deploy_model_android_4.kt

// Detect faces in the given image and crop them.
// Pass the cropped faces to the AgeDetectionModel
private fun detectFaces(image: Bitmap) {
    val inputImage = InputImage.fromBitmap(image, 0)
    firebaseFaceDetector.process(inputImage)
        .addOnSuccessListener { faces ->
            if ( faces.size != 0 ) {
                progressDialog.apply {
                    dismiss()
                    setMessage( "📍 Posting to server ...")
                    show()
                }
                // Crop the image using the boundingBox predicted by the face detector
                val inputImage = cropToBBox( image , faces[ 0 ].boundingBox )
                activityMainBinding.imageView.setImageBitmap( inputImage )
                // Pass the cropped face to AgeDetectionModel
                ageDetectionModel.pass( inputImage , predictionCallback )
            }
            else {
                // Display a warning to the user
                val dialog = AlertDialog.Builder( this ).apply {
                    title = "No Faces Found"
                    setMessage( "We could not find any faces in the image you just clicked. " +
                            "Try clicking another image or improve the lightning or the device rotation." )
                    setPositiveButton( "OK") { dialog, which ->
                        dialog.dismiss()
                    }
                    setCancelable( false )
                    create()
                }
                dialog.show()
            }
        }
}

// A callback to get the age detection results from the AgeDetectionModel
// This callback is passed to the `AgeDetectionModel.pass` method in `detectFaces()`
private val predictionCallback = object : AgeDetectionModel.PredictionCallback {
    override fun onError(error: String) {
        runOnUiThread {
            progressDialog.dismiss()
            val dialog = AlertDialog.Builder( this@MainActivity ).apply {
                title = "An error unoccured"
                setMessage( error )
                setPositiveButton( "OK") { dialog, which ->
                    dialog.dismiss()
                }
                setCancelable( false )
                create()
            }
            dialog.show()
        }
    }

    override fun onResult(age: Int) {
        runOnUiThread {
            progressDialog.dismiss()
            val dialog = AlertDialog.Builder( this@MainActivity ).apply {
                title = "Result"
                setMessage( "The result is $age years" )
                setPositiveButton( "OK") { dialog, which ->
                    dialog.dismiss()
                }
                setCancelable( false )
                create()
            }
            dialog.show()
        }
    }
}

// Crop the given image using bbox
private fun cropToBBox(image: Bitmap, bbox: Rect) : Bitmap {
    return Bitmap.createBitmap(
        image,
        bbox.left - 0,
        bbox.top,
        bbox.width() ,
        bbox.height()
    )
}