Single source of truth for camera settings (#122)

* Update CameraUseCase to reactive model

 CameraUseCase (and CameraXCameraUseCase implementation) will now hold on
 to CameraAppSettings and react to changes in those settings which are
 initiated through the CameraUseCase API.

* PreviewViewModel should not edit CameraAppState

 CameraAppState is now owned by CameraUseCase. It will have the single source of
 truth, and PreviewViewModel will only communicate changes through PreviewUiState,
 it will not edit CameraAppState directly.

* Setting aspect ratio and flipping camera no longer restarts camera job

 The camera job is started once by runCamera(), any changes that restart
 the camera will happen contained inside this coroutine. We no longer need
 to explicitly stop the camera before applying changes that would normally
 restart the camera.

* Fix tests to work with API changes

 Also changes FakeCameraUseCase to use a similar reactive model
 to CameraXCameraUseCase

* Fix more tests

data/settings/src/main/java/com/google/jetpackcamera/settings/model/CameraAppSettings.kt

@@ -30,7 +30,8 @@ data class CameraAppSettings(
     val videoCaptureStabilization: Stabilization = Stabilization.UNDEFINED,
     val supportedStabilizationModes: List<SupportedStabilizationMode> = emptyList(),
     val dynamicRange: DynamicRange = DynamicRange.SDR,
-    val supportedDynamicRanges: List<DynamicRange> = listOf(DynamicRange.SDR)
+    val supportedDynamicRanges: List<DynamicRange> = listOf(DynamicRange.SDR),
+    val zoomScale: Float = 1f
 )
 
 val DEFAULT_CAMERA_APP_SETTINGS = CameraAppSettings()

domain/camera/build.gradle.kts

@@ -54,10 +54,11 @@ android {
 dependencies {
     // Testing
     testImplementation(libs.junit)
-    androidTestImplementation(libs.androidx.junit)
-    androidTestImplementation(libs.androidx.espresso.core)
+    testImplementation(libs.truth)
     testImplementation("org.jetbrains.kotlinx:kotlinx-coroutines-test:1.7.3")
     testImplementation("org.mockito:mockito-core:5.2.0")
+    androidTestImplementation(libs.androidx.junit)
+    androidTestImplementation(libs.androidx.espresso.core)
 
     // Futures
     implementation(libs.futures.ktx)

domain/camera/src/main/java/com/google/jetpackcamera/domain/camera/CameraUseCase.kt

@@ -36,17 +36,17 @@ interface CameraUseCase {
      *
      * @return list of available lenses.
      */
-    suspend fun initialize(currentCameraSettings: CameraAppSettings): List<Int>
+    suspend fun initialize()
 
     /**
-     * Starts the camera with given [CameraAppSettings].
+     * Starts the camera.
      *
      * This will start to configure the camera, but frames won't stream until a [SurfaceRequest]
      * from [getSurfaceRequest] has been fulfilled.
      *
      * The camera will run until the calling coroutine is cancelled.
      */
-    suspend fun runCamera(currentCameraSettings: CameraAppSettings)
+    suspend fun runCamera()
 
     suspend fun takePicture()
 
@@ -64,13 +64,15 @@ interface CameraUseCase {
 
     fun getScreenFlashEvents(): SharedFlow<ScreenFlashEvent>
 
-    fun setFlashMode(flashMode: SettingsFlashMode, isFrontFacing: Boolean)
+    fun getCurrentSettings(): StateFlow<CameraAppSettings?>
+
+    fun setFlashMode(flashMode: SettingsFlashMode)
 
     fun isScreenFlashEnabled(): Boolean
 
-    suspend fun setAspectRatio(aspectRatio: SettingsAspectRatio, isFrontFacing: Boolean)
+    suspend fun setAspectRatio(aspectRatio: SettingsAspectRatio)
 
-    suspend fun flipCamera(isFrontFacing: Boolean, flashMode: SettingsFlashMode)
+    suspend fun flipCamera(isFrontFacing: Boolean)
 
     fun tapToFocus(display: Display, surfaceWidth: Int, surfaceHeight: Int, x: Float, y: Float)