Use cross fade transitions for displaying gallery and asset picker if

Reduce Motion/Prefer Cross Fade is enabled

Closes #108

Tusker.xcodeproj/project.pbxproj

@@ -252,6 +252,7 @@
 		D6D3F4C424FDB6B700EC4A6A /* View+ConditionalModifier.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6D3F4C324FDB6B700EC4A6A /* View+ConditionalModifier.swift */; };
 		D6D3FDE024F41B8400FF50A5 /* ComposeContainerView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6D3FDDF24F41B8400FF50A5 /* ComposeContainerView.swift */; };
 		D6D3FDE224F46A8D00FF50A5 /* ComposeUIState.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6D3FDE124F46A8D00FF50A5 /* ComposeUIState.swift */; };
+		D6D4CC91250D2C3100FCCF8D /* UIAccessibility.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6D4CC90250D2C3100FCCF8D /* UIAccessibility.swift */; };
 		D6D4DDD0212518A000E1C4BB /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6D4DDCF212518A000E1C4BB /* AppDelegate.swift */; };
 		D6D4DDD7212518A200E1C4BB /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = D6D4DDD6212518A200E1C4BB /* Assets.xcassets */; };
 		D6D4DDDA212518A200E1C4BB /* LaunchScreen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = D6D4DDD8212518A200E1C4BB /* LaunchScreen.storyboard */; };
@@ -573,6 +574,7 @@
 		D6D3F4C324FDB6B700EC4A6A /* View+ConditionalModifier.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "View+ConditionalModifier.swift"; sourceTree = "<group>"; };
 		D6D3FDDF24F41B8400FF50A5 /* ComposeContainerView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ComposeContainerView.swift; sourceTree = "<group>"; };
 		D6D3FDE124F46A8D00FF50A5 /* ComposeUIState.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ComposeUIState.swift; sourceTree = "<group>"; };
+		D6D4CC90250D2C3100FCCF8D /* UIAccessibility.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UIAccessibility.swift; sourceTree = "<group>"; };
 		D6D4DDCC212518A000E1C4BB /* Tusker.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = Tusker.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		D6D4DDCF212518A000E1C4BB /* AppDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
 		D6D4DDD6212518A200E1C4BB /* Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Assets.xcassets; sourceTree = "<group>"; };
@@ -1104,6 +1106,7 @@
 				D67895BB24671E6D00D4CD9E /* PKDrawing+Render.swift */,
 				D690797224A4EF9700023A34 /* UIBezierPath+Helpers.swift */,
 				D6D3F4C324FDB6B700EC4A6A /* View+ConditionalModifier.swift */,
+				D6D4CC90250D2C3100FCCF8D /* UIAccessibility.swift */,
 			);
 			path = Extensions;
 			sourceTree = "<group>";
@@ -1851,6 +1854,7 @@
 				D6B053AE23BD322B00A066FA /* AssetPickerSheetContainerViewController.swift in Sources */,
 				D6C693EF216192C2007D6A6D /* TuskerNavigationDelegate.swift in Sources */,
 				D6C94D872139E62700CB5196 /* LargeImageViewController.swift in Sources */,
+				D6D4CC91250D2C3100FCCF8D /* UIAccessibility.swift in Sources */,
 				D627943E23A564D400D38C68 /* ExploreViewController.swift in Sources */,
 				D6B053AB23BD2F1400A066FA /* AssetCollectionViewCell.swift in Sources */,
 				D622757A24EE21D900B82A16 /* ComposeAttachmentRow.swift in Sources */,

Tusker.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -15,7 +15,7 @@
         "repositoryURL": "https://git.shadowfacts.net/shadowfacts/SheetController.git",
         "state": {
           "branch": "master",
-          "revision": "7ac34efeabb5b5eb08fcf3d1235dbc9ca0441662",
+          "revision": "ab77ad89b449b8c415441a6ac97e0922d6900dcc",
           "version": null
         }
       },

Tusker/Extensions/UIAccessibility.swift

@@ -0,0 +1,21 @@
+//
+//  UIAccessibility.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 9/12/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+
+extension UIAccessibility {
+    
+    static var prefersCrossFadeTransitionsBackwardsCompat: Bool {
+        if #available(iOS 14.0, *) {
+            return prefersCrossFadeTransitions
+        } else {
+            return isReduceMotionEnabled
+        }
+    }
+    
+}

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

@@ -38,8 +38,12 @@ extension LargeImageAnimatableViewController {
 class LargeImageExpandAnimationController: NSObject, UIViewControllerAnimatedTransitioning {
     
     func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
+        if UIAccessibility.prefersCrossFadeTransitionsBackwardsCompat {
+            return 0.2
+        } else {
             return 0.4
         }
+    }
     
     func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
         guard let fromVC = transitionContext.viewController(forKey: .from),
@@ -47,6 +51,11 @@ class LargeImageExpandAnimationController: NSObject, UIViewControllerAnimatedTra
                 return
         }
         
+        if UIAccessibility.prefersCrossFadeTransitionsBackwardsCompat {
+            animateCrossFadeTransition(using: transitionContext)
+            return
+        }
+        
         let containerView = transitionContext.containerView
         containerView.addSubview(toVC.view)
 
@@ -112,4 +121,20 @@ class LargeImageExpandAnimationController: NSObject, UIViewControllerAnimatedTra
         }
     }
     
+    func animateCrossFadeTransition(using transitionContext: UIViewControllerContextTransitioning) {
+        guard let toVC = transitionContext.viewController(forKey: .to) as? LargeImageAnimatableViewController else {
+            return
+        }
+        
+        transitionContext.containerView.addSubview(toVC.view)
+        toVC.view.alpha = 0
+        
+        let duration = transitionDuration(using: transitionContext)
+        UIView.animate(withDuration: duration) {
+            toVC.view.alpha = 1
+        } completion: { (_) in
+            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
+        }
+    }
+    
 }

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

@@ -27,6 +27,11 @@ class LargeImageShrinkAnimationController: NSObject, UIViewControllerAnimatedTra
                 return
         }
         
+        if UIAccessibility.prefersCrossFadeTransitionsBackwardsCompat && !transitionContext.isInteractive {
+            animateCrossFadeTransition(using: transitionContext)
+            return
+        }
+        
         guard let sourceView = fromVC.animationSourceView,
             let sourceFrame = fromVC.sourceViewFrame(in: toVC.view),
             let image = fromVC.animationImage else {
@@ -86,4 +91,21 @@ class LargeImageShrinkAnimationController: NSObject, UIViewControllerAnimatedTra
         })
     }
     
+    func animateCrossFadeTransition(using transitionContext: UIViewControllerContextTransitioning) {
+        guard let fromVC = transitionContext.viewController(forKey: .from) as? LargeImageAnimatableViewController,
+              let toVC = transitionContext.viewController(forKey: .to) else {
+            return
+        }
+        
+        transitionContext.containerView.addSubview(toVC.view)
+        transitionContext.containerView.addSubview(fromVC.view)
+        
+        let duration = transitionDuration(using: transitionContext)
+        UIView.animate(withDuration: duration) {
+            fromVC.view.alpha = 0
+        } completion: { (_) in
+            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
+        }
+    }
+    
 }