TensorFlow - Hot or Not example. Taking a photo.

MainActivity.kt

private const val REQUEST_PERMISSIONS = 1
private const val REQUEST_TAKE_PICTURE = 2

class MainActivity : AppCompatActivity() {

    private var photoFilePath = ""

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        checkPermissions()
    }

    private fun checkPermissions() {
        if (arePermissionAlreadyGranted()) {
            takePhoto()
        } else {
            requestPermissions()
        }
    }

    private fun arePermissionAlreadyGranted() =
            ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED

    private fun requestPermissions() {
        ActivityCompat.requestPermissions(this,
                arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE),
                REQUEST_PERMISSIONS)
    }

    private fun takePhoto() {
        photoFilePath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).absolutePath + "/${System.currentTimeMillis()}.jpg"
        val currentPhotoUri = UriHelper.getUriFromFilePath(this, photoFilePath)

        val takePictureIntent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
        takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, currentPhotoUri)
        takePictureIntent.flags = Intent.FLAG_GRANT_READ_URI_PERMISSION

        if (takePictureIntent.resolveActivity(packageManager) != null) {
            startActivityForResult(takePictureIntent, REQUEST_TAKE_PICTURE)
        }
    }

    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
        if (requestCode == REQUEST_PERMISSIONS && arePermissionGranted(grantResults)) {
            takePhoto()
        } else {
            requestPermissions()
        }
    }

    private fun arePermissionGranted(grantResults: IntArray) =
            grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        val file = File(photoFilePath)
        if (requestCode == REQUEST_TAKE_PICTURE && file.exists()) {
            //classify photo
        }
    }
}