Camera page kept the session running while the host app was
backgrounded — wastes battery, holds the hardware, and blocks
other apps from grabbing the camera. Add per-platform observers
that pause/resume the session on app foreground/background, with
a uniform `pauseForBackground` / `resumeForForeground` pair on the
shared CameraInstance.
Behaviour:
- On background: any in-flight recording is hard-cancelled
(matches every messaging app — the take ends with the app
switch). The session stops so the OS can release the camera.
- On foreground: session restarts iff it had been running.
Emits `sessionInterrupted` (`reason: appBackgrounded`) and
`sessionResumed` events so the Dart side can surface UX
affordances if needed.
iOS — `ios/Classes/Camera/CameraInstance+iOS.swift`:
Subscribes to UIApplication.{willResignActive, didBecomeActive}
notifications. Work hops onto sessionQueue so AV mutations stay
serialised. Storage uses the shared
`CameraInstance.lifecycleCleanup` closure slot — extension
doesn't need to add stored properties.
Android — added `androidx.lifecycle:lifecycle-process:2.7.0`,
observes `ProcessLifecycleOwner.get().lifecycle`. ON_STOP →
`pauseForBackground` (cancels recording + drops
CustomLifecycleOwner to CREATED → CameraX releases camera).
ON_START → `resumeForForeground`. Observer add/remove on main
thread per `ProcessLifecycleOwner` contract.
macOS — `macos/Classes/Camera/CameraInstance+macOS.swift`:
Intentional no-op. macOS desktop background semantics are
softer; the chat composer's Card dialog typically stays
foregrounded. Slot is wired so the shared
`observeLifecycle()` call still compiles.
Verified: all four platforms (iOS / Android / macOS / app tests)
build clean. Pod install picks up the new iOS extension file
once Pods/ is fresh — `flutter clean` if mid-iteration.
CameraX 1.3.4 (May 2024) ships `libimage_processing_util_jni.so`
with 0x1000 (4 KB) ELF LOAD alignment. Android 15's 16-KB page
requirement rejects that — the user hit "elf alignment check failed"
on device. 1.4.0+ corrected the linker flags; 1.4.2 is the current
stable.
Also adds `camera-video` to the dep set so Phase 4b can use
`VideoCapture<Recorder>` without another bump.
Verified post-bump:
$ zipalign -v -c -p 16 app-release.apk → all lib/*/*.so (OK)
$ llvm-readelf -l libimage_processing_util_jni.so →
LOAD … 0x4000 (16 KB) on all four ABIs.
