QR Scanner

Full-screen camera-based QR scanner. Returns the decoded string to the caller via activity result.

Activity — `QrScannerActivity`

File: ui/home/QrScannerActivity.kt. Hosts a CameraX preview + analysis pipeline backed by de.markusfisch.android.zxingcpp.ZxingCpp.

Reader Options

ZxingCpp.ReaderOptions(
    tryHarder = true,
    tryRotate = true,
    tryInvert = true,
    tryDownscale = true,
    maxNumberOfSymbols = 1,
    textMode = ZxingCpp.TextMode.PLAIN,
)

Camera Pipeline

startCamera() (QrScannerActivity.kt:186-240):

ProcessCameraProvider.getInstance()
Builds Preview and ImageAnalysis with HIGHEST_AVAILABLE_STRATEGY + RATIO_16_9_FALLBACK_AUTO_STRATEGY
Analyser receives STRATEGY_KEEP_ONLY_LATEST frames; reads the Y-plane via ZxingCpp.readYBuffer(...) with the image rotation applied
On first hit, deliverResult(text) sets Activity.RESULT_OK with EXTRA_QR_CONTENT and finishes

Lock Guard

onCreate (QrScannerActivity.kt:101-106) checks CredentialStore.loadSecurityHash() and app.isUnlocked; if a lock exists and the app is locked, it forwards to LockActivity and finishes — direct intent launches cannot bypass the lock screen.

UI Controls

Control	Behaviour
Flashlight (`btnFlashlight`)	Toggles `camera.cameraControl.enableTorch()`; icon swaps between `ic_flashlight_to_on` / `ic_flashlight_to_off` with an `Animatable` transition
Zoom slider (`zoomSlider`)	Linear zoom via `setLinearZoom()`; updated live from the camera's `zoomState` observer
Pinch-to-zoom	`ScaleGestureDetector` on the preview view, mapped through `cameraControl.setZoomRatio()` clamped to the device's `[minZoomRatio, maxZoomRatio]`
Pick image (`btnPickImage`)	`GetContent("image/*")`; decodes the picked bitmap with the same reader options

Image Decoder Fallback

Bitmap.decodeQr() (QrScannerActivity.kt:243-249) mirrors BinaryEye: tries Binarizer.LOCAL_AVERAGE first, then falls back to GLOBAL_HISTOGRAM for tricky lighting.

Callers

Each caller registers an ActivityResultContracts.StartActivityForResult launcher and reads EXTRA_QR_CONTENT from the result intent.

Caller	Result handling
TransferFragment	Routes PayMV / BML URL via `PaymvQrParser` + `extractBmlGatewayUrl`
PayMvQrFragment	Generation only — does not call the scanner directly
`CredentialsFragment` (login)	`OtpauthParser.parse(raw)` → fills `etOtpSeed` or shows a chooser for multi-entry QRs
DashboardFragment	BML URL → BML QR pay; PayMV → pre-fill Transfer; otherwise toast
CardsFragment	Same routing as Dashboard, scoped to the active BML card

When another app shares an image directly to the activity-alias .ScanToPayActivity, MainActivity decodes the QR from the image before routing (it holds the URI permission only at that point). The decoded string is then forwarded as the share_qr_text extra. This bypasses the camera entirely.

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