App Bar Final

action_menu_08.kt

sealed interface ActionMenuItem {
    val title: String
    val onClick: () -> Unit

    sealed interface IconMenuItem : ActionMenuItem {
        val icon: ImageVector
        val contentDescription: String?

        data class AlwaysShown(
            override val title: String,
            override val contentDescription: String?,
            override val onClick: () -> Unit,
            override val icon: ImageVector,
        ) : IconMenuItem

        data class ShownIfRoom(
            override val title: String,
            override val contentDescription: String?,
            override val onClick: () -> Unit,
            override val icon: ImageVector,
        ) : IconMenuItem
    }

    data class NeverShown(
        override val title: String,
        override val onClick: () -> Unit,
    ) : ActionMenuItem
}

@Composable
fun ActionsMenu(
    items: List<ActionMenuItem>,
    isOpen: Boolean,
    onToggleOverflow: () -> Unit,
    maxVisibleItems: Int,
) {
    val menuItems = remember(
        key1 = items,
        key2 = maxVisibleItems,
    ) {
        splitMenuItems(items, maxVisibleItems)
    }

    menuItems.alwaysShownItems.forEach { item ->
        IconButton(onClick = item.onClick) {
            Icon(
                imageVector = item.icon,
                contentDescription = item.contentDescription,
            )
        }
    }

    if (menuItems.overflowItems.isNotEmpty()) {
        IconButton(onClick = onToggleOverflow) {
            Icon(
                imageVector = Icons.Filled.MoreVert,
                contentDescription = "Overflow",
            )
        }
        DropdownMenu(
            expanded = isOpen,
            onDismissRequest = onToggleOverflow,
        ) {
            menuItems.overflowItems.forEach { item ->
                DropdownMenuItem(
                    text = {
                        Text(item.title)
                    },
                    onClick = item.onClick
                )
            }
        }
    }
}

private data class MenuItems(
    val alwaysShownItems: List<ActionMenuItem.IconMenuItem>,
    val overflowItems: List<ActionMenuItem>,
)

private fun splitMenuItems(
    items: List<ActionMenuItem>,
    maxVisibleItems: Int,
): MenuItems {
    val alwaysShownItems: MutableList<ActionMenuItem.IconMenuItem> =
        items.filterIsInstance<ActionMenuItem.IconMenuItem.AlwaysShown>().toMutableList()
    val ifRoomItems: MutableList<ActionMenuItem.IconMenuItem> =
        items.filterIsInstance<ActionMenuItem.IconMenuItem.ShownIfRoom>().toMutableList()
    val overflowItems = items.filterIsInstance<ActionMenuItem.NeverShown>()

    val hasOverflow = overflowItems.isNotEmpty() ||
        (alwaysShownItems.size + ifRoomItems.size - 1) > maxVisibleItems
    val usedSlots = alwaysShownItems.size + (if (hasOverflow) 1 else 0)
    val availableSlots = maxVisibleItems - usedSlots
    if (availableSlots > 0 && ifRoomItems.isNotEmpty()) {
        val visible = ifRoomItems.subList(0, availableSlots.coerceAtMost(ifRoomItems.size))
        alwaysShownItems.addAll(visible)
        ifRoomItems.removeAll(visible)
    }

    return MenuItems(
        alwaysShownItems = alwaysShownItems,
        overflowItems = ifRoomItems + overflowItems,
    )
}

@OptIn(ExperimentalMaterial3Api::class)
@Preview(widthDp = 440, showBackground = true)
@Preview(widthDp = 440, uiMode = Configuration.UI_MODE_NIGHT_YES, showBackground = true)
@Composable
private fun ActionMenuPreview(
    @PreviewParameter(ActionMenuParameterProvider::class) items: List<ActionMenuItem>
) {
    PlaygroundTheme {
        var menuOpen by remember {
            mutableStateOf(false)
        }
        val numAlwaysShown = items.count { item -> item is ActionMenuItem.IconMenuItem.AlwaysShown }
        val numIfRoom = items.count { item -> item is ActionMenuItem.IconMenuItem.ShownIfRoom }
        val numOverflow = items.count { item -> item is ActionMenuItem.NeverShown }
        val label = "Always: $numAlwaysShown Room: $numIfRoom Over: $numOverflow"
        TopAppBar(
            title = { Text(label) },
            modifier = Modifier.fillMaxWidth(),
            actions = {
                ActionsMenu(
                    items = items,
                    isOpen = menuOpen,
                    onToggleOverflow = { menuOpen = !menuOpen },
                    maxVisibleItems = 3
                )
            }
        )
    }
}

private class ActionMenuParameterProvider : PreviewParameterProvider<List<ActionMenuItem>> {
    override val values: Sequence<List<ActionMenuItem>>
        get() = sequenceOf(
            listOf(
                ActionMenuItem.IconMenuItem.AlwaysShown(
                    title = "Search",
                    onClick = {},
                    icon = Icons.Filled.Search,
                    contentDescription = null,
                ),
                ActionMenuItem.IconMenuItem.AlwaysShown(
                    title = "Favorite",
                    onClick = {},
                    icon = Icons.Filled.FavoriteBorder,
                    contentDescription = null,
                ),
                ActionMenuItem.IconMenuItem.AlwaysShown(
                    title = "Star",
                    onClick = {},
                    icon = Icons.Filled.Star,
                    contentDescription = null,
                ),
                ActionMenuItem.IconMenuItem.ShownIfRoom(
                    title = "Refresh",
                    onClick = {},
                    icon = Icons.Filled.Refresh,
                    contentDescription = null,
                ),
                ActionMenuItem.NeverShown(
                    title = "Settings",
                    onClick = {},
                ),
                ActionMenuItem.NeverShown(
                    title = "About",
                    onClick = {},
                ),
            ),
            listOf(
                ActionMenuItem.IconMenuItem.AlwaysShown(
                    title = "Search",
                    onClick = {},
                    icon = Icons.Filled.Search,
                    contentDescription = null,
                ),
                ActionMenuItem.IconMenuItem.AlwaysShown(
                    title = "Favorite",
                    onClick = {},
                    icon = Icons.Filled.FavoriteBorder,
                    contentDescription = null,
                ),
                ActionMenuItem.IconMenuItem.ShownIfRoom(
                    title = "Star",
                    onClick = {},
                    icon = Icons.Filled.Star,
                    contentDescription = null,
                ),
                ActionMenuItem.IconMenuItem.ShownIfRoom(
                    title = "Refresh",
                    onClick = {},
                    icon = Icons.Filled.Refresh,
                    contentDescription = null,
                ),
                ActionMenuItem.NeverShown(
                    title = "Settings",
                    onClick = {},
                ),
                ActionMenuItem.NeverShown(
                    title = "About",
                    onClick = {},
                ),
            ),
            listOf(
                ActionMenuItem.IconMenuItem.AlwaysShown(
                    title = "Search",
                    onClick = {},
                    icon = Icons.Filled.Search,
                    contentDescription = null,
                ),
                ActionMenuItem.IconMenuItem.ShownIfRoom(
                    title = "Favorite",
                    onClick = {},
                    icon = Icons.Filled.FavoriteBorder,
                    contentDescription = null,
                ),
                ActionMenuItem.IconMenuItem.ShownIfRoom(
                    title = "Star",
                    onClick = {},
                    icon = Icons.Filled.Star,
                    contentDescription = null,
                ),
                ActionMenuItem.IconMenuItem.ShownIfRoom(
                    title = "Refresh",
                    onClick = {},
                    icon = Icons.Filled.Refresh,
                    contentDescription = null,
                ),
                ActionMenuItem.NeverShown(
                    title = "Settings",
                    onClick = {},
                ),
                ActionMenuItem.NeverShown(
                    title = "About",
                    onClick = {},
                ),
            ),
            listOf(
                ActionMenuItem.IconMenuItem.ShownIfRoom(
                    title = "Search",
                    onClick = {},
                    icon = Icons.Filled.Search,
                    contentDescription = null,
                ),
                ActionMenuItem.IconMenuItem.ShownIfRoom(
                    title = "Favorite",
                    onClick = {},
                    icon = Icons.Filled.FavoriteBorder,
                    contentDescription = null,
                ),
                ActionMenuItem.IconMenuItem.ShownIfRoom(
                    title = "Star",
                    onClick = {},
                    icon = Icons.Filled.Star,
                    contentDescription = null,
                ),
                ActionMenuItem.IconMenuItem.ShownIfRoom(
                    title = "Refresh",
                    onClick = {},
                    icon = Icons.Filled.Refresh,
                    contentDescription = null,
                ),
                ActionMenuItem.NeverShown(
                    title = "Settings",
                    onClick = {},
                ),
                ActionMenuItem.NeverShown(
                    title = "About",
                    onClick = {},
                ),
            ),
            listOf(
                ActionMenuItem.IconMenuItem.ShownIfRoom(
                    title = "Search",
                    onClick = {},
                    icon = Icons.Filled.Search,
                    contentDescription = null,
                ),
                ActionMenuItem.IconMenuItem.ShownIfRoom(
                    title = "Favorite",
                    onClick = {},
                    icon = Icons.Filled.FavoriteBorder,
                    contentDescription = null,
                ),
            ),
            listOf(
                ActionMenuItem.NeverShown(
                    title = "Search",
                    onClick = {},
                ),
                ActionMenuItem.NeverShown(
                    title = "Favorite",
                    onClick = {},
                ),
            ),
        )
}