forked from shihaam/thijooree
77 lines
3.2 KiB
Markdown
77 lines
3.2 KiB
Markdown
# QR Scanner
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Full-screen camera-based QR scanner. Returns the decoded string to the caller via activity result.
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---
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## Activity — `QrScannerActivity`
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File: `ui/home/QrScannerActivity.kt`. Hosts a CameraX preview + analysis pipeline backed by `de.markusfisch.android.zxingcpp.ZxingCpp`.
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### Reader Options
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```kotlin
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ZxingCpp.ReaderOptions(
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tryHarder = true,
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tryRotate = true,
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tryInvert = true,
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tryDownscale = true,
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maxNumberOfSymbols = 1,
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textMode = ZxingCpp.TextMode.PLAIN,
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)
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```
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### Camera Pipeline
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`startCamera()` (`QrScannerActivity.kt:186-240`):
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1. `ProcessCameraProvider.getInstance()`
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2. Builds `Preview` and `ImageAnalysis` with `HIGHEST_AVAILABLE_STRATEGY` + `RATIO_16_9_FALLBACK_AUTO_STRATEGY`
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3. Analyser receives `STRATEGY_KEEP_ONLY_LATEST` frames; reads the Y-plane via `ZxingCpp.readYBuffer(...)` with the image rotation applied
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4. On first hit, `deliverResult(text)` sets `Activity.RESULT_OK` with `EXTRA_QR_CONTENT` and finishes
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### Lock Guard
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`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.
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---
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## UI Controls
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| Control | Behaviour |
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|---|---|
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| Flashlight (`btnFlashlight`) | Toggles `camera.cameraControl.enableTorch()`; icon swaps between `ic_flashlight_to_on` / `ic_flashlight_to_off` with an `Animatable` transition |
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| Zoom slider (`zoomSlider`) | Linear zoom via `setLinearZoom()`; updated live from the camera's `zoomState` observer |
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| Pinch-to-zoom | `ScaleGestureDetector` on the preview view, mapped through `cameraControl.setZoomRatio()` clamped to the device's `[minZoomRatio, maxZoomRatio]` |
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| Pick image (`btnPickImage`) | `GetContent("image/*")`; decodes the picked bitmap with the same reader options |
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### Image Decoder Fallback
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`Bitmap.decodeQr()` (`QrScannerActivity.kt:243-249`) mirrors BinaryEye: tries `Binarizer.LOCAL_AVERAGE` first, then falls back to `GLOBAL_HISTOGRAM` for tricky lighting.
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---
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## Callers
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Each caller registers an `ActivityResultContracts.StartActivityForResult` launcher and reads `EXTRA_QR_CONTENT` from the result intent.
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| Caller | Result handling |
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|---|---|
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| [TransferFragment](07-transfer.md) | Routes PayMV / BML URL via `PaymvQrParser` + `extractBmlGatewayUrl` |
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| [PayMvQrFragment](11-paymv-qr-screen.md) | Generation only — does not call the scanner directly |
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| `CredentialsFragment` (login) | `OtpauthParser.parse(raw)` → fills `etOtpSeed` or shows a chooser for multi-entry QRs |
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| [DashboardFragment](21-dashboard.md) | BML URL → BML QR pay; PayMV → pre-fill Transfer; otherwise toast |
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| [CardsFragment](22-cards.md) | Same routing as Dashboard, scoped to the active BML card |
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### Share-to-Scan Fast Path
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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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---
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---
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[← Notifications](24-notifications.md) **Next →** [Circular Nav](26-circular-nav.md)
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