Update add linked devices screen.

qr/lib/src/main/java/org/signal/qr/QrScannerView.kt

@@ -23,6 +23,7 @@ class QrScannerView @JvmOverloads constructor(
 
   private var scannerView: ScannerView? = null
   private val qrDataPublish: PublishSubject<String> = PublishSubject.create()
+  private var forceLegacy: Boolean = false
 
   val qrData: Observable<String> = qrDataPublish
 
@@ -37,12 +38,14 @@ class QrScannerView @JvmOverloads constructor(
     addView(scannerView)
 
     this.scannerView = (scannerView as ScannerView)
+    this.forceLegacy = forceLegacy
   }
 
   @JvmOverloads
   fun start(lifecycleOwner: LifecycleOwner, forceLegacy: Boolean = false) {
     if (scannerView != null) {
       Log.w(TAG, "Attempt to start scanning that has already started")
+      scannerView?.resume()
       return
     }
 
@@ -61,6 +64,14 @@ class QrScannerView @JvmOverloads constructor(
     scannerView?.toggleCamera()
   }
 
+  // Biometrics require use of camera so we disable when needed
+  fun destroy() {
+    scannerView?.destroy()
+    if (!forceLegacy) {
+      scannerView = null
+    }
+  }
+
   companion object {
     private val TAG = Log.tag(QrScannerView::class.java)
   }

qr/lib/src/main/java/org/signal/qr/ScannerView.kt

@@ -8,4 +8,6 @@ import androidx.lifecycle.LifecycleOwner
 interface ScannerView {
   fun start(lifecycleOwner: LifecycleOwner)
   fun toggleCamera()
+  fun resume()
+  fun destroy()
 }

qr/lib/src/main/java/org/signal/qr/ScannerView19.kt

@@ -59,4 +59,16 @@ internal class ScannerView19 constructor(
       lifecycleObserver.onResume(it)
     }
   }
+
+  override fun resume() {
+    lifecycleOwner?.let {
+      lifecycleObserver.onResume(it)
+    }
+  }
+
+  override fun destroy() {
+    lifecycleOwner?.let {
+      lifecycleObserver.onPause(it)
+    }
+  }
 }

qr/lib/src/main/java/org/signal/qr/ScannerView21.kt

@@ -36,6 +36,7 @@ internal class ScannerView21 constructor(
 
   private val lifecycleObserver: DefaultLifecycleObserver = object : DefaultLifecycleObserver {
     override fun onDestroy(owner: LifecycleOwner) {
+      cameraProvider?.unbindAll()
       cameraProvider = null
       camera = null
       analyzerExecutor.shutdown()
@@ -78,6 +79,14 @@ internal class ScannerView21 constructor(
     lifecycleOwner.lifecycle.addObserver(lifecycleObserver)
   }
 
+  override fun resume() = Unit
+
+  override fun destroy() {
+    lifecyleOwner?.let {
+      lifecycleObserver.onDestroy(it)
+    }
+  }
+
   private fun onCameraProvider(lifecycle: LifecycleOwner, cameraProvider: ProcessCameraProvider?) {
     if (cameraProvider == null) {
       Log.w(TAG, "Camera provider is null")