Merge "Move page count to rememberPagerState" into aosp-main-future

import androidx.compose.foundation.layout.Column

import androidx.compose.foundation.layout.padding

import androidx.compose.foundation.pager.HorizontalPager

import androidx.compose.foundation.pager.PagerState

import androidx.compose.foundation.pager.rememberPagerState

import androidx.compose.material3.TabRow

import androidx.compose.runtime.Composable

import androidx.compose.runtime.LaunchedEffect

import androidx.compose.runtime.SideEffect

import androidx.compose.runtime.getValue

import androidx.compose.runtime.mutableStateOf

import androidx.compose.runtime.rememberCoroutineScope

import androidx.compose.runtime.saveable.rememberSaveable

import androidx.compose.runtime.setValue

import androidx.compose.ui.Modifier

import androidx.compose.ui.graphics.Color

import androidx.compose.ui.platform.LocalConfiguration

import com.android.settingslib.spa.framework.theme.SettingsDimension

import kotlin.math.absoluteValue

import kotlinx.coroutines.launch

    Column {

        val coroutineScope = rememberCoroutineScope()

        val pagerState = rememberPageStateFixed()

        val pagerState = rememberPagerState { titles.size }

        TabRow(

            selectedTabIndex = pagerState.currentPage,

            }

        }

        HorizontalPager(pageCount = titles.size, state = pagerState) { page ->

        HorizontalPager(state = pagerState) { page ->

            content(page)

        }

    }

}

/**

 * Gets the state of [PagerState].

 *

 * This is a work around.

 *

 * TODO: Remove this and replace with rememberPageState() after the Compose Foundation 1.5.0-alpha04

 *       updated in the platform.

 */

@Composable

@OptIn(ExperimentalFoundationApi::class)

private fun rememberPageStateFixed(): PagerState {

    var currentPage by rememberSaveable { mutableStateOf(0) }

    var targetPage by rememberSaveable { mutableStateOf(-1) }

    val pagerState = rememberPagerState()

    val configuration = LocalConfiguration.current

    var lastScreenWidthDp by rememberSaveable { mutableStateOf(-1) }

    val screenWidthDp = configuration.screenWidthDp

    LaunchedEffect(screenWidthDp) {

        // Reset pager state to fix an issue after configuration change.

        // When we declare android:configChanges in the manifest, the pager state is in a weird

        // state after configuration change.

        targetPage = currentPage

        lastScreenWidthDp = screenWidthDp

    }

    LaunchedEffect(targetPage) {

        if (targetPage != -1) {

            pagerState.scrollToPage(targetPage)

            targetPage = -1

        }

    }

    SideEffect {

        if (lastScreenWidthDp == screenWidthDp) {

            currentPage = pagerState.currentPage

        }

    }

    return pagerState

}