Credit Card Text Extraction using movable rectangle

VisionCreditScan/VisionCreditScan/TextExtractorVC.swift

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+//
+// TextExtractorVC.swift
+// VisionCreditScan
+//
+// Created by Anupam Chugh on 27/01/20.
+// Copyright © 2020 iowncode. All rights reserved.
+//
+
+import UIKit
+import Vision
+//import CoreMotion
+
+class TextExtractorVC: UIViewController {
+
+ //let manager = CMMotionManager()
+ let queue = OperationQueue()
+
+ let overlay = UIView()
+ var lastPoint = CGPoint.zero
+
+ var textRecognitionRequest = VNRecognizeTextRequest(completionHandler: nil)
+ private let textRecognitionWorkQueue = DispatchQueue(label: "MyVisionScannerQueue", qos: .userInitiated, attributes: [], autoreleaseFrequency: .workItem)
+
+ var scannedImage : UIImage?
+
+ private var maskLayer = [CAShapeLayer]()
+
+ lazy var imageView : UIImageView = {
+
+ let b = UIImageView()
+ b.contentMode = .scaleAspectFit
+
+ view.addSubview(b)
+
+ b.translatesAutoresizingMaskIntoConstraints = false
+ b.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
+ b.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
+ b.topAnchor.constraint(equalTo: view.topAnchor, constant: 30).isActive = true
+ b.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
+
+ return b
+
+ }()
+
+ lazy var button : UIButton = {
+
+ let b = UIButton(type: .system)
+ b.setTitle("Extract Digits", for: .normal)
+ view.addSubview(b)
+
+ b.translatesAutoresizingMaskIntoConstraints = false
+ b.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
+ b.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
+ b.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
+ b.heightAnchor.constraint(equalToConstant: 50).isActive = true
+
+ return b
+
+ }()
+
+ lazy var digitsLabel : UILabel = {
+
+ let b = UILabel(frame: .zero)
+
+ view.addSubview(b)
+
+ b.translatesAutoresizingMaskIntoConstraints = false
+ b.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
+ b.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
+ b.bottomAnchor.constraint(equalTo: self.button.topAnchor, constant: -20).isActive = true
+ b.heightAnchor.constraint(equalToConstant: 30).isActive = true
+
+ return b
+
+ }()
+
+ @objc func doExtraction(sender: UIButton!){
+ processImage(snapshot(in: imageView, rect: overlay.frame))
+ }
+
+ func snapshot(in imageView: UIImageView, rect: CGRect) -> UIImage {
+ return UIGraphicsImageRenderer(bounds: rect).image { _ in
+
+ clearOverlay()
+ imageView.drawHierarchy(in: imageView.bounds, afterScreenUpdates: true)
+
+ }
+ }
+
+ override func viewDidLoad() {
+ super.viewDidLoad()
+
+ setupVision()
+ self.view.backgroundColor = .black
+
+ imageView.image = scannedImage
+
+ overlay.backgroundColor = UIColor.red.withAlphaComponent(0.5)
+ overlay.isHidden = true
+
+ imageView.addSubview(overlay)
+ imageView.bringSubviewToFront(overlay)
+
+ button.addTarget(self, action: #selector(doExtraction(sender:)), for: .touchUpInside)
+
+ }
+
+ private func setupVision() {
+ textRecognitionRequest = VNRecognizeTextRequest { (request, error) in
+ guard let observations = request.results as? [VNRecognizedTextObservation] else { return }
+
+ var detectedText = ""
+ for observation in observations {
+ guard let topCandidate = observation.topCandidates(1).first else { return }
+
+
+ detectedText += topCandidate.string
+ detectedText += "\n"
+ }
+
+ DispatchQueue.main.async{
+ self.digitsLabel.text = detectedText
+ }
+ }
+
+ textRecognitionRequest.recognitionLevel = .accurate
+ }
+
+ private func processImage(_ image: UIImage) {
+ recognizeTextInImage(image)
+ }
+
+ private func recognizeTextInImage(_ image: UIImage) {
+ guard let cgImage = image.cgImage else { return }
+
+ textRecognitionWorkQueue.async {
+ let requestHandler = VNImageRequestHandler(cgImage: cgImage, options: [:])
+ do {
+ try requestHandler.perform([self.textRecognitionRequest])
+ } catch {
+ print(error)
+ }
+ }
+ }
+
+ func clearOverlay(){
+ overlay.isHidden = false
+ overlay.frame = CGRect.zero
+ }
+
+ override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
+
+ clearOverlay()
+ if let touch = touches.first {
+ lastPoint = touch.location(in: self.view)
+ }
+ }
+
+
+ override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
+ if let touch = touches.first {
+ let currentPoint = touch.location(in: view)
+ drawSelectionArea(fromPoint: lastPoint, toPoint: currentPoint)
+ }
+ }
+
+ func drawSelectionArea(fromPoint: CGPoint, toPoint: CGPoint) {
+
+ let rect = CGRect(x: min(fromPoint.x, toPoint.x), y: min(fromPoint.y, toPoint.y), width: abs(fromPoint.x - toPoint.x), height: abs(fromPoint.y - toPoint.y))
+ overlay.frame = rect
+ }
+}