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leanback-to-compose-tv-migration

Provides instructions and architectural patterns for migrating Android

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技能内容

The 10-foot UI

A "10-foot UI" is a design paradigm for televisions that tailors an interface

for viewing from approximately 3 meters (10 feet) away. When designing for this

experience, account for these key characteristics:

  • Viewing distance: Viewers are sitting far from the screen, "leaning back". Screen layouts are uncluttered, with text and UI elements that are large enough to be comfortably readable from a distance, without dense blocks of text.
  • Color contrast: To avoid washed out colors on TV displays with low contrast ratios, the design uses high-contrast palettes and distinct visual indicators so focused states remain visible across different TV panels.
  • D-pad navigation : Interaction relies on a directional remote control with limited 4-way navigation (Up, Down, Left, Right) with components organized into clear spatial grids and carousels without focus traps.

Core architecture and library selection

When migrating an Android TV application to Jetpack Compose, you must use

androidx.tv libraries and follow these 10-foot UI patterns:

  • UI modernization: Focus on custom, cinematic layouts over legacy direct 1:1 templates. You must use Jetpack Compose for TV features like dynamic gradient hero backdrops, custom focus animations, custom navigation drawers, and custom layouts.
  • Primary design system : You must always use androidx.tv.material3. (androidx.tv:tv-material) over mobile androidx.compose.material3.. TV Material 3 provides built-in D-Pad focus handling, focus zoom scaling, and TV-optimized typography and shapes. To set up Compose for TV dependencies, follow [Compose for TV setup](references/android/training/tv/playback/compose/index.md).
  • Focus zoom animation : For interactive cards, you must use CompactCard, ClassicCard, or WideCardContainer with `scale =

CardDefaults.scale(focusedScale = 1.1f)` to provide standard TV focus animation.

  • Coil image loading : To use declarative `AsyncImage(model,

contentDescription, ...) without passing an explicit ImageLoader parameter, you must include io.coil-kt:coil-compose` in your Gradle dependencies.

  • Explicit imports : You must always import TV Material 3 classes explicitly (for example, import androidx.tv.material3.Surface, `import

androidx.tv.material3.ListItem) instead of using wildcard imports (import

androidx.tv.material3.*`).

  • File naming conventions : You must name Composable screen files after the screen (for example, name BrowseScreen as BrowseScreen.kt, PlaybackScreen as PlaybackScreen.kt, and AuthenticationScreen as AuthenticationScreen.kt). Don't use generic prefixes like Main.
  • Overscan and bezels : You must apply horizontal padding (for example, horizontal = 48.dp or 32.dp, vertical = 24.dp) to root containers, carousels, and top bars to prevent clipping.
  • Reading width constrainment : You must constrain reading width using Modifier.widthIn(max = 600.dp) on text columns for long-form text.
  • Media3 Compose dependencies : Include androidx.media3:media3-ui-compose in app/build.gradle when modernizing media playback screens.
  • Prohibition of legacy AndroidView wrappers : Don't use legacy AndroidView wrappers to embed View-based components into Jetpack Compose screens. All migrated screens must use Compose components or Media3 Compose surfaces (PlayerSurface).

D-pad focus handling and navigation

Jetpack Compose for TV (androidx.tv.material3) requires explicit focus

management, as components don't receive initial focus automatically and

navigation uses 2D spatial coordinates. To configure TV D-pad navigation, follow

instructions in [TV Navigation guide](references/android/training/tv/get-started/navigation.md).

Initial focus

You must assign initial focus to the primary interactive element on every screen

(such as the first action button, card, or ListItem) using FocusRequester

when entering a screen. Define `val focusRequester = remember { FocusRequester()

}, attach Modifier.focusRequester(focusRequester)` to the primary element, and

request focus inside LaunchedEffect(Unit) { focusRequester.requestFocus() }:

val focusRequester = remember { FocusRequester() }
val focusManager = LocalFocusManager.current

LaunchedEffect(Unit) {
    focusRequester.requestFocus()
}

<br />

*Note: For screens with dynamic state or pagers (like OnboardingScreen using

HorizontalPager), you must pass the state key to LaunchedEffect (for example

LaunchedEffect(pagerState.currentPage)) so that focus is re-applied when the

page changes.*

Bidirectional focus routing and avoiding focus traps

When interactive elements sit on opposite sides of the display, standard 2D

spatial navigation fails to find targets across them. This creates focus traps

where users are unable to navigate out of an area using the D-pad.

For symmetrical, bidirectional D-pad navigation without focus traps, you must

rely on Compose's 2D spatial focus engine whenever possible. When connecting

adjacent UI elements across scrollable containers (like LazyColumn or

LazyRow), don't set directional overrides (up = ..., down = ...) targeting

individual items inside lazy lists. When an item scrolls off-screen during

vertical navigation, its FocusRequester becomes uninitialized, throwing

IllegalStateException during focus searches:

Row(
    modifier = Modifier
        .fillMaxWidth()
        .padding(horizontal = 48.dp, vertical = 16.dp),
    horizontalArrangement = Arrangement.End
) {
    Button(
        onClick = { /* Search */ },
        modifier = Modifier.focusRequester(topBarFocusRequester)
    ) { Text("Search") }
}

<br />

Row focus recollection (Modifier.focusRestorer)

When navigating vertically between horizontal carousels (LazyRow), Compose's

default 2D spatial focus engine searches along the X coordinate of the focused

item. If a user scrolls right in Row 1 (for example to Item 4 at X=800dp) and

presses DOWN to navigate to Row 2, spatial routing focuses whatever item sits at

X=800dp in Row 2.

To make every row maintain its own recollection of card focus (restoring focus

to the previously visited item when revisited), you must attach

Modifier.focusRestorer (with no arguments) directly to the LazyRow.

Don't pass custom fallback FocusRequester lambdas in lazy containers, as

calling requestFocus on an unattached or off-screen item during rapid D-pad

scrolling throws IllegalStateException.

LazyRow(
    modifier = Modifier.focusRestorer(),
    contentPadding = PaddingValues(horizontal = 48.dp),
    horizontalArrangement = Arrangement.spacedBy(16.dp)
) {
    itemsIndexed(videos) { vidIndex, video ->
        CompactCard(
            onClick = { onVideoClick(video) },
            image = {
                AsyncImage(
                    model = video.cardImageUrl,
                    contentDescription = video.title,
                    contentScale = ContentScale.Crop,
                    modifier = Modifier.fillMaxSize()
                )
            },
            title = { Text(video.title) },
            modifier = Modifier
                .then(
                    if (catIndex == 0 && vidIndex == 0) {
                        Modifier.focusRequester(firstCardFocusRequester)
                    } else {
                        Modifier
                    }
                )
                .onFocusChanged { focusState ->
                    if (focusState.isFocused) {
                        focusedVideo = video
                        focusedCategoryIndex = catIndex
                    }
                }
        )
    }
}

<br />

Text input, hardware keyboard enter interception, and IME focus chaining

When migrating search bars or login forms from Leanback

(SearchSupportFragment, GuidedStepSupportFragment), don't use bare

BasicTextField containers or empty Surface(onClick = {}) wrappers, as they

prevent D-pad CENTER from attaching the virtual keyboard (IME).

  1. **Clickable TV surface wrapper with Back-key interception

(onPreviewKeyEvent)** : Wrap standard M3 TextField inside a focusable TV `Surface(onClick = { focusRequester.requestFocus() }, scale =

ClickableSurfaceDefaults.scale(focusedScale = 1.01f), border =

ClickableSurfaceDefaults.border(focusedBorder = Border(BorderStroke(2.dp,

Color.White)))) to provide a focused border outline and D-pad focus scaling. You must attach Modifier.onPreviewKeyEvent on the text field or wrapper to intercept Key.Back and Key.Escape` so the user's able to remove focus from the input field without exiting the screen.

  1. Why Back-key interception is mandatory : When editing a text field on Android TV, pressing the D-pad Back button normally navigates back and exits the screen. By intercepting Key.Back and Key.Escape on KeyUp in onPreviewKeyEvent to stop editing (clearing focus), the user's able to return to D-pad form navigation without being trapped in the text field or accidentally exiting the screen.
  2. IME focus chaining : For multi-field forms (such as Username and Password in authentication screens), attach `KeyboardActions(onNext = {

focusManager.moveFocus(FocusDirection.Down) }) with ImeAction.Next on top fields to route focus down to the next input box, and ImeAction.Done` on the bottom field to route focus directly to the submit button:

Surface(
    onClick = { focusRequester.requestFocus() },
    border = ClickableSurfaceDefaults.border(focusedBorder = Border(border = BorderStroke(2.dp, Color.White))),
    modifier = Modifier
        .fillMaxWidth()
        .focusRequester(focusRequester)
) {
    OutlinedTextField(
        value = username,
        onValueChange = { username = it },
        label = { Text("Username") },
        singleLine = true,
        keyboardOptions = KeyboardOptions(imeAction = ImeAction.Next),
        keyboardActions = KeyboardActions(onNext = { focusManager.moveFocus(FocusDirection.Down) }),
        modifier = Modifier
            .fillMaxWidth()
            .onPreviewKeyEvent { event ->
                if (event.type == KeyEventType.KeyDown && (event.key == Key.Enter || event.key == Key.NumPadEnter)) {
                    focusManager.moveFocus(FocusDirection.Down)
                    true
                } else false
            }
    )
}

Surface(
    onClick = {},
    border = ClickableSurfaceDefaults.border(focusedBorder = Border(border = BorderStroke(2.dp, Color.White))),
    modifier = Modifier.fillMaxWidth()
) {
    OutlinedTextField(
        value = password,
        onValueChange = { password = it },
        label = { Text("Password") },
        singleLine = true,
        visualTransformation = PasswordVisualTransformation(),
        keyboardOptions = KeyboardOptions(imeAction = ImeAction.Done),
        keyboardActions = KeyboardActions(onDone = { onLoginSuccess() }),
        modifier = Modifier
            .fillMaxWidth()
            .onPreviewKeyEvent { event ->
                if (event.type == KeyEventType.KeyDown && (event.key == Key.Enter || event.key == Key.NumPadEnter)) {
                    onLoginSuccess()
                    true
                } else false
            }
    )
}

<br />

Lazy containers

When implementing scrollable lists or grids in Jetpack Compose for TV, you must

use standard LazyColumn, LazyRow, and LazyVerticalGrid from

androidx.compose.foundation.lazy and androidx.compose.foundation.lazy.grid.

For catalog browsing layouts, follow instructions in [Catalog Browser guide](references/android/training/tv/playback/compose/browse.md).

  1. Pivot scrolling with BringIntoViewSpec : When defining a custom pivot scroll line for catalog rows using BringIntoViewSpec and CompositionLocalProvider(LocalBringIntoViewSpec provides ...), you must ensure your project compiles against Compose Foundation 1.7.0+ by adding implementation platform('androidx.compose:compose-bom:2024.06.00') (or newer) or implementation 'androidx.compose.foundation:foundation:1.7.0' in app/build.gradle. Without Compose Foundation 1.7.0+, `import

androidx.compose.foundation.gestures.LocalBringIntoViewSpec will fail with Unresolved reference: LocalBringIntoViewSpec`.

  1. Row focus recollection (Modifier.focusRestorer) : Annotate your composable with `@OptIn(ExperimentalFocusRestorerApi::class,

ExperimentalComposeUiApi::class) and attach Modifier.focusRestorer on every category LazyRow` to remember and restore the last focused card when navigating vertically across catalog rows.

When populated with focusable TV Material 3 components (CompactCard,

ListItem, Button), standard Compose lazy containers handle 2D D-Pad focus

routing, focus memory, and edge scrolling automatically:

@Composable
fun CatalogBrowser(
    featuredContentList: List<Movie>,
    sectionList: List<Section>,
    modifier: Modifier = Modifier,
    onItemSelected: (Movie) -> Unit = {},
) {
    LazyColumn(
        modifier = modifier.fillMaxSize(),
        verticalArrangement = Arrangement.spacedBy(16.dp)
    ) {
        items(sectionList.size) { index ->
            val section = sectionList[index]
            SectionRow(section, onItemSelected = onItemSelected)
        }
    }
}

<br />

Media3 video playback and transport controls

When migrating legacy Leanback video playback (VideoSupportFragment /

PlaybackGlue), use Compose Media3 PlayerSurface

(androidx.media3.ui.compose.PlayerSurface) combined with a translucent

transport controls overlay:

  1. Mandatory Media3 transport control buttons (PlayPauseButton) : Over the PlayerSurface, you must layer a translucent bottom controls bar (Box(modifier = Modifier.align(Alignment.BottomCenter))) containing explicit Media3 UI Compose buttons: at minimum PlayPauseButton, SeekBackButton, and SeekForwardButton. Never leave the transport controls overlay empty. To use these composables, you must add implementation 'androidx.media3:media3-ui-compose-material3:1.6.0' alongside androidx.media3:media3-ui-compose in your app/build.gradle dependencies.
  2. D-pad directional seeking (onPreviewKeyEvent) : To support seeking backward and forward with the remote control D-pad, attach Modifier.onPreviewKeyEvent on the container or controls overlay and intercept Compose Key.DirectionLeft and Key.DirectionRight (for example, keyEvent.key == Key.DirectionLeft) to seek backward and forward by 10 seconds (exoPlayer.seekTo(exoPlayer.currentPosition - 10000)). Never use legacy Android View keycodes (KeyEvent.KEYCODE_DPAD_LEFT or nativeKeyEvent.keyCode).
  3. Prohibition of legacy AndroidView wrappers : Don't wrap legacy PlayerView or StyledPlayerView in AndroidView { ... }. You must use PlayerSurface (androidx.media3.ui.compose.PlayerSurface) with ExoPlayer for video rendering in Compose for TV.

Phased migration strategy

To migrate an app cleanly without breaking compilation or introducing circular

dependencies, execute in five distinct phases:

  • Phase 1: Foundation and design system
  • Phase 2: Leaf and standalone screens
  • Phase 3: Core browsing and discovery screens
  • Phase 4: Details and media playback
  • Phase 5: Final unification and cleanup

Phase 1: Foundation and design system

  • Create TvTheme.kt wrapping TvMaterialTheme with custom ColorScheme, Typography, and Shapes.
  • Build atomic reusable components: MovieCard, SectionHeader, LoadingIndicator, ErrorState.

Phase 2: Leaf and standalone screens

  • Migrate screens with no outbound navigation first, such as error messages, onboarding screens, or settings screens, by replacing them with ErrorDialog, OnboardingScreen, and SettingsScreen.
  • Replace anything using BaseLeanbackPreferenceFragmentCompat, BaseLeanbackPreferenceFragment, or LeanbackSettingsFragment to use Compose, for example by using ListItem + Switch bound directly to SharedPreferences and replacing the findPreference implementation.
  • Ensure screens receive initial D-pad focus on the first or main component of that screen using FocusRequester, for example on the first ListItem.
  • Replace legacy Fragment classes with activities of type ComponentActivity that declaratively use components in Compose.
  • Clean up legacy style and theme references in res/values/styles.xml and res/values/themes.xml (such as removing preferenceTheme that points to @style/PreferenceThemeOverlay.v14.Leanback) that aren't supported once leanback dependencies are removed:
@Composable
fun TvSettingsScreen(
    modifier: Modifier = Modifier
) {
    var autoPlayNext by remember { mutableStateOf(true) }
    var highQualityAudio by remember { mutableStateOf(false) }

    Column(
        modifier = modifier
            .fillMaxSize()
            .padding(48.dp)
    ) {
        Text(
            text = "Settings",
            style = MaterialTheme.typography.headlineMedium,
            modifier = Modifier.padding(bottom = 24.dp)
        )

        LazyColumn(
            verticalArrangement = Arrangement.spacedBy(12.dp),
            contentPadding = PaddingValues(vertical = 8.dp)
        ) {
            item {
                ListItem(
                    selected = false,
                    onClick = { autoPlayNext = !autoPlayNext },
                    headlineContent = { Text("Autoplay Next Video") },
                    supportingContent = { Text("Automatically start playing next item in queue") },
                    trailingContent = {
                        Switch(
                            checked = autoPlayNext,
                            onCheckedChange = null
                        )
                    }
                )
            }

            item {
                ListItem(
                    selected = false,
                    onClick = { highQualityAudio = !highQualityAudio },
                    headlineContent = { Text("High Quality Audio") },
                    supportingContent = { Text("Use spatial audio and multi-channel output when available") },
                    trailingContent = {
                        Switch(
                            checked = highQualityAudio,
                            onCheckedChange = null
                        )
                    }
                )
            }
        }
    }
}

<br />

Phase 3: Core browsing and discovery screens

  • Migrate VerticalGridScreen (LazyVerticalGrid), SearchScreen (BasicTextField with live list filtering), and BrowseScreen (LazyColumn of LazyRows).
  • Eradicate legacy ArrayObjectAdapter, ListRowPresenter, CardPresenter, and HeaderItem classes.

Phase 4: Details and media playback

  • Migrate VideoDetailsScreen and GuidedStepScreen.
  • Migrate PlaybackScreen using Compose Media3 PlayerSurface (androidx.media3.ui.compose.PlayerSurface) paired with a translucent bottom overlay containing Media3 Compose transport controls (such as PlayPauseButton, SeekBackButton, SeekForwardButton).

Phase 5: Final unification and cleanup

  • Remove all remaining legacy .java activities, fragments, presenters, and XML layout files.
  • Ensure all activities extend ComponentActivity or FragmentActivity calling setContent { ... }.
  • Completely remove legacy Leanback themes and style declarations from res/values/styles.xml and res/values/themes.xml (for example, any styles inheriting from Theme.Leanback or referencing lb_ styles).

Component and class mapping guide

| Legacy Leanback / View Class | Modern Jetpack Compose Equivalent |

|---|---|

| BrowseSupportFragment / MainFragment | BrowseScreen (LazyColumn containing categorized LazyRows + Hero Banner) |

| DetailsSupportFragment | VideoDetailsScreen (Poster image, text column, action buttons, related LazyRow) |

| VideoSupportFragment / PlaybackGlue | PlaybackScreen (Media3 ExoPlayer + Compose PlayerSurface) |

| GuidedStepSupportFragment | GuidedStepScreen (Split-screen layout: 40% left guidance pane, 60% right actions pane) |

| SearchSupportFragment | SearchScreen (BasicTextField + live filtering + LazyVerticalGrid) |

| VerticalGridSupportFragment | VerticalGridScreen (LazyVerticalGrid(columns = GridCells.Fixed(5))) |

| ArrayObjectAdapter / Presenter | Declarative @Composable functions observing immutable State<List<T>> |

| CursorMapper / LoaderManager / CursorLoader | Kotlin Coroutines / withContext(Dispatchers.IO) in a Repository object |

| OnboardingSupportFragment | OnboardingScreen (HorizontalPager + D-Pad navigation buttons) |

| LeanbackSettingsFragment / PreferenceFragment | SettingsScreen (FocusRequester on first ListItem + trailing Switch bound to SharedPreferences) |

Reference implementations and battle-tested patterns

Modern TV immersive list architecture (BrowseScreen)

When building a 10-foot TV browse screen or Immersive List, don't place a hero

banner before or outside a scrolling list, and don't fight Compose's automatic

BringIntoView system with programmatic animateScrollToItem calls.

Instead, use BringIntoViewSpec with LocalBringIntoViewSpec from Compose

Foundation to define exact TV pivot scrolling (for example, pivoting active rows

at 35% from the top edge of the display). Combine this with a reshaping

immersive row: when lower rows are focused (focusedCategoryIndex > 0), hide

the hero text and display a normal section header on Row 0:

@Composable
fun ImmersiveBrowseScreen(
    categories: Map<String, List<Video>>,
    onVideoClick: (Video) -> Unit
) {
    var focusedVideo by remember { mutableStateOf<Video?>(null) }
    var focusedCategoryIndex by remember { mutableStateOf(0) }
    val listState = rememberLazyListState()
    val topBarFocusRequester = remember { FocusRequester() }
    val firstCardFocusRequester = remember { FocusRequester() }

    Box(modifier = Modifier.fillMaxSize()) {
        AsyncImage(
            model = focusedVideo?.bgImageUrl,
            contentDescription = null,
            contentScale = ContentScale.Crop,
            modifier = Modifier.fillMaxSize()
        )

        PositionFocusedItemInLazyLayout(parentFraction = 0.35f, childFraction = 0.5f) {
            LazyColumn(
                state = listState,
                contentPadding = PaddingValues(top = 36.dp, bottom = 64.dp),
                verticalArrangement = Arrangement.spacedBy(28.dp),
                modifier = Modifier.fillMaxSize()
            ) {
                item {
                    Row(
                        modifier = Modifier
                            .fillMaxWidth()
                            .padding(horizontal = 48.dp, vertical = 16.dp),
                        horizontalArrangement = Arrangement.End
                    ) {
                        Button(
                            onClick = { /* Search */ },
                            modifier = Modifier.focusRequester(topBarFocusRequester)
                        ) { Text("Search") }
                    }
                }

                itemsIndexed(categories.entries.toList()) { catIndex, (categoryName, videos) ->
                    Column {
                        if (catIndex == 0 && focusedCategoryIndex == 0) {
                            Column(
                                modifier = Modifier
                                    .heightIn(min = 200.dp)
                                    .padding(horizontal = 48.dp)
                            ) {
                                Text(
                                    text = focusedVideo?.title ?: "",
                                    style = MaterialTheme.typography.displayMedium
                                )
                                Text(
                                    text = focusedVideo?.description ?: "",
                                    style = MaterialTheme.typography.bodyLarge
                                )
                            }
                        } else {
                            Text(
                                text = categoryName,
                                style = MaterialTheme.typography.titleMedium,
                                modifier = Modifier.padding(horizontal = 48.dp, vertical = 8.dp)
                            )
                        }

                        LazyRow(
                            modifier = Modifier.focusRestorer(),
                            contentPadding = PaddingValues(horizontal = 48.dp),
                            horizontalArrangement = Arrangement.spacedBy(16.dp)
                        ) {
                            itemsIndexed(videos) { vidIndex, video ->
                                CompactCard(
                                    onClick = { onVideoClick(video) },
                                    image = {
                                        AsyncImage(
                                            model = video.cardImageUrl,
                                            contentDescription = video.title,
                                            contentScale = ContentScale.Crop,
                                            modifier = Modifier.fillMaxSize()
                                        )
                                    },
                                    title = { Text(video.title) },
                                    modifier = Modifier
                                        .then(
                                            if (catIndex == 0 && vidIndex == 0) {
                                                Modifier.focusRequester(firstCardFocusRequester)
                                            } else {
                                                Modifier
                                            }
                                        )
                                        .onFocusChanged { focusState ->
                                            if (focusState.isFocused) {
                                                focusedVideo = video
                                                focusedCategoryIndex = catIndex
                                            }
                                        }
                                )
                            }
                        }
                    }
                }
            }
        }
    }
}

@OptIn(ExperimentalFoundationApi::class)
@Composable
private fun PositionFocusedItemInLazyLayout(
    parentFraction: Float = 0.35f,
    childFraction: Float = 0.5f,
    content: @Composable () -> Unit,
) {
    val bringIntoViewSpec = remember(parentFraction, childFraction) {
        object : BringIntoViewSpec {
            override fun calculateScrollDistance(
                offset: Float,
                size: Float,
                containerSize: Float
            ): Float {
                if (offset >= 0f && offset <= containerSize * 0.45f) {
                    return 0f
                }
                val initialTargetForLeadingEdge = parentFraction * containerSize - (childFraction * size)
                val targetForLeadingEdge = if (size <= containerSize && (containerSize - initialTargetForLeadingEdge) < size) {
                    containerSize - size
                } else {
                    initialTargetForLeadingEdge
                }
                return offset - targetForLeadingEdge
            }
        }
    }
    CompositionLocalProvider(LocalBringIntoViewSpec provides bringIntoViewSpec, content = content)
}

<br />

Media3 playback in Compose TV (PlaybackScreen)

Implement a custom playback screen using

androidx.media3.ui.compose.PlayerSurface as the video rendering canvas. Layer

Material3 transport controls (SeekBackButton, PlayPauseButton,

SeekForwardButton from androidx.media3:media3-ui-compose-material3) over the

surface in a translucent bottom overlay, and handle D-pad remote key events with

an auto-hide timeout:

@OptIn(UnstableApi::class)
@Composable
fun Media3PlaybackScreen(
    video: Video,
    onFinish: () -> Unit,
    modifier: Modifier = Modifier
) {
    val context = LocalContext.current
    val exoPlayer = remember(context) { ExoPlayer.Builder(context).build() }
    var showControls by remember { mutableStateOf(true) }
    val focusRequester = remember { FocusRequester() }
    val coroutineScope = rememberCoroutineScope()
    var autoHideJob by remember { mutableStateOf<Job?>(null) }

    fun scheduleAutoHide() {
        autoHideJob?.cancel()
        autoHideJob = coroutineScope.launch {
            delay(5000)
            showControls = false
        }
    }

    DisposableEffect(exoPlayer) {
        val listener = object : Player.Listener {
            override fun onPlaybackStateChanged(playbackState: Int) {
                if (playbackState == Player.STATE_ENDED) {
                    onFinish()
                }
            }
        }
        exoPlayer.addListener(listener)
        onDispose {
            autoHideJob?.cancel()
            exoPlayer.removeListener(listener)
            exoPlayer.release()
        }
    }

    LaunchedEffect(video) {
        focusRequester.requestFocus()
        scheduleAutoHide()

        val mediaItem = MediaItem.fromUri(video.videoUrl)
        exoPlayer.setMediaItem(mediaItem)
        exoPlayer.prepare()
        exoPlayer.playWhenReady = true
    }

    Box(
        modifier = modifier
            .fillMaxSize()
            .background(Color.Black)
            .focusRequester(focusRequester)
            .focusable()
            .onPreviewKeyEvent { event ->
                if (event.type == KeyEventType.KeyDown) {
                    when (event.key) {
                        Key.DirectionCenter, Key.Enter, Key.NumPadEnter, Key.MediaPlayPause, Key.Spacebar -> {
                            if (exoPlayer.isPlaying) exoPlayer.pause() else exoPlayer.play()
                            showControls = true
                            scheduleAutoHide()
                            true
                        }
                        Key.DirectionLeft, Key.MediaRewind -> {
                            val newPos = (exoPlayer.currentPosition - 10_000L).coerceAtLeast(0L)
                            exoPlayer.seekTo(newPos)
                            showControls = true
                            scheduleAutoHide()
                            true
                        }
                        Key.DirectionRight, Key.MediaFastForward -> {
                            val duration = exoPlayer.duration.coerceAtLeast(0L)
                            val newPos = (exoPlayer.currentPosition + 10_000L).coerceAtMost(duration)
                            exoPlayer.seekTo(newPos)
                            showControls = true
                            scheduleAutoHide()
                            true
                        }
                        Key.DirectionUp, Key.DirectionDown -> {
                            showControls = !showControls
                            if (showControls) scheduleAutoHide() else autoHideJob?.cancel()
                            true
                        }
                        else -> false
                    }
                } else false
            },
        contentAlignment = Alignment.Center
    ) {
        PlayerSurface(
            player = exoPlayer,
            modifier = Modifier.fillMaxSize()
        )

        if (showControls) {
            Box(
                modifier = Modifier
                    .fillMaxSize()
                    .background(Color(0x80000000))
                    .padding(48.dp),
                contentAlignment = Alignment.BottomCenter
            ) {
                Row(
                    horizontalArrangement = Arrangement.spacedBy(24.dp),
                    verticalAlignment = Alignment.CenterVertically
                ) {
                    SeekBackButton(player = exoPlayer)
                    PlayPauseButton(player = exoPlayer)
                    SeekForwardButton(player = exoPlayer)
                }
            }
        }
    }
}

<br />

Replacing CursorLoader with reactive coroutine flow

Replace legacy LoaderManager.LoaderCallbacks<Cursor> and CursorObjectAdapter

with a repository returning a Flow that observes database changes and triggers

asynchronous fetching when empty:

object VideoFlowRepository {
    fun getVideosFlow(context: Context, contentUri: Uri): Flow<List<Video>> = callbackFlow {
        val contentObserver = object : ContentObserver(Handler(Looper.getMainLooper())) {
            override fun onChange(selfChange: Boolean) {
                trySend(queryVideos(context, contentUri))
            }
        }

        context.contentResolver.registerContentObserver(
            contentUri,
            true,
            contentObserver
        )

        val initialVideos = queryVideos(context, contentUri)
        trySend(initialVideos)

        awaitClose {
            context.contentResolver.unregisterContentObserver(contentObserver)
        }
    }.flowOn(Dispatchers.IO)

    private fun queryVideos(context: Context, uri: Uri): List<Video> {
        // Query database or ContentProvider
        return emptyList()
    }
}

<br />

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星标★ 7,406
本站分层T1
该仓技能数24
原文件路径tv/leanback-to-compose-tv-migration/SKILL.md

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