Improve gallery video autoplay behavior

Packages/GalleryVC/Sources/GalleryVC/GalleryContentViewController.swift

@@ -18,6 +18,8 @@ public protocol GalleryContentViewController: UIViewController {
     var canAnimateFromSourceView: Bool { get }
     
     func setControlsVisible(_ visible: Bool, animated: Bool)
+    func galleryContentDidAppear()
+    func galleryContentWillDisappear()
 }
 
 public extension GalleryContentViewController {
@@ -35,4 +37,10 @@ public extension GalleryContentViewController {
     
     func setControlsVisible(_ visible: Bool, animated: Bool) {
     }
+    
+    func galleryContentDidAppear() {
+    }
+    
+    func galleryContentWillDisappear() {
+    }
 }

Packages/GalleryVC/Sources/GalleryVC/GalleryPresentationAnimationController.swift

@@ -9,16 +9,11 @@ import UIKit
 
 class GalleryPresentationAnimationController: NSObject, UIViewControllerAnimatedTransitioning {
     private let sourceView: UIView
-    private var completionHandlers: [() -> Void] = []
     
     init(sourceView: UIView) {
         self.sourceView = sourceView
     }
     
-    func addCompletionHandler(_ block: @escaping () -> Void) {
-        completionHandlers.append(block)
-    }
-    
     func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
         return 0.4
     }
@@ -28,8 +23,6 @@ class GalleryPresentationAnimationController: NSObject, UIViewControllerAnimated
             fatalError()
         }
         
-        to.presentationAnimationController = self
-        
         let itemViewController = to.currentItemViewController
 
         if !itemViewController.content.canAnimateFromSourceView || UIAccessibility.prefersCrossFadeTransitions {
@@ -65,14 +58,13 @@ class GalleryPresentationAnimationController: NSObject, UIViewControllerAnimated
         
         let content = itemViewController.takeContent()
         content.view.translatesAutoresizingMaskIntoConstraints = true
-        
+        container.insertSubview(content.view, belowSubview: to.view)
+
         // Use a separate dimming view from to.view, so that the gallery controls can be in front of the moving content.
         let dimmingView = UIView()
         dimmingView.backgroundColor = .black
         dimmingView.frame = container.bounds
         dimmingView.layer.opacity = 0
-        
-        container.insertSubview(content.view, belowSubview: to.view)
         container.insertSubview(dimmingView, belowSubview: content.view)
 
         to.view.backgroundColor = nil
@@ -118,11 +110,7 @@ class GalleryPresentationAnimationController: NSObject, UIViewControllerAnimated
             
             transitionContext.completeTransition(true)
             
-            for block in self.completionHandlers {
-                block()
-            }
-            
-            to.presentationAnimationController = nil
+            to.presentationAnimationCompleted()
         }
         
         animator.startAnimation()
@@ -144,11 +132,7 @@ class GalleryPresentationAnimationController: NSObject, UIViewControllerAnimated
         animator.addCompletion { _ in
             transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
             
-            for block in self.completionHandlers {
-                block()
-            }
-            
-            to.presentationAnimationController = nil
+            to.presentationAnimationCompleted()
         }
         animator.startAnimation()
     }

Packages/GalleryVC/Sources/GalleryVC/GalleryViewController.swift

@@ -24,7 +24,7 @@ public class GalleryViewController: UIPageViewController {
     }
     
     private var dismissInteraction: GalleryDismissInteraction!
-    var presentationAnimationController: GalleryPresentationAnimationController?
+    private var presentationAnimationCompletionHandlers: [() -> Void] = []
     
     override public var prefersStatusBarHidden: Bool {
         true
@@ -54,7 +54,7 @@ public class GalleryViewController: UIPageViewController {
         fatalError("init(coder:) has not been implemented")
     }
     
-    override public func viewDidLoad() {
+    public override func viewDidLoad() {
         super.viewDidLoad()
         
         dismissInteraction = GalleryDismissInteraction(viewController: self)
@@ -63,14 +63,30 @@ public class GalleryViewController: UIPageViewController {
         overrideUserInterfaceStyle = .dark
         
         dataSource = self
+        delegate = self
         
         setViewControllers([makeItemVC(index: initialItemIndex)], direction: .forward, animated: false)
     }
     
+    public override func viewWillDisappear(_ animated: Bool) {
+        super.viewWillDisappear(animated)
+        
+        if isBeingDismissed {
+            currentItemViewController.content.galleryContentWillDisappear()
+        }
+    }
+    
     private func makeItemVC(index: Int) -> GalleryItemViewController {
         let content = galleryDataSource.galleryContentViewController(forItemAt: index)
         return GalleryItemViewController(delegate: self, itemIndex: index, content: content)
     }
+    
+    func presentationAnimationCompleted() {
+        for block in presentationAnimationCompletionHandlers {
+            block()
+        }
+        currentItemViewController.content.galleryContentDidAppear()
+    }
 }
 
 extension GalleryViewController: UIPageViewControllerDataSource {
@@ -95,13 +111,23 @@ extension GalleryViewController: UIPageViewControllerDataSource {
     }
 }
 
+extension GalleryViewController: UIPageViewControllerDelegate {
+    public func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController]) {
+        currentItemViewController.content.galleryContentWillDisappear()
+    }
+    
+    public func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
+        currentItemViewController.content.galleryContentDidAppear()
+    }
+}
+
 extension GalleryViewController: GalleryItemViewControllerDelegate {
     func isGalleryBeingPresented() -> Bool {
         isBeingPresented
     }
     
     func addPresentationAnimationCompletion(_ block: @escaping () -> Void) {
-        presentationAnimationController?.addCompletionHandler(block)
+        presentationAnimationCompletionHandlers.append(block)
     }
     
     func galleryItemClose(_ item: GalleryItemViewController) {

Tusker/Screens/Gallery/LoadingGalleryContentViewController.swift

@@ -104,4 +104,12 @@ class LoadingGalleryContentViewController: UIViewController, GalleryContentViewC
         wrapped?.setControlsVisible(visible, animated: animated)
     }
     
+    func galleryContentDidAppear() {
+        wrapped?.galleryContentDidAppear()
+    }
+    
+    func galleryContentWillDisappear() {
+        wrapped?.galleryContentWillDisappear()
+    }
+    
 }

Tusker/Screens/Gallery/VideoGalleryContentViewController.swift

@@ -87,21 +87,6 @@ class VideoGalleryContentViewController: UIViewController, GalleryContentViewCon
         preferredContentSize = item.presentationSize
     }
     
-    override func viewWillAppear(_ animated: Bool) {
-        super.viewWillAppear(animated)
-        
-        if isFirstAppearance {
-            isFirstAppearance = false
-            player.play()
-        }
-    }
-    
-    override func viewWillDisappear(_ animated: Bool) {
-        super.viewWillDisappear(animated)
-        
-        player.pause()
-    }
-    
     // MARK: GalleryContentViewController
     
     var container: (any GalleryVC.GalleryContentViewControllerContainer)?
@@ -126,6 +111,17 @@ class VideoGalleryContentViewController: UIViewController, GalleryContentViewCon
         hideControlsWorkItem?.cancel()
     }
     
+    func galleryContentDidAppear() {
+        if isFirstAppearance {
+            isFirstAppearance = false
+            player.play()
+        }
+    }
+    
+    func galleryContentWillDisappear() {
+        player.pause()
+    }
+    
 }
 
 private class PlayerView: UIView {