【Android】CameraXの導入

はじめに

現時点でのCameraXの導入手順のメモ。

ライブラリの導入

build.gradle(:app)に以下のライブラリを追加

build.gradle

implementation "androidx.camera:camera-core:1.0.2"
implementation "androidx.camera:camera-camera2:1.0.2"
implementation "androidx.camera:camera-lifecycle:1.0.2"
implementation 'androidx.camera:camera-view:1.0.0-alpha31'

カメラパーミッションの使用

マニフェストファイルにカメラを使用することを宣言。

AndroidManifest.xml

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

レイアウト作成

PreviewViewを使用してカメラ映像を表示。

activity_main.xml

<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/camera_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/black">

    <androidx.camera.view.PreviewView
        android:id="@+id/view_finder"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>

処理部分

カメラのパーミッション許可部分がややこしいが、ポイントはstartCameraメソッド。ここでカメラを起動している。

MainActivity.kt

class MainActivity : AppCompatActivity() {

    companion object {
        private const val REQUEST_CODE_PERMISSIONS = 10
        private val REQUIRED_PERMISSIONS = arrayOf(Manifest.permission.CAMERA)
    }

    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)
        if (allPermissionsGranted()) {
            startCamera()
        } else {
            ActivityCompat.requestPermissions(this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS)
        }
    }

    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String>, grantResults: IntArray) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        if (requestCode == REQUEST_CODE_PERMISSIONS) {
            if (allPermissionsGranted()) {
                startCamera()
            } else {
                Toast.makeText(this, "Permissions not granted by the user.", Toast.LENGTH_SHORT).show()
                finish()
            }
        }
    }

    private fun allPermissionsGranted() = REQUIRED_PERMISSIONS.all {
        ContextCompat.checkSelfPermission(baseContext, it) == PackageManager.PERMISSION_GRANTED
    }

    private fun startCamera() {
        val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
        cameraProviderFuture.addListener({ bindPreview(cameraProviderFuture.get()) }, ContextCompat.getMainExecutor(this))
    }

    private fun bindPreview(cameraProvider: ProcessCameraProvider) {
        val preview = Preview.Builder().build()
        val cameraSelector = CameraSelector.Builder().requireLensFacing(CameraSelector.LENS_FACING_BACK).build()
        preview.setSurfaceProvider(binding.viewFinder.surfaceProvider)
        cameraProvider.bindToLifecycle(this as LifecycleOwner, cameraSelector, preview)
    }
}