159 lines
6.9 KiB
Swift
159 lines
6.9 KiB
Swift
// Copyright © 2020 Metabolist. All rights reserved.
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import UIKit
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final class ZoomDismissalInteractionController: NSObject {
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var transitionContext: UIViewControllerContextTransitioning?
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var animator: UIViewControllerAnimatedTransitioning?
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var fromReferenceViewFrame: CGRect?
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var toReferenceViewFrame: CGRect?
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// swiftlint:disable:next function_body_length
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func didPanWith(gestureRecognizer: UIPanGestureRecognizer) {
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guard let transitionContext = self.transitionContext,
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let animator = self.animator as? ZoomAnimator,
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let transitionView = animator.transitionView,
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let fromVC = transitionContext.viewController(forKey: .from),
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let toVC = transitionContext.viewController(forKey: .to),
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let fromReferenceView = animator.fromDelegate?.referenceView(for: animator),
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let fromReferenceViewFrame = self.fromReferenceViewFrame
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else { return }
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let toReferenceView = animator.toDelegate?.referenceView(for: animator)
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fromReferenceView.isHidden = true
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let anchorPoint = CGPoint(x: fromReferenceViewFrame.midX, y: fromReferenceViewFrame.midY)
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let dismissThreshold = fromReferenceViewFrame.height / 10
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let translatedPoint = gestureRecognizer.translation(in: fromReferenceView)
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let backgroundAlpha = backgroundAlphaFor(view: fromVC.view, withPanningVerticalDelta: translatedPoint.y)
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let scale = scaleFor(view: fromVC.view, withPanningVerticalDelta: translatedPoint.y)
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fromVC.view.alpha = backgroundAlpha
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transitionView.transform = CGAffineTransform(scaleX: scale, y: scale)
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let newCenter = CGPoint(
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x: anchorPoint.x + translatedPoint.x,
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y: anchorPoint.y + translatedPoint.y - transitionView.frame.height * (1 - scale) / 2.0)
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transitionView.center = newCenter
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toReferenceView?.isHidden = true
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transitionContext.updateInteractiveTransition(1 - scale)
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toVC.tabBarController?.tabBar.alpha = 1 - backgroundAlpha
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if gestureRecognizer.state == .ended {
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if abs(anchorPoint.y - newCenter.y) < dismissThreshold {
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// cancel
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UIView.animate(
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withDuration: 0.5,
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delay: 0,
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usingSpringWithDamping: 0.9,
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initialSpringVelocity: 0,
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options: []) {
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transitionView.frame = fromReferenceViewFrame
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fromVC.view.alpha = 1.0
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toVC.tabBarController?.tabBar.alpha = 0
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} completion: { _ in
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toReferenceView?.isHidden = false
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fromReferenceView.isHidden = false
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transitionView.removeFromSuperview()
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animator.transitionView = nil
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transitionContext.cancelInteractiveTransition()
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transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
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animator.toDelegate?.transitionDidEndWith(zoomAnimator: animator)
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animator.fromDelegate?.transitionDidEndWith(zoomAnimator: animator)
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self.transitionContext = nil
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}
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return
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}
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// start animation
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UIView.animate(
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withDuration: .shortAnimationDuration) {
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fromVC.view.alpha = 0
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if let toReferenceViewFrame = self.toReferenceViewFrame {
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transitionView.frame = toReferenceViewFrame
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} else {
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transitionView.alpha = 0
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}
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transitionView.layer.contentsRect = toReferenceView?.layer.contentsRect ?? .defaultContentsRect
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transitionView.layer.cornerRadius = toReferenceView?.layer.cornerRadius ?? 0
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toVC.tabBarController?.tabBar.alpha = 1
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} completion: { _ in
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transitionView.removeFromSuperview()
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toReferenceView?.isHidden = false
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fromReferenceView.isHidden = false
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self.transitionContext?.finishInteractiveTransition()
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transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
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animator.toDelegate?.transitionDidEndWith(zoomAnimator: animator)
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animator.fromDelegate?.transitionDidEndWith(zoomAnimator: animator)
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self.transitionContext = nil
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}
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}
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}
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func backgroundAlphaFor(view: UIView, withPanningVerticalDelta verticalDelta: CGFloat) -> CGFloat {
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let startingAlpha: CGFloat = 1.0
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let finalAlpha: CGFloat = 0.0
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let totalAvailableAlpha = startingAlpha - finalAlpha
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let maximumDelta = view.bounds.height / 4.0
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let deltaAsPercentageOfMaximun = min(abs(verticalDelta) / maximumDelta, 1.0)
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return startingAlpha - (deltaAsPercentageOfMaximun * totalAvailableAlpha)
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}
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func scaleFor(view: UIView, withPanningVerticalDelta verticalDelta: CGFloat) -> CGFloat {
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let startingScale: CGFloat = 1.0
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let finalScale: CGFloat = 0.5
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let totalAvailableScale = startingScale - finalScale
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let maximumDelta = view.bounds.height / 2.0
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let deltaAsPercentageOfMaximun = min(abs(verticalDelta) / maximumDelta, 1.0)
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return startingScale - (deltaAsPercentageOfMaximun * totalAvailableScale)
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}
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}
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extension ZoomDismissalInteractionController: UIViewControllerInteractiveTransitioning {
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func startInteractiveTransition(_ transitionContext: UIViewControllerContextTransitioning) {
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guard let animator = animator as? ZoomAnimator else { return }
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animator.fromDelegate?.transitionWillStartWith(zoomAnimator: animator)
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animator.toDelegate?.transitionWillStartWith(zoomAnimator: animator)
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self.transitionContext = transitionContext
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let containerView = transitionContext.containerView
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guard
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let fromVC = transitionContext.viewController(forKey: .from),
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let toVC = transitionContext.viewController(forKey: .to),
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var fromReferenceViewFrame = animator.fromDelegate?.referenceViewFrameInTransitioningView(for: animator),
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let fromReferenceView = animator.fromDelegate?.referenceView(for: animator)
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else { return }
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fromReferenceViewFrame = fromReferenceViewFrame.containsNaN ? .zero : fromReferenceViewFrame
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self.fromReferenceViewFrame = fromReferenceViewFrame
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toReferenceViewFrame = animator.toDelegate?.referenceViewFrameInTransitioningView(for: animator)
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containerView.insertSubview(toVC.view, belowSubview: fromVC.view)
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if animator.transitionView == nil,
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let transitionView = (fromReferenceView as? ZoomAnimatableView)?.transitionView() {
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transitionView.frame = fromReferenceViewFrame
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animator.transitionView = transitionView
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containerView.addSubview(transitionView)
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}
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}
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}
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