Popp

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Modern Android Concurrent Camera. Jetpack Compose + CameraX. Live dual-camera composite · PiP Swap Mid-Recording (GLES + MediaCodec) · Scoped-Storage

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# Popp

**Modern Android camera. Jetpack Compose + CameraX.**
Live Dual-Camera composite · Live Draggable Primary/PiP Swap Mid-Recording (GLES + MediaCodec) · 
app-private gallery.

<br/>

![Kotlin](https://img.shields.io/badge/Kotlin-2.3.21-7F52FF?logo=kotlin&logoColor=white)
![AGP](https://img.shields.io/badge/AGP-9.1.1-3DDC84?logo=android&logoColor=white)
![minSdk](https://img.shields.io/badge/minSdk-24-orange)
![compileSdk](https://img.shields.io/badge/compileSdk-36-blue)
![CameraX](https://img.shields.io/badge/CameraX-1.6.1-4285F4)
![Compose](https://img.shields.io/badge/Compose%20BOM-2026.05.00-4285F4)
![Hilt](https://img.shields.io/badge/Hilt-2.59.2-DD2C00)

</div>

<br/>

<br/>

### Features

| | | | |
|---|---|---|---|
| 📸 **Photo** `ZERO_SHUTTER_LAG` | 🎥 **Video** `HIGHEST` / `HD` dual | 🔀 **Live dual-camera** one MP4 | ♻️ **Mid-record PiP swap** no split |
| 🎨 **5 composite layouts** | 🖐️ **Draggable PiP** off recompose path | 🖼️ **Private gallery** prefix-filtered | 🔐 **Queue-based perms** auto-advance |

---

## Demo

## Camera Modes

<table>
<tr>
<td width="50%" align="center">
  <img src="docs/assets/camara_features.png" alt="Single camera" width="280" />
  <br/><sub><b>Single camera</b> — flash, zoom presets, lens flip via <code>cameraControl</code></sub>
</td>
<td width="50%" align="center">
  <img src="docs/assets/concurrent_view_draggable.png" alt="Draggable PiP" width="280" />
  <br/><sub><b>Draggable PiP</b> — pinch 20–55% canvas width, snap-to-corner on release</sub>
</td>
</tr>
</table>

## Composite Layouts

Tap the preview to cycle `DualLayout`. Each variant is a branch in the GL shader.

<table>
<tr>
<td align="center" width="20%">
  <img src="docs/assets/concurrent_view_01.png" width="160" /><br/>
  <sub><code>PIP_RECT</code></sub>
</td>
<td align="center" width="20%">
  <img src="docs/assets/concurrent_view_02.png" width="160" /><br/>
  <sub><code>PIP_CIRCLE</code></sub>
</td>
<td align="center" width="20%">
  <img src="docs/assets/concurrent_view_03.png" width="160" /><br/>
  <sub><code>SPLIT_VERTICAL</code></sub>
</td>
<td align="center" width="20%">
  <img src="docs/assets/concurrent_view_04.png" width="160" /><br/>
  <sub><code>SPLIT_HORIZONTAL</code></sub>
</td>
<td align="center" width="20%">
  <img src="docs/assets/concurrent_view_05.png" width="160" /><br/>
  <sub><code>REACTION_STRIP</code></sub>
</td>
</tr>
</table>

<sub>Layout cycling blocked mid-recording — encoder canvas is dim-locked at record-start.</sub>

## Gallery

`LazyColumn` + `stickyHeader` per group. Toggle **Daily** ↔ **Monthly** grouping without re-querying.

`DISPLAY_NAME LIKE 'POPP_%'` selection means the gallery shows **only** Popp captures — files written without the `POPP_IMG_` / `POPP_VID_` prefix are invisible by design.

</td>
</tr>
</table>

---

## Architecture

Single-Activity Compose app. `MainActivity` → `PoppTheme` → permission gate → `MainContent` (Navigation3).

```
com.debanshu777.popp
├── data/{camera,media}    — repositories + MediaStoreGateway
├── di/                    — Hilt modules + dispatcher qualifiers
├── navigation/            — Navigation3 destinations
└── ui/features/{camera,gallery,permissions}
```

Per-action use cases. ViewModels orchestrate UI only. Hardware state lives in `CameraSessionRepository` (`StateFlow<CameraSessionState>`). `@ApplicationContext` injected in exactly two places: `DefaultCameraProviderRepository`, `MediaStoreGateway`.

<details>
<summary><b>📷 Live dual-camera swap</b> — GLES + MediaCodec composite pipeline</summary>

<br/>

`ConcurrentCamera` + `CompositionSettings` is bind-time only — any layered solution that re-binds to swap PiP kills the encoder and splits the MP4. Popp composites itself.

```
back cam ──→ SurfaceTexture(back) ─┐
                                    ├─→ GL composite shader ─→ shared EGL ┬─→ SurfaceView (preview)
front cam ─→ SurfaceTexture(front) ┘    (reads dualBackPrimary)           └─→ MediaCodec ─→ MediaMuxer ─→ MP4
```

- Two `Preview` use cases, one `SurfaceTexture` each, bound via `ConcurrentCamera.bindToLifecycle(listOf(...))`.
- `HandlerThread`-backed renderer owns EGL14 context with **two `eglSurface`s** (preview + encoder) sharing the same context.
- Primary/PiP = one `@Volatile var backPrimary: Boolean`. Flip → next frame swaps texture roles. No rebind.
- Encoder PTS via `eglPresentationTimeANDROID(...)` from the back camera's `SurfaceTexture.getTimestamp()`, rebased to start at 0.
- Encoder dims computed at record-start from viewport pixel aspect, capped 1280 long edge, rounded DOWN to 16-multiple. `orientationHint = 0`.

> **Rotation gotcha** — CameraX's `SurfaceTexture.getTransformMatrix(...)` **already bakes** display rotation. Stacking `Matrix.rotateM(...)` on top → 90° tilted preview. Tex matrix order: `ST · mirror · crop`. No rotation.

Deep dive → [`docs/06-live-dual-swap.md`](docs/06-live-dual-swap.md)

</details>

<details>
<summary><b>🏗️ Use-case architecture</b> — per-action use cases, repositories, sealed Result types</summary>

<br/>

- Use cases own threading. Blocking work wrapped in `withContext(@IoDispatcher)`. CameraX binds on `Dispatchers.Main.immediate`.
- `CameraSessionRepository` is a singleton `StateFlow<CameraSessionState>` holding live `Camera`, `ImageCapture`, `VideoCapture`, `SurfaceRequest`, `Recording`, `DualCameraSession`, `DualVideoEncoder`.
- `Start/Stop/ToggleVideoRecording/ToggleDualRecording` use cases return sealed `Result` unions. VM `when`-switches once, pushes snackbar + UiState.
- Use cases never inject raw `Context`. Writes go through `MediaStoreGateway`, reads through `MediaRepository`.

Deep dive → [`docs/07-usecase-architecture.md`](docs/07-usecase-architecture.md)

</details>

<details>
<summary><b>🖼️ Camera preview + capture</b> — SurfaceRequest, MediaStore, prefix contract</summary>

<br/>

`CameraXViewfinder` (from `androidx.camera.compose`) consumes a `SurfaceRequest` directly — no `AndroidView`, no `SurfaceHolder` callbacks.

```kotlin
LifecycleStartEffect(useFront, useDualCamera, dualBackPrimary) {
    viewModel.startCamera(lifecycleOwner)
    onStopOrDispose { viewModel.stopCamera() }
}
```

Photo↔Video is **not** a rebind key — both use cases are pre-bound in single mode.

All writes go through `MediaStore` → `DCIM/Popp/` → prefixed filenames. Same prefix is the read-side `LIKE` selection. App-private gallery, scoped-storage compliant.

Deep dives → [`01-camera-preview`](docs/01-camera-preview.md), [`02-photo-and-video-capture`](docs/02-photo-and-video-capture.md)

</details>

<details>
<summary><b>🔐 Permissions</b> — sealed enum + queue, auto-advancing UI</summary>

<br/>

Three layers:

1. **Activity gate** — main UI composes only when `MultiplePermissionsState.allPermissionsGranted`.
2. **Sealed `PermissionEnum`** — each branch owns manifest string, icon, strings, optionality flag.
3. **One-screen queue** — `PermissionsViewModel` walks queue in order. Optional perms (`RECORD_AUDIO`) drop on first decline; required perms stay until granted or settings deep-link.

SDK split (TIRAMISU+) for `READ_MEDIA_IMAGES` / `READ_MEDIA_VIDEO` vs `READ_EXTERNAL_STORAGE` lives in two places — `MainActivity.requiredPermissions` and `PermissionEnum.getRequiredPermissions()` — keep them in sync.

Deep dive → [`docs/05-permissions.md`](docs/05-permissions.md)

</details>

---

## Build

```bash
./gradlew assembleDebug              # Build debug APK
./gradlew installDebug               # Install on device/emulator
./gradlew lint                       # Android lint
./gradlew test                       # JVM unit tests
./gradlew connectedDebugAndroidTest  # Instrumented tests
```

**Device requirements**

| Feature                | Requirement                                                                              |
| ---------------------- | ---------------------------------------------------------------------------------------- |
| Single-camera + gallery | API 24+                                                                                  |
| Dual-camera recording  | API 26+ (`MediaMuxer(FileDescriptor)`, `IS_PENDING` are 26+/29+)                         |
| Dual-camera button     | `PackageManager.FEATURE_CAMERA_CONCURRENT` + back+front pair in `availableConcurrentCameraInfos` |

---

## Docs

| # | Doc | Topic |
| - | --- | ----- |
| 01 | [Camera preview pipeline](docs/01-camera-preview.md) | `SurfaceRequest` ↔ `CameraXViewfinder`, lifecycle keys |
| 02 | [Photo & video capture](docs/02-photo-and-video-capture.md) | MediaStore writes, prefix contract |
| 03 | [Concurrent (dual) camera](docs/03-concurrent-camera.md) | Legacy `ConcurrentCamera` (historical) |
| 04 | [Recording the dual feed](docs/04-concurrent-video-recording.md) | Legacy `CompositionSettings` recording (historical) |
| 05 | [Permissions](docs/05-permissions.md) | Accompanist + sealed-enum queue |
| 06 | [Live dual-camera swap](docs/06-live-dual-swap.md) | GLES + MediaCodec composite pipeline |
| 07 | [Use-case architecture](docs/07-usecase-architecture.md) | Per-action use cases, repositories, threading |

---

<div align="center">
<sub>Built by <a href="https://github.com/debanshu777">@debanshu777</a></sub>
</div>

Popp

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