[CameraX • Compose] Migrate 3 Other Key CameraX Samples to Compose #312
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Summary of Changes
Hello @madebymozart, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!
This pull request is the second phase of modernizing the camera-samples repository by converting more CameraX examples to Jetpack Compose. It focuses on migrating the Video, Extensions, and MLKit samples, providing fully Compose-based implementations that leverage declarative UI and simplified logic compared to their original XML counterparts.
Highlights
- Compose Migration: Migrated three key CameraX samples (Video, Extensions, and MLKit) from XML Views to Jetpack Compose, modernizing their UI and underlying logic.
- CameraX Extensions Sample: Introduced a new Compose sample demonstrating how to use CameraX Extensions (like Bokeh, HDR, Night) and switch between available extensions and camera lenses.
- CameraX MLKit Sample: Introduced a new Compose sample showcasing integration between CameraX and MLKit for real-time QR code detection in the camera feed, including drawing bounding boxes and handling interactions.
- CameraX Video Sample: Introduced a new Compose sample for basic video capture using CameraX, including handling recording state, saving video to MediaStore, and providing a simple playback screen.
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Code Review
This pull request successfully migrates three CameraX samples (Video, Extensions, MLKit) to Jetpack Compose. The changes involve re-architecting the UI layer, simplifying logic using Compose's declarative paradigm, and ensuring full Compose implementation. The code is generally well-structured and follows modern Android development practices.
I've identified a few areas for improvement, primarily related to resource management in the MLKit sample, potential null pointer exceptions, and an unused/buggy executor in the Video sample. These suggestions aim to enhance robustness and clarity.
| var barcodeScanner = remember { | ||
| BarcodeScanning.getClient( | ||
| BarcodeScannerOptions.Builder() | ||
| .setBarcodeFormats(Barcode.FORMAT_QR_CODE) | ||
| .build(), | ||
| ) |
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The barcodeScanner is initialized within remember and its value doesn't change after initialization. It's more idiomatic to declare it as a val.
val barcodeScanner = remember {
BarcodeScanning.getClient(
BarcodeScannerOptions.Builder()
.setBarcodeFormats(Barcode.FORMAT_QR_CODE)
.build(),
)
}| var barcodeScanner = remember { | ||
| BarcodeScanning.getClient( | ||
| BarcodeScannerOptions.Builder() | ||
| .setBarcodeFormats(Barcode.FORMAT_QR_CODE) | ||
| .build(), | ||
| ) | ||
| } |
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BarcodeScanner implements java.io.Closeable. It's important to close it when it's no longer needed to free up resources. Consider using DisposableEffect to close the scanner when the composable leaves the composition.
| try { | ||
| cameraController.cameraInfo | ||
| } catch (e: Exception) { | ||
| Log.e("Test", "Camera error: $e") |
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Using a generic log tag like "Test" can make debugging harder in a larger application. It's recommended to use a specific TAG, often defined as a companion object constant (e.g., private const val TAG = "CameraXMlKitSample").
Log.e(TAG, "Camera error: $e")| init { | ||
| when (barcode.valueType) { | ||
| Barcode.TYPE_URL -> { | ||
| qrContent = barcode.url!!.url!! |
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The chained non-null assertions (!!) on barcode.url!!.url!! could lead to a NullPointerException if the barcode.url object or its nested url string is unexpectedly null, even if barcode.valueType is Barcode.TYPE_URL. Consider using safe calls (?.) and elvis operators (?:) for more robust handling.
| qrContent = barcode.url!!.url!! | |
| qrContent = barcode.url?.url ?: "Invalid URL" |
| val localCameraExecutor = | ||
| remember { Executors.newSingleThreadExecutor() } // Or pass from parent |
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The localCameraExecutor initialized here appears to be unused for CameraX binding operations, as ProcessCameraProvider.addListener uses ContextCompat.getMainExecutor(context) and bindToLifecycle manages its own threading. This executor might be redundant.
| DisposableEffect(Unit) { | ||
| onDispose { | ||
| localCameraExecutor.isShutdown.not() | ||
| } | ||
| } |
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The onDispose block for localCameraExecutor currently contains localCameraExecutor.isShutdown.not(), which evaluates to a boolean but doesn't perform any action. If the intention was to shut down the executor, it should be localCameraExecutor.shutdown(). However, as noted in another comment, this executor might be unnecessary.
DisposableEffect(Unit) {
onDispose {
// If localCameraExecutor is deemed necessary and needs cleanup:
// localCameraExecutor.shutdown()
}
}
🚀 Jetpack Compose Migration for Camera Samples (Video, Extensions, MLKit)
📝 Description
This pull request continues our initiative to modernize the
camera-samplesrepository by converting existing XML View-based examples to Jetpack Compose.In this 2nd iteration, 3 key samples has been successfully migrated from their original implementations in the android/camera-samples repository. The migration involved:
✅ How Has This Been Tested?
Manual testing has been performed on the following configuration to ensure the core functionality of the migrated samples remains intact:
Test Configuration #1
Next Steps: