenteredAround(initialSourceCenter, originalFrame.size);
	// Bottom right
	corner = CGPointMake(CGRectGetMaxX(initialMaskedFrame), CGRectGetMaxY(initialMaskedFrame));

	} else {
	initialMaskedFrame = CGRectMake(CGRectGetMinX(transitionContext.containerView.bounds),
	CGRectGetMinY(initialSourceFrame) - 20,
	CGRectGetWidth(originalFrame), CGRectGetHeight(originalFrame));
	if (CGRectGetMidX(initialSourceFrame) < CGRectGetMidX(initialMaskedFrame)) {
	// Middle-right
	corner = CGPointMake(CGRectGetMaxX(initialMaskedFrame), CGRectGetMidY(initialMaskedFrame));
	} else {
	// Middle-left
	corner = CGPointMake(CGRectGetMinX(initialMaskedFrame), CGRectGetMidY(initialMaskedFrame));
	}
	}

	maskedView.frame = initialMaskedFrame;
	const CGRect initialSourceFrameInMask = [maskedView convertRect:initialSourceFrame
	fromView:transitionContext.containerView];

	const CGFloat initialRadius = CGRectGetWidth(_sourceView.bounds) / 2;
	const CGFloat finalRadius = LengthOfVector(
	CGVectorMake(initialSourceCenter.x - corner.x, initialSourceCenter.y - corner.y));
	const CGFloat finalScale = finalRadius / initialRadius;

	CAShapeLayer *shapeLayer = [[CAShapeLayer alloc] init];
	{
	// Ensures that we transform from the center of the source view's frame.
	shapeLayer.anchorPoint =
	AnchorPointFromPosition(CenterOfFrame(initialSourceFrameInMask), maskedView.layer.bounds);
	shapeLayer.frame = maskedView.layer.bounds;
	shapeLayer.path = [[UIBezierPath bezierPathWithOvalInRect:initialSourceFrameInMask] CGPath];
	}
	maskedView.layer.mask = shapeLayer;

	_sourceView.frame = initialSourceFrameInMask;
	_sourceView.backgroundColor = nil;
	[maskedView addSubview:_sourceView];

	[CATransaction begin];
	[CATransaction setCompletionBlock:^{
	presentedViewController.view.frame = originalFrame;
	[originalSuperview addSubview:presentedViewController.view];

	self->_sourceView.frame = originalSourceFrame;
	self->_sourceView.backgroundColor = originalSourceBackgroundColor;
	if (motionSpecification.shouldSlideWhenCollapsed &&
	transitionContext.presentationStyle != UIModalPresentationCustom) {
	// If we're going to slide when collapsed then this transition won't be invoked. If we also
	// don't have a presentation controller (because of the presentation style) then we need to
	// restore the source view's visibility somehow. This is the only place I could think of to
	// do so, but it unfortunately means if the presented view controller is somehow presented
	// such that the source view is still visible then the source view will appear to flash back
	// into existence at the end of the transition, breaking the illusion of continuity.
	self->_sourceView.alpha = 1;
	}
	[originalSourceSuperview addSubview:self->_sourceView];

	[maskedView removeFromSuperview];

	[transitionContext completeTransition:YES]; // Hand off back to UIKit
	}];

	MDCMaskedTransitionMotionTiming motion =
	((_direction == MDMTransitionDirectionForward) ? motionSpecification.expansion
	: motionSpecification.collapse);

	MDMMotionAnimator *animator = [[MDMMotionAnimator alloc] init];
	animator.shouldReverseValues = _direction == MDMTransitionDirectionBackward;

	if (_direction == MDMTransitionDirectionForward) {
	_initialSourceViewAlpha = _sourceView.alpha;
	}

	[animator animateWithTiming:motion.iconFade
	toLayer:_sourceView.layer
	withValues:@[ @(_initialSourceViewAlpha), @0 ]
	keyPath:MDMKeyPathOpacity];

	[animator animateWithTiming:motion.contentFade
	toLayer:presentedViewController.view.layer
	withValues:@[ @0, @1 ]
	keyPath:MDMKeyPathOpacity];

	// TODO(featherless): Support shadow + elevation changes. May need companion transition for this?

	{
	UIColor *initialColor = floodFillView.backgroundColor;
	if (!initialColor) {
	initialColor = [UIColor clearColor];
	}
	UIColor *finalColor = presentedViewController.view.backgroundColor;
	if (!finalColor) {
	finalColor = [UIColor whiteColor];
	}
	[animator animateWithTiming:motion.floodBackgroundColor
	toLayer:floodFillView.layer
	withValues:@[ initialColor, finalColor ]
	keyPath:MDMKeyPathBackgroundColor];
	}

	{
	void (^completion)(void) = nil;
	if (_direction == MDMTransitionDirectionForward) {
	completion = ^{
	// Upon completion of the animation we want all of the content to be visible, so we jump
	// to a full bounds mask.
	shapeLayer.transform = CATransform3DIdentity;
	shapeLayer.path =
	[[UIBezierPath bezierPathWithRect:presentedViewController.view.bounds] CGPath];
	};
	}
	[animator animateWithTiming:motion.maskTransformation
	toLayer:shapeLayer
	withValues:@[ @1, @(finalScale) ]
	keyPath:MDMKeyPathScale
	completion:completion];
	}

	[animator animateWithTiming:motion.horizontalMovement
	toLayer:maskedView.layer
	withValues:@[
	@(CGRectGetMidX(initialMaskedFrame)), @(CGRectGetMidX(finalMaskedFrame))
	]
	keyPath:MDMKeyPathX];

	[animator animateWithTiming:motion.verticalMovement
	toLayer:maskedView.layer
	withValues:@[
	@(CGRectGetMidY(initialMaskedFrame)), @(CGRectGetMidY(finalMaskedFrame))
	]
	keyPath:MDMKeyPathY];

	[CATransaction commit];
	}

	@end