From Setup to Preview: CameraX Integration in Jetpack Compose
In the world of Android development, CameraX stands as Google’s answer to the complexities of the traditional Camera API, offering a more streamlined and accessible approach for developers. Originally designed with XML
in mind, it presented a challenge for those venturing into the modern declarative UI toolkit of Jetpack Compose. However, the solution is at hand with the AndroidView()
composable, which acts as a bridge, seamlessly integrating CameraX
with Compose. This unlocks new possibilities for camera app development in today’s Android ecosystem.
Our goal is simple: to create a camera preview, the core of any camera app, using Android Compose. We’ll explore how to effectively use CameraX
with this modern UI framework, turning our vision into reality. Let’s begin!
Environment
- Android Studio Hedgehog | 2023.1.1 Patch 2
- Compose version:
androidx.compose:compose-bom:2023.08.00
- Pixel 4 API 28 Emulator
Step 1: Setting the Stage for CameraX in Compose
Before diving into the code, the initial step involves preparing our environment for CameraX
integration with Android Compose. This begins with creating an Empty Compose Project. Ensuring your project is ready to handle camera functionalities requires adding specific dependencies to your app’s build.gradle.kt
file. Insert the following lines inside the dependencies
block.
implementation("androidx.camera:camera-camera2:1.3.1")
implementation("androidx.camera:camera-view:1.3.1")
Since we are just dealing with the preview of the camera (feedback on what the hardware is capturing on the screen), we need only these 2 dependencies:
androidx.camera:camera-camera2
is the backbone, providing access to theCamera2
API in a more simplified and manageable manner. This library is essential for camera operations, including the setup and management of the camera session.androidx.camera:camera-view
offers a high-level view that handles the camera lifecycle and renders the preview with minimal setup required on our end.
Next, update your project’s AndroidManifest.xml
to include the necessary permissions and hardware features. This step is critical for ensuring your application has the ability to access the camera hardware and perform its intended functions without security hitches.
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools">
<uses-permission android:name="android.permission.CAMERA"/>
<uses-feature android:name="android.hardware.camera" android:required="false" />
<application
...
Step 2: Navigating Permissions with BaseActivity
Create the BaseActivity.kt
class to streamline camera permissions management. This base activity consolidates permission handling, providing a unified and reusable approach across your app. For an in-depth guide on leveraging BaseActivity
to simplify permissions management and its application in different projects, explore the resource “Android Camera Permission Essentials: Streamlining with BaseActivity.”
// Your package
import android.Manifest
import android.content.pm.PackageManager
import android.widget.Toast
import androidx.activity.ComponentActivity
import androidx.activity.result.ActivityResultLauncher
import androidx.activity.result.contract.ActivityResultContracts
import androidx.core.content.ContextCompat
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
// Open class allowing extension, so activities like MainActivity can inherit from it
// for common camera permission handling functionality
open class BaseActivity : ComponentActivity() {
// Key Point: Managing Camera Permission State
private val _isCameraPermissionGranted = MutableStateFlow(false)
val isCameraPermissionGranted: StateFlow<Boolean> = _isCameraPermissionGranted
// Declare a launcher for the camera permission request, handling the permission result
private val cameraPermissionRequestLauncher: ActivityResultLauncher<String> =
registerForActivityResult(ActivityResultContracts.RequestPermission()) { isGranted: Boolean ->
if (isGranted) {
// Permission granted, update the state
_isCameraPermissionGranted.value = true
} else {
// Permission denied: inform the user to enable it through settings
Toast.makeText(
this,
"Go to settings and enable camera permission to use this feature",
Toast.LENGTH_SHORT
).show()
}
}
// Checks camera permission and either starts the camera directly or requests permission
fun handleCameraPermission() {
when {
ContextCompat.checkSelfPermission(
this,
Manifest.permission.CAMERA
) == PackageManager.PERMISSION_GRANTED -> {
// Permission is already granted, update the state
_isCameraPermissionGranted.value = true
}
else -> {
// Permission is not granted: request it
cameraPermissionRequestLauncher.launch(Manifest.permission.CAMERA)
}
}
}
}
Key Point: Managing Camera Permission State
- Streamlines Permission Handling: Utilizing
MutableStateFlow
for the camera permission state simplifies observing and responding to permission changes within your Compose UI, leveragingcollectAsState()
for reactive updates. - Facilitates Compose Integration: This approach aligns with Compose’s reactive nature, automatically allowing UI components to update based on the current permission state.
- Advocates for Clean Architecture: While
BaseActivity
serves well for demonstration, adopting aViewModel
for state management in production code fosters better separation of concerns and enhances maintainability.
Step 3: Bringing the Camera to Life with CameraPreview
Creating the CameraPreview
composable function is a pivotal step in our journey to craft a fully functional camera application using Android Compose and CameraX
. This composable acts as the visual interface, displaying what the camera lens captures in real time. Add the CameraPreview.kt
file with the following code.
// Your package
import androidx.camera.view.LifecycleCameraController
import androidx.camera.view.PreviewView
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.platform.LocalLifecycleOwner
import androidx.compose.ui.viewinterop.AndroidView
@Composable
fun CameraPreview() {
// Obtain the current context and lifecycle owner
val context = LocalContext.current
val lifecycleOwner = LocalLifecycleOwner.current
// Remember a LifecycleCameraController for this composable
val cameraController = remember {
LifecycleCameraController(context).apply {
// Bind the LifecycleCameraController to the lifecycleOwner
bindToLifecycle(lifecycleOwner)
}
}
// Key Point: Displaying the Camera Preview
AndroidView(
modifier = Modifier.fillMaxSize(),
factory = { ctx ->
// Initialize the PreviewView and configure it
PreviewView(ctx).apply {
scaleType = PreviewView.ScaleType.FILL_START
implementationMode = PreviewView.ImplementationMode.COMPATIBLE
controller = cameraController // Set the controller to manage the camera lifecycle
}
},
onRelease = {
// Release the camera controller when the composable is removed from the screen
cameraController.unbind()
}
)
}
Key Point: Displaying the Camera Preview
- Seamless Integration with Compose: Leveraging
AndroidView
allows us to incorporate traditional Android views, likePreviewView
, into our Compose layout with minimal hassle, bridging the gap between the two UI paradigms. PreviewView:
CameraX
’s component designed for displaying the camera's live feed, simplifying the integration of real-time camera visuals into an app's interface. It manages the rendering of camera frames, ensuring the live preview is automatically aligned with the application's lifecycle for optimal performance and resource management.- Lifecycle Management: Utilizing the
LifecycleCameraController
is essential for aligning the camera’s operational lifecycle with that of our composable. This synchronization ensures optimal resource utilization and prevents memory leaks, enabling the camera to be precisely controlled within the Compose environment.
Step 4: Merging Components in MainActivity
Finally, proceed to update the MainActivity
to integrate all components seamlessly. This step combines the permission handling from BaseActivity
with the CameraPreview
composable, culminating in a cohesive application flow.
// Your package
import android.os.Bundle
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.material3.Button
import androidx.compose.material3.Text
import androidx.compose.runtime.collectAsState
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
// MainActivity inherits from BaseActivity to utilize its camera permission handling logic
class MainActivity : BaseActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContent {
// Collect the camera permission state as a Compose state to automatically update the UI upon change
val permissionGranted = isCameraPermissionGranted.collectAsState().value
Box(modifier = Modifier.fillMaxSize()) {
// Conditional UI rendering based on camera permission state
if (permissionGranted) {
// If permission is granted, display the camera preview
CameraPreview()
} else {
// If permission is not granted, display a button to request camera permission
Button(
onClick = {
// Invoke the method from BaseActivity to handle permission request
handleCameraPermission()
},
modifier = Modifier.align(Alignment.Center)
) {
Text(text = "Start Preview")
}
}
}
}
}
}
Upon launching the app and tapping on the Start Preview
button, you’ll be prompted with a camera permission dialog. Granting permission activates the CameraPreview()
, showcasing the live camera feed directly within the app. This process demonstrates the effective permission management and dynamic rendering capabilities of CameraX
in a Compose environment.
Conclusion
That concludes our journey into integrating CameraX
with Jetpack Compose for Android development. While blending CameraX
’s capabilities with Compose’s declarative UI paradigm presents challenges, the outlined strategies offer effective solutions. The next exciting steps could involve capturing images and managing storage or further exploring CameraX
’s advanced features.
For developers eager to deepen their understanding or explore more about modern Android development, a wealth of resources and guides await.
Your thoughts and involvement are truly priceless. If you’ve found this guide helpful, I’d love to hear from you. Consider sharing your support through claps or a follow, and stay tuned for more insights into the evolving landscape of Android development. See you in the next tutorial!
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