camera1-to-camerax

by android

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SKILL.md About

---
name: camera1-to-camerax
description: Use this skill to migrate legacy Android camera implementations (Camera1
  or raw Camera2 APIs) to CameraX. CameraX is a lifecycle-aware Jetpack library built
  on top of Camera2 that resolves camera rotation issues and handles device dependencies.
license: Complete terms in LICENSE.txt
metadata:
  author: Google LLC
  keywords:
  - Android
  - CameraX
  - Camera1 Migration
  - Jetpack Compose
  - Dependencies
  - Image Capture
  - Lifecycle
  - PreviewView
---

## 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" }
    # If using Android Views (Option A)
    androidx-camera-view = { group = "androidx.camera", name = "camera-view", version.ref = "camerax" }
    # If using Jetpack Compose (Option B)
    androidx-camera-compose = { group = "androidx.camera", name = "camera-compose", version.ref = "camerax" }

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

// Core dependencies
    implementation(libs.androidx.camera.core)
    implementation(libs.androidx.camera.camera2)
    implementation(libs.androidx.camera.lifecycle)

// If using Android Views (Option A)
    implementation(libs.androidx.camera.view)

// If using Jetpack Compose (Option B)
    implementation(libs.androidx.camera.compose)

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

// Core 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>"

// If using Android Views (Option A)
 implementation "androidx.camera:camera-view:<minimum_version_needed>"

// If using Jetpack Compose (Option B)
 implementation "androidx.camera:camera-compose:<minimum_version_needed>"

## 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.

```kotlin
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)
  )
}
```

## 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**:

```kotlin
preview.setSurfaceProvider(previewView.surfaceProvider)
```

**2. Handle tap-to-focus**:

```kotlin
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)
```

### Option B: For Jetpack Compose

Use `androidx.camera.compose.CameraXViewfinder`.

**1. Set up preview and SurfaceRequest**:

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

**2. Render viewfinder**:

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

**3. Handle tap-to-focus in Compose**:

```kotlin
// 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)
```

**4. Update target rotation for Compose**:

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

## Step 4: Capture Photo

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

```kotlin
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)
    }
  }
)
```

## Step 5: Switch Cameras

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

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

## What not to do.

- **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.