View
Integration of MobaiBiometric View with plain camera feed
This example shows how to integrate the Biometric Capture Session to your project. The Biometric Capture Session extracts a frames collection from the camera preview.
This Example app uses ViewBinding
, so enable it with the following (at the end of the android{}
block):
buildFeatures {
viewBinding true
}
When prompted, click Sync Now, and we will be ready to use the Biometric Capture Session in our app.
Create a capture layout.
In the UI for this example app, we use the following layout structure:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".CaptureFragment">
<LinearLayout
android:id="@+id/ll_capture_session_view_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" />
<Button
android:id="@+id/btn_start_capture"
android:layout_width="170dp"
android:layout_height="50dp"
android:layout_gravity="center"
android:layout_marginTop="300dp"
android:textColor="#DBD7E4"
android:background="@color/colorPrimary"
android:visibility="gone"/>
</FrameLayout>
This LinealLayout hosts MBCaptureSessionView
.
<LinearLayout
android:id="@+id/ll_capture_session_view_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" />
The capture button is enabled when the capture process is not automatic.
<Button
android:id="@+id/btn_start_capture"
android:layout_width="170dp"
android:layout_height="50dp"
android:layout_gravity="center"
android:layout_marginTop="300dp"
android:textColor="#DBD7E4"
android:background="@color/colorPrimary"
android:visibility="gone"/>
Setup CaptureFragment.kt.
CaptureFragment
is the host element for the camera preview. And extends from MBCaptureSessionServiceListener.
class CaptureFragment : Fragment(R.layout.fragment_capture), MBCaptureSessionServiceListener {
private var captureSessionService: MBCaptureSessionService? = null
private lateinit var mBinding : FragmentCaptureBinding
@SuppressLint("UnsafeOptInUsageError")
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
mBinding = FragmentCaptureBinding.inflate(inflater,container,false)
val options = MBCaptureSessionOptions.Builder().build()
captureSessionService = MBCaptureSessionService(requireContext(), this, options, this)
mBinding.container.addView(captureSessionService!!.getCaptureSessionView())
captureSessionService!!.startCamera()
if (!captureSessionService!!.getAutomaticCapture()) {
mBinding.btnStartCapture.visibility = View.VISIBLE
mBinding.btnStartCapture.setOnClickListener {
captureSessionService!!.startCaptureSession()
}
}
return mBinding.root
}
override fun onCaptureFinished(result: MBCaptureSessionResult?){ }
override fun onCountdown(timeCounter: Int) { }
override fun onValidating(faceStatus: MBFaceStatus) { }
override fun onFailure(errorEnum: MBCaptureSessionError) { }
override fun onCaptureStarted() { }
}
Creates a CaptureFragment
viewBinding instance:
private lateinit var mBinding : FragmentCaptureBinding
Create MBCaptureSessionService
.This is the communication bridge between the caller and the biometric features.
private var captureSessionService: MBCaptureSessionService? = null
onCreateView
method execution.
@SuppressLint("UnsafeOptInUsageError")
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
mBinding = FragmentCaptureBinding.inflate(inflater,container,false)
val options = MBCaptureSessionOptions.Builder().build()
captureSessionService = MBCaptureSessionService(requireContext(), this, options, this)
mBinding.container.addView(captureSessionService!!.getCaptureSessionView())
captureSessionService!!.startCamera()
if (!captureSessionService!!.getAutomaticCapture()) {
mBinding.btnStartCapture.visibility = View.VISIBLE
mBinding.btnStartCapture.setOnClickListener {
captureSessionService!!.startCaptureSession()
}
}
return mBinding.root
}
Create an instance of MBCaptureSessionOptions
builder. This is the capture session's entry point configuration and it has its own default values . In this case the automaticCapture
is set to false and that means the capture is manual.
val options = MBCaptureSessionOptions.Builder().build()
MBCaptureSessionOption.Builder
arguments description:
numberOfFrameToCollect
Describes the number of frames to collect during the capture session.frameInterval
After collecting the first frame, is the number of frames to skip before collecting a frame.numberOfFramesBeforeCapture
Describes the number of frames to skip before it starts collecting.automaticCapture
Tells whether the capture is automatic or manualtargetResolution
Are the resolution values from the caller device.timeBeforeAutomaticCapture
Is the set time in seconds the capture should wait to start collecting frames.cameraSelector
Describes whether we want to use a front or rear camera.
MBCaptureSessionInstance
initialization.
captureSessionService = MBCaptureSessionService(requireContext(), this, options, this, null)
MBCaptureSessionService
arguments.
context
Is an instance of the caller's context needed to implement MBCameraService and MBCaptureSessionView.lifecycleOwner
Is an instance of the caller's life cycle owner needed to implement MBCameraService.options
Represents the capture session's entry point configuration for ist correct functioning.callback
Updates the caller with any change during the whole capture process, including a capture result, it has to be set to null while implementing MBCaptureSessionFragment.
Adds the CaptureSessionView as view child to CaptureFragment
.
mBinding.llCaptureSessionViewContainer.addView(captureSessionService!!.getCaptureSessionView())
Starts Camera if camera permission is granted. It is very important to verify the camera permission to get the feature up running.
captureSessionService!!.startCamera()
This block of code enables the capture button if automaticCapture is set to false mining the capture process is manual, or disables it if the automaticCapture is set to true.
if (!captureSessionService!!.getAutomaticCapture()) {
mBinding.btnStartCapture.visibility = View.VISIBLE
mBinding.btnStartCapture.setOnClickListener {
captureSessionService!!.startCaptureSession()
}
}
The function onCaptureFinished
gets a result of the capture process if it is successfully finished. result contains a list of nullable Bitmaps. In this case send it as an argument to another screen by using ViewModel and LiveData. And then I start another activity.
override fun onCaptureFinished(result: MBCaptureSessionResult?){ }
onCaptureFinished
is executed for MBCaptureSessionService
when the capture session has successfully finished. MBCaptureSessionResult
arguments:
faceImage
A high quality image captured after collecting frames (not implemented).captureSessionData
Is all the collected data in protobuf format (not implemented).frames
Is the frame collection.
Function onFailure
is executed when the capture process fails. MBCaptureSessionError
tells the type of error that occurred.
override fun onFailure(errorEnum: MBCaptureSessionError) { }
MBCaptureSessionError
entries:
UNABLE_TO_OPEN_CAMERA
Describes failure while opening the cameraUNABLE_TO_COLLECT_FRAMES
The capture has is aborted
Function onValidating
is executed when frames are being analyzed.
override fun onValidating(faceStatus: MBFaceStatus) { }
MBFaceStatus
entries:
TOO_FAR_AWAY
Face is too far awayTOO_CLOSE
Face is too closeTOO_FAR_UP
Face is too far upTOO_FAR_LEFT
Face is too far leftTOO_FAR_DOWN
Face is too far downTOO_FAR_RIGHT
Face is too far rightNOT_FOUND
Face not foundTOO_MANY
Too many facesVALID
Face is valid
Function onCountdown
is executed during the automatic capture. timeCounter
is the current time in seconds.
override fun onCountdown(timeCounter: Int) { }
The method onCaptureStarted
is executed every time a face is valid and starts capturing.
override fun onCaptureStarted() { }