DOT iOS Document library

v3.2.0

Introduction

DOT iOS Document provides components for document capture and related functionalities which are easy to integrate into an iOS application.

Requirements

Xcode 11.4+
iOS 11.0+
Swift or Objective-C
CocoaPods

DOT iOS Document is distributed as a XCFramework - DotDocument.xcframework using Cocoapods with its dependencies stored in our public github repository. It can be easily integrated into XCode with custom definition of podspecs. First step is to insert following line of code on top of you Podfile.

Podfile

source 'https://github.com/innovatrics/innovatrics-podspecs'

Then DOT iOS Document dependency must be specified in Podfile. Dependencies of DOT iOS Document will be downloaded alongside it.

Podfile

source 'https://github.com/innovatrics/innovatrics-podspecs'

use_frameworks!

target 'YOUR_TARGET' do

pod 'dot-document'

end

In case of CocoaPods problem with pod install, try to clone the private pod repository manually.

pod repo remove innovatrics
pod repo add innovatrics https://github.com/innovatrics/innovatrics-podspecs

Supported Architectures

DOT iOS Document provides all supported architectures in the distributed XCFramework package. Device binary contains: arm64. Simulator binary contains: x86_64, arm64.

Permissions

Set the following permission in Info.plist:

Info.plist

<key>NSCameraUsageDescription</key>
	<string>Your usage description</string>

Basic Setup

Logging

DOT iOS Document supports logging using a global Logger class. You can set the log level as follows:

import DotDocument

Logger.logLevel = .debug

Log levels:

info
debug
warning
error
none

Each log message contains dot-document tag. Keep in mind that logging should be used just for debugging purposes.

Components

Overview

DOT iOS Document provides both non-UI and UI components. Non-UI components are aimed to be used by developers who want to build their own UI using the DOT iOS Document functionality. UI components are build on top of non-UI components. Components having UI are available as UIViewController classes and can be embedded into the application’s existing UI or presented using the standard methods.

List of Non-UI Components

DOCUMENT DETECTOR: A component for performing document detection on an image.
IMAGE PARAMETERS ANALYZER: A component for computing image parameters such as sharpness, brightness or hotspots score.
IMAGE PERSPECTIVE WARPER: A component for warping the perspective of an image according to the detected document corners.
DOCUMENT AUTO CAPTURE CONTROLLER: A component for capturing good quality photos suitable for optical character recognition.
MACHINE READABLE ZONE READER: A component for reading Machine Readable Zone (MRZ).

List of UI Components

DOCUMENT AUTO CAPTURE: An visual component for capturing good quality photos suitable for optical character recognition.

Non-UI Components

Document Detector

The DocumentDetector class provides a document detection functionality.

Create a DocumentDetector:

let documentDetector = DocumentDetector()

To perform detection, call the following method on the background thread:

let result = try? documentDetector.detect(bgraRawImage: bgraRawImage)

Image Parameters Analyzer

The ImageParametersAnalyzer class provides an image parameters analysis functionality.

Create ImageParametersAnalyzer:

let imageParametersAnalyzer = ImageParametersAnalyzer()

To perform analysis, call the following method on the background thread:

let imageParameters = try? imageParametersAnalyzer.analyze(bgraRawImage: bgraRawImage)

Image Perspective Warper

The ImagePerspectiveWarper class provides perspective warping functionality.

Create ImagePerspectiveWarper:

let imagePerspectiveWarper = ImagePerspectiveWarper()

To perform perspective warping, call the following method on the background thread:

let warpedBgraRawImage = try? imagePerspectiveWarper.warp(bgraRawImage: bgraRawImage, corners: corners, targetImageSize: targetImageSize)

Document Auto Capture Controller

The DocumentAutoCaptureController class provides a stateful document auto capture functionality.

Create DocumentAutoCaptureController:

let configuration = DocumentAutoCaptureControllerConfiguration(
            validators: validators,
            minValidFramesInRowToStartCandidateSelection: 2
            candidateSelectionDurationMillis: 1000,
            detectionNormalizedRectangle: detectionNormalizedRectangle,
            imageParametersNormalizedRectangle: imageParametersNormalizedRectangle,
            isMrzReadingEnabled: false)
let controller = DocumentAutoCaptureController(configuration: configuration)

DocumentAutoCaptureControllerConfiguration

(Required) [-] validators: [DocumentAutoCaptureDetectionValidator] - Array of validators which will be used to validate input image.
(Optional) [2] minValidFramesInRowToStartCandidateSelection: Int - Minimum number of valid frames in a row to start candidate selection.
(Optional) [1000] candidateSelectionDurationMillis: Int - Duration of candidate selection phase.
(Optional) [-] detectionNormalizedRectangle: RectangleDouble - Crop an input image to normalized detection rectangle and use that for document detection.
(Optional) [-] imageParametersNormalizedRectangle: RectangleDouble - Crop an input image to normalized image parameters rectangle and use that to analyze image parameters.
(Optional) [false] isMrzReadingEnabled: Bool - Use this flag to enable MRZ reading during document auto capture process.

You can use detectionNormalizedRectangle to specify the region in the input image which will be used for document detection. For example, if you want to ignore top 30% and bottom 30% of the input image, you can do it as follows:

let detectionNormalizedRectangle = RectangleDouble(left: 0, top: 0.3, right: 1.0, bottom: 0.7)

If detectionNormalizedRectangle is set to nil(default) the full input image is used for document detection.

You can use imageParametersNormalizedRectangle to specify the region in the input image which will be used to analyze image parameters. For example, if you want to ignore top 35%, left 5%, right 5% and bottom 35% of the input image, you can do it as follows:

let imageParametersNormalizedRectangle = RectangleDouble(left: 0.05, top: 0.35, right: 0.95, bottom: 0.65)

If imageParametersNormalizedRectangle is set to nil(default) the full input image is used to analyze image parameters.

To capture a good quality document image, repeatedly call the process() method using the camera frames:

documentAutoCaptureController.process(bgraRawImage: bgraRawImage)

The controller evaluates the document image requirements for each frame. Once the controller detects enough (minValidFramesInRowToStartCandidateSelection) valid frames in a row, candidate selection is started with duration of candidateSelectionDurationMillis milliseconds. After the candidate selection is finished, the best document image candidate is returned by the delegate and the document auto capture process is over.

In case you want to force the capture event, call the requestCapture() method. After you call the next process() method, the input image will be returned as a result by the delegate and the document auto capture process will be finished.

documentAutoCaptureController.requestCapture();

In case you want to restart the document auto capture process, call the restart() method.

documentAutoCaptureController.restart();

Machine Readable Zone Reader

The MrzReader class provides a Machine Readable Zone (MRZ) reading functionality.

Create MrzReader:

let mrzReader = MrzReader()

To read a MRZ, call the following method on the background thread:

let result = mrzReader.read(bgraRawImage: bgraRawImage, documentDetectorResult: documentDetectorResult)

Or alternatively, if you know the travel document type, call this method to increase the precision of the reading process:

let result = mrzReader.read(bgraRawImage: bgraRawImage, documentDetectorResult: documentDetectorResult, travelDocumentType: travelDocumentType)

The documentDetectorResult argument is a product of either Document Detector component, Document Auto Capture Controller component or Document Auto Capture UI component.

The result of successful MRZ reading contains travel document type and machine readable zone. If MRZ reading was not successful, the result will contain an error and travelDocumentType and/or machineReadableZone may be nil.

UI Components

View Controller Configuration

Components containing UI are embedded into the application as view controllers. All view controllers can be embedded into your own view controller or presented directly. Each view controller can be configured using its *Configuration class and each view controller can have its appearance customized using its *Style class.

To present view controller:

let controller = DocumentAutoCaptureViewController.create(configuration: .init(), style: .init())
controller.delegate = self
navigationController?.pushViewController(controller, animated: true)

To embed view controller into your view controller:

override func viewDidLoad() {
    super.viewDidLoad()

    addChild(viewController)
    view.addSubview(viewController.view)
    viewController.view.translatesAutoresizingMaskIntoConstraints = false
    viewController.didMove(toParent: self)

    NSLayoutConstraint.activate([
        viewController.view.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor),
        viewController.view.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor),
        viewController.view.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
        viewController.view.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor)
    ])
}

Safe Area

DOT iOS Document view controllers ignore safe area layout guide when they layout their subviews. Therefore, for example if you push DOT iOS Document view controller using UINavigationController, you will get incorrect layout. If you want to respect safe area layout guide, you should embed DOT iOS Document view controller in a container view controller and setup the layout constraints accordingly.

Document Auto Capture

The view controller with document placeholder which is used for capturing document images.

The following properties are available in DocumentAutoCaptureConfiguration:

(Optional) [CameraFacing.back] cameraFacing: CameraFacing – Camera facing
- CameraFacing.front
- CameraFacing.back
(Optional) [CameraPreviewScaleType.fit] cameraPreviewScaleType: CameraPreviewScaleType – The camera preview scale type
- CameraPreviewScaleType.fit
(Optional) [CameraPreset.fullHD] cameraPreset: CameraPreset – Camera preset
- CameraPreset.photo
- CameraPreset.hd
- CameraPreset.fullHD
(Optional) [0.6] confidenceThreshold: Double - Document detection confidence threshold in range [0, 1.0].
(Optional) [0.85] sharpnessLowThreshold: Double - Minimal accepted sharpness threshold in range [0, 1.0].
(Optional) [0.25] brightnessLowThreshold: Double - Minimal accepted brightness threshold in range [0, 1.0].
(Optional) [0.9] brightnessHighThreshold: Double - Maximal accepted brightness threshold in range [0, 1.0].
(Optional) [0.008] hotspotsScoreHighThreshold: Double - Maximal accepted hotspots score threshold in range [0, 1.0].
(Optional) [false] isMrzReadingEnabled: Bool - Use this flag to enable MRZ reading during document auto capture process.

The following properties are available in DocumentAutoCaptureStyle:

(Optional) [UIFont.systemFont(ofSize: 17, weight: .bold)] instructionFont: UIFont - Instruction label font.
(Optional) [UIColor.black] instructionTextColor: UIColor - Instruction label text color.
(Optional) [UIColor.black] instructionCapturingTextColor: UIColor - Instruction label text color during capture.
(Optional) [UIColor.white] instructionBackgroundColor: UIColor - Instruction background color.
(Optional) [UIColor.white] instructionCapturingBackgroundColor: UIColor - Instruction background color during capture.
(Optional) [UIColor.black] placeholderColor: UIColor - Placeholder color.
(Optional) [UIColor.green] placeholderCapturingColor: UIColor - Placeholder color during capture.

You can handle the DocumentAutoCaptureViewController events using its delegate DocumentAutoCaptureViewControllerDelegate.

@objc(DOTDocumentAutoCaptureViewControllerDelegate) public protocol DocumentAutoCaptureViewControllerDelegate: AnyObject {

    /// Tells the delegate that the document was captured.
    @objc func documentAutoCaptureViewController(_ viewController: DocumentAutoCaptureViewController, captured result: DocumentAutoCaptureResult)

    /// Tells the delegate that the new detection was processed.
    @objc optional func documentAutoCaptureViewController(_ viewController: DocumentAutoCaptureViewController, detected detection: DocumentAutoCaptureDetection)

    /// Tells the delegate that the candidate selection phase has started.
    @objc optional func documentAutoCaptureViewControllerCandidateSelectionStarted(_ viewController: DocumentAutoCaptureViewController)

    /// Tells the delegate that you have no permission for camera usage.
    @objc optional func documentAutoCaptureViewControllerNoCameraPermission(_ viewController: DocumentAutoCaptureViewController)

    @objc optional func documentAutoCaptureViewControllerViewDidLoad(_ viewController: DocumentAutoCaptureViewController)
    @objc optional func documentAutoCaptureViewControllerViewDidLayoutSubviews(_ viewController: DocumentAutoCaptureViewController)
    @objc optional func documentAutoCaptureViewControllerViewWillAppear(_ viewController: DocumentAutoCaptureViewController)
    @objc optional func documentAutoCaptureViewControllerViewDidAppear(_ viewController: DocumentAutoCaptureViewController)
    @objc optional func documentAutoCaptureViewControllerViewWillDisappear(_ viewController: DocumentAutoCaptureViewController)
    @objc optional func documentAutoCaptureViewControllerViewDidDisappear(_ viewController: DocumentAutoCaptureViewController)
    @objc optional func documentAutoCaptureViewControllerViewWillTransition(_ viewController: DocumentAutoCaptureViewController)
}

In order to start the document auto capture process call the start() method.

In case you want to handle detection data, implement documentAutoCaptureViewController(:detected:) delegate callback. This callback is called with each processed camera frame. There is also documentAutoCaptureViewControllerCandidateSelectionStarted(:) delegate callback, which is called only once during the whole process, when candidate selection is started.

In case you want to force the capture event, call the requestCapture() method.

In case you want to restart the document auto capture process (e.g. you want to capture both sides of the document, one after another), call the restart() method. The whole process will start from the beginning.

Customization of UI Components

Localization

String resources can be overridden in your application and alternative strings for supported languages can be provided following these two steps:

Add your own Localizable.strings file to your project using standard iOS localization mechanism. To change a specific text override corresponding key in this Localizable.strings file.
Set the localization bundle to the bundle of your application (preferably during the application launch in your AppDelegate).

Use this setup if you want to use standard iOS localization mechanism, which means your iOS application uses system defined locale.

import DotDocument

Localization.bundle = .main

Custom Localization

You can override standard iOS localization mechanism by providing your own translation dictionary and setting the Localization.useLocalizationDictionary flag to true. Use this setup if you do not want to use standard iOS localization mechanism, which means your iOS application ignores system defined locale and uses its own custom locale.

import DotDocument

guard let localizableUrl = Bundle.main.url(forResource: "Localizable", withExtension: "strings", subdirectory: nil, localization: "de"),
      let dictionary = NSDictionary(contentsOf: localizableUrl) as? [String: String]
else { return }

Localization.useLocalizationDictionary = true
Localization.localizationDictionary = dictionary

Localizable.strings

"dot.document_auto_capture.instruction.brightness_too_high" = "Less light needed";
"dot.document_auto_capture.instruction.brightness_too_low" = "More light needed";
"dot.document_auto_capture.instruction.candidate_selection" = "Hold still...";
"dot.document_auto_capture.instruction.document_centering" = "Center document";
"dot.document_auto_capture.instruction.document_not_present" = "Scan document";
"dot.document_auto_capture.instruction.document_too_close" = "Move back";
"dot.document_auto_capture.instruction.document_too_far" = "Move closer";
"dot.document_auto_capture.instruction.hotspots_present" = "Avoid reflections";
"dot.document_auto_capture.instruction.mrz_not_valid" = "Scan valid machine readable document";
"dot.document_auto_capture.instruction.sharpness_too_low" = "More light needed";

Common Classes

`ImageSize`

Class which represents a size of an image. To create an instance:

let imageSize = ImageSize(width: 100, height: 100)

`BgraRawImage`

Class which represents an image.

To create an instance from CGImage:

let bgraRawImage = BgraRawImageFactory.create(cgImage: cgImage)

To create CGImage from BgraRawImage:

let cgImage = CGImageFactory.create(bgraRawImage: bgraRawImage)

`Corners`

Class which represents a document card corners. To create an instance:

let corners = Corners(topLeft: topLeft, topRight: topRight, bottomRight: bottomRight, bottomLeft: bottomLeft)

improved DocumentDoesNotFitPlaceholderValidator
DocumentDoesNotFitPlaceholderValidator.detectedToPlaceholderCornersDistanceThreshold to .penaltyThreshold

3.1.0 - 2021-11-04

Added

DocumentAutoCaptureViewControllerDelegate.documentAutoCaptureViewController(_:detected:)
DocumentAutoCaptureViewControllerDelegate.documentAutoCaptureViewControllerCandidateSelectionStarted(_:)