fix(screensaver): match night brightness across hosts, end on leave

The dream now turns its window down to the same near-zero brightness as
the in-app screen saver, not just to the system's dim level, and builds
its ComposeView from the window's context rather than the service's.
The in-app screen saver finishes once it is no longer shown, so waking
the phone shows the lock screen, and rotating it into a stand no longer
recreates it. The outgoing minute of the crossfade is hidden from screen
readers.

app/src/main/AndroidManifest.xml

@@ -307,13 +307,14 @@
             android:theme="@style/Theme.Clockula" />
 
         <!-- The same screen saver on demand, from the tabs' overflow menu: an
-             app cannot start the system's dream itself. Not exported, and
-             no history: leaving it by Home or Recents finishes it, so the app
-             never comes back to a dim screen saver instead of its tabs. -->
+             app cannot start the system's dream itself. Not exported; it
+             finishes itself once no longer shown. Rotating into a dock or a
+             stand re-lays it out rather than recreating it, which would
+             flash black and reset its brightness. -->
         <activity
             android:name=".ui.screensaver.ScreenSaverActivity"
+            android:configChanges="orientation|screenSize|smallestScreenSize|screenLayout|keyboardHidden"
             android:exported="false"
-            android:noHistory="true"
             android:theme="@style/Theme.Clockula.ScreenSaver" />
 
         <!-- Persists the per-app language on API < 33, where the platform

app/src/main/java/de/jeanlucmakiola/clockula/ui/screensaver/ClockulaDreamService.kt

@@ -10,7 +10,9 @@ import javax.inject.Inject
  * Clockula's screen saver, as the system starts it — on a charger or a dock,
  * from Settings → Display → Screen saver. Non-interactive: any touch wakes
  * the device, as a screen saver should. Night mode turns the display down to
- * the system's dim level ([setScreenBright]) on top of the dimmed colours.
+ * the system's dim level ([setScreenBright]) and the window's own
+ * brightness to the same near-zero the in-app host uses, on top of the
+ * dimmed colours.
  *
  * Lives in `ui/` because it hosts Compose. Its `ComposeView` finds its
  * lifecycle, view-model store and saved-state owners on the window's decor
@@ -32,14 +34,20 @@ class ClockulaDreamService : DreamService() {
         isFullscreen = true
         // Dim until the settings say otherwise (ScreenSaverRoot).
         isScreenBright = false
+        window.applyScreenSaverBrightness(nightMode = true)
 
         val owner = DreamViewOwner().also { owner = it }
         owner.create(window.decorView)
         setContentView(
-            ComposeView(this).apply {
+            // The window's context, not the service's: a Service is not a UI
+            // context, and the window's knows its display's density and size.
+            ComposeView(window.context).apply {
                 setViewCompositionStrategy(ViewCompositionStrategy.DisposeOnDetachedFromWindow)
                 setContent {
-                    ScreenSaverRoot(source, onNightModeChanged = { night -> isScreenBright = !night })
+                    ScreenSaverRoot(source, onNightModeChanged = { night ->
+                        isScreenBright = !night
+                        window.applyScreenSaverBrightness(night)
+                    })
                 }
             },
         )

app/src/main/java/de/jeanlucmakiola/clockula/ui/screensaver/ScreenSaverActivity.kt

@@ -48,13 +48,13 @@ class ScreenSaverActivity : ComponentActivity() {
         super.onCreate(savedInstanceState)
         setShowWhenLocked(true)
         window.addFlags(WindowManager.LayoutParams.FLAG_ALLOW_LOCK_WHILE_SCREEN_ON)
-        applyNightBrightness(true)
+        window.applyScreenSaverBrightness(nightMode = true)
         WindowCompat.setDecorFitsSystemWindows(window, false)
         WindowCompat.getInsetsController(window, window.decorView).apply {
             hide(WindowInsetsCompat.Type.systemBars())
             systemBarsBehavior = WindowInsetsControllerCompat.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE
         }
-        setContent { ScreenSaverRoot(source, onNightModeChanged = ::applyNightBrightness) }
+        setContent { ScreenSaverRoot(source, onNightModeChanged = window::applyScreenSaverBrightness) }
     }
 
     override fun onStart() {
@@ -73,6 +73,11 @@ class ScreenSaverActivity : ComponentActivity() {
     override fun onStop() {
         unregisterReceiver(powerReceiver)
         super.onStop()
+        // Gone once it is no longer shown — Home, Recents, or the screen
+        // timing out on battery — as a dream ends, so the next wake shows the
+        // lock screen and the next launch the app, never a screen saver left
+        // behind. A rotation recreates nothing (configChanges in the manifest).
+        if (!isChangingConfigurations) finish()
     }
 
     override fun onUserInteraction() {
@@ -90,15 +95,4 @@ class ScreenSaverActivity : ComponentActivity() {
             window.clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
         }
     }
-
-    private fun applyNightBrightness(nightMode: Boolean) {
-        window.attributes = window.attributes.apply {
-            screenBrightness = if (nightMode) NIGHT_BRIGHTNESS else WindowManager.LayoutParams.BRIGHTNESS_OVERRIDE_NONE
-        }
-    }
-
-    private companion object {
-        /** Near the bottom of the panel's range; not 0, which some panels take as "off". */
-        const val NIGHT_BRIGHTNESS = 0.01f
-    }
 }

app/src/main/java/de/jeanlucmakiola/clockula/ui/screensaver/ScreenSaverContent.kt

@@ -29,6 +29,7 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.layout.Layout
 import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.clearAndSetSemantics
 import androidx.compose.ui.semantics.contentDescription
 import androidx.compose.ui.semantics.semantics
 import androidx.compose.ui.text.SpanStyle
@@ -80,15 +81,18 @@ internal fun ScreenSaverContent(state: ScreenSaverUiState, modifier: Modifier =
             animationSpec = if (reduceMotion) snap() else tween(ScreenSaverDefaults.MOVE_MILLIS),
             label = "drift",
         ) { shown ->
-            Drifting(shown.position) { Clock(shown, side) }
+            // The outgoing minute is only a picture while it fades: a screen
+            // reader finds one time on screen, never two.
+            val semantics = if (shown == state) Modifier else Modifier.clearAndSetSemantics {}
+            Drifting(shown.position, semantics) { Clock(shown, side) }
         }
     }
 }
 
 /** Places its one child at [position]'s fractions of the space the child leaves free. */
 @Composable
-private fun Drifting(position: ScreenSaverDrift.Position, content: @Composable () -> Unit) {
-    Layout(content = content, modifier = Modifier.fillMaxSize()) { measurables, constraints ->
+private fun Drifting(position: ScreenSaverDrift.Position, modifier: Modifier, content: @Composable () -> Unit) {
+    Layout(content = content, modifier = modifier.fillMaxSize()) { measurables, constraints ->
         val placeable = measurables.single().measure(constraints.copy(minWidth = 0, minHeight = 0))
         layout(constraints.maxWidth, constraints.maxHeight) {
             placeable.place(

app/src/main/java/de/jeanlucmakiola/clockula/ui/screensaver/ScreenSaverRoot.kt

@@ -1,5 +1,7 @@
 package de.jeanlucmakiola.clockula.ui.screensaver
 
+import android.view.Window
+import android.view.WindowManager
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxSize
@@ -13,6 +15,21 @@ import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import de.jeanlucmakiola.clockula.ui.theme.ScreenSaverTheme
 import de.jeanlucmakiola.floret.prefs.Appearance
 
+/** Near the bottom of the panel's range; not 0, which some panels take as "off". */
+private const val NIGHT_BRIGHTNESS = 0.01f
+
+/**
+ * Both hosts' display brightness for [nightMode]: almost nothing at night,
+ * the user's own otherwise. The same window setting for the dream and the
+ * activity, so the system's screen saver is no brighter at night than the
+ * one opened from the menu.
+ */
+internal fun Window.applyScreenSaverBrightness(nightMode: Boolean) {
+    attributes = attributes.apply {
+        screenBrightness = if (nightMode) NIGHT_BRIGHTNESS else WindowManager.LayoutParams.BRIGHTNESS_OVERRIDE_NONE
+    }
+}
+
 /**
  * What both hosts set as their content: [source]'s state in the screen
  * saver's theme. Collected with the host's lifecycle, so a stopped dream or

app/src/main/java/de/jeanlucmakiola/clockula/ui/screensaver/ScreenSaverSettingsSection.kt

@@ -15,7 +15,7 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.unit.dp
-import androidx.hilt.lifecycle.viewmodel.compose.hiltViewModel
+import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import de.jeanlucmakiola.clockula.R
 import de.jeanlucmakiola.clockula.domain.screensaver.ScreenSaverStyle