Cách làm việc với Camera trên Android (CameraX

Giới thiệu

API Camera cũ (android.hardware.Camera) và MediaStore.ACTION_IMAGE_CAPTURE intent đã **deprecated**. Google khuyến nghị dùng **CameraX** (Jetpack) - API hiện đại, lifecycle-aware, xử lý tự động rotation, aspect ratio, và tương thích ngược.

Yêu cầu

minSdk 21+ (Android 5.0+)
Dependencies CameraX (xem bên dưới)

Các bước thực hiện

Bước 1: Tạo dự án mới

Android Studio → File → New Project → Empty View Activity.

Bước 2: Thêm dependencies (build.gradle.kts)

dependencies {
    // CameraX core
    def camerax_version = "1.4.0-alpha02"
    implementation "androidx.camera:camera-core:${camerax_version}"
    implementation "androidx.camera:camera-camera2:${camerax_version}"
    implementation "androidx.camera:camera-lifecycle:${camerax_version}"
    implementation "androidx.camera:camera-view:${camerax_version}"
    implementation "androidx.camera:camera-video:${camerax_version}"
    implementation "androidx.camera:camera-extensions:${camerax_version}"

    // ViewBinding
    implementation "androidx.lifecycle:lifecycle-runtime-ktx:2.7.0"
}

Bước 3: Cấu hình AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="https://schemas.android.com/apk/res/android"
    package="com.example.cameraxdemo">

    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" 
        android:maxSdkVersion="28" />
    <!-- Android 10+ không cần WRITE_EXTERNAL_STORAGE cho MediaStore -->

    <uses-feature android:name="android.hardware.camera.any" android:required="true" />
    <uses-feature android:name="android.hardware.camera.autofocus" android:required="false" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.CameraXDemo">

    <activity
        android:name=".MainActivity"
        android:exported="true">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>
</manifest>

Bước 4: Thiết kế giao diện (res/layout/activity_main.xml)

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="https://schemas.android.com/apk/res/android"
    xmlns:app="https://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.camera.view.PreviewView
        android:id="@+id/previewView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toTopOf="@id/btnCapture"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

    <Button
        android:id="@+id/btnCapture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="32dp"
        android:text="Chụp ảnh"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

Bước 5: Code chính (MainActivity.kt)

package com.example.cameraxdemo

import android.Manifest
import android.content.pm.PackageManager
import android.net.Uri
import android.os.Bundle
import android.provider.MediaStore
import android.util.Log
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.camera.core.CameraSelector
import androidx.camera.core.ImageCapture
import androidx.camera.core.ImageCaptureException
import androidx.camera.core.Preview
import androidx.camera.lifecycle.ProcessCameraProvider
import androidx.camera.view.PreviewView
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import androidx.lifecycle.LifecycleOwner
import com.example.cameraxdemo.databinding.ActivityMainBinding
import com.google.common.util.concurrent.ListenableFuture
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.launch
import java.text.SimpleDateFormat
import java.util.Date
import java.util.Locale
import java.util.concurrent.ExecutorService
import java.util.concurrent.Executors

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding
    private var imageCapture: ImageCapture? = null
    private val cameraExecutor = Executors.newSingleThreadExecutor()
    private val cameraProviderFuture: ListenableFuture 
        by lazy { ProcessCameraProvider.getInstance(this) }

    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)
        }

        binding.btnCapture.setOnClickListener { takePhoto() }
    }

    private fun startCamera() {
        cameraProviderFuture.addListener({
            val cameraProvider = cameraProviderFuture.get()
            bindCameraUseCases(cameraProvider)
        }, ContextCompat.getMainExecutor(this))
    }

    private fun bindCameraUseCases(cameraProvider: ProcessCameraProvider) {
        // Preview
        val preview = Preview.Builder().build().also {
            it.setSurfaceProvider(binding.previewView.surfaceProvider)
        }

        // ImageCapture
        imageCapture = ImageCapture.Builder()
            .setCaptureMode(ImageCapture.CAPTURE_MODE_MINIMIZE_LATENCY)
            .build()

        // CameraSelector (back camera mặc định)
        val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA

        try {
            cameraProvider.unbindAll()
            cameraProvider.bindToLifecycle(
                this as LifecycleOwner, cameraSelector, preview, imageCapture
            )
        } catch (e: Exception) {
            Log.e("CameraX", "Use case binding failed", e)
        }
    }

    private fun takePhoto() {
        val imageCapture = this.imageCapture ?: return
        val timeStamp = SimpleDateFormat("yyyyMMdd_HHmmss", Locale.getDefault()).format(Date())
        val contentValues = android.content.ContentValues().apply {
            put(MediaStore.MediaColumns.DISPLAY_NAME, "IMG_$timeStamp.jpg")
            put(MediaStore.MediaColumns.MIME_TYPE, "image/jpeg")
            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.Q) {
                put(MediaStore.MediaColumns.RELATIVE_PATH, "Pictures/CameraXDemo")
            }
        }

        val outputOptions = ImageCapture.OutputFileOptions.Builder(
            contentResolver,
            MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
            contentValues
        ).build()

        imageCapture.takePicture(
            outputOptions,
            cameraExecutor,
            object : ImageCapture.OnImageSavedCallback {
                override fun onError(exc: ImageCaptureException) {
                    runOnUiThread { 
                        Toast.makeText(this@MainActivity, "Lỗi chụp ảnh: ${exc.message}", Toast.LENGTH_SHORT).show()
                        Log.e("CameraX", "Photo capture failed", exc)
                    }
                }

                override fun onImageSaved(output: ImageCapture.OutputFileResults) {
                    runOnUiThread {
                        Toast.makeText(this@MainActivity, "Đã lưu ảnh vào thư viện", Toast.LENGTH_SHORT).show()
                    }
                }
            }
        )
    }

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

    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array, grantResults: IntArray) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        if (requestCode == REQUEST_CODE_PERMISSIONS) {
            if (allPermissionsGranted()) {
                startCamera()
            } else {
                Toast.makeText(this, "Cần quyền Camera để chụp ảnh", Toast.LENGTH_SHORT).show()
                finish()
            }
        }
    }

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

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

So sánh: CameraX vs Intent ACTION_IMAGE_CAPTURE vs Camera2

Đặc điểm	CameraX (Khuyến nghị)	Intent ACTION_IMAGE_CAPTURE	Camera2 API
Độ phức tạp	Trung bình	Thấp	Rất cao
Tùy biến UI	Hoàn toàn (PreviewView)	Không (mở app camera hệ thống)	Hoàn toàn
Xử lý rotation	Tự động	Tự động	Manual
Lifecycle aware	Có	Không	Manual
Extensions (HDR, Night, Bokeh)	Có	Không	Manual
Kết quả trả về	File/Byte array/Uri	Thumbnail bitmap (nhỏ)	ImageReader/Buffer

Lưu ý quan trọng

CameraX cần androidx.camera:camera-view cho PreviewView.
Luôn bind lifecycle: cameraProvider.bindToLifecycle(this, ...).
Lưu ảnh dùng MediaStore (Android 10+) thay vì ghi file trực tiếp.
Request permission CAMERA trước khi start camera.
Shutdown cameraExecutor trong onDestroy().
Test trên thiết bị thật (emulator camera hạn chế).

Cách làm việc với Camera trên Android (CameraX - hiện đại)