Add multi-image gallery

Closes #18

Tusker.xcodeproj/project.pbxproj

@@ -7,10 +7,15 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		0411610022B442870030A9B7 /* AttachmentViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 041160FE22B442870030A9B7 /* AttachmentViewController.swift */; };
+		0411610122B442870030A9B7 /* AttachmentViewController.xib in Resources */ = {isa = PBXBuildFile; fileRef = 041160FF22B442870030A9B7 /* AttachmentViewController.xib */; };
 		04496BD721625361001F1B23 /* ContentLabel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 04496BD621625361001F1B23 /* ContentLabel.swift */; };
 		0450531F22B0097E00100BA2 /* Timline+UI.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0450531E22B0097E00100BA2 /* Timline+UI.swift */; };
+		0454DDAF22B462EF00B8BB8E /* GalleryExpandAnimationController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0454DDAE22B462EF00B8BB8E /* GalleryExpandAnimationController.swift */; };
+		0454DDB122B467AA00B8BB8E /* GalleryShrinkAnimationController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0454DDB022B467AA00B8BB8E /* GalleryShrinkAnimationController.swift */; };
 		0461A3902163CBAE00C0A807 /* Cache.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 0461A38F2163CBAE00C0A807 /* Cache.framework */; };
 		0461A3912163CBAE00C0A807 /* Cache.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = 0461A38F2163CBAE00C0A807 /* Cache.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
+		04D14BB022B34A2800642648 /* GalleryViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 04D14BAE22B34A2800642648 /* GalleryViewController.swift */; };
 		04DACE8C212CB14B009840C4 /* MainTabBarViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 04DACE8B212CB14B009840C4 /* MainTabBarViewController.swift */; };
 		04DACE8E212CC7CC009840C4 /* ImageCache.swift in Sources */ = {isa = PBXBuildFile; fileRef = 04DACE8D212CC7CC009840C4 /* ImageCache.swift */; };
 		04ED00B121481ED800567C53 /* SteppedProgressView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 04ED00B021481ED800567C53 /* SteppedProgressView.swift */; };
@@ -235,9 +240,14 @@
 /* End PBXCopyFilesBuildPhase section */
 
 /* Begin PBXFileReference section */
+		041160FE22B442870030A9B7 /* AttachmentViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AttachmentViewController.swift; sourceTree = "<group>"; };
+		041160FF22B442870030A9B7 /* AttachmentViewController.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = AttachmentViewController.xib; sourceTree = "<group>"; };
 		04496BD621625361001F1B23 /* ContentLabel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ContentLabel.swift; sourceTree = "<group>"; };
 		0450531E22B0097E00100BA2 /* Timline+UI.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Timline+UI.swift"; sourceTree = "<group>"; };
+		0454DDAE22B462EF00B8BB8E /* GalleryExpandAnimationController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GalleryExpandAnimationController.swift; sourceTree = "<group>"; };
+		0454DDB022B467AA00B8BB8E /* GalleryShrinkAnimationController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GalleryShrinkAnimationController.swift; sourceTree = "<group>"; };
 		0461A38F2163CBAE00C0A807 /* Cache.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = Cache.framework; sourceTree = BUILT_PRODUCTS_DIR; };
+		04D14BAE22B34A2800642648 /* GalleryViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GalleryViewController.swift; sourceTree = "<group>"; };
 		04DACE8B212CB14B009840C4 /* MainTabBarViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MainTabBarViewController.swift; sourceTree = "<group>"; };
 		04DACE8D212CC7CC009840C4 /* ImageCache.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ImageCache.swift; sourceTree = "<group>"; };
 		04ED00B021481ED800567C53 /* SteppedProgressView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SteppedProgressView.swift; sourceTree = "<group>"; };
@@ -455,6 +465,33 @@
 /* End PBXFrameworksBuildPhase section */
 
 /* Begin PBXGroup section */
+		0411610422B4571E0030A9B7 /* Attachment */ = {
+			isa = PBXGroup;
+			children = (
+				041160FE22B442870030A9B7 /* AttachmentViewController.swift */,
+				041160FF22B442870030A9B7 /* AttachmentViewController.xib */,
+			);
+			path = Attachment;
+			sourceTree = "<group>";
+		};
+		0411610522B457290030A9B7 /* Gallery */ = {
+			isa = PBXGroup;
+			children = (
+				0411610622B457360030A9B7 /* Transitions */,
+				04D14BAE22B34A2800642648 /* GalleryViewController.swift */,
+			);
+			path = Gallery;
+			sourceTree = "<group>";
+		};
+		0411610622B457360030A9B7 /* Transitions */ = {
+			isa = PBXGroup;
+			children = (
+				0454DDAE22B462EF00B8BB8E /* GalleryExpandAnimationController.swift */,
+				0454DDB022B467AA00B8BB8E /* GalleryShrinkAnimationController.swift */,
+			);
+			path = Transitions;
+			sourceTree = "<group>";
+		};
 		D60A548C21ED515800F1F87C /* GMImagePicker */ = {
 			isa = PBXGroup;
 			children = (
@@ -617,6 +654,8 @@
 				D641C786213DD852004B4513 /* Notifications */,
 				D641C787213DD862004B4513 /* Compose */,
 				D641C788213DD86D004B4513 /* Large Image */,
+				0411610422B4571E0030A9B7 /* Attachment */,
+				0411610522B457290030A9B7 /* Gallery */,
 				D641C789213DD87E004B4513 /* Preferences */,
 			);
 			path = Screens;
@@ -1261,6 +1300,7 @@
 				D663626621360DD700C9CBA2 /* Preferences.storyboard in Resources */,
 				D627FF79217E950100CC0648 /* DraftsTableViewController.xib in Resources */,
 				D67C57B221E28FAD00C3118B /* ComposeStatusReplyView.xib in Resources */,
+				0411610122B442870030A9B7 /* AttachmentViewController.xib in Resources */,
 				D60C07E421E8176B0057FAA8 /* ComposeMediaView.xib in Resources */,
 				D667E5E12134937B0057A976 /* StatusTableViewCell.xib in Resources */,
 				D6A5FAF1217B7E05003DB2D9 /* ComposeViewController.xib in Resources */,
@@ -1357,10 +1397,12 @@
 				04DACE8C212CB14B009840C4 /* MainTabBarViewController.swift in Sources */,
 				D6C693F92162E4DB007D6A6D /* StatusContentLabel.swift in Sources */,
 				D6D58DF922074B74009C8DD9 /* LinkLabel.swift in Sources */,
+				0454DDAF22B462EF00B8BB8E /* GalleryExpandAnimationController.swift in Sources */,
 				D6285B5121EA6E6E00FE4B39 /* AdvancedTableViewController.swift in Sources */,
 				0450531F22B0097E00100BA2 /* Timline+UI.swift in Sources */,
 				D667E5F52135BCD50057A976 /* ConversationTableViewController.swift in Sources */,
 				D6F953F021251A2900CF0F2B /* MastodonController.swift in Sources */,
+				0411610022B442870030A9B7 /* AttachmentViewController.swift in Sources */,
 				D62D2426217ABF63005076CC /* UserActivityType.swift in Sources */,
 				D66362712136338600C9CBA2 /* ComposeViewController.swift in Sources */,
 				D627FF81217FE8F400CC0648 /* BehaviorTableViewController.swift in Sources */,
@@ -1369,6 +1411,7 @@
 				D62D2424217ABF3F005076CC /* NSUserActivity+Extensions.swift in Sources */,
 				D646C958213B367000269FB5 /* LargeImageShrinkAnimationController.swift in Sources */,
 				D646C956213B365700269FB5 /* LargeImageExpandAnimationController.swift in Sources */,
+				0454DDB122B467AA00B8BB8E /* GalleryShrinkAnimationController.swift in Sources */,
 				D667E5F82135C3040057A976 /* Mastodon+Equatable.swift in Sources */,
 				D67C57B421E2910700C3118B /* ComposeStatusReplyView.swift in Sources */,
 				04DACE8E212CC7CC009840C4 /* ImageCache.swift in Sources */,
@@ -1409,6 +1452,7 @@
 				D6F953EC212519E700CF0F2B /* TimelineTableViewController.swift in Sources */,
 				D663626A2136163000C9CBA2 /* PreferencesAdaptive.swift in Sources */,
 				D667E5EB21349EF80057A976 /* ProfileHeaderTableViewCell.swift in Sources */,
+				04D14BB022B34A2800642648 /* GalleryViewController.swift in Sources */,
 				D641C77D213CB024004B4513 /* FollowNotificationTableViewCell.swift in Sources */,
 				D641C773213CAA25004B4513 /* NotificationsTableViewController.swift in Sources */,
 				D6757A7C2157E01900721E32 /* XCBManager.swift in Sources */,

Tusker/Extensions/UIViewController+Delegates.swift

@@ -12,27 +12,31 @@ extension UIViewController: UIViewControllerTransitioningDelegate {
     public func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
         if presented is LargeImageViewController {
             return LargeImageExpandAnimationController()
-        } else {
+        } else if presented is GalleryViewController {
-            return nil
+            return GalleryExpandAnimationController()
         }
+        return nil
     }
 
     public func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
         if let dismissed = dismissed as? LargeImageViewController {
             return LargeImageShrinkAnimationController(interactionController: dismissed.dismissInteractionController)
-        } else {
+        } else if let dismissed = dismissed as? GalleryViewController {
-            return nil
+            return GalleryShrinkAnimationController(interactionController: dismissed.dismissInteractionController)
         }
+        return nil
     }
 
     public func interactionControllerForDismissal(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
         if let animator = animator as? LargeImageShrinkAnimationController,
             let interactionController = animator.interactionController,
             interactionController.inProgress {
-
             return interactionController
-        } else {
+        } else if let animator = animator as? GalleryShrinkAnimationController,
+            let interactionController = animator.interactionController,
+            interactionController.inProgress {
+            return interactionController
+        }
         return nil
     }
-    }
 }

Tusker/Screens/Attachment/AttachmentViewController.swift

@@ -0,0 +1,74 @@
+//  AttachmentViewController.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 6/14/19.
+//  Copyright © 2019 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+import Pachyderm
+
+class AttachmentViewController: UIViewController {
+    
+    let attachment: Attachment
+    
+    var largeImageVC: LargeImageViewController?
+    var loadingVC: LoadingViewController?
+    
+    private var initialControlsVisible: Bool = true
+    var controlsVisible: Bool {
+        get {
+            return largeImageVC?.controlsVisible ?? initialControlsVisible
+        }
+        set {
+            if let largeImageVC = largeImageVC {
+                largeImageVC.setControlsVisible(newValue, animated: false)
+            } else {
+                initialControlsVisible = newValue
+            }
+        }
+    }
+    
+    override var childForHomeIndicatorAutoHidden: UIViewController? {
+        return largeImageVC
+    }
+    
+    init(attachment: Attachment) {
+        self.attachment = attachment
+        
+        super.init(nibName: "AttachmentViewController", bundle: nil)
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        
+        if let data = ImageCache.attachments.get(attachment.url) {
+            createLargeImage(data: data)
+        } else {
+            loadingVC = LoadingViewController()
+            embedChild(loadingVC!)
+            ImageCache.attachments.get(attachment.url) { [weak self] (data) in
+                DispatchQueue.main.async {
+                    self?.loadingVC?.removeViewAndController()
+                    self?.createLargeImage(data: data!)
+                }
+            }
+        }
+    }
+    
+    func createLargeImage(data: Data) {
+        guard let image = UIImage(data: data) else { return }
+        largeImageVC = LargeImageViewController(image: image, description: attachment.description, sourceFrame: nil, sourceCornerRadius: nil)
+        largeImageVC!.initialControlsVisible = initialControlsVisible
+        largeImageVC!.shrinkGestureEnabled = false
+        if attachment.url.pathExtension == "gif" {
+            largeImageVC!.gifData = data
+        }
+        embedChild(largeImageVC!)
+    }
+    
+}

Tusker/Screens/Attachment/AttachmentViewController.xib

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="14810.11" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES">
+    <device id="retina6_1" orientation="portrait" appearance="light"/>
+    <dependencies>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="14766.13"/>
+        <capability name="Safe area layout guides" minToolsVersion="9.0"/>
+        <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
+    </dependencies>
+    <objects>
+        <placeholder placeholderIdentifier="IBFilesOwner" id="-1" userLabel="File's Owner" customClass="AttachmentViewController" customModule="Tusker" customModuleProvider="target">
+            <connections>
+                <outlet property="view" destination="i5M-Pr-FkT" id="sfx-zR-JGt"/>
+            </connections>
+        </placeholder>
+        <placeholder placeholderIdentifier="IBFirstResponder" id="-2" customClass="UIResponder"/>
+        <view clearsContextBeforeDrawing="NO" contentMode="scaleToFill" id="i5M-Pr-FkT">
+            <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+            <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+            <color key="backgroundColor" red="1" green="1" blue="1" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+            <viewLayoutGuide key="safeArea" id="fnl-2z-Ty3"/>
+            <point key="canvasLocation" x="139" y="3"/>
+        </view>
+    </objects>
+</document>

Tusker/Screens/Gallery/GalleryViewController.swift

@@ -0,0 +1,92 @@
+//  GalleryViewController.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 6/13/19.
+//  Copyright © 2019 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+import Pachyderm
+
+class GalleryViewController: UIPageViewController, UIPageViewControllerDataSource, UIPageViewControllerDelegate {
+
+    var dismissInteractionController: LargeImageInteractionController?
+    
+    let attachments: [Attachment]
+    let sourcesInfo: [(CGRect, CGFloat)]
+    let startIndex: Int
+    
+    let pages: [AttachmentViewController]
+    
+    var currentIndex: Int {
+        guard let vc = viewControllers?.first as? AttachmentViewController,
+            let index = pages.firstIndex(of: vc) else {
+                fatalError()
+        }
+        return index
+    }
+    
+    override var prefersStatusBarHidden: Bool {
+        return true
+    }
+    override var childForHomeIndicatorAutoHidden: UIViewController? {
+        return
+            viewControllers?.first
+    }
+    
+    init(attachments: [Attachment], sourcesInfo: [(CGRect, CGFloat)], startIndex: Int) {
+        self.attachments = attachments
+        self.sourcesInfo = sourcesInfo
+        self.startIndex = startIndex
+        
+        self.pages = attachments.map(AttachmentViewController.init)
+        
+        super.init(transitionStyle: .scroll, navigationOrientation: .horizontal)
+        
+        setViewControllers([pages[startIndex]], direction: .forward, animated: false)
+        
+        modalPresentationStyle = .fullScreen
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    override func viewDidLoad() {
+        super.viewDidLoad()
+
+        self.dataSource = self
+        self.delegate = self
+        
+        dismissInteractionController = LargeImageInteractionController(viewController: self)
+    }
+
+    
+    // MARK: - Page View Controller Data Source
+    
+    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
+        guard let attachment = viewController as? AttachmentViewController,
+            let index = pages.firstIndex(of: attachment),
+            index > 0 else {
+            return nil
+        }
+        return pages[index - 1]
+    }
+    
+    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
+        guard let attachment = viewController as? AttachmentViewController,
+            let index = pages.firstIndex(of: attachment),
+            index < pages.count - 1 else {
+                return nil
+        }
+        return pages[index + 1]
+    }
+    
+    // MARK: - Page View Controller Delegate
+    func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController]) {
+        let pending = pendingViewControllers.first as! AttachmentViewController
+        let current = viewControllers!.first as! AttachmentViewController
+        pending.controlsVisible = current.controlsVisible
+    }
+
+}

Tusker/Screens/Gallery/Transitions/GalleryExpandAnimationController.swift

@@ -0,0 +1,83 @@
+//  GalleryExpandAnimationController.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 6/14/19.
+//  Copyright © 2019 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+import Gifu
+
+class GalleryExpandAnimationController: NSObject, UIViewControllerAnimatedTransitioning {
+    
+    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
+        return 0.2
+    }
+    
+    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
+        guard let fromVC = transitionContext.viewController(forKey: .from),
+            let toVC = transitionContext.viewController(forKey: .to) as? GalleryViewController else {
+                return
+        }
+        let attachment = toVC.attachments[toVC.startIndex]
+        let (sourceFrame, sourceCornerRadius) = toVC.sourcesInfo[toVC.startIndex]
+        
+        let finalVCFrame = transitionContext.finalFrame(for: toVC)
+        
+        guard let data = ImageCache.attachments.get(attachment.url), let image = UIImage(data: data) else {
+            toVC.view.frame = finalVCFrame
+            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
+            return
+        }
+        
+        let ratio = image.size.width / image.size.height
+        var width = finalVCFrame.width
+        var height = width / ratio
+        let maxHeight = fromVC.view.bounds.height - fromVC.view.safeAreaInsets.top - fromVC.view.safeAreaInsets.bottom
+        if height > maxHeight {
+            let scaleFactor = maxHeight / height
+            width *= scaleFactor
+            height = maxHeight
+        }
+        let finalFrame = CGRect(x: finalVCFrame.midX - width / 2, y: finalVCFrame.midY - height / 2, width: width, height: height)
+        
+        let containerView = transitionContext.containerView
+        
+        let imageView = GIFImageView(frame: sourceFrame)
+        imageView.image = image
+        if attachment.url.pathExtension == "gif" {
+            imageView.animate(withGIFData: data)
+        }
+        imageView.contentMode = .scaleAspectFill
+        imageView.layer.cornerRadius = sourceCornerRadius
+        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)
+        
+        toVC.view.isHidden = true
+        
+        let duration = transitionDuration(using: transitionContext)
+        UIView.animate(withDuration: duration, animations: {
+            imageView.frame = finalFrame
+            imageView.layer.cornerRadius = 0
+            blackView.alpha = 1
+        }, completion: { _ in
+            toVC.view.frame = finalVCFrame
+            
+            toVC.view.isHidden = false
+            fromVC.view.isHidden = false
+            blackView.removeFromSuperview()
+            imageView.removeFromSuperview()
+            
+            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
+        })
+        
+    }
+    
+}

Tusker/Screens/Gallery/Transitions/GalleryShrinkAnimationController.swift

@@ -0,0 +1,85 @@
+//  GalleryShrinkAnimationController.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 6/14/19.
+//  Copyright © 2019 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+import Gifu
+
+class GalleryShrinkAnimationController: NSObject, UIViewControllerAnimatedTransitioning {
+    
+    let interactionController: LargeImageInteractionController?
+    
+    init(interactionController: LargeImageInteractionController?) {
+        self.interactionController = interactionController
+    }
+    
+    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
+        return 0.2
+    }
+    
+    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
+        guard let fromVC = transitionContext.viewController(forKey: .from) as? GalleryViewController,
+            let toVC = transitionContext.viewController(forKey: .to) else {
+                return
+        }
+        
+        let (sourceFrame, sourceCornerRadius) = fromVC.sourcesInfo[fromVC.currentIndex]
+        let originalVCFrame = fromVC.view.frame
+        
+        let attachment = fromVC.attachments[fromVC.currentIndex]
+        
+        guard let data = ImageCache.attachments.get(attachment.url),
+            let image = UIImage(data: data) else {
+                transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
+                return
+        }
+        
+        let ratio = image.size.width / image.size.height
+        var width = originalVCFrame.width
+        var height = width / ratio
+        let maxHeight = fromVC.view.bounds.height - fromVC.view.safeAreaInsets.top - fromVC.view.safeAreaInsets.bottom
+        if height > maxHeight {
+            let scaleFactor = maxHeight / height
+            width *= scaleFactor
+            height = maxHeight
+        }
+        let originalFrame = CGRect(x: originalVCFrame.midX - width / 2, y: originalVCFrame.midY - height / 2, width: width, height: height)
+        
+        let imageView = GIFImageView(frame: originalFrame)
+        imageView.image = image
+        if attachment.url.pathExtension == "gif" {
+            imageView.animate(withGIFData: data)
+        }
+        imageView.contentMode = .scaleAspectFill
+        imageView.layer.cornerRadius = 0
+        imageView.layer.masksToBounds = true
+        
+        let blackView = UIView(frame: originalVCFrame)
+        blackView.backgroundColor = .black
+        blackView.alpha = 1
+        
+        let containerView = transitionContext.containerView
+        containerView.addSubview(toVC.view)
+        containerView.addSubview(blackView)
+        containerView.addSubview(imageView)
+        
+        let duration = transitionDuration(using: transitionContext)
+        UIView.animate(withDuration: duration, animations: {
+            imageView.frame = sourceFrame
+            imageView.layer.cornerRadius = sourceCornerRadius
+            blackView.alpha = 0
+        }, completion: { _ in
+            blackView.removeFromSuperview()
+            imageView.removeFromSuperview()
+            
+            if transitionContext.transitionWasCancelled {
+                toVC.view.removeFromSuperview()
+            }
+            
+            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
+        })
+    }
+}

Tusker/Screens/Large Image/LargeImageViewController.swift

@@ -7,6 +7,7 @@
 //
 
 import UIKit
+import Pachyderm
 import Photos
 import Gifu
 
@@ -41,20 +42,13 @@ class LargeImageViewController: UIViewController, UIScrollViewDelegate {
     var gifData: Data?
     var imageDescription: String?
     
-    var controlsVisible = true {
+    var initialControlsVisible = true
+    private(set) var controlsVisible = true {
         didSet {
             setNeedsUpdateOfHomeIndicatorAutoHidden()
-            
-            UIView.animate(withDuration: 0.2) {
-                let topOffset = self.controlsVisible ? 0 : -self.topControlsView.bounds.height
-                self.topControlsView.transform = CGAffineTransform(translationX: 0, y: topOffset)
-                if self.imageDescription != nil {
-                    let bottomOffset = self.controlsVisible ? 0 : self.bottomControlsView.bounds.height + self.view.safeAreaInsets.bottom
-                    self.bottomControlsView.transform = CGAffineTransform(translationX: 0, y: bottomOffset)
-                }
-            }
         }
     }
+    var shrinkGestureEnabled = true
     
     var prevZoomScale: CGFloat?
     
@@ -73,6 +67,8 @@ class LargeImageViewController: UIViewController, UIScrollViewDelegate {
         self.originCornerRadius = sourceCornerRadius
         
         super.init(nibName: "LargeImageViewController", bundle: nil)
+        
+        modalPresentationStyle = .fullScreen
     }
     
 //    init(gifData: Data?, description: String?, sourceFrame: CGRect, sourceCornerRadius: CGFloat, router: AppRouter) {
@@ -92,6 +88,8 @@ class LargeImageViewController: UIViewController, UIScrollViewDelegate {
     override func viewDidLoad() {
         super.viewDidLoad()
 
+        setControlsVisible(initialControlsVisible, animated: false)
+        
         imageView.image = image
         if let gifData = gifData {
             imageView.animate(withGIFData: gifData)
@@ -106,7 +104,9 @@ class LargeImageViewController: UIViewController, UIScrollViewDelegate {
             bottomControlsView.isHidden = true
         }
         
+        if shrinkGestureEnabled {
             dismissInteractionController = LargeImageInteractionController(viewController: self)
+        }
         
         view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(scrollViewPressed(_:))))
         let doubleTap = UITapGestureRecognizer(target: self, action: #selector(scrollViewDoubleTapped(_:)))
@@ -143,6 +143,26 @@ class LargeImageViewController: UIViewController, UIScrollViewDelegate {
         }
     }
 
+    func setControlsVisible(_ controlsVisible: Bool, animated: Bool) {
+        self.controlsVisible = controlsVisible
+        if animated {
+            UIView.animate(withDuration: 0.2) {
+                self.updateControlsView()
+            }
+        } else {
+            updateControlsView()
+        }
+    }
+    
+    func updateControlsView() {
+        let topOffset = self.controlsVisible ? 0 : -self.topControlsView.bounds.height
+        self.topControlsView.transform = CGAffineTransform(translationX: 0, y: topOffset)
+        if self.imageDescription != nil {
+            let bottomOffset = self.controlsVisible ? 0 : self.bottomControlsView.bounds.height + self.view.safeAreaInsets.bottom
+            self.bottomControlsView.transform = CGAffineTransform(translationX: 0, y: bottomOffset)
+        }
+    }
+    
     func viewForZooming(in scrollView: UIScrollView) -> UIView? {
         return imageView
     }
@@ -190,7 +210,7 @@ class LargeImageViewController: UIViewController, UIScrollViewDelegate {
         if scrollView.zoomScale > scrollView.minimumZoomScale {
             animateZoomOut()
         } else {
-            controlsVisible = !controlsVisible
+            setControlsVisible(!controlsVisible, animated: true)
         }
     }
     

Tusker/Screens/Profile/ProfileTableViewController.swift

@@ -66,7 +66,7 @@ class ProfileTableViewController: EnhancedTableViewController, PreferencesAdapti
                 updateAccountUI()
             } else {
                 loadingVC = LoadingViewController()
-                add(loadingVC!)
+                embedChild(loadingVC!)
                 MastodonCache.account(for: accountID) { (account) in
                     guard account != nil else {
                         let alert = UIAlertController(title: "Something Went Wrong", message: "Couldn't load the selected account", preferredStyle: .alert)
@@ -86,7 +86,7 @@ class ProfileTableViewController: EnhancedTableViewController, PreferencesAdapti
             }
         } else {
             loadingVC = LoadingViewController()
-            add(loadingVC!)
+            embedChild(loadingVC!)
             shouldLoadOnAccountIDSet = true
         }
     }
@@ -127,7 +127,7 @@ class ProfileTableViewController: EnhancedTableViewController, PreferencesAdapti
     }
     
     func updateAccountUI() {
-        loadingVC?.remove()
+        loadingVC?.removeViewAndController()
         
         updateUIForPreferences()
         

Tusker/Screens/Utilities/LoadingViewController.swift

@@ -16,8 +16,10 @@ class LoadingViewController: UIViewController {
     override func viewDidLoad() {
         super.viewDidLoad()
         
+        view.backgroundColor = .systemBackground
+        
         activityIndicator = UIActivityIndicatorView(style: .large)
-        activityIndicator.color = .darkGray
+        activityIndicator.color = .secondaryLabel
         activityIndicator.translatesAutoresizingMaskIntoConstraints = false
         
         view.addSubview(activityIndicator)

Tusker/Screens/Utilities/UIViewController+Children.swift

@@ -8,18 +8,80 @@
 
 import UIKit
 
+// Based on MVCTodo by Dave DeLong: https://github.com/davedelong/MVCTodo/blob/841649dd6aa31bacda3ad7ef9a9a836f66281e50/MVCTodo/Extensions/UIViewController.swift
 extension UIViewController {
-    func add(_ child: UIViewController) {
+    func embedChild(_ newChild: UIViewController, in container: UIView? = nil) {
-        addChild(child)
+        // if the view controller is already a child of something else, remove it
-        view.addSubview(child.view)
+        if let oldParent = newChild.parent, oldParent != self {
-        child.didMove(toParent: self)
+            newChild.beginAppearanceTransition(false, animated: false)
+            newChild.willMove(toParent: nil)
+            newChild.removeFromParent()
+            
+            if newChild.viewIfLoaded?.superview != nil {
+                newChild.viewIfLoaded?.removeFromSuperview()
             }
             
-    func remove() {
+            newChild.endAppearanceTransition()
-        guard parent != nil else { return }
+        }
         
-        willMove(toParent: nil)
+        // since .view returns an IUO, by default the type of this is "UIView?"
-        removeFromParent()
+        // explicitly type the variable because We Know Better™
+        var targetContainer: UIView = container ?? self.view
+        if !targetContainer.isContainedWithin(view) {
+            targetContainer = view
+        }
+        
+        // add the view controller as a child
+        if newChild.parent != self {
+            newChild.beginAppearanceTransition(true, animated: false)
+            addChild(newChild)
+            newChild.didMove(toParent: self)
+            targetContainer.embedSubview(newChild.view)
+            newChild.endAppearanceTransition()
+        } else {
+            // the view controller is already a child
+            // make sure it's in the right view
+            
+            // we don't do the appearance transition stuff here,
+            // because the vc is already a child, so *presumably*
+            // that transition stuff has already appened
+            targetContainer.embedSubview(newChild.view)
+        }
+    }
+    
+    func removeViewAndController() {
         view.removeFromSuperview()
+        removeFromParent()
     }
 }
+
+// Based on MVCTodo by Dave DeLong: https://github.com/davedelong/MVCTodo/blob/841649dd6aa31bacda3ad7ef9a9a836f66281e50/MVCTodo/Extensions/UIView.swift
+extension UIView {
+    func embedSubview(_ subview: UIView) {
+        if subview.superview == self { return }
+        
+        if subview.superview != nil {
+            subview.removeFromSuperview()
+        }
+        
+        subview.frame = bounds
+        addSubview(subview)
+        
+        NSLayoutConstraint.activate([
+            subview.leadingAnchor.constraint(equalTo: leadingAnchor),
+            subview.trailingAnchor.constraint(equalTo: trailingAnchor),
+            subview.topAnchor.constraint(equalTo: topAnchor),
+            subview.bottomAnchor.constraint(equalTo: bottomAnchor)
+            ])
+    }
+    
+    func isContainedWithin(_ other: UIView) -> Bool {
+        var current: UIView? = self
+        while let proposedView = current {
+            if proposedView == other { return true }
+            current = proposedView.superview
+        }
+        return false
+    }
+}
+

Tusker/TuskerNavigationDelegate.swift

@@ -34,6 +34,10 @@ protocol TuskerNavigationDelegate {
     
     func showLargeImage(gifData: Data, description: String?, animatingFrom sourceView: UIView)
     
+    func gallery(attachments: [Attachment], sourceViews: [UIView], startIndex: Int) -> GalleryViewController
+    
+    func showGallery(attachments: [Attachment], sourceViews: [UIView], startIndex: Int)
+    
     func showMoreOptions(forStatus statusID: String)
     
     func showMoreOptions(forURL url: URL)
@@ -95,7 +99,7 @@ extension TuskerNavigationDelegate where Self: UIViewController {
         present(vc, animated: true)
     }
     
-    func largeImage(_ image: UIImage, description: String?, sourceView: UIView) -> LargeImageViewController {
+    private func sourceViewInfo(_ sourceView: UIView) -> (CGRect, CGFloat) {
         var sourceFrame = sourceView.convert(sourceView.bounds, to: view)
         if let scrollView = view as? UIScrollView {
             let scale = scrollView.zoomScale
@@ -105,28 +109,21 @@ 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)
         }
-        let sourceCornerRadius = sourceView.layer.cornerRadius
+        return (sourceFrame, sourceView.layer.cornerRadius)
+    }
+    
+    func largeImage(_ image: UIImage, description: String?, sourceView: UIView) -> LargeImageViewController {
+        let (sourceFrame, sourceCornerRadius) = sourceViewInfo(sourceView)
         let vc = LargeImageViewController(image: image, description: description, sourceFrame: sourceFrame, sourceCornerRadius: sourceCornerRadius)
         vc.transitioningDelegate = self
-        vc.modalPresentationStyle = .fullScreen
         return vc
     }
     
     func largeImage(gifData: Data, description: String?, sourceView: UIView) -> LargeImageViewController {
-        var sourceFrame = sourceView.convert(sourceView.bounds, to: view)
+        let (sourceFrame, sourceCornerRadius) = sourceViewInfo(sourceView)
-        if let scrollView = view as? UIScrollView {
-            let scale = scrollView.zoomScale
-            let width = sourceFrame.width * scale
-            let height = sourceFrame.height * scale
-            let x = sourceFrame.minX * scale - scrollView.contentOffset.x + scrollView.frame.minX
-            let y = sourceFrame.minY * scale - scrollView.contentOffset.y + scrollView.frame.minY
-            sourceFrame = CGRect(x: x, y: y, width: width, height: height)
-        }
-        let sourceCornerRadius = sourceView.layer.cornerRadius
         let vc = LargeImageViewController(image: UIImage(data: gifData)!, description: description, sourceFrame: sourceFrame, sourceCornerRadius: sourceCornerRadius)
         vc.transitioningDelegate = self
         vc.gifData = gifData
-        vc.modalPresentationStyle = .fullScreen
         return vc
     }
     
@@ -138,6 +135,17 @@ extension TuskerNavigationDelegate where Self: UIViewController {
         present(largeImage(gifData: gifData, description: description, sourceView: sourceView), animated: true)
     }
     
+    func gallery(attachments: [Attachment], sourceViews: [UIView], startIndex: Int) -> GalleryViewController {
+        let sourcesInfo = sourceViews.map(sourceViewInfo)
+        let vc = GalleryViewController(attachments: attachments, sourcesInfo: sourcesInfo, startIndex: startIndex)
+        vc.transitioningDelegate = self
+        return vc
+    }
+    
+    func showGallery(attachments: [Attachment], sourceViews: [UIView], startIndex: Int) {
+        present(gallery(attachments: attachments, sourceViews: sourceViews, startIndex: startIndex), animated: true)
+    }
+    
     private func moreOptions(forURL url: URL) -> UIAlertController {
         let alert = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
         alert.title = url.absoluteString

Tusker/Views/AttachmentView.swift

@@ -65,9 +65,7 @@ class AttachmentView: UIImageView, GIFAnimatable {
     }
     
     @objc func imagePressed() {
-        if image != nil {
         delegate?.showLargeAttachment(for: self)
     }
-    }
 
 }

Tusker/Views/Status/StatusTableViewCell.swift

@@ -340,11 +340,12 @@ extension StatusTableViewCell: TableViewSwipeActionProvider {
 
 extension StatusTableViewCell: AttachmentViewDelegate {
     func showLargeAttachment(for attachmentView: AttachmentView) {
-        if let gifData = attachmentView.gifData {
+        guard let status = MastodonCache.status(for: statusID) else { fatalError("Missing cached status \(statusID!)") }
-            delegate?.showLargeImage(gifData: gifData, description: attachmentView.attachment.description, animatingFrom: attachmentView)
+        let startIndex = status.attachments.firstIndex { $0.id == attachmentView.attachment.id } ?? 0
-        } else {
+        let sourceViews = status.attachments.map { attachment in
-            delegate?.showLargeImage(attachmentView.image!, description: attachmentView.attachment.description, animatingFrom: attachmentView)
+            attachmentsView.subviews.first { ($0 as! AttachmentView).attachment.id == attachment.id }!
         }
+        delegate?.showGallery(attachments: status.attachments, sourceViews: sourceViews, startIndex: startIndex)
     }
 }