Add text recognition image description for image attachments

Tusker/Screens/Compose/ComposeAttachmentsViewController.swift

@@ -315,6 +315,15 @@ class ComposeAttachmentsViewController: UITableViewController {
                     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)
                     }))
+                case .asset(_), .image(_):
+                    if attachment.data.type == .image,
+                        let cell = tableView.cellForRow(at: indexPath) as? ComposeAttachmentTableViewCell {
+                        
+                        let title = NSLocalizedString("Recognize Text", comment: "recognize image attachment text menu item title")
+                        actions.append(UIAction(title: title, image: UIImage(systemName: "doc.text.viewfinder"), identifier: nil, discoverabilityTitle: nil, attributes: [], state: .off, handler: { (_) in
+                            cell.recognizeTextFromImage()
+                        }))
+                    }
                 default:
                     break
                 }
@@ -503,6 +512,10 @@ extension ComposeAttachmentsViewController: AssetPickerViewControllerDelegate {
 }
 
 extension ComposeAttachmentsViewController: ComposeAttachmentTableViewCellDelegate {
+    func composeAttachment(_ cell: ComposeAttachmentTableViewCell, present viewController: UIViewController, animated: Bool) {
+        self.present(viewController, animated: animated)
+    }
+    
     func removeAttachment(_ cell: ComposeAttachmentTableViewCell) {
         guard let indexPath = tableView.indexPath(for: cell) else { return }
         attachments.remove(at: indexPath.row)

Tusker/Views/Attachment Cells/ComposeAttachmentTableViewCell.swift

@@ -9,8 +9,10 @@
 import UIKit
 import Photos
 import AVFoundation
+import Vision
 
 protocol ComposeAttachmentTableViewCellDelegate: class {
+    func composeAttachment(_ cell: ComposeAttachmentTableViewCell, present viewController: UIViewController, animated: Bool)
     func removeAttachment(_ cell: ComposeAttachmentTableViewCell)
     func attachmentDescriptionChanged(_ cell: ComposeAttachmentTableViewCell)
 }
@@ -23,9 +25,27 @@ class ComposeAttachmentTableViewCell: UITableViewCell {
     @IBOutlet weak var descriptionTextView: UITextView!
     @IBOutlet weak var descriptionPlaceholderLabel: UILabel!
     @IBOutlet weak var removeButton: UIButton!
+    @IBOutlet weak var activityIndicator: UIActivityIndicatorView!
     
     var attachment: CompositionAttachment!
     
+    var state: State = .allowEntry {
+        didSet {
+            switch state {
+            case .allowEntry:
+                descriptionTextView.isEditable = true
+                updateDescriptionPlaceholderLabel()
+                activityIndicator.stopAnimating()
+            case .recognizingText:
+                descriptionTextView.isEditable = false
+                descriptionPlaceholderLabel.isHidden = true
+                activityIndicator.startAnimating()
+            }
+        }
+    }
+    
+    private var textRecognitionRequest: VNRecognizeTextRequest?
+
     override func awakeFromNib() {
         super.awakeFromNib()
         
@@ -74,17 +94,69 @@ class ComposeAttachmentTableViewCell: UITableViewCell {
         removeButton.isEnabled = enabled
     }
     
+    func recognizeTextFromImage() {
+        precondition(attachment.data.type == .image)
+        state = .recognizingText
+        
+        DispatchQueue.global(qos: .userInitiated).async {
+            self.attachment.data.getData { (data, mimeType) in
+                let handler = VNImageRequestHandler(data: data, options: [:])
+                let request = VNRecognizeTextRequest { (request, error) in
+                    DispatchQueue.main.async {
+                        self.state = .allowEntry
+    
+                        if let results = request.results as? [VNRecognizedTextObservation] {
+                            var text = ""
+                            for observation in results {
+                                let result = observation.topCandidates(1).first!
+                                text.append(result.string)
+                                text.append("\n")
+                            }
+                            self.descriptionTextView.text = text
+                            self.textViewDidChange(self.descriptionTextView)
+                        }
+                    }
+                }
+                request.recognitionLevel = .accurate
+                request.usesLanguageCorrection = true
+                self.textRecognitionRequest = request
+                DispatchQueue.global(qos: .userInitiated).async {
+                    do {
+                        try handler.perform([request])
+                    } catch {
+                        // The perform call throws an error with code 1 if the request is cancelled, which we don't want to show an alert for.
+                        guard (error as NSError).code != 1 else { return }
+                        DispatchQueue.main.async {
+                            self.state = .allowEntry
+                            let title = NSLocalizedString("Text Recognition Failed", comment: "text recognition error alert title")
+                            let message = error.localizedDescription
+                            let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
+                            self.delegate?.composeAttachment(self, present: alert, animated: true)
+                        }
+                    }
+                }
+            }
+        }
+    }
+    
     override func prepareForReuse() {
         super.prepareForReuse()
         assetImageView.image = nil
     }
 
     @IBAction func removeButtonPressed(_ sender: Any) {
+        textRecognitionRequest?.cancel()
         delegate?.removeAttachment(self)
     }
     
 }
 
+extension ComposeAttachmentTableViewCell {
+    enum State {
+        case allowEntry, recognizingText
+    }
+}
+
 extension ComposeAttachmentTableViewCell: UITextViewDelegate {
     func textViewDidChange(_ textView: UITextView) {
         attachment.attachmentDescription = textView.text

Tusker/Views/Attachment Cells/ComposeAttachmentTableViewCell.xib

@@ -57,6 +57,9 @@
                             <constraint firstAttribute="height" relation="greaterThanOrEqual" constant="80" id="jWo-An-3h6"/>
                         </constraints>
                     </stackView>
+                    <activityIndicatorView hidden="YES" opaque="NO" contentMode="scaleToFill" horizontalHuggingPriority="750" verticalHuggingPriority="750" hidesWhenStopped="YES" style="medium" translatesAutoresizingMaskIntoConstraints="NO" id="Kzy-5r-UW8">
+                        <rect key="frame" x="179" y="38" width="20" height="20"/>
+                    </activityIndicatorView>
                 </subviews>
                 <constraints>
                     <constraint firstAttribute="bottom" secondItem="xRe-ec-Coh" secondAttribute="bottom" constant="8" id="DOS-Wv-G3s"/>
@@ -64,12 +67,15 @@
                     <constraint firstItem="h6T-x4-yzl" firstAttribute="trailing" secondItem="cwP-Eh-5dJ" secondAttribute="trailing" constant="4" id="KN2-Ve-3B2"/>
                     <constraint firstItem="h6T-x4-yzl" firstAttribute="top" secondItem="cwP-Eh-5dJ" secondAttribute="top" constant="8" id="P3B-Jo-XMs"/>
                     <constraint firstItem="h6T-x4-yzl" firstAttribute="leading" secondItem="cwP-Eh-5dJ" secondAttribute="leading" constant="4" id="UjP-Gs-ZjO"/>
+                    <constraint firstItem="Kzy-5r-UW8" firstAttribute="centerX" secondItem="cwP-Eh-5dJ" secondAttribute="centerX" id="czP-Ia-Ddc"/>
+                    <constraint firstItem="Kzy-5r-UW8" firstAttribute="centerY" secondItem="cwP-Eh-5dJ" secondAttribute="centerY" id="eel-xx-aFq"/>
                     <constraint firstItem="xRe-ec-Coh" firstAttribute="leading" secondItem="H2p-sc-9uM" secondAttribute="leading" constant="8" id="gRN-PV-gm6"/>
                     <constraint firstAttribute="trailing" secondItem="xRe-ec-Coh" secondAttribute="trailing" constant="8" id="tyE-HK-4qb"/>
                 </constraints>
             </tableViewCellContentView>
             <viewLayoutGuide key="safeArea" id="njF-e1-oar"/>
             <connections>
+                <outlet property="activityIndicator" destination="Kzy-5r-UW8" id="lmy-NY-Owu"/>
                 <outlet property="assetImageView" destination="GLY-o8-47z" id="hZH-ur-m4z"/>
                 <outlet property="descriptionPlaceholderLabel" destination="h6T-x4-yzl" id="jBe-R0-Sfn"/>
                 <outlet property="descriptionTextView" destination="cwP-Eh-5dJ" id="pxJ-zF-GKC"/>