Improve large image/gallery animation handling when images aren't loaded

Tusker/Extensions/UIViewController+Delegates.swift

@@ -10,20 +10,22 @@ import UIKit
 
 extension UIViewController: UIViewControllerTransitioningDelegate {
     public func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
-        if presented is LargeImageViewController {
+        if let presented = presented as? LargeImageViewController,
+            presented.sourceInfo?.image != nil {
             return LargeImageExpandAnimationController()
         } else if let presented = presented as? GalleryViewController,
-            presented.sourcesInfo[presented.startIndex] != nil {
+            presented.sourcesInfo[presented.startIndex]?.image != nil {
             return GalleryExpandAnimationController()
         }
         return nil
     }
 
     public func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
-        if let dismissed = dismissed as? LargeImageViewController {
+        if let dismissed = dismissed as? LargeImageViewController,
+            dismissed.imageForDismissalAnimation() != nil {
             return LargeImageShrinkAnimationController(interactionController: dismissed.dismissInteractionController)
         } else if let dismissed = dismissed as? GalleryViewController,
-            dismissed.sourcesInfo[dismissed.currentIndex] != nil {
+            dismissed.imageForDismissalAnimation() != nil {
             return GalleryShrinkAnimationController(interactionController: dismissed.dismissInteractionController)
         }
         return nil

Tusker/Screens/Gallery/GalleryViewController.swift

@@ -96,6 +96,14 @@ class GalleryViewController: UIPageViewController, UIPageViewControllerDataSourc
             vc.player?.play()
         }
     }
+    
+    func imageForDismissalAnimation() -> UIImage? {
+        if let sourceImage = sourcesInfo[currentIndex]?.image {
+            return sourceImage
+        } else {
+            return (pages[currentIndex] as? AttachmentViewController)?.largeImageVC?.image
+        }
+    }
 
     // MARK: - Page View Controller Data Source
     

Tusker/Screens/Gallery/Transitions/GalleryExpandAnimationController.swift

@@ -20,16 +20,18 @@ class GalleryExpandAnimationController: NSObject, UIViewControllerAnimatedTransi
                 return
         }
         
-        let finalVCFrame = transitionContext.finalFrame(for: toVC)
-        guard let (image, sourceFrame, sourceCornerRadius) = toVC.sourcesInfo[toVC.startIndex] else {
-            toVC.view.frame = finalVCFrame
-            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
-            return
-        }
-        
-        let attachment = toVC.attachments[toVC.startIndex]
-
         let containerView = transitionContext.containerView
+        containerView.addSubview(toVC.view)
+
+        let finalVCFrame = transitionContext.finalFrame(for: toVC)
+        guard let sourceInfo = toVC.sourcesInfo[toVC.startIndex],
+            let image = sourceInfo.image else {
+                toVC.view.frame = finalVCFrame
+                transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
+                return
+        }
+
+        let attachment = toVC.attachments[toVC.startIndex]
 
         let ratio = image.size.width / image.size.height
         var width = finalVCFrame.width
@@ -42,21 +44,20 @@ class GalleryExpandAnimationController: NSObject, UIViewControllerAnimatedTransi
         }
         let finalFrame = CGRect(x: finalVCFrame.midX - width / 2, y: finalVCFrame.midY - height / 2, width: width, height: height)
         
-        let imageView = GIFImageView(frame: sourceFrame)
+        let imageView = GIFImageView(frame: sourceInfo.frame)
         imageView.image = image
         if attachment.url.pathExtension == "gif",
             let data = ImageCache.attachments.get(attachment.url) {
             imageView.animate(withGIFData: data)
         }
         imageView.contentMode = .scaleAspectFill
-        imageView.layer.cornerRadius = sourceCornerRadius
+        imageView.layer.cornerRadius = sourceInfo.cornerRadius
         imageView.layer.masksToBounds = true
         
         let blackView = UIView(frame: finalVCFrame)
         blackView.backgroundColor = .black
         blackView.alpha = 0
         
-        containerView.addSubview(toVC.view)
         containerView.addSubview(blackView)
         containerView.addSubview(imageView)
         

Tusker/Screens/Gallery/Transitions/GalleryShrinkAnimationController.swift

@@ -26,7 +26,8 @@ class GalleryShrinkAnimationController: NSObject, UIViewControllerAnimatedTransi
                 return
         }
         
-        guard let (image, sourceFrame, sourceCornerRadius) = fromVC.sourcesInfo[fromVC.currentIndex] else {
+        guard let sourceInfo = fromVC.sourcesInfo[fromVC.currentIndex],
+            let image = fromVC.imageForDismissalAnimation() else {
             transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
             return
         }
@@ -66,8 +67,8 @@ class GalleryShrinkAnimationController: NSObject, UIViewControllerAnimatedTransi
         
         let duration = transitionDuration(using: transitionContext)
         UIView.animate(withDuration: duration, animations: {
-            imageView.frame = sourceFrame
+            imageView.frame = sourceInfo.frame
-            imageView.layer.cornerRadius = sourceCornerRadius
+            imageView.layer.cornerRadius = sourceInfo.cornerRadius
             blackView.alpha = 0
         }, completion: { _ in
             blackView.removeFromSuperview()

Tusker/Screens/Large Image/LargeImageViewController.swift

@@ -13,7 +13,7 @@ import Gifu
 
 class LargeImageViewController: UIViewController, UIScrollViewDelegate {
 
-    typealias SourceInfo = (image: UIImage, frame: CGRect, cornerRadius: CGFloat)
+    typealias SourceInfo = (image: UIImage?, frame: CGRect, cornerRadius: CGFloat)
     
     var sourceInfo: SourceInfo?
     var dismissInteractionController: LargeImageInteractionController?
@@ -132,6 +132,10 @@ class LargeImageViewController: UIViewController, UIScrollViewDelegate {
             }
         }
     }
+    
+    func imageForDismissalAnimation() -> UIImage? {
+        return sourceInfo?.image ?? image
+    }
 
     func setControlsVisible(_ controlsVisible: Bool, animated: Bool) {
         self.controlsVisible = controlsVisible

Tusker/Screens/Large Image/Transitions/LargeImageExpandAnimationController.swift

@@ -21,33 +21,35 @@ class LargeImageExpandAnimationController: NSObject, UIViewControllerAnimatedTra
                 return
         }
         
-        let finalVCFrame = transitionContext.finalFrame(for: toVC)
-        guard let (image, originFrame, originCornerRadius) = toVC.sourceInfo else {
-            toVC.view.frame = finalVCFrame
-            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
-            return
-        }
-        
         let containerView = transitionContext.containerView
+        containerView.addSubview(toVC.view)
+
+        let finalVCFrame = transitionContext.finalFrame(for: toVC)
+        guard let sourceInfo = toVC.sourceInfo,
+            let image = sourceInfo.image else {
+                toVC.view.frame = finalVCFrame
+                transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
+                return
+        }
+
         let ratio = image.size.width / image.size.height
         let width = finalVCFrame.width
         let height = width / ratio
         let finalFrame = CGRect(x: finalVCFrame.midX - width / 2, y: finalVCFrame.midY - height / 2, width: width, height: height)
         
-        let imageView = GIFImageView(frame: originFrame)
+        let imageView = GIFImageView(frame: sourceInfo.frame)
-        imageView.image = toVC.imageView.image!
+        imageView.image = image
         if let gifData = toVC.gifData {
             imageView.animate(withGIFData: gifData)
         }
         imageView.contentMode = .scaleAspectFill
-        imageView.layer.cornerRadius = originCornerRadius
+        imageView.layer.cornerRadius = sourceInfo.cornerRadius
         imageView.layer.masksToBounds = true
         
         let blackView = UIView(frame: finalVCFrame)
         blackView.backgroundColor = .black
         blackView.alpha = 0
         
-        containerView.addSubview(toVC.view)
         containerView.addSubview(blackView)
         containerView.addSubview(imageView)
         

Tusker/Screens/Large Image/Transitions/LargeImageShrinkAnimationController.swift

@@ -27,11 +27,12 @@ class LargeImageShrinkAnimationController: NSObject, UIViewControllerAnimatedTra
                 return
         }
         
-        guard let (image, finalFrame, finalCornerRadius) = fromVC.sourceInfo else {
+        guard let sourceInfo = fromVC.sourceInfo,
-            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
+            let image = fromVC.imageForDismissalAnimation() else {
-            return
+                transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
+                return
         }
-        
+
         let originalVCFrame = fromVC.view.frame
         
         let containerView = transitionContext.containerView
@@ -59,8 +60,8 @@ class LargeImageShrinkAnimationController: NSObject, UIViewControllerAnimatedTra
         
         let duration = transitionDuration(using: transitionContext)
         UIView.animate(withDuration: duration, animations: {
-            imageView.frame = finalFrame
+            imageView.frame = sourceInfo.frame
-            imageView.layer.cornerRadius = finalCornerRadius
+            imageView.layer.cornerRadius = sourceInfo.cornerRadius
             blackView.alpha = 0
         }, completion: { _ in
             blackView.removeFromSuperview()

Tusker/TuskerNavigationDelegate.swift

@@ -148,7 +148,7 @@ extension TuskerNavigationDelegate where Self: UIViewController {
     }
     
     private func sourceViewInfo(_ sourceView: UIImageView?) -> LargeImageViewController.SourceInfo? {
-        guard let sourceView = sourceView, let image = sourceView.image else { return nil }
+        guard let sourceView = sourceView else { return nil }
         
         var sourceFrame = sourceView.convert(sourceView.bounds, to: view)
         if let scrollView = view as? UIScrollView {
@@ -159,7 +159,7 @@ extension TuskerNavigationDelegate where Self: UIViewController {
             let y = sourceFrame.minY * scale - scrollView.contentOffset.y + scrollView.frame.minY
             sourceFrame = CGRect(x: x, y: y, width: width, height: height)
         }
-        return (image: image, frame: sourceFrame, cornerRadius: sourceView.layer.cornerRadius)
+        return (image: sourceView.image, frame: sourceFrame, cornerRadius: sourceView.layer.cornerRadius)
     }
     
     func largeImage(_ image: UIImage, description: String?, sourceView: UIImageView) -> LargeImageViewController {