Meshtastic-Android/core/barcode/README.md

# `:core:barcode`

## Overview
The `:core:barcode` module provides barcode and QR code scanning capabilities using CameraX and flavor-specific decoding engines. It is used for scanning node configuration, pairing, and contact sharing.

The shared contract (`BarcodeScanner` interface + `LocalBarcodeScannerProvider`) lives in `core:ui/commonMain`, keeping this module Android-only.

## Key Components

### 1. `rememberBarcodeScanner`
A Composable function (in `main/`) that provides camera permission handling, a full-screen scanner dialog with live preview and reticule overlay, and returns a `BarcodeScanner` instance.

- **Technology:** Uses **CameraX** for camera lifecycle management.
- **Flavors:** Barcode decoding is the only flavor-specific code:
  - `google/` — **ML Kit** (`BarcodeScanning` + `InputImage`) via `createBarcodeAnalyzer()`
  - `fdroid/` — **ZXing** (`MultiFormatReader` + `PlanarYUVLuminanceSource`) via `createBarcodeAnalyzer()`
- All shared UI (dialog, reticule, permissions, camera lifecycle) lives in `main/`.

## Source Layout

```
src/
├── main/     BarcodeScannerProvider.kt (shared UI)
├── google/   BarcodeAnalyzerFactory.kt (ML Kit decoder)
├── fdroid/   BarcodeAnalyzerFactory.kt (ZXing decoder)
├── test/     Unit tests
└── androidTest/ Instrumented tests
```

## Usage

```kotlin
// In a Composable (typically wired via LocalBarcodeScannerProvider in app/)
val scanner = rememberBarcodeScanner { result ->
    // Handle scanned QR code string (or null on dismiss)
}
scanner.startScan()
```

## Module dependency graph

<!--region graph-->
```mermaid
graph TB
  :core:barcode[barcode]:::android-library
  :core:barcode -.-> :core:resources
  :core:barcode -.-> :core:ui

classDef android-application fill:#CAFFBF,stroke:#000,stroke-width:2px,color:#000;
classDef android-application-compose fill:#CAFFBF,stroke:#000,stroke-width:2px,color:#000;
classDef compose-desktop-application fill:#CAFFBF,stroke:#000,stroke-width:2px,color:#000;
classDef android-feature fill:#FFD6A5,stroke:#000,stroke-width:2px,color:#000;
classDef android-library fill:#9BF6FF,stroke:#000,stroke-width:2px,color:#000;
classDef android-library-compose fill:#9BF6FF,stroke:#000,stroke-width:2px,color:#000;
classDef android-test fill:#A0C4FF,stroke:#000,stroke-width:2px,color:#000;
classDef jvm-library fill:#BDB2FF,stroke:#000,stroke-width:2px,color:#000;
classDef kmp-feature fill:#FFD6A5,stroke:#000,stroke-width:2px,color:#000;
classDef kmp-library-compose fill:#FFC1CC,stroke:#000,stroke-width:2px,color:#000;
classDef kmp-library fill:#FFC1CC,stroke:#000,stroke-width:2px,color:#000;
classDef unknown fill:#FFADAD,stroke:#000,stroke-width:2px,color:#000;

```
<!--endregion-->