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CameraX Android

CameraX Introduction and Examples.

In this tutorial, we will explore CameraX, a Jetpack library introduced by Google to make it easier to add camera functionality to Android apps. CameraX provides a consistent and simplified API for accessing camera features across different Android devices.

Introduction to CameraX​

CameraX is built on top of the Camera2 API and aims to address the complexities and inconsistencies developers face when working directly with the Camera2 API. It provides a higher-level, lifecycle-aware API that handles common camera tasks, such as preview, image capture, and analysis.

CameraX offers the following key features:

  1. Lifecycle-aware components: CameraX integrates seamlessly with the Android lifecycle, making it easy to handle camera operations in response to lifecycle events.

  2. Simplified configuration: CameraX provides a simplified and declarative way to configure camera settings, such as resolution, focus, flash, and more.

  3. Compatibility across devices: CameraX abstracts the underlying camera implementation, ensuring consistent behavior across different Android devices. It automatically handles device-specific quirks and optimizations, such as vendor-specific camera features.

  4. Extensions: CameraX offers extensions that enable additional camera features, such as portrait mode and HDR.

Now let's dive into the setup and usage of CameraX in a Kotlin Android project.

Setup​

To use CameraX in your project, you need to add the necessary dependencies to your build.gradle file.

  1. Open your project's build.gradle file and add the following code inside the dependencies block:
dependencies {
    // CameraX core library
    implementation 'androidx.camera:camera-core:1.1.0-alpha04'

    // CameraX camera view
    implementation 'androidx.camera:camera-view:1.0.0-alpha27'
}
  1. Sync your project to download the required dependencies.

Usage​

To use CameraX in your app, follow these steps:

  1. Add a PreviewView to your layout file. This view will display the camera preview.
<androidx.camera.view.PreviewView
    android:id="@+id/previewView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />
  1. In your activity or fragment, initialize CameraX by calling CameraX.bindToLifecycle() and passing the lifecycles that CameraX should be bound to.
val cameraProviderFuture = ProcessCameraProvider.getInstance(context)

cameraProviderFuture.addListener({
    val cameraProvider = cameraProviderFuture.get()
    val preview = Preview.Builder().build().also {
        it.setSurfaceProvider(previewView.surfaceProvider)
    }

    val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA

    try {
        cameraProvider.unbindAll()
        cameraProvider.bindToLifecycle(lifecycleOwner, cameraSelector, preview)
    } catch (exception: Exception) {
        Log.e(TAG, "Error binding camera", exception)
    }
}, ContextCompat.getMainExecutor(context))
  1. Run your app and you should see the camera preview displayed in the PreviewView.

Capturing Images​

CameraX provides an easy way to capture images from the camera.

  1. Create an ImageCapture use case and attach it to the camera lifecycle.
val imageCapture = ImageCapture.Builder().build()

cameraProvider.bindToLifecycle(lifecycleOwner, cameraSelector, preview, imageCapture)
  1. Capture an image by calling the takePicture() method on the ImageCapture instance.
val imageFile = File(externalMediaDirs.first(), "image.jpg")

imageCapture.takePicture(imageFile, ContextCompat.getMainExecutor(context),
    object : ImageCapture.OnImageSavedCallback {
        override fun onImageSaved(file: File) {
            // Image saved successfully
        }

        override fun onError(imageCaptureError: ImageCapture.ImageCaptureError, message: String, cause: Throwable?) {
            // Error capturing image
        }
    })

Analyzing Images​

CameraX also provides an API for analyzing images in real-time.

  1. Create an ImageAnalysis use case and attach it to the camera lifecycle.
val imageAnalyzer = ImageAnalysis.Builder().build()

imageAnalyzer.setAnalyzer(ContextCompat.getMainExecutor(context), { image ->
    // Analyze the image here
    
    image.close()
})

cameraProvider.bindToLifecycle(lifecycleOwner, cameraSelector, preview, imageAnalyzer)
  1. Inside the analyzer, you can access the image data and perform your desired analysis.
val imageBuffer = image.planes[0].buffer
val imageData = ByteArray(imageBuffer.remaining())
imageBuffer.get(imageData)

// Process the image data here

CameraX Examples​