mob_camera

# mob_camera
Native camera capture, live preview, and frame streaming for apps built with
[Mob](https://hexdocs.pm/mob) — `Mob.Camera`, extracted from mob core as a plugin.
iOS: `UIImagePickerController` + a shared `AVCaptureSession` (vImage frame
conversion). Android: `TakePicture`/`CaptureVideo` activity contracts + CameraX
`ImageAnalysis`.
## Installation
```elixir
# mix.exs
{:mob_camera, "~> 0.1"}
# mob.exs
config :mob, :plugins, [:mob_camera]
```
The plugin manifest merges `NSCameraUsageDescription` (iOS) and `CAMERA` /
`RECORD_AUDIO` (Android) into the host app at build time, and registers the
`:camera` permission capability — request it via
`Mob.Permissions.request(socket, :camera)` before capturing. (`:microphone`,
needed for video, stays in core.)
## Usage
```elixir
socket = MobCamera.capture_photo(socket, quality: :high)
socket = MobCamera.capture_video(socket, max_duration: 60)
def handle_info({:camera, :photo, %{path: path, width: w, height: h}}, socket), do: ...
def handle_info({:camera, :video, %{path: path, duration: seconds}}, socket), do: ...
def handle_info({:camera, :cancelled}, socket), do: ...
```
`path` is a local temp file — copy it elsewhere before the next capture.
For real-time work (object detection, AR, custom filters), stream frames:
```elixir
socket = MobCamera.start_frame_stream(socket, width: 640, height: 640, format: :rgb_f32)
def handle_info({:camera, :frame, %{bytes: bin, width: w, height: h,
                                    format: :rgb_f32, timestamp_ms: _t,
                                    dropped: _n}}, socket) do
  # :rgb_f32 is Nx-ready: Nx.from_binary(bin, :f32) |> Nx.reshape({1, h, w, 3})
end
```
Resize + format conversion happen natively, and late frames are dropped
natively, so the BEAM mailbox stays bounded. Other options: `format: :bgra_u8`,
`facing: :front`, `throttle_ms:`. Stop with `MobCamera.stop_frame_stream/1`.
Live preview pairs a session from this plugin with a view component from core:
```elixir
socket = MobCamera.start_preview(socket, facing: :back)
# in render/1:
{Mob.UI.camera_preview(facing: :back)}
```
## Host app requirements
Photo/video capture saves through a FileProvider: `AndroidManifest.xml` must
declare an `androidx.core.content.FileProvider` `<provider>` with
`res/xml/file_provider_paths.xml`. mob_new-generated apps include it;
hand-rolled hosts must add it or capture returns `:cancelled`.
## Limits
- The preview *view* node (`Mob.UI.camera_preview/1`) stays in mob core for
  now — this plugin owns the session (`start_preview/2` / `stop_preview/1`).
  Moving the view here waits on the plugin native-view capability.
- Frame size is capped at ~4 MP; mismatched aspect ratios are center-cropped
  on the long axis before scaling.
## Development
Clone, then run once:
```bash
mix setup
```
That fetches deps and activates the repo's git hooks (`.githooks/pre-push`):
`mix format --check`, `mix credo --strict` (incl. ExSlop), and `mix compile --warnings-as-errors` run on every push, plus the full test
suite when `mix.exs` changes — the same gate CI enforces before publishing.
## License
MIT