camera1-to-camerax

Step 0: Add Dependencies

Check for and add the required CameraX dependencies. Use version 1.3.0 or higher for interoperability, or version 1.5.0 or higher for Compose extensions.

If you are using a Version Catalog (libs.versions.toml), add the following:

[versions]
camerax = "<minimum_version_needed>"

[libraries]
androidx-camera-core = { group = "androidx.camera", name = "camera-core", version.ref = "camerax" }
androidx-camera-camera2 = { group = "androidx.camera", name = "camera-camera2", version.ref = "camerax" }
androidx-camera-lifecycle = { group = "androidx.camera", name = "camera-lifecycle", version.ref = "camerax" }
androidx-camera-view = { group = "androidx.camera", name = "camera-view", version.ref = "camerax" }
androidx-camera-compose = { group = "androidx.camera", name = "camera-compose", version.ref = "camerax" }

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And in your build.gradle.kts (or build.gradle):

implementation(libs.androidx.camera.core)
implementation(libs.androidx.camera.camera2)
implementation(libs.androidx.camera.lifecycle)
implementation(libs.androidx.camera.view)
implementation(libs.androidx.camera.compose)

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Without a Version Catalog, fall back to these standard Gradle dependencies:

implementation "androidx.camera:camera-core:<minimum_version_needed>"
implementation "androidx.camera:camera-camera2:<minimum_version_needed>"
implementation "androidx.camera:camera-lifecycle:<minimum_version_needed>"
implementation "androidx.camera:camera-view:<minimum_version_needed>"
implementation "androidx.camera:camera-compose:<minimum_version_needed>"

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Step 1: Remove Legacy Implementation

1. Delete all android.hardware.Camera instances.
2. Delete SurfaceView and SurfaceHolder.Callback implementations (surfaceCreated, surfaceChanged, surfaceDestroyed).
3. Remove custom lifecycle handling that opens or releases the camera in onResume or onPause.
4. Remove manual matrix calculations for orientation.

Step 2: Initialize ProcessCameraProvider

Request the ProcessCameraProvider and bind use cases to the Activity or Fragment lifecycle.

val context = LocalContext.current
val lifecycleOwner = LocalLifecycleOwner.current
LaunchedEffect(context, lifecycleOwner) {
  val cameraProviderFuture = ProcessCameraProvider.getInstance(context)
  cameraProviderFuture.addListener({
      val cameraProvider = cameraProviderFuture.get()

      val cameraSelector = CameraSelector.Builder()
        .requireLensFacing(CameraSelector.LENS_FACING_BACK)
        .build()

      val preview = Preview.Builder().build()
      val imageCapture = ImageCapture.Builder()
        .setCaptureMode(ImageCapture.CAPTURE_MODE_MINIMIZE_LATENCY)
        .build()

      cameraProvider.unbindAll() // Unbind before rebinding

      val camera = cameraProvider.bindToLifecycle(
        lifecycleOwner,
        cameraSelector,
        preview,
        imageCapture
      )
      val cameraControl = camera.cameraControl
    }, ContextCompat.getMainExecutor(context)
  )
}

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Step 3: Implement the Preview & Tap-to-Focus

Choose exactly one of the following patterns based on the app's UI toolkit:

Option A: For Android Views (XML Legacy)

Use androidx.camera.view.PreviewView.

1. Set up preview:

preview.setSurfaceProvider(previewView.surfaceProvider)

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2. Handle tap-to-focus:

val factory = previewView.meteringPointFactory
val point = factory.createPoint(x, y) // x, y from touch event
val action = FocusMeteringAction.Builder(point, FocusMeteringAction.FLAG_AF).build()
cameraControl?.startFocusAndMetering(action)

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Option B: For Jetpack Compose

Use androidx.camera.compose.CameraXViewfinder.

1. Set up preview and SurfaceRequest:

var surfaceRequest by remember { mutableStateOf<SurfaceRequest?>(null) }
val preview = remember {
  Preview.Builder().build().apply {
    setSurfaceProvider { request -> surfaceRequest = request }
  }
}

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2. Render viewfinder:

surfaceRequest?.let { request ->
  CameraXViewfinder(
    surfaceRequest = request,
    coordinateTransformer = coordinateTransformer,
    modifier = Modifier
  )
}

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3. Handle tap-to-focus in Compose:

// Inside your tap gesture handler...
val surfaceCoords = with(coordinateTransformer) { offset.transform() }
val factory = SurfaceOrientedMeteringPointFactory(
  request.resolution.width.toFloat(),
  request.resolution.height.toFloat()
)
val point = factory.createPoint(surfaceCoords.x, surfaceCoords.y)
val action = FocusMeteringAction.Builder(point, FocusMeteringAction.FLAG_AF).build()
cameraControl?.startFocusAndMetering(action)

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4. Update target rotation for Compose:

LaunchedEffect(configuration) {
  if (!view.isInEditMode) {
    val rotation = view.display?.rotation ?: Surface.ROTATION_0
    imageCapture.targetRotation = rotation
    preview.targetRotation = rotation
  }
}

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Step 4: Capture Photo

Use the ImageCapture use case to take the picture. The ImageProxy handles rotation directly.

imageCapture.takePicture(
  cameraExecutor,
  object : ImageCapture.OnImageCapturedCallback() {
    override fun onCaptureSuccess(image: ImageProxy) {
      val buffer = image.planes[0].buffer
      val bytes = ByteArray(buffer.remaining())
      buffer.get(bytes)
      val bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.size)

      // Adjust rotation natively via ImageProxy
      val matrix = Matrix()
      matrix.postRotate(image.imageInfo.rotationDegrees.toFloat())
      if (lensFacing == CameraSelector.LENS_FACING_FRONT) {
        matrix.postScale(-1f, 1f) // Mirror for front camera
      }

      val rotatedBitmap = Bitmap.createBitmap(
        bitmap, 0, 0, bitmap.width, bitmap.height, matrix, true
      )

      // MUST close proxy
      image.close()
    }

    override fun onError(exception: ImageCaptureException) {
      Log.e("CameraX", "Capture failed: ${exception.message}", exception)
    }
  }
)

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Step 5: Switch Cameras

To flip between front and rear cameras, change the CameraSelector and re-trigger the ProcessCameraProvider logic.

lensFacing = if (lensFacing == CameraSelector.LENS_FACING_BACK) {
  CameraSelector.LENS_FACING_FRONT
} else {
  CameraSelector.LENS_FACING_BACK
}

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Constraints

• Don't manage the camera lifecycle manually : Bind the camera to a LifecycleOwner through the ProcessCameraProvider. Avoid manual camera open or close logic in onResume or onPause.
• Don't calculate focus matrices manually : MeteringPointFactory handles coordinate transformations, including device rotation offsets. Avoid custom matrix implementations.
• Don't forget to close the ImageProxy : Remember to invoke image.close() in the capture callback. Skipping this call locks the capture pipeline and interrupts subsequent photos.
• Don't wrap PreviewView in AndroidView for Compose code : For Compose UI layouts, use CameraXViewfinder. Compiling PreviewView in an AndroidView is an old fallback option that introduces resizing issues.