Add drawing attachments using PencilKit

Tusker.xcodeproj/project.pbxproj

@@ -157,6 +157,7 @@
 		D6757A7C2157E01900721E32 /* XCBManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6757A7B2157E01900721E32 /* XCBManager.swift */; };
 		D6757A7E2157E02600721E32 /* XCBRequestSpec.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6757A7D2157E02600721E32 /* XCBRequestSpec.swift */; };
 		D6757A822157E8FA00721E32 /* XCBSession.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6757A812157E8FA00721E32 /* XCBSession.swift */; };
+		D67895BC24671E6D00D4CD9E /* PKDrawing+Render.swift in Sources */ = {isa = PBXBuildFile; fileRef = D67895BB24671E6D00D4CD9E /* PKDrawing+Render.swift */; };
 		D679C09F215850EF00DA27FE /* XCBActions.swift in Sources */ = {isa = PBXBuildFile; fileRef = D679C09E215850EF00DA27FE /* XCBActions.swift */; };
 		D67C57AD21E265FC00C3118B /* LargeAccountDetailView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D67C57AC21E265FC00C3118B /* LargeAccountDetailView.swift */; };
 		D67C57AF21E28EAD00C3118B /* Array+Uniques.swift in Sources */ = {isa = PBXBuildFile; fileRef = D67C57AE21E28EAD00C3118B /* Array+Uniques.swift */; };
@@ -164,6 +165,7 @@
 		D67C57B421E2910700C3118B /* ComposeStatusReplyView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D67C57B321E2910700C3118B /* ComposeStatusReplyView.swift */; };
 		D68015402401A6BA00D6103B /* ComposingPrefsView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D680153F2401A6BA00D6103B /* ComposingPrefsView.swift */; };
 		D68015422401A74600D6103B /* MediaPrefsView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D68015412401A74600D6103B /* MediaPrefsView.swift */; };
+		D68232F72464F4FD00325FB8 /* ComposeDrawingViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D68232F62464F4FD00325FB8 /* ComposeDrawingViewController.swift */; };
 		D68FEC4F232C5BC300C84F23 /* SegmentedPageViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D68FEC4E232C5BC300C84F23 /* SegmentedPageViewController.swift */; };
 		D693DE5723FE1A6A0061E07D /* EnhancedNavigationViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D693DE5623FE1A6A0061E07D /* EnhancedNavigationViewController.swift */; };
 		D693DE5923FE24310061E07D /* InteractivePushTransition.swift in Sources */ = {isa = PBXBuildFile; fileRef = D693DE5823FE24300061E07D /* InteractivePushTransition.swift */; };
@@ -451,6 +453,7 @@
 		D6757A7B2157E01900721E32 /* XCBManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = XCBManager.swift; sourceTree = "<group>"; };
 		D6757A7D2157E02600721E32 /* XCBRequestSpec.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = XCBRequestSpec.swift; sourceTree = "<group>"; };
 		D6757A812157E8FA00721E32 /* XCBSession.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = XCBSession.swift; sourceTree = "<group>"; };
+		D67895BB24671E6D00D4CD9E /* PKDrawing+Render.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "PKDrawing+Render.swift"; sourceTree = "<group>"; };
 		D679C09E215850EF00DA27FE /* XCBActions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = XCBActions.swift; sourceTree = "<group>"; };
 		D67C57AC21E265FC00C3118B /* LargeAccountDetailView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LargeAccountDetailView.swift; sourceTree = "<group>"; };
 		D67C57AE21E28EAD00C3118B /* Array+Uniques.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Array+Uniques.swift"; sourceTree = "<group>"; };
@@ -458,6 +461,7 @@
 		D67C57B321E2910700C3118B /* ComposeStatusReplyView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ComposeStatusReplyView.swift; sourceTree = "<group>"; };
 		D680153F2401A6BA00D6103B /* ComposingPrefsView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ComposingPrefsView.swift; sourceTree = "<group>"; };
 		D68015412401A74600D6103B /* MediaPrefsView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MediaPrefsView.swift; sourceTree = "<group>"; };
+		D68232F62464F4FD00325FB8 /* ComposeDrawingViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ComposeDrawingViewController.swift; sourceTree = "<group>"; };
 		D68FEC4E232C5BC300C84F23 /* SegmentedPageViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SegmentedPageViewController.swift; sourceTree = "<group>"; };
 		D693DE5623FE1A6A0061E07D /* EnhancedNavigationViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = EnhancedNavigationViewController.swift; sourceTree = "<group>"; };
 		D693DE5823FE24300061E07D /* InteractivePushTransition.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = InteractivePushTransition.swift; sourceTree = "<group>"; };
@@ -910,6 +914,7 @@
 				D6A5FAF0217B7E05003DB2D9 /* ComposeViewController.xib */,
 				D66362702136338600C9CBA2 /* ComposeViewController.swift */,
 				D60309B42419D4F100A465FF /* ComposeAttachmentsViewController.swift */,
+				D68232F62464F4FD00325FB8 /* ComposeDrawingViewController.swift */,
 			);
 			path = Compose;
 			sourceTree = "<group>";
@@ -1025,6 +1030,7 @@
 				D6EBF01423C55C0900AE061B /* UIApplication+Scenes.swift */,
 				D6EBF01623C55E0D00AE061B /* UISceneSession+MastodonController.swift */,
 				D6969E9D240C81B9002843CE /* NSTextAttachment+Emoji.swift */,
+				D67895BB24671E6D00D4CD9E /* PKDrawing+Render.swift */,
 			);
 			path = Extensions;
 			sourceTree = "<group>";
@@ -1758,11 +1764,13 @@
 				D646C95A213B5D0500269FB5 /* LargeImageInteractionController.swift in Sources */,
 				D6A3BC7C232195C600FD64D5 /* ActionNotificationGroupTableViewCell.swift in Sources */,
 				D6F953EC212519E700CF0F2B /* TimelineTableViewController.swift in Sources */,
+				D68232F72464F4FD00325FB8 /* ComposeDrawingViewController.swift in Sources */,
 				04586B4122B2FFB10021BD04 /* PreferencesView.swift in Sources */,
 				D620483223D2A6A3008A63EF /* CompositionState.swift in Sources */,
 				D6BC9DB5232D4CE3002CA326 /* NotificationsMode.swift in Sources */,
 				D68015402401A6BA00D6103B /* ComposingPrefsView.swift in Sources */,
 				D667E5EB21349EF80057A976 /* ProfileHeaderTableViewCell.swift in Sources */,
+				D67895BC24671E6D00D4CD9E /* PKDrawing+Render.swift in Sources */,
 				04D14BB022B34A2800642648 /* GalleryViewController.swift in Sources */,
 				D641C773213CAA25004B4513 /* NotificationsTableViewController.swift in Sources */,
 				D64BC18A23C16487000D0238 /* UnpinStatusActivity.swift in Sources */,

Tusker/Extensions/PKDrawing+Render.swift

@@ -0,0 +1,33 @@
+//
+//  PKDrawing+Render.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 5/9/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+import PencilKit
+
+extension PKDrawing {
+    
+    func imageInLightMode(from rect: CGRect, scale: CGFloat = UIScreen.main.scale) -> UIImage {
+        let lightTraitCollection = UITraitCollection(userInterfaceStyle: .light)
+        var drawingImage: UIImage!
+        lightTraitCollection.performAsCurrent {
+            drawingImage = self.image(from: rect, scale: scale)
+        }
+        
+        let imageRect = CGRect(origin: .zero, size: rect.size)
+        let format = UIGraphicsImageRendererFormat()
+        format.opaque = false
+        format.scale = scale
+        let renderer = UIGraphicsImageRenderer(size: rect.size, format: format)
+        return renderer.image { (context) in
+            UIColor.white.setFill()
+            context.fill(imageRect)
+            drawingImage.draw(in: imageRect)
+        }
+    }
+    
+}

Tusker/Models/CompositionAttachmentData.swift

@@ -9,11 +9,13 @@
 import UIKit
 import Photos
 import MobileCoreServices
+import PencilKit
 
 enum CompositionAttachmentData {
     case asset(PHAsset)
     case image(UIImage)
     case video(URL)
+    case drawing(PKDrawing)
     
     var type: AttachmentType {
         switch self {
@@ -23,6 +25,8 @@ enum CompositionAttachmentData {
             return .image
         case .video(_):
             return .video
+        case .drawing(_):
+            return .image
         }
     }
     
@@ -44,7 +48,7 @@ enum CompositionAttachmentData {
         }
     }
     
-    func getData(completion: @escaping (Data, String) -> Void) {
+    func getData(completion: @escaping (_ data: Data, _ mimeType: String) -> Void) {
         switch self {
         case let .image(image):
             completion(image.pngData()!, "image/png")
@@ -90,6 +94,10 @@ enum CompositionAttachmentData {
                 fatalError("failed to create export session")
             }
             CompositionAttachmentData.exportVideoData(session: session, completion: completion)
+            
+        case let .drawing(drawing):
+            let image = drawing.imageInLightMode(from: drawing.bounds, scale: 1)
+            completion(image.pngData()!, "image/png")
         }
     }
     
@@ -138,6 +146,10 @@ extension CompositionAttachmentData: Codable {
             try container.encode(image.pngData()!, forKey: .imageData)
         case .video(_):
             throw EncodingError.invalidValue(self, EncodingError.Context(codingPath: [], debugDescription: "video CompositionAttachments cannot be encoded"))
+        case let .drawing(drawing):
+            try container.encode("drawing", forKey: .type)
+            let drawingData = drawing.dataRepresentation()
+            try container.encode(drawingData, forKey: .drawing)
         }
     }
     
@@ -156,6 +168,10 @@ extension CompositionAttachmentData: Codable {
                 throw DecodingError.dataCorruptedError(forKey: .imageData, in: container, debugDescription: "Could not decode UIImage from image data")
             }
             self = .image(image)
+        case "drawing":
+            let drawingData = try container.decode(Data.self, forKey: .drawing)
+            let drawing = try PKDrawing(data: drawingData)
+            self = .drawing(drawing)
         default:
             throw DecodingError.dataCorruptedError(forKey: .type, in: container, debugDescription: "CompositionAttachment type must be one of 'image' or 'asset'")
         }
@@ -166,6 +182,8 @@ extension CompositionAttachmentData: Codable {
         case imageData
         /// The local identifier of the PHAsset for this attachment
         case assetIdentifier
+        /// The PKDrawing object for this attachment.
+        case drawing
     }
 }
 
@@ -178,6 +196,8 @@ extension CompositionAttachmentData: Equatable {
             return a == b
         case let (.video(a), .video(b)):
             return a == b
+        case let (.drawing(a), .drawing(b)):
+            return a == b
         default:
             return false
         }

Tusker/Screens/Asset Picker/AssetPreviewViewController.swift

@@ -52,6 +52,9 @@ class AssetPreviewViewController: UIViewController {
             default:
                 fatalError("asset mediaType must be image or video")
             }
+        case let .drawing(drawing):
+            let image = drawing.imageInLightMode(from: drawing.bounds)
+            showImage(image)
         }
     }
     

Tusker/Screens/Compose/ComposeAttachmentsViewController.swift

@@ -9,6 +9,7 @@
 import UIKit
 import Pachyderm
 import MobileCoreServices
+import PencilKit
 
 protocol ComposeAttachmentsViewControllerDelegate: class {
     func composeSelectedAttachmentsDidChange()
@@ -38,6 +39,8 @@ class ComposeAttachmentsViewController: UITableViewController {
         }
     }
     
+    private var currentlyEditedDrawingIndex: Int?
+
     init(attachments: [CompositionAttachment], mastodonController: MastodonController) {
         self.attachments = attachments
         self.mastodonController = mastodonController
@@ -139,6 +142,23 @@ class ComposeAttachmentsViewController: UITableViewController {
         }
     }
     
+    func presentComposeDrawingViewController(editingAttachmentAt attachmentIndex: Int? = nil) {
+        let drawingVC: ComposeDrawingViewController
+        
+        if let index = attachmentIndex,
+            case let .drawing(drawing) = attachments[index].data {
+            drawingVC = ComposeDrawingViewController(editing: drawing)
+            currentlyEditedDrawingIndex = index
+        } else {
+            drawingVC = ComposeDrawingViewController()
+        }
+        
+        drawingVC.delegate = self
+        let nav = UINavigationController(rootViewController: drawingVC)
+        nav.modalPresentationStyle = .fullScreen
+        present(nav, animated: true)
+    }
+    
     func uploadAll(stepProgress: @escaping () -> Void, completion: @escaping (_ success: Bool, _ uploadedAttachments: [Attachment]) -> Void) {
         let group = DispatchGroup()
         
@@ -270,19 +290,49 @@ class ComposeAttachmentsViewController: UITableViewController {
     }
     
     override func tableView(_ tableView: UITableView, contextMenuConfigurationForRowAt indexPath: IndexPath, point: CGPoint) -> UIContextMenuConfiguration? {
-        guard indexPath.section == 0 else { return nil }
+        if indexPath.section == 0 {
-        
             let attachment = attachments[indexPath.row]
             // cast to NSIndexPath because identifier needs to conform to NSCopying
             return UIContextMenuConfiguration(identifier: indexPath as NSIndexPath, previewProvider: { () -> UIViewController? in
                 return AssetPreviewViewController(attachment: attachment.data)
             }) { (_) -> UIMenu? in
+                var actions = [UIAction]()
+                
+                switch attachment.data {
+                case .drawing(_):
+                    actions.append(UIAction(title: "Edit Drawing", image: UIImage(systemName: "hand.draw"), identifier: nil, discoverabilityTitle: nil, attributes: [], state: .off, handler: { (_) in
+                        self.presentComposeDrawingViewController(editingAttachmentAt: indexPath.row)
+                    }))
+                default:
+                    break
+                }
+                
+                if actions.isEmpty {
+                    return nil
+                } else {
+                    return UIMenu(title: "", image: nil, identifier: nil, options: [], children: actions)
+                }
+            }
+        } else if indexPath.section == 1 {
+            guard isAddAttachmentsButtonEnabled() else {
+                return nil
+            }
+            // show context menu for drawing/file uploads
+            return UIContextMenuConfiguration(identifier: nil, previewProvider: nil) { (_) -> UIMenu? in
+                return UIMenu(title: "", image: nil, identifier: nil, options: [], children: [
+                    UIAction(title: "Draw Something", image: UIImage(systemName: "hand.draw"), identifier: nil, discoverabilityTitle: nil, attributes: [], state: .off, handler: { (_) in
+                        self.presentComposeDrawingViewController()
+                    })
+                ])
+            }
+        } else {
             return nil
         }
     }
     
     private func targetedPreview(forConfiguration configuration: UIContextMenuConfiguration) -> UITargetedPreview? {
         if let indexPath = (configuration.identifier as? NSIndexPath) as IndexPath?,
+            indexPath.section == 0,
             let cell = tableView.cellForRow(at: indexPath) as? ComposeAttachmentTableViewCell {
             let parameters = UIPreviewParameters()
             parameters.backgroundColor = .black
@@ -452,3 +502,26 @@ extension ComposeAttachmentsViewController: ComposeAttachmentTableViewCellDelega
         delegate?.composeRequiresAttachmentDescriptionsDidChange()
     }
 }
+
+extension ComposeAttachmentsViewController: ComposeDrawingViewControllerDelegate {
+    func composeDrawingViewControllerClose(_ drawingController: ComposeDrawingViewController) {
+        dismiss(animated: true)
+        currentlyEditedDrawingIndex = nil
+    }
+    
+    func composeDrawingViewController(_ drawingController: ComposeDrawingViewController, saveDrawing drawing: PKDrawing) {
+        let newAttachment = CompositionAttachment(data: .drawing(drawing))
+        
+        if let currentlyEditedDrawingIndex = currentlyEditedDrawingIndex {
+            attachments[currentlyEditedDrawingIndex] = newAttachment
+            tableView.reloadRows(at: [IndexPath(row: currentlyEditedDrawingIndex, section: 0)], with: .automatic)
+        } else {
+            attachments.append(newAttachment)
+            tableView.insertRows(at: [IndexPath(row: self.attachments.count - 1, section: 0)], with: .automatic)
+            updateHeightConstraint()
+        }
+
+        dismiss(animated: true)
+        currentlyEditedDrawingIndex = nil
+    }
+}

Tusker/Screens/Compose/ComposeDrawingViewController.swift

@@ -0,0 +1,174 @@
+//
+//  ComposeDrawingViewController.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 5/7/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+import PencilKit
+
+protocol ComposeDrawingViewControllerDelegate: class {
+    func composeDrawingViewControllerClose(_ drawingController: ComposeDrawingViewController)
+    func composeDrawingViewController(_ drawingController: ComposeDrawingViewController, saveDrawing drawing: PKDrawing)
+}
+
+class ComposeDrawingViewController: UIViewController {
+    
+    weak var delegate: ComposeDrawingViewControllerDelegate?
+    
+    private(set) var canvasView: PKCanvasView!
+    private(set) var cancelBarButtonItem: UIBarButtonItem!
+    private(set) var undoBarButtonItem: UIBarButtonItem!
+    private(set) var redoBarButtonItem: UIBarButtonItem!
+    
+    private var initialDrawing: PKDrawing?
+
+    init() {
+        super.init(nibName: nil, bundle: nil)
+    }
+    
+    convenience init(editing initialDrawing: PKDrawing) {
+        self.init()
+        
+        self.initialDrawing = initialDrawing
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        
+        overrideUserInterfaceStyle = .light
+
+        navigationItem.title = NSLocalizedString("Draw", comment: "compose drawing screen title")
+        cancelBarButtonItem = UIBarButtonItem(barButtonSystemItem: .cancel, target: self, action: #selector(cancelPressed))
+        undoBarButtonItem = UIBarButtonItem(image: UIImage(systemName: "arrow.uturn.left.circle"), style: .plain, target: self, action: #selector(undoPressed))
+        undoBarButtonItem.isEnabled = false
+        redoBarButtonItem = UIBarButtonItem(image: UIImage(systemName: "arrow.uturn.right.circle"), style: .plain, target: self, action: #selector(redoPressed))
+        redoBarButtonItem.isEnabled = false
+        navigationItem.leftBarButtonItems = [cancelBarButtonItem]
+        navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .save, target: self, action: #selector(savePressed))
+        
+        canvasView = PKCanvasView()
+        if let initialDrawing = initialDrawing {
+            canvasView.drawing = initialDrawing
+        }
+        canvasView.delegate = self
+        canvasView.allowsFingerDrawing = true
+        canvasView.minimumZoomScale = 0.5
+        canvasView.maximumZoomScale = 2
+        canvasView.backgroundColor = .systemBackground
+        canvasView.translatesAutoresizingMaskIntoConstraints = false
+        view.addSubview(canvasView)
+        NSLayoutConstraint.activate([
+            canvasView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+            canvasView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+            canvasView.topAnchor.constraint(equalTo: view.topAnchor),
+            canvasView.bottomAnchor.constraint(equalTo: view.bottomAnchor)
+        ])
+    }
+    
+    override func viewWillAppear(_ animated: Bool) {
+        super.viewWillAppear(animated)
+        
+        if let window = parent?.view.window, let toolPicker = PKToolPicker.shared(for: window) {
+            toolPicker.setVisible(true, forFirstResponder: canvasView)
+            toolPicker.addObserver(canvasView)
+            toolPicker.addObserver(self)
+            
+            updateLayout(for: toolPicker)
+            canvasView.becomeFirstResponder()
+            
+            // wait until the next run loop iteration so that the canvas view has become first responder and it's undo manager exists
+            DispatchQueue.main.async {
+                NotificationCenter.default.addObserver(self, selector: #selector(self.updateUndoRedoButtonState), name: .NSUndoManagerDidUndoChange, object: self.undoManager!)
+                NotificationCenter.default.addObserver(self, selector: #selector(self.updateUndoRedoButtonState), name: .NSUndoManagerDidRedoChange, object: self.undoManager!)
+            }
+        }
+    }
+
+    func updateLayout(for toolPicker: PKToolPicker) {
+        let obscuredFrame = toolPicker.frameObscured(in: view)
+        
+        // if there is no obscured frame, the tool picker is floating
+        // which means we don't need to change inset or show undo/redo
+        if obscuredFrame.isNull {
+            navigationItem.leftBarButtonItems = [cancelBarButtonItem]
+            canvasView.contentInset = .zero
+            canvasView.automaticallyAdjustsScrollIndicatorInsets = true
+        } else {
+            navigationItem.leftBarButtonItems = [cancelBarButtonItem, undoBarButtonItem, redoBarButtonItem]
+            canvasView.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: obscuredFrame.height, right: 0)
+            canvasView.automaticallyAdjustsScrollIndicatorInsets = false
+            // we don't care about the botom safe area inset becaused the tool picker obscured frame includes the safe area
+            canvasView.scrollIndicatorInsets = UIEdgeInsets(top: view.safeAreaInsets.top, left: view.safeAreaInsets.left, bottom: obscuredFrame.height, right: view.safeAreaInsets.right)
+        }
+    }
+    
+    func updateContentSizeForDrawing() {
+        let overscrollAmount: CGFloat = 100
+        let drawingBounds = canvasView.drawing.bounds
+        let newSize: CGSize
+        if !drawingBounds.isNull {
+            let width = max(canvasView.bounds.width, (drawingBounds.maxX + overscrollAmount) * canvasView.zoomScale)
+            let height = max(canvasView.bounds.height, (drawingBounds.maxY + overscrollAmount) * canvasView.zoomScale)
+            newSize = CGSize(width: width, height: height)
+        } else {
+            newSize = canvasView.bounds.size
+        }
+        canvasView.contentSize = newSize
+    }
+    
+    @objc func updateUndoRedoButtonState() {
+        undoBarButtonItem.isEnabled = undoManager!.canUndo
+        redoBarButtonItem.isEnabled = undoManager!.canRedo
+    }
+    
+    // MARK: Interaction
+    
+    @objc func cancelPressed() {
+        delegate?.composeDrawingViewControllerClose(self)
+    }
+    
+    @objc func savePressed() {
+        delegate?.composeDrawingViewController(self, saveDrawing: canvasView.drawing)
+    }
+    
+    @objc func undoPressed() {
+        undoManager!.undo()
+    }
+    
+    @objc func redoPressed() {
+        undoManager!.redo()
+    }
+
+}
+
+extension ComposeDrawingViewController: PKCanvasViewDelegate {
+    func canvasViewDrawingDidChange(_ canvasView: PKCanvasView) {
+        if !undoManager!.isUndoing && !undoManager!.isRedoing {
+            updateUndoRedoButtonState()
+        }
+        updateContentSizeForDrawing()
+    }
+}
+
+extension ComposeDrawingViewController: PKToolPickerObserver {
+    func toolPickerFramesObscuredDidChange(_ toolPicker: PKToolPicker) {
+        updateLayout(for: toolPicker)
+    }
+    
+    func toolPickerVisibilityDidChange(_ toolPicker: PKToolPicker) {
+        updateLayout(for: toolPicker)
+    }
+}
+
+extension ComposeDrawingViewController: UIGestureRecognizerDelegate {
+    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
+        return otherGestureRecognizer == canvasView.drawingGestureRecognizer
+    }
+}

Tusker/Views/Attachment Cells/ComposeAttachmentTableViewCell.swift

@@ -7,7 +7,6 @@
 //
 
 import UIKit
-//import Combine
 import Photos
 import AVFoundation
 
@@ -42,6 +41,8 @@ class ComposeAttachmentTableViewCell: UITableViewCell {
         descriptionTextView.text = attachment.attachmentDescription
         updateDescriptionPlaceholderLabel()
 
+        assetImageView.contentMode = .scaleAspectFill
+        assetImageView.backgroundColor = .secondarySystemBackground
         switch attachment.data {
         case let .image(image):
             assetImageView.image = image
@@ -57,6 +58,10 @@ class ComposeAttachmentTableViewCell: UITableViewCell {
             if let cgImage = try? imageGenerator.copyCGImage(at: .zero, actualTime: nil) {
                 assetImageView.image = UIImage(cgImage: cgImage)
             }
+        case let .drawing(drawing):
+            assetImageView.image = drawing.imageInLightMode(from: drawing.bounds)
+            assetImageView.contentMode = .scaleAspectFit
+            assetImageView.backgroundColor = .white
         }
     }
     

Tusker/Views/Draft Cell/DraftTableViewCell.swift

@@ -34,6 +34,9 @@ class DraftTableViewCell: UITableViewCell {
             attachmentsStackView.addArrangedSubview(imageView)
             imageView.widthAnchor.constraint(equalTo: imageView.heightAnchor).isActive = true
             
+            imageView.backgroundColor = .secondarySystemBackground
+            imageView.contentMode = .scaleAspectFill
+            
             switch attachment.data {
             case let .asset(asset):
                 PHImageManager.default().requestImage(for: asset, targetSize: size, contentMode: .aspectFill, options: nil) { (image, _) in
@@ -44,6 +47,10 @@ class DraftTableViewCell: UITableViewCell {
             case .video(_):
                 // videos aren't saved to drafts, so this is unreachable
                 return
+            case let .drawing(drawing):
+                imageView.image = drawing.imageInLightMode(from: drawing.bounds)
+                imageView.backgroundColor = .white
+                imageView.contentMode = .scaleAspectFit
             }
         }
     }