Scan the QR code on an Android phone.

Priyanka Kumari

30 January 2024

Use to Scan the QR code on an Android phone (abbreviated from Quick Response code) is a type of matrix barcode (or two-dimensional barcode).

QR codes often contain data for a locator, identifier, or tracker that points to a website or application. This means we can scan multiple barcodes, QR Codes, and faces together. Be it with Scan the QR code on an Android phone is video, a picture, or a video stream. But covering all of this in a single article is not possible.
It uses four standardized encoding modes (numeric, alphanumeric, byte/binary, and kanji) to store data efficiently; extensions may also be used. It consists of black squares arranged in a square grid on a white background, which can be read by an imaging device such as a camera.

You can find out more about the Flutter app development services page.

At the very first, We have to add the Google Play Services Integration in our app and add the GMS services dependency in build.gradle

dependencies {
   compile 'com.google.android.gms:play-services-vision:11.4.0'
}

dependencies {

compile 'com.google.android.gms:play-services-vision:11.4.0'

}

And at the global build.gradle must have

allprojects {
    repositories {
        jcenter()
        maven {
            url "https://maven.google.com"
        }
    }
}

allprojects {

repositories {

jcenter()

maven {

url "https://maven.google.com"

}

Before installation, Scan the QR Code to make Mobile Vision APIs functional and add the metadata tag inside the Manifest file

<meta-data
            android:name="com.google.android.gms.vision.DEPENDENCIES"
            android:value="barcode"/>

<meta-data

android:name="com.google.android.gms.vision.DEPENDENCIES"

android:value="barcode"/>

Also, add the uses permission and uses feature inside the Manifest file

<uses-feature
        android:name="android.hardware.camera"
        android:required="true"/>
    <uses-permission
        android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

<uses-feature

android:name="android.hardware.camera"

android:required="true"/>

<uses-permission

android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

Now, Make the xml file for show the QR scan code

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".barcbarode.BarCodeActivity">
        <ImageView
            android:id="@+id/img_launcher"
            android:layout_width="150dp"
            android:layout_height="150dp"
            android:layout_marginTop="100dp"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            android:src="@mipmap/ic_launcher_round"/>
        <TextView
            android:id="@+id/text_scanner_result"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="50dp"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toBottomOf="@id/img_launcher"
            android:text="Scanner Results:"
            android:textStyle="bold"/>
        <TextView
            android:id="@+id/text_scan_value"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:layout_constraintStart_toStartOf="parent" 
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toBottomOf="@id/text_scanner_result"
            android:layout_marginTop="10dp"/>
        <Button
            android:id="@+id/button_scan"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            android:layout_marginBottom="80dp"
            android:layout_marginTop="20dp"
            android:text="Scan"/>
    
</androidx.constraintlayout.widget.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:app="http://schemas.android.com/apk/res-auto"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

tools:context=".barcbarode.BarCodeActivity">

<ImageView

android:id="@+id/img_launcher"

android:layout_width="150dp"

android:layout_height="150dp"

android:layout_marginTop="100dp"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintTop_toTopOf="parent"

android:src="@mipmap/ic_launcher_round"/>

<TextView

android:id="@+id/text_scanner_result"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_marginTop="50dp"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintTop_toBottomOf="@id/img_launcher"

android:text="Scanner Results:"

android:textStyle="bold"/>

<TextView

android:id="@+id/text_scan_value"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintTop_toBottomOf="@id/text_scanner_result"

android:layout_marginTop="10dp"/>

<Button

android:id="@+id/button_scan"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintBottom_toBottomOf="parent"

android:layout_marginBottom="80dp"

android:layout_marginTop="20dp"

android:text="Scan"/>

</androidx.constraintlayout.widget.ConstraintLayout>

Now, the BarCodeActivity code is given below:

For more understanding please go through these links:

https://mobikul.com/swift-qr-code-scanner-generator/

class BarCodeActivity : AppCompatActivity() {
    private val LOG_TAG = "Barcode Scanning"
    private val PHOTO_REQUEST = 10
    private var detector: BarcodeDetector? = null
    private var imageUri: Uri? = null
    private val REQUEST_WRITE_PERMISSION = 20
    private val SAVED_INSTANCE_URI = "uri"
    private val SAVED_INSTANCE_RESULT = "result"
    var activityBarCodeBinding: ActivityBarCodeBinding?=null
    

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        activityBarCodeBinding = DataBindingUtil.setContentView(this,R.layout.activity_bar_code)

        setBarCode(savedInstanceState)
    }

    private fun setBarCode(savedInstanceState: Bundle?){
        if (savedInstanceState != null) {
            imageUri = Uri.parse(savedInstanceState.getString(SAVED_INSTANCE_URI))
            activityBarCodeBinding?.textScannerResult?.text = savedInstanceState.getString(SAVED_INSTANCE_RESULT)
        }
        activityBarCodeBinding?.buttonScan?.setOnClickListener({
            ActivityCompat.requestPermissions(
                applicationContext as Activity,
                arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE),
                REQUEST_WRITE_PERMISSION
            )
        })
        detector = BarcodeDetector.Builder(applicationContext)
            .setBarcodeFormats(Barcode.DATA_MATRIX or Barcode.QR_CODE)
            .build()
        if (!detector!!.isOperational) {
            activityBarCodeBinding?.textScannerResult?.text = "Could not set up the detector!"
            return
        }
    }

    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<String?>,
        grantResults: IntArray
    ) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        when (requestCode) {
            REQUEST_WRITE_PERMISSION -> if (grantResults.size > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                takePicture()
            } else {
                Toast.makeText(this@BarCodeActivity, "Permission Denied!", Toast.LENGTH_SHORT).show()
            }
        }
    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        if (requestCode == PHOTO_REQUEST && resultCode == RESULT_OK) {
            launchMediaScanIntent()
            try {
                val bitmap = decodeBitmapUri(this, imageUri!!)
                if (detector!!.isOperational && bitmap != null) {
                    val frame: Frame = Frame.Builder().setBitmap(bitmap).build()
                    val barcodes = detector!!.detect(frame)
                    for (index in 0 until barcodes.size()) {
                        val code = barcodes.valueAt(index)
                        activityBarCodeBinding?.textScannerResult?.text = activityBarCodeBinding?.textScannerResult?.text.toString() + code.displayValue + "\n"
                        //Required only if you need to extract the type of barcode
                        val type = barcodes.valueAt(index).valueFormat
                        when (type) {
                            Barcode.CONTACT_INFO -> Log.i(LOG_TAG, code.contactInfo.title)
                            Barcode.EMAIL -> Log.i(LOG_TAG, code.email.address)
                            Barcode.ISBN -> Log.i(LOG_TAG, code.rawValue)
                            Barcode.PHONE -> Log.i(LOG_TAG, code.phone.number)
                            Barcode.PRODUCT -> Log.i(LOG_TAG, code.rawValue)
                            Barcode.SMS -> Log.i(LOG_TAG, code.sms.message)
                            Barcode.TEXT -> Log.i(LOG_TAG, code.rawValue)
                            Barcode.URL -> Log.i(LOG_TAG, "url: " + code.url.url)
                            Barcode.WIFI -> Log.i(LOG_TAG, code.wifi.ssid)
                            Barcode.GEO -> Log.i(
                                LOG_TAG,
                                code.geoPoint.lat.toString() + ":" + code.geoPoint.lng
                            )
                            Barcode.CALENDAR_EVENT -> Log.i(LOG_TAG, code.calendarEvent.description)
                            Barcode.DRIVER_LICENSE -> Log.i(
                                LOG_TAG,
                                code.driverLicense.licenseNumber
                            )
                            else -> Log.i(LOG_TAG, code.rawValue)
                        }
                    }
                    if (barcodes.size() == 0) {
                        activityBarCodeBinding?.textScannerResult?.text = "Scan Failed: Found nothing to scan"
                    }
                } else {
                    activityBarCodeBinding?.textScannerResult?.text = "Could not set up the detector!"
                }
            } catch (e: Exception) {
                Toast.makeText(this, "Failed to load Image", Toast.LENGTH_SHORT)
                    .show()
                Log.e(LOG_TAG, e.toString())
            }
        }
    }

    private fun takePicture() {
        val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
        val photo = File(Environment.getExternalStorageDirectory(), "picture.jpg")
        imageUri = FileProvider.getUriForFile(
            this@BarCodeActivity,
            BuildConfig.APPLICATION_ID.toString() + ".provider",
            photo
        )
        intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri)
        startActivityForResult(intent, PHOTO_REQUEST)
    }

    override fun onSaveInstanceState(outState: Bundle) {
        if (imageUri != null) {
            outState.putString(SAVED_INSTANCE_URI, imageUri.toString())
            outState.putString(SAVED_INSTANCE_RESULT, activityBarCodeBinding?.textScannerResult?.text.toString())
        }
        super.onSaveInstanceState(outState)
    }

    private fun launchMediaScanIntent() {
        val mediaScanIntent = Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE)
        mediaScanIntent.data = imageUri
        this.sendBroadcast(mediaScanIntent)
    }

    @Throws(FileNotFoundException::class)
    private fun decodeBitmapUri(ctx: Context, uri: Uri): Bitmap? {
        val targetW = 600
        val targetH = 600
        val bmOptions = BitmapFactory.Options()
        bmOptions.inJustDecodeBounds = true
        BitmapFactory.decodeStream(ctx.getContentResolver().openInputStream(uri), null, bmOptions)
        val photoW = bmOptions.outWidth
        val photoH = bmOptions.outHeight
        val scaleFactor = Math.min(photoW / targetW, photoH / targetH)
        bmOptions.inJustDecodeBounds = false
        bmOptions.inSampleSize = scaleFactor
        return BitmapFactory.decodeStream(
            ctx.getContentResolver()
                .openInputStream(uri), null, bmOptions
        )
    }
}

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class BarCodeActivity : AppCompatActivity() {

private val LOG_TAG = "Barcode Scanning"

private val PHOTO_REQUEST = 10

private var detector: BarcodeDetector? = null

private var imageUri: Uri? = null

private val REQUEST_WRITE_PERMISSION = 20

private val SAVED_INSTANCE_URI = "uri"

private val SAVED_INSTANCE_RESULT = "result"

var activityBarCodeBinding: ActivityBarCodeBinding?=null

override fun onCreate(savedInstanceState: Bundle?) {

super.onCreate(savedInstanceState)

activityBarCodeBinding = DataBindingUtil.setContentView(this,R.layout.activity_bar_code)

setBarCode(savedInstanceState)

}

private fun setBarCode(savedInstanceState: Bundle?){

if (savedInstanceState != null) {

imageUri = Uri.parse(savedInstanceState.getString(SAVED_INSTANCE_URI))

activityBarCodeBinding?.textScannerResult?.text = savedInstanceState.getString(SAVED_INSTANCE_RESULT)

}

activityBarCodeBinding?.buttonScan?.setOnClickListener({

ActivityCompat.requestPermissions(

applicationContext as Activity,

arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE),

REQUEST_WRITE_PERMISSION

)

})

detector = BarcodeDetector.Builder(applicationContext)

.setBarcodeFormats(Barcode.DATA_MATRIX or Barcode.QR_CODE)

.build()

if (!detector!!.isOperational) {

activityBarCodeBinding?.textScannerResult?.text = "Could not set up the detector!"

return

}

override fun onRequestPermissionsResult(

requestCode: Int,

permissions: Array<String?>,

grantResults: IntArray

) {

super.onRequestPermissionsResult(requestCode, permissions, grantResults)

when (requestCode) {

REQUEST_WRITE_PERMISSION -> if (grantResults.size > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

takePicture()

} else {

Toast.makeText(this@BarCodeActivity, "Permission Denied!", Toast.LENGTH_SHORT).show()

}

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {

super.onActivityResult(requestCode, resultCode, data)

if (requestCode == PHOTO_REQUEST && resultCode == RESULT_OK) {

launchMediaScanIntent()

try {

val bitmap = decodeBitmapUri(this, imageUri!!)

if (detector!!.isOperational && bitmap != null) {

val frame: Frame = Frame.Builder().setBitmap(bitmap).build()

val barcodes = detector!!.detect(frame)

for (index in 0 until barcodes.size()) {

val code = barcodes.valueAt(index)

activityBarCodeBinding?.textScannerResult?.text = activityBarCodeBinding?.textScannerResult?.text.toString() + code.displayValue + "\n"

//Required only if you need to extract the type of barcode

val type = barcodes.valueAt(index).valueFormat

when (type) {

Barcode.CONTACT_INFO -> Log.i(LOG_TAG, code.contactInfo.title)

Barcode.EMAIL -> Log.i(LOG_TAG, code.email.address)

Barcode.ISBN -> Log.i(LOG_TAG, code.rawValue)

Barcode.PHONE -> Log.i(LOG_TAG, code.phone.number)

Barcode.PRODUCT -> Log.i(LOG_TAG, code.rawValue)

Barcode.SMS -> Log.i(LOG_TAG, code.sms.message)

Barcode.TEXT -> Log.i(LOG_TAG, code.rawValue)

Barcode.URL -> Log.i(LOG_TAG, "url: " + code.url.url)

Barcode.WIFI -> Log.i(LOG_TAG, code.wifi.ssid)

Barcode.GEO -> Log.i(

LOG_TAG,

code.geoPoint.lat.toString() + ":" + code.geoPoint.lng

)

Barcode.CALENDAR_EVENT -> Log.i(LOG_TAG, code.calendarEvent.description)

Barcode.DRIVER_LICENSE -> Log.i(

LOG_TAG,

code.driverLicense.licenseNumber

)

else -> Log.i(LOG_TAG, code.rawValue)

}

if (barcodes.size() == 0) {

activityBarCodeBinding?.textScannerResult?.text = "Scan Failed: Found nothing to scan"

}

} else {

activityBarCodeBinding?.textScannerResult?.text = "Could not set up the detector!"

}

} catch (e: Exception) {

Toast.makeText(this, "Failed to load Image", Toast.LENGTH_SHORT)

.show()

Log.e(LOG_TAG, e.toString())

}

private fun takePicture() {

val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)

val photo = File(Environment.getExternalStorageDirectory(), "picture.jpg")

imageUri = FileProvider.getUriForFile(

this@BarCodeActivity,

BuildConfig.APPLICATION_ID.toString() + ".provider",

photo

)

intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri)

startActivityForResult(intent, PHOTO_REQUEST)

}

override fun onSaveInstanceState(outState: Bundle) {

if (imageUri != null) {

outState.putString(SAVED_INSTANCE_URI, imageUri.toString())

outState.putString(SAVED_INSTANCE_RESULT, activityBarCodeBinding?.textScannerResult?.text.toString())

}

super.onSaveInstanceState(outState)

}

private fun launchMediaScanIntent() {

val mediaScanIntent = Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE)

mediaScanIntent.data = imageUri

this.sendBroadcast(mediaScanIntent)

}

@Throws(FileNotFoundException::class)

private fun decodeBitmapUri(ctx: Context, uri: Uri): Bitmap? {

val targetW = 600

val targetH = 600

val bmOptions = BitmapFactory.Options()

bmOptions.inJustDecodeBounds = true

BitmapFactory.decodeStream(ctx.getContentResolver().openInputStream(uri), null, bmOptions)

val photoW = bmOptions.outWidth

val photoH = bmOptions.outHeight

val scaleFactor = Math.min(photoW / targetW, photoH / targetH)

bmOptions.inJustDecodeBounds = false

bmOptions.inSampleSize = scaleFactor

return BitmapFactory.decodeStream(

ctx.getContentResolver()

.openInputStream(uri), null, bmOptions

)

}

You can also check this link: https://developers.google.com/vision/android/barcodes-overview

Conclusion:

In this post, you learned that it shows the bar code text after scanning the bar code using the Mobile Vision APIs. It reads the data, as well as understands what type of data it is.