Antigravity Agent
146 lines
5.0 KiB
Markdown
146 lines
5.0 KiB
Markdown
---
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id: android-camerax-patterns
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title: Android CameraX — 카메라 / 이미지 분석
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category: Coding
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status: draft
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source_trust_level: B
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verification_status: conceptual
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created_at: 2026-05-09
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updated_at: 2026-05-09
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tags: [android, camera, camerax, vibe-coding]
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tech_stack: { language: "Kotlin / CameraX 1.4+", applicable_to: ["Android"] }
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applied_in: []
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aliases: [Camera2, ImageCapture, ImageAnalysis, Preview, lifecycle camera]
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---
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# Android CameraX
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> Camera2 의 lifecycle-aware wrapper. **Preview / ImageCapture / ImageAnalysis / VideoCapture** 4종 use case. 디바이스 호환성 자동 처리.
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## 📖 핵심 개념
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- ProcessCameraProvider: 부팅.
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- UseCase: Preview / ImageCapture / ImageAnalysis / VideoCapture.
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- bindToLifecycle: lifecycle 에 묶어 자동 시작/정지.
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## 💻 코드 패턴
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### 의존성
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```kotlin
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implementation("androidx.camera:camera-core:1.4.0")
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implementation("androidx.camera:camera-camera2:1.4.0")
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implementation("androidx.camera:camera-lifecycle:1.4.0")
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implementation("androidx.camera:camera-view:1.4.0")
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```
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### Preview + Capture (Compose)
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```kotlin
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@Composable
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fun CameraScreen() {
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val ctx = LocalContext.current
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val lifecycleOwner = LocalLifecycleOwner.current
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val previewView = remember { PreviewView(ctx) }
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var imageCapture by remember { mutableStateOf<ImageCapture?>(null) }
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LaunchedEffect(Unit) {
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val provider = ProcessCameraProvider.getInstance(ctx).get()
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val preview = Preview.Builder().build().also {
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it.setSurfaceProvider(previewView.surfaceProvider)
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}
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val capture = ImageCapture.Builder()
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.setCaptureMode(ImageCapture.CAPTURE_MODE_MINIMIZE_LATENCY)
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.build()
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imageCapture = capture
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try {
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provider.unbindAll()
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provider.bindToLifecycle(
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lifecycleOwner,
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CameraSelector.DEFAULT_BACK_CAMERA,
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preview, capture
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)
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} catch (e: Exception) { log.error("camera bind failed", e) }
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}
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Box {
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AndroidView(factory = { previewView })
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Button(onClick = { imageCapture?.takePictureToDisk(ctx) }) { Text("촬영") }
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}
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}
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fun ImageCapture.takePictureToDisk(ctx: Context) {
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val file = File(ctx.cacheDir, "shot_${System.currentTimeMillis()}.jpg")
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val output = ImageCapture.OutputFileOptions.Builder(file).build()
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takePicture(output, ContextCompat.getMainExecutor(ctx),
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object : ImageCapture.OnImageSavedCallback {
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override fun onImageSaved(o: ImageCapture.OutputFileResults) { /* file ready */ }
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override fun onError(e: ImageCaptureException) { log.error("capture failed", e) }
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})
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}
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```
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### ImageAnalysis — ML / barcode
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```kotlin
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val analyzer = ImageAnalysis.Builder()
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.setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
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.build()
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.also {
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it.setAnalyzer(Executors.newSingleThreadExecutor()) { imageProxy ->
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val mediaImage = imageProxy.image ?: return@setAnalyzer
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val image = InputImage.fromMediaImage(mediaImage, imageProxy.imageInfo.rotationDegrees)
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barcodeScanner.process(image)
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.addOnSuccessListener { codes -> codes.forEach { onScan(it.rawValue) } }
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.addOnCompleteListener { imageProxy.close() } // 반드시 close
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}
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}
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provider.bindToLifecycle(lifecycleOwner, CameraSelector.DEFAULT_BACK_CAMERA, preview, analyzer)
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```
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### Permission
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```kotlin
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val permission = rememberPermissionState(Manifest.permission.CAMERA)
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LaunchedEffect(Unit) { permission.launchPermissionRequest() }
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if (!permission.status.isGranted) return // PermissionRationale UI
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```
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### Video capture
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```kotlin
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val recorder = Recorder.Builder()
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.setQualitySelector(QualitySelector.from(Quality.HD))
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.build()
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val videoCapture = VideoCapture.withOutput(recorder)
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provider.bindToLifecycle(lifecycleOwner, selector, preview, videoCapture)
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val output = MediaStoreOutputOptions.Builder(...).build()
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recording = videoCapture.output.prepareRecording(ctx, output)
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.start(ContextCompat.getMainExecutor(ctx)) { event -> ... }
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// 종료
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recording?.stop()
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```
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## 🤔 의사결정 기준
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| 사용 | UseCase 조합 |
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|---|---|
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| 단순 사진 | Preview + ImageCapture |
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| QR / barcode 스캔 | Preview + ImageAnalysis |
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| ML 분석 (얼굴, OCR) | Preview + ImageAnalysis |
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| 비디오 녹화 | Preview + VideoCapture |
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| 사진 + 비디오 동시 | Preview + ImageCapture + VideoCapture (제한 있음) |
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## ❌ 안티패턴
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- **imageProxy.close() 누락**: backpressure → analyzer 멈춤.
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- **lifecycle 안 묶음**: 백그라운드에서 카메라 점유 → 배터리.
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- **메인 스레드에서 ML 처리**: UI 멈춤. 별도 executor.
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- **여러 use case 가 디바이스 한계 초과**: bind 실패. 한 번에 적게.
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- **Preview rotation 안 처리**: 회전 시 이상.
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- **권한 거부 후 silent**: 가이드 UI.
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## 🤖 LLM 활용 힌트
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- CameraX + lifecycle bind + 단일 executor analyzer 패턴 표준.
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- ML Kit 결합 자주.
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## 🔗 관련 문서
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- [[Android_Lifecycle_Aware_Components]]
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- [[iOS_Background_Tasks]]
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