Move DisplayRepository from SystemUI to displaylib (803c1079) · Commits · e / os / android_frameworks_libs_systemui

displaylib/Android.bp

+1 −0

Original line number	Diff line number	Diff line
		@@ -23,6 +23,7 @@ java_library {
		"kotlinx_coroutines_android",
		"dagger2",
		"jsr330",
		"//frameworks/libs/systemui:tracinglib-platform",
		],
		plugins: ["dagger2-compiler"],
		srcs: ["src/*/.kt"],

displaylib/src/com/android/app/displaylib/DisplayLibComponent.kt

+22 −4

Original line number	Diff line number	Diff line
		@@ -15,10 +15,15 @@
		*/
		package com.android.app.displaylib

		import android.hardware.display.DisplayManager
		import android.os.Handler
		import dagger.Binds
		import dagger.BindsInstance
		import dagger.Component
		import dagger.Module
		import javax.inject.Singleton
		import kotlinx.coroutines.CoroutineDispatcher
		import kotlinx.coroutines.CoroutineScope

		/**
		* Component that creates all classes in displaylib.
		@@ -33,7 +38,12 @@ interface DisplayLibComponent {

		@Component.Factory
		interface Factory {
		fun create(): DisplayLibComponent
		fun create(
		@BindsInstance displayManager: DisplayManager,
		@BindsInstance bgHandler: Handler,
		@BindsInstance bgApplicationScope: CoroutineScope,
		@BindsInstance backgroundCoroutineDispatcher: CoroutineDispatcher,
		): DisplayLibComponent
		}

		val displayRepository: DisplayRepository
		@@ -47,8 +57,16 @@ interface DisplayLibModule {
		/**
		* Just a wrapper to make the generated code to create the component more explicit.
		*
		* This should be called only once per process.
		* This should be called only once per process. Note that [bgHandler], [bgApplicationScope] and
		* [backgroundCoroutineDispatcher] are expected to be backed by background threads. In the future
		* this might throw an exception if they are tied to the main thread!
		*/
		fun createDisplayLibComponent(): DisplayLibComponent {
		return DaggerDisplayLibComponent.factory().create()
		fun createDisplayLibComponent(
		displayManager: DisplayManager,
		bgHandler: Handler,
		bgApplicationScope: CoroutineScope,
		backgroundCoroutineDispatcher: CoroutineDispatcher,
		): DisplayLibComponent {
		return DaggerDisplayLibComponent.factory()
		.create(displayManager, bgHandler, bgApplicationScope, backgroundCoroutineDispatcher)
		}

displaylib/src/com/android/app/displaylib/DisplayRepository.kt

+437 −2

Original line number	Diff line number	Diff line
		@@ -15,19 +15,454 @@
		*/
		package com.android.app.displaylib

		import android.hardware.display.DisplayManager
		import android.hardware.display.DisplayManager.DISPLAY_CATEGORY_ALL_INCLUDING_DISABLED
		import android.hardware.display.DisplayManager.DisplayListener
		import android.hardware.display.DisplayManager.EVENT_TYPE_DISPLAY_ADDED
		import android.hardware.display.DisplayManager.EVENT_TYPE_DISPLAY_CHANGED
		import android.hardware.display.DisplayManager.EVENT_TYPE_DISPLAY_REMOVED
		import android.os.Handler
		import android.util.Log
		import android.view.Display
		import com.android.app.tracing.FlowTracing.traceEach
		import com.android.app.tracing.traceSection
		import javax.inject.Inject
		import javax.inject.Singleton
		import kotlinx.coroutines.CoroutineDispatcher
		import kotlinx.coroutines.CoroutineScope
		import kotlinx.coroutines.channels.awaitClose
		import kotlinx.coroutines.flow.Flow
		import kotlinx.coroutines.flow.MutableStateFlow
		import kotlinx.coroutines.flow.SharingStarted
		import kotlinx.coroutines.flow.StateFlow
		import kotlinx.coroutines.flow.asFlow
		import kotlinx.coroutines.flow.callbackFlow
		import kotlinx.coroutines.flow.combine
		import kotlinx.coroutines.flow.conflate
		import kotlinx.coroutines.flow.distinctUntilChanged
		import kotlinx.coroutines.flow.filter
		import kotlinx.coroutines.flow.filterIsInstance
		import kotlinx.coroutines.flow.flatMapLatest
		import kotlinx.coroutines.flow.flow
		import kotlinx.coroutines.flow.flowOn
		import kotlinx.coroutines.flow.map
		import kotlinx.coroutines.flow.onEach
		import kotlinx.coroutines.flow.onStart
		import kotlinx.coroutines.flow.scan
		import kotlinx.coroutines.flow.stateIn

		/** Repository for providing access to display related information and events. */
		interface DisplayRepository {
		/** Provides the current set of displays. */
		val displays: StateFlow<Set<Display>>

		/** Display change event indicating a change to the given displayId has occurred. */
		val displayChangeEvent: Flow<Int>

		/** Display addition event indicating a new display has been added. */
		val displayAdditionEvent: Flow<Display?>

		/** Display removal event indicating a display has been removed. */
		val displayRemovalEvent: Flow<Int>

		/**
		* Provides the current set of display ids.
		*
		* Note that it is preferred to use this instead of [displays] if only the
		* [Display.getDisplayId] is needed.
		*/
		val displayIds: StateFlow<Set<Int>>

		/**
		* Pending display id that can be enabled/disabled.
		*
		* When `null`, it means there is no pending display waiting to be enabled.
		*/
		val pendingDisplay: Flow<PendingDisplay?>

		/** Whether the default display is currently off. */
		val defaultDisplayOff: Flow<Boolean>

		/**
		* Given a display ID int, return the corresponding Display object, or null if none exist.
		*
		* This method is guaranteed to not result in any binder call.
		*/
		fun getDisplay(displayId: Int): Display? =
		displays.value.firstOrNull { it.displayId == displayId }

		/** Represents a connected display that has not been enabled yet. */
		interface PendingDisplay {
		/** Id of the pending display. */
		val id: Int

		/** Enables the display, making it available to the system. */
		suspend fun enable()

		/**
		* Ignores the pending display. When called, this specific display id doesn't appear as
		* pending anymore until the display is disconnected and reconnected again.
		*/
		suspend fun ignore()

		/** Disables the display, making it unavailable to the system. */
		suspend fun disable()
		}
		}

		@Singleton
		class DisplayRepositoryImpl @Inject constructor() : DisplayRepository {
		override val displays: StateFlow<Set<Display>> = MutableStateFlow(emptySet())
		class DisplayRepositoryImpl
		@Inject
		constructor(
		private val displayManager: DisplayManager,
		backgroundHandler: Handler,
		bgApplicationScope: CoroutineScope,
		backgroundCoroutineDispatcher: CoroutineDispatcher,
		) : DisplayRepository {
		private val allDisplayEvents: Flow<DisplayEvent> =
		callbackFlow {
		val callback =
		object : DisplayListener {
		override fun onDisplayAdded(displayId: Int) {
		trySend(DisplayEvent.Added(displayId))
		}

		override fun onDisplayRemoved(displayId: Int) {
		trySend(DisplayEvent.Removed(displayId))
		}

		override fun onDisplayChanged(displayId: Int) {
		trySend(DisplayEvent.Changed(displayId))
		}
		}
		displayManager.registerDisplayListener(
		callback,
		backgroundHandler,
		EVENT_TYPE_DISPLAY_ADDED or
		EVENT_TYPE_DISPLAY_CHANGED or
		EVENT_TYPE_DISPLAY_REMOVED,
		)
		awaitClose { displayManager.unregisterDisplayListener(callback) }
		}
		.conflate()
		.onStart { emit(DisplayEvent.Changed(Display.DEFAULT_DISPLAY)) }
		.debugLog("allDisplayEvents")
		.flowOn(backgroundCoroutineDispatcher)

		override val displayChangeEvent: Flow<Int> =
		allDisplayEvents.filterIsInstance<DisplayEvent.Changed>().map { event -> event.displayId }

		override val displayRemovalEvent: Flow<Int> =
		allDisplayEvents.filterIsInstance<DisplayEvent.Removed>().map { it.displayId }

		// This is necessary because there might be multiple displays, and we could
		// have missed events for those added before this process or flow started.
		// Note it causes a binder call from the main thread (it's traced).
		private val initialDisplays: Set<Display> =
		traceSection("$TAG#initialDisplays") { displayManager.displays?.toSet() ?: emptySet() }
		private val initialDisplayIds = initialDisplays.map { display -> display.displayId }.toSet()

		/** Propagate to the listeners only enabled displays */
		private val enabledDisplayIds: StateFlow<Set<Int>> =
		allDisplayEvents
		.scan(initial = initialDisplayIds) { previousIds: Set<Int>, event: DisplayEvent ->
		val id = event.displayId
		when (event) {
		is DisplayEvent.Removed -> previousIds - id
		is DisplayEvent.Added,
		is DisplayEvent.Changed -> previousIds + id
		}
		}
		.distinctUntilChanged()
		.debugLog("enabledDisplayIds")
		.stateIn(bgApplicationScope, SharingStarted.WhileSubscribed(), initialDisplayIds)

		private val defaultDisplay by lazy {
		getDisplayFromDisplayManager(Display.DEFAULT_DISPLAY)
		?: error("Unable to get default display.")
		}
		/**
		* Represents displays that went though the [DisplayListener.onDisplayAdded] callback.
		*
		* Those are commonly the ones provided by [DisplayManager.getDisplays] by default.
		*/
		private val enabledDisplays: StateFlow<Set<Display>> =
		enabledDisplayIds
		.mapElementsLazily { displayId -> getDisplayFromDisplayManager(displayId) }
		.onEach {
		if (it.isEmpty()) Log.wtf(TAG, "No enabled displays. This should never happen.")
		}
		.flowOn(backgroundCoroutineDispatcher)
		.debugLog("enabledDisplays")
		.stateIn(
		bgApplicationScope,
		started = SharingStarted.WhileSubscribed(),
		// This triggers a single binder call on the UI thread per process. The
		// alternative would be to use sharedFlows, but they are prohibited due to
		// performance concerns.
		// Ultimately, this is a trade-off between a one-time UI thread binder call and
		// the constant overhead of sharedFlows.
		initialValue = initialDisplays,
		)

		/**
		* Represents displays that went though the [DisplayListener.onDisplayAdded] callback.
		*
		* Those are commonly the ones provided by [DisplayManager.getDisplays] by default.
		*/
		override val displays: StateFlow<Set<Display>> = enabledDisplays

		override val displayIds: StateFlow<Set<Int>> = enabledDisplayIds

		/**
		* Implementation that maps from [displays], instead of [allDisplayEvents] for 2 reasons:
		* 1. Guarantee that it emits __after__ [displays] emitted. This way it is guaranteed that
		* calling [getDisplay] for the newly added display will be non-null.
		* 2. Reuse the existing instance of [Display] without a new call to [DisplayManager].
		*/
		override val displayAdditionEvent: Flow<Display?> =
		displays
		.pairwiseBy { previousDisplays, currentDisplays -> currentDisplays - previousDisplays }
		.flatMapLatest { it.asFlow() }

		val _ignoredDisplayIds = MutableStateFlow<Set<Int>>(emptySet())
		private val ignoredDisplayIds: Flow<Set<Int>> = _ignoredDisplayIds.debugLog("ignoredDisplayIds")

		private fun getInitialConnectedDisplays(): Set<Int> =
		traceSection("$TAG#getInitialConnectedDisplays") {
		displayManager
		.getDisplays(DISPLAY_CATEGORY_ALL_INCLUDING_DISABLED)
		.map { it.displayId }
		.toSet()
		.also {
		if (DEBUG) {
		Log.d(TAG, "getInitialConnectedDisplays: $it")
		}
		}
		}

		/* keeps connected displays until they are disconnected. */
		private val connectedDisplayIds: StateFlow<Set<Int>> =
		callbackFlow {
		val connectedIds = getInitialConnectedDisplays().toMutableSet()
		val callback =
		object : DisplayConnectionListener {
		override fun onDisplayConnected(id: Int) {
		if (DEBUG) {
		Log.d(TAG, "display with id=$id connected.")
		}
		connectedIds += id
		_ignoredDisplayIds.value -= id
		trySend(connectedIds.toSet())
		}

		override fun onDisplayDisconnected(id: Int) {
		connectedIds -= id
		if (DEBUG) {
		Log.d(TAG, "display with id=$id disconnected.")
		}
		_ignoredDisplayIds.value -= id
		trySend(connectedIds.toSet())
		}
		}
		trySend(connectedIds.toSet())
		displayManager.registerDisplayListener(
		callback,
		backgroundHandler,
		/* eventFlags */ 0,
		DisplayManager.PRIVATE_EVENT_TYPE_DISPLAY_CONNECTION_CHANGED,
		)
		awaitClose { displayManager.unregisterDisplayListener(callback) }
		}
		.conflate()
		.distinctUntilChanged()
		.debugLog("connectedDisplayIds")
		.stateIn(
		bgApplicationScope,
		started = SharingStarted.WhileSubscribed(),
		// The initial value is set to empty, but connected displays are gathered as soon as
		// the flow starts being collected. This is to ensure the call to get displays (an
		// IPC) happens in the background instead of when this object
		// is instantiated.
		initialValue = emptySet(),
		)

		private val connectedExternalDisplayIds: Flow<Set<Int>> =
		connectedDisplayIds
		.map { connectedDisplayIds ->
		traceSection("$TAG#filteringExternalDisplays") {
		connectedDisplayIds
		.filter { id -> getDisplayType(id) == Display.TYPE_EXTERNAL }
		.toSet()
		}
		}
		.flowOn(backgroundCoroutineDispatcher)
		.debugLog("connectedExternalDisplayIds")

		private fun getDisplayType(displayId: Int): Int? =
		traceSection("$TAG#getDisplayType") { displayManager.getDisplay(displayId)?.type }

		private fun getDisplayFromDisplayManager(displayId: Int): Display? =
		traceSection("$TAG#getDisplay") { displayManager.getDisplay(displayId) }

		/**
		* Pending displays are the ones connected, but not enabled and not ignored.
		*
		* A connected display is ignored after the user makes the decision to use it or not. For now,
		* the initial decision from the user is final and not reversible.
		*/
		private val pendingDisplayIds: Flow<Set<Int>> =
		combine(enabledDisplayIds, connectedExternalDisplayIds, ignoredDisplayIds) {
		enabledDisplaysIds,
		connectedExternalDisplayIds,
		ignoredDisplayIds ->
		if (DEBUG) {
		Log.d(
		TAG,
		"combining enabled=$enabledDisplaysIds, " +
		"connectedExternalDisplayIds=$connectedExternalDisplayIds, " +
		"ignored=$ignoredDisplayIds",
		)
		}
		connectedExternalDisplayIds - enabledDisplaysIds - ignoredDisplayIds
		}
		.debugLog("allPendingDisplayIds")

		/** Which display id should be enabled among the pending ones. */
		private val pendingDisplayId: Flow<Int?> =
		pendingDisplayIds.map { it.maxOrNull() }.distinctUntilChanged().debugLog("pendingDisplayId")

		override val pendingDisplay: Flow<DisplayRepository.PendingDisplay?> =
		pendingDisplayId
		.map { displayId ->
		val id = displayId ?: return@map null
		object : DisplayRepository.PendingDisplay {
		override val id = id

		override suspend fun enable() {
		traceSection("DisplayRepository#enable($id)") {
		if (DEBUG) {
		Log.d(TAG, "Enabling display with id=$id")
		}
		displayManager.enableConnectedDisplay(id)
		}
		// After the display has been enabled, it is automatically ignored.
		ignore()
		}

		override suspend fun ignore() {
		traceSection("DisplayRepository#ignore($id)") {
		_ignoredDisplayIds.value += id
		}
		}

		override suspend fun disable() {
		ignore()
		traceSection("DisplayRepository#disable($id)") {
		if (DEBUG) {
		Log.d(TAG, "Disabling display with id=$id")
		}
		displayManager.disableConnectedDisplay(id)
		}
		}
		}
		}
		.debugLog("pendingDisplay")

		override val defaultDisplayOff: Flow<Boolean> =
		displayChangeEvent
		.filter { it == Display.DEFAULT_DISPLAY }
		.map { defaultDisplay.state == Display.STATE_OFF }
		.distinctUntilChanged()

		private fun <T> Flow<T>.debugLog(flowName: String): Flow<T> {
		return if (DEBUG) {
		traceEach(flowName, logcat = true, traceEmissionCount = true)
		} else {
		this
		}
		}

		/**
		* Maps a set of T to a set of V, minimizing the number of `createValue` calls taking into
		* account the diff between each root flow emission.
		*
		* This is needed to minimize the number of [getDisplayFromDisplayManager] in this class. Note
		* that if the [createValue] returns a null element, it will not be added in the output set.
		*/
		private fun <T, V> Flow<Set<T>>.mapElementsLazily(createValue: (T) -> V?): Flow<Set<V>> {
		data class State<T, V>(
		val previousSet: Set<T>,
		// Caches T values from the previousSet that were already converted to V
		val valueMap: Map<T, V>,
		val resultSet: Set<V>,
		)

		val emptyInitialState = State(emptySet<T>(), emptyMap(), emptySet<V>())
		return this.scan(emptyInitialState) { state, currentSet ->
		if (currentSet == state.previousSet) {
		state
		} else {
		val removed = state.previousSet - currentSet
		val added = currentSet - state.previousSet
		val newMap = state.valueMap.toMutableMap()

		added.forEach { key -> createValue(key)?.let { newMap[key] = it } }
		removed.forEach { key -> newMap.remove(key) }

		val resultSet = newMap.values.toSet()
		State(currentSet, newMap, resultSet)
		}
		}
		.filter { it != emptyInitialState }
		.map { it.resultSet }
		}

		private companion object {
		const val TAG = "DisplayRepository"
		val DEBUG = Log.isLoggable(TAG, Log.DEBUG)
		}
		}

		/** Used to provide default implementations for all methods. */
		private interface DisplayConnectionListener : DisplayListener {

		override fun onDisplayConnected(id: Int) {}

		override fun onDisplayDisconnected(id: Int) {}

		override fun onDisplayAdded(id: Int) {}

		override fun onDisplayRemoved(id: Int) {}

		override fun onDisplayChanged(id: Int) {}
		}

		private sealed interface DisplayEvent {
		val displayId: Int

		data class Added(override val displayId: Int) : DisplayEvent

		data class Removed(override val displayId: Int) : DisplayEvent

		data class Changed(override val displayId: Int) : DisplayEvent
		}

		/**
		* Returns a new [Flow] that combines the two most recent emissions from [this] using [transform].
		* Note that the new Flow will not start emitting until it has received two emissions from the
		* upstream Flow.
		*
		* Useful for code that needs to compare the current value to the previous value.
		*/
		// TODO b/401305290 - This should be moved to a shared lib, as it's also used by SystemUI.
		fun <T, R> Flow<T>.pairwiseBy(transform: suspend (old: T, new: T) -> R): Flow<R> = flow {
		val noVal = Any()
		var previousValue: Any? = noVal
		collect { newVal ->
		if (previousValue != noVal) {
		@Suppress("UNCHECKED_CAST") emit(transform(previousValue as T, newVal))
		}
		previousValue = newVal
		}
		}

displaylib/tests/Android.bp

+1 −0

Original line number	Diff line number	Diff line
		@@ -24,6 +24,7 @@ android_test {
		"androidx.test.ext.junit",
		"androidx.test.rules",
		"truth",
		"//frameworks/libs/systemui:tracinglib-platform",
		],
		srcs: [
		"tests/src/*/.kt",

displaylib/tests/src/com/android/app/displaylib/DisplayRepositoryTest.kt

+1 −6

Original line number	Diff line number	Diff line
		@@ -17,16 +17,11 @@ package com.android.app.displaylib

		import androidx.test.ext.junit.runners.AndroidJUnit4
		import androidx.test.filters.SmallTest
		import com.google.common.truth.Truth.assertThat
		import org.junit.Test
		import org.junit.runner.RunWith

		@SmallTest
		@RunWith(AndroidJUnit4::class)
		class DisplayRepositoryTest {

		@Test
		fun displays_empty() {
		assertThat(DisplayRepositoryImpl().displays.value).isEmpty()
		}
		// TODO b/401305290 - Move tests from The SystemUI DisplayRepositoryImpl to here.
		}