프로젝트 생성

"Empty Activity"를 클릭하고 "Next"

Name은 원하는대로 지어주고, Language는 Kotlin, Minimum SDK는 21 이상이어야 한다. "Finish"

build.gradle 모듈 파일에 코드를 추가한다.

  def camerax_version = "1.1.0-beta01"
  implementation "androidx.camera:camera-core:${camerax_version}"
  implementation "androidx.camera:camera-camera2:${camerax_version}"
  implementation "androidx.camera:camera-lifecycle:${camerax_version}"
  implementation "androidx.camera:camera-video:${camerax_version}"

  implementation "androidx.camera:camera-view:${camerax_version}"
  implementation "androidx.camera:camera-extensions:${camerax_version}"

android 안에 buildTypes 안에 코드를 추가하라고 했는데 나는 이미 있어서 패스.

sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8

ViewBinding을 사용하기 위해서 해당 코드도 추가한다.

buildFeatures {
    viewBinding true
}

상단의 "Sync now"를 누른 후에 기다린다.

레이아웃 만들기

• activity_main.xml 수정

<?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=".MainActivity">

   <androidx.camera.view.PreviewView
       android:id="@+id/viewFinder"
       android:layout_width="match_parent"
       android:layout_height="match_parent" />

   <Button
       android:id="@+id/image_capture_button"
       android:layout_width="110dp"
       android:layout_height="110dp"
       android:layout_marginBottom="50dp"
       android:layout_marginEnd="50dp"
       android:elevation="2dp"
       android:text="@string/take_photo"
       app:layout_constraintBottom_toBottomOf="parent"
       app:layout_constraintLeft_toLeftOf="parent"
       app:layout_constraintEnd_toStartOf="@id/vertical_centerline" />

   <Button
       android:id="@+id/video_capture_button"
       android:layout_width="110dp"
       android:layout_height="110dp"
       android:layout_marginBottom="50dp"
       android:layout_marginStart="50dp"
       android:elevation="2dp"
       android:text="@string/start_capture"
       app:layout_constraintBottom_toBottomOf="parent"
       app:layout_constraintStart_toEndOf="@id/vertical_centerline" />

   <androidx.constraintlayout.widget.Guideline
       android:id="@+id/vertical_centerline"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:orientation="vertical"
       app:layout_constraintGuide_percent=".50" />

</androidx.constraintlayout.widget.ConstraintLayout>

• strings.xml 수정

<resources>
   <string name="app_name">CameraXApp</string>
   <string name="take_photo">Take Photo</string>
   <string name="start_capture">Start Capture</string>
   <string name="stop_capture">Stop Capture</string>
</resources>

• MainActivity.kt 수정

package com.example.cameraxapp

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.Manifest
import android.content.pm.PackageManager
import android.util.Log
import android.widget.Toast
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import java.util.concurrent.Executors
import androidx.camera.core.*
import androidx.camera.lifecycle.ProcessCameraProvider
import androidx.camera.video.*
import androidx.camera.video.VideoCapture
import androidx.core.content.PermissionChecker
import com.example.cameraxapp.databinding.ActivityMainBinding
import java.nio.ByteBuffer
import java.text.SimpleDateFormat
import java.util.*
import java.util.concurrent.ExecutorService
import android.provider.MediaStore

import android.content.ContentValues
import android.os.Build

typealias LumaListener = (luma: Double) -> Unit


class MainActivity : AppCompatActivity() {
    private lateinit var viewBinding: ActivityMainBinding

    private var imageCapture: ImageCapture? = null

    private var videoCapture: VideoCapture<Recorder>? = null
    private var recording: Recording? = null

    private lateinit var cameraExecutor: ExecutorService

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        viewBinding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(viewBinding.root)

        // Request camera permissions
        if (allPermissionsGranted()) {
            startCamera()
        } else {
            ActivityCompat.requestPermissions(
                this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS)
        }

        // Set up the listeners for take photo and video capture buttons
        viewBinding.imageCaptureButton.setOnClickListener { takePhoto() }
        viewBinding.videoCaptureButton.setOnClickListener { captureVideo() }

        cameraExecutor = Executors.newSingleThreadExecutor()
    }

    private fun takePhoto() {}

    private fun captureVideo() {}

    private fun startCamera() {}

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

    override fun onDestroy() {
        super.onDestroy()
        cameraExecutor.shutdown()
    }

    companion object {
        private const val TAG = "CameraXApp"
        private const val FILENAME_FORMAT = "yyyy-MM-dd-HH-mm-ss-SSS"
        private const val REQUEST_CODE_PERMISSIONS = 10
        private val REQUIRED_PERMISSIONS =
            mutableListOf (
                Manifest.permission.CAMERA,
                Manifest.permission.RECORD_AUDIO
            ).apply {
                if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.P) {
                    add(Manifest.permission.WRITE_EXTERNAL_STORAGE)
                }
            }.toTypedArray()
    }
}

onCreate()는 카메라 권한 확인, 카메라 시작, 사진 및 캡처 버튼을 위해 onClickListener() 설정, cameraExecutor를 구현해두었다. onCreate()가 있기는 하지만 파일에서 메소드가 구현될 때까지는 카메라가 작동하지 않을 것이다.

권한 요청

• AndroidManifest.xml 추가
  

<uses-feature android:name="android.hardware.camera.any" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" android:maxSdkVersion="28" />

• MainActivity.kt 수정
  
  onCreate 함수 아래에 코드를 추가했더니 빨간줄이 떴다. Add super call을 눌렀다.
  오류가 없어지고 코드가 조금 수정되었다.

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

여기까지 하고 실행을 하면 카메라와 마이크에 대한 사용권한을 요청할 것이다.

촬영 화면 미리보기

• MainActivity.kt 수정
  기존에 있던 startCamera 함수 대신 완성된 코드를 넣어준다.

private fun startCamera() {
   val cameraProviderFuture = ProcessCameraProvider.getInstance(this)

   cameraProviderFuture.addListener({
       // Used to bind the lifecycle of cameras to the lifecycle owner
       val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()

       // Preview
       val preview = Preview.Builder()
          .build()
          .also {
              it.setSurfaceProvider(viewBinding.viewFinder.surfaceProvider)
          }

       // Select back camera as a default
       val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA

       try {
           // Unbind use cases before rebinding
           cameraProvider.unbindAll()

           // Bind use cases to camera
           cameraProvider.bindToLifecycle(
               this, cameraSelector, preview)

       } catch(exc: Exception) {
           Log.e(TAG, "Use case binding failed", exc)
       }

   }, ContextCompat.getMainExecutor(this))
}

실행해보면 권한 허용 이후에 까맣게 나오던 화면 대신에 카메라가 보는 장면을 보여준다.

• MainActivity.kt 수정
  기존에 있던 takePhoto 함수 대신 완성된 코드를 넣어준다.

private fun takePhoto() {
   // Get a stable reference of the modifiable image capture use case
   val imageCapture = imageCapture ?: return

   // Create time stamped name and MediaStore entry.
   val name = SimpleDateFormat(FILENAME_FORMAT, Locale.US)
              .format(System.currentTimeMillis())
   val contentValues = ContentValues().apply {
       put(MediaStore.MediaColumns.DISPLAY_NAME, name)
       put(MediaStore.MediaColumns.MIME_TYPE, "image/jpeg")
       if(Build.VERSION.SDK_INT > Build.VERSION_CODES.P) {
           put(MediaStore.Images.Media.RELATIVE_PATH, "Pictures/CameraX-Image")
       }
   }

   // Create output options object which contains file + metadata
   val outputOptions = ImageCapture.OutputFileOptions
           .Builder(contentResolver,
                    MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
                    contentValues)
           .build()

   // Set up image capture listener, which is triggered after photo has
   // been taken
   imageCapture.takePicture(
       outputOptions,
       ContextCompat.getMainExecutor(this),
       object : ImageCapture.OnImageSavedCallback {
           override fun onError(exc: ImageCaptureException) {
               Log.e(TAG, "Photo capture failed: ${exc.message}", exc)
           }

           override fun
               onImageSaved(output: ImageCapture.OutputFileResults){
               val msg = "Photo capture succeeded: ${output.savedUri}"
               Toast.makeText(baseContext, msg, Toast.LENGTH_SHORT).show()
               Log.d(TAG, msg)
           }
       }
   )
}

• MainActivity.kt 수정
  startCamera 함수를 아래의 코드로 다시 변경해준다.

private fun startCamera() {
                val cameraProviderFuture = ProcessCameraProvider.getInstance(this)

                cameraProviderFuture.addListener({
                    // Used to bind the lifecycle of cameras to the lifecycle owner
                    val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()

                    // Preview
                    val preview = Preview.Builder()
                        .build()
                        .also {
                            it.setSurfaceProvider(viewBinding.viewFinder.surfaceProvider)
                        }

                    imageCapture = ImageCapture.Builder()
                        .build()

                    // Select back camera as a default
                    val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA

                    try {
                        // Unbind use cases before rebinding
                        cameraProvider.unbindAll()

                        // Bind use cases to camera
                        cameraProvider.bindToLifecycle(
                            this, cameraSelector, preview, imageCapture)

                    } catch(exc: Exception) {
                        Log.e(TAG, "Use case binding failed", exc)
                    }

                }, ContextCompat.getMainExecutor(this))
            }

앱을 다시 실행하고 사진 찍기를 누르면 화면에 토스트에 로그 메시지가 표시된다.