DOT Android Document library

v7.1.0

Introduction

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

Requirements

DOT Android Document has the following requirements:

Minimum Android API level 21
Minimum Kotlin Gradle plugin version 1.6.0 (if used)

Distribution

Maven Repository

DOT Android Document is distributed as an Android library (.aar package) stored in the Innovatrics maven repository.

In order to integrate DOT Android Document into your project, the first step is to include the Innovatrics maven repository and Google repository to your top level build.gradle file.

build.gradle

allprojects {
    repositories {
        maven {
            url 'https://maven.innovatrics.com/releases'
        }
    }
}

Then, specify the dependency on DOT Android Document library in the module’s build.gradle file. Dependencies of this library will be downloaded alongside the library.

build.gradle

dependencies {
    //…
    implementation "com.innovatrics.dot:dot-document:$dotVersion"
    //…
}

Supported Architectures

DOT Android Document provides binaries for these architectures:

armeabi-v7a
arm64-v8a
x86
x86_64

If your target application format is APK and not Android App Bundle, and the APK splits are not specified, the generated APK file will contain binaries for all available architectures. Therefore we recommend to use APK splits. For example, to generate arm64-v8a APK, add the following section into your module build.gradle:

build.gradle

splits {
    abi {
        enable true
        reset()
        include 'arm64-v8a'
        universalApk false
    }
}

If you do not specify this section, the resulting application can become too large in size.

Licensing

In order to use DOT SDK in other apps, it must be licensed. The license can be compiled into the application as it is bound to the application ID specified in build.gradle:

build.gradle

defaultConfig {
    applicationId "com.innovatrics.dot.sample"
    //…
}

The application ID can be also retrieved in runtime by calling DotSdk.getApplicationId().

In order to obtain the license, please contact your Innovatrics’ representative specifying the application ID. If the application uses build flavors with different application IDs, each flavor must contain a separate license. Put the license file into the raw resource folder.

Permissions

DOT Android Document declares the following permission in AndroidManifest.xml:

AndroidManifest.xml

<uses-permission android:name="android.permission.CAMERA" />

Basic Setup

Initialization

Before using any of the components, you need to initialize DOT SDK with the license and DotDocumentLibrary object.

InitializeDotSdkUseCase class in the Samples project shows how to initialize DOT SDK with DotDocumentLibrary. DotSdk.initialize() method should be called on background thread.

Keep in mind that if you try to use any component without initialization, it will throw an exception.

Deinitialization

When a process (e.g. onboarding) using the DOT Android Document has been completed, it is usually a good practice to free the resources used by it.

You can perform this by calling DotSdk.deinitialize(). If you want to use the DOT Android Document components again after that point, you need to call DotSdk.initialize() again. This shouldn’t be performed within the lifecycle of individual Android components.

Logging

Although logging is disabled by default, it can be enabled explicitly by using the following method from the com.innovatrics.dot.core.Logger class.

Logger.setLoggingEnabled(true);

The appropriate place for this call is within the onCreate() method of your subclass of android.app.Application. Each TAG of a log message starts with the prefix dot-document:.

This setting enables logging for all DOT Android libraries.

Keep in mind that logging should be used just for debug purposes as it might produce a lot of log messages.

Components

Overview

DOT Android 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 Android Document functionality. UI components are build on top of non-UI components. These are available as abstract fragments and can be extended and then embedded into the application’s existing activity providing more control.

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 perspective warping an image according detected document card corners.
DOCUMENT AUTO CAPTURE CONTROLLER: A component for capturing good quality images suitable for optical character recognition.
MACHINE READABLE ZONE READER: A component for reading Machine Readable Zone (MRZ).

List of UI Components

DOCUMENT AUTO CAPTURE: A visual component for capturing good quality images suitable for optical character recognition.

Non-UI Components

Document Detector

The DocumentDetector interface provides a document detection functionality.

Create a DocumentDetector:

DocumentDetector documentDetector = DocumentDetectorFactory.create();

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

DocumentDetector.Result result = documentDetector.detect(bgraRawImage);

Image Parameters Analyzer

The ImageParametersAnalyzer interface provides an image parameters analysis functionality.

Create ImageParametersAnalyzer:

ImageParametersAnalyzer imageParametersAnalyzer = ImageParametersAnalyzerFactory.create();

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

ImageParameters imageParameters = imageParametersAnalyzer.analyze(bgraRawImage);

Image Perspective Warper

The ImagePerspectiveWarper interface provides perspective warping functionality.

Create ImagePerspectiveWarper:

ImagePerspectiveWarper imagePerspectiveWarper = ImagePerspectiveWarperFactory.create();

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

BgraRawImage warpedBgraRawImage = imagePerspectiveWarper.warp(bgraRawImage, corners, targetImageSize);

Document Auto Capture Controller

The DocumentAutoCaptureController interface provides a stateful document auto capture functionality.

Create DocumentAutoCaptureController:

DocumentAutoCaptureControllerConfiguration configuration = new DocumentAutoCaptureControllerConfiguration.Builder(context, validators)
    .minValidFramesInRowToStartCandidateSelection(minValidFramesInRowToStartCandidateSelection)
    .detectionNormalizedRectangle(detectionNormalizedRectangle)
    .imageParametersNormalizedRectangle(imageParametersNormalizedRectangle)
    .build();
DocumentAutoCaptureController documentAutoCaptureController = DocumentAutoCaptureControllerFactory.create(configuration);

`DocumentAutoCaptureControllerConfiguration.Builder` arguments

(Required) [-] Context context - Android context.
(Required) [-] List<DocumentAutoCaptureDetectionValidator> validators - List of validators. Validations are applied in the same order in which they are stored in the list.
(Optional) [2] int minValidFramesInRowToStartCandidateSelection - Minimum number of valid frames in a row to start candidate selection.
(Optional) [1000] int candidateSelectionDurationMillis - Duration of candidate selection in milliseconds.
(Optional) [-] RectangleDouble detectionNormalizedRectangle - Crop an input image to normalized detection rectangle and use that for document detection.
(Optional) [-] RectangleDouble imageParametersNormalizedRectangle - Crop an input image to normalized image parameters rectangle and use that to analyze image parameters.
(Optional) [false] boolean mrzReadingEnabled - If Machine Readable Zone reading is enabled.

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:

RectangleDouble detectionNormalizedRectangle = RectangleDouble.of(0.0d, 0.3d, 1.0d, 0.7d);

If detectionNormalizedRectangle is not specified, the source 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:

RectangleDouble imageParametersNormalizedRectangle = RectangleDouble.of(0.05d, 0.35d, 0.95d, 0.65d);

If imageParametersNormalizedRectangle is not specified, the source 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.ProcessingResult processingResult = documentAutoCaptureController.process(bgraRawImage, timestampMillis);

The controller evaluates the image requirements for each frame. Once there are 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 and the document auto capture process is over.

Machine Readable Zone Reader

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

Create MrzReader:

MrzReaderConfiguration configuration = new MrzReaderConfiguration.Builder(context).build();
MrzReader mrzReader = MrzReaderFactory.create(configuration);

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

MrzReader.Result result = mrzReader.read(bgraRawImage, documentDetectorResult);

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

MrzReader.Result result = mrzReader.read(bgraRawImage, documentDetectorResult, travelDocumentType);

Argument documentDetectorResult 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 exception and travelDocumentType and/or machineReadableZone may be null.

UI Components

Fragment Configuration

Components containing UI are embedded into the application as fragments from Android Support Library. All fragments are abstract. They must be subclassed and override their abstract methods.

Fragments requiring runtime interaction provide public methods, for example start().

public class DemoDocumentAutoCaptureFragment extends DocumentAutoCaptureFragment {

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        start();
    }

    …
}

For configuration not intended to be changed in runtime, fragment arguments are available.

DocumentAutoCaptureConfiguration documentAutoCaptureConfiguration = new DocumentAutoCaptureConfiguration.Builder().build();

Bundle arguments = new Bundle();
arguments.putSerializable(DocumentAutoCaptureFragment.CONFIGURATION, documentAutoCaptureConfiguration);

Fragment fragment = new DemoDocumentAutoCaptureFragment();
fragment.setArguments(arguments);

getSupportFragmentManager()
        .beginTransaction()
        .replace(android.R.id.content, fragment)
        .commit();

Configuration parameters are wrapped by the *Configuration data class and you must put them as a Serializable under the CONFIGURATION key to the fragment.

Builder.build() method throws IllegalArgumentException if any of the arguments is not valid. Keep in mind to handle the exception.

Camera permission

A fragment (UI component) will check the camera permission (Manifest.permission.CAMERA) right before the camera is started. If the camera permission is granted the fragment will start the camera. If the camera permission is not granted the fragment will use Android API - ActivityResultContracts.RequestPermission to request the camera permission. Android OS will present the system dialog to the user of the app. If the user explicitly denies the permission at this point, onNoCameraPermission() callback is called. Implement this callback in order to navigate the user further in your app workflow.

Orientation Change

In order to handle the orientation change in multi-window mode correctly, configure the activity in your AndroidManifest.xml file as follows:

<activity
    android:name=".MyActivity"
    android:configChanges="screenSize|smallestScreenSize|screenLayout|orientation" />

Document Auto Capture

The fragment with instructions for obtaining quality document images suitable for further processing.

In order to configure the behaviour of DocumentAutoCaptureFragment, use DocumentAutoCaptureConfiguration (see Fragment Configuration).

To use the fragment, create a subclass of DocumentAutoCaptureFragment and override appropriate callbacks.

To start the document auto capture process call the start() method. You can start the process any time.

In case you want to handle detection data, implement onProcessed() callback. This callback is called with each processed camera frame. The callback onCandidateSelectionStarted() is called only once for the whole process, when candidate selection is started. When the document auto capture process finishes successfully, the result will be returned via the onCaptured() callback.

In case you want to force the capture event, call the requestCapture() method. The most recent image will be returned via the onCaptured() callback asynchronously.

Call start() method again in case you need to start over the document auto capture process (e.g. you want to capture both sides of the document, one after another). You can also call start() method to stop and start over ongoing process as well.

In case you want to stop the document auto capture process prematurely, call the stopAsync() method. The onStopped() callback indicates that the processing is over.

Customization of UI components

Strings

You can override the string resources in your application and provide alternative strings for supported languages using the standard Android localization mechanism.

<string name="dot_document_auto_capture_instruction_brightness_too_high">Less light needed</string>
<string name="dot_document_auto_capture_instruction_brightness_too_low">More light needed</string>
<string name="dot_document_auto_capture_instruction_candidate_selection">Hold still…</string>
<string name="dot_document_auto_capture_instruction_document_does_not_fit_placeholder">Center document</string>
<string name="dot_document_auto_capture_instruction_document_not_detected">Scan document</string>
<string name="dot_document_auto_capture_instruction_document_out_of_bounds">Center document</string>
<string name="dot_document_auto_capture_instruction_hotspots_score_too_high">Avoid reflections</string>
<string name="dot_document_auto_capture_instruction_mrz_not_valid">Scan valid machine readable document</string>
<string name="dot_document_auto_capture_instruction_sharpness_too_low">More light needed</string>
<string name="dot_document_auto_capture_instruction_size_too_small">Move closer</string>

Colors

You may customize the colors used by DOT Android Document in your application. To use custom colors, override the specific color.

<color name="dot_detection_layer">#ffffffff</color>
<color name="dot_instruction_background">#fff8fbfb</color>
<color name="dot_instruction_candidate_selection_background">#ff00bfb2</color>
<color name="dot_instruction_text">#ff131313</color>
<color name="dot_placeholder">#ffffffff</color>
<color name="dot_placeholder_candidate_selection">#ff00bfb2</color>
<color name="dot_placeholder_overlay">#80131313</color>

Styles

Text views and buttons can be styled by overriding the parent style in the application.

<style name="TextAppearance.Dot.Medium" parent="TextAppearance.AppCompat.Medium" />
<style name="TextAppearance.Dot.Medium.Instruction" />

Common Classes

`ImageSize`

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

ImageSize imageSize = ImageSize.of(width, height);

`BgraRawImage`

DTO which represents and an image. To create an instance:

BgraRawImage bgraRawImage = BgraRawImage.of(size, bytes);

To create an instance from Bitmap:

BgraRawImage bgraRawImage = BgraRawImageFactory.create(bitmap);

`Corners`

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

Corners corners = Corners.of(topLeft, topRight, bottomRight, bottomLeft);

Property DocumentAutoCaptureDetection.imageParameters.
Property DocumentAutoCaptureResult.imageParameters.

7.0.2 - 2023-12-05

Technical release. No changes.

7.0.1 - 2023-11-21

Technical release. No changes.

7.0.0 - 2023-11-02

Added

Class DotSdk.
Class DotSdkConfiguration.
Interface DotLibrary.
License file is required. To obtain one, please contact support@innovatrics.com.

Changed

Class DotDocumentLibrary reworked.
Machine Readable Zone reading accuracy is improved.

DOT Android Document library

v7.1.0#

v7.1.0