[New Reader] Hide menu on scroll

app/src/main/kotlin/com/hippo/ehviewer/ui/reader/ReaderScreen.kt

@@ -107,10 +107,10 @@ fun ReaderScreen(info: BaseGalleryInfo, page: Int = -1, navigator: DestinationsN
         val lazyListState = rememberLazyListState()
         val pagerState = rememberPagerState { pageLoader.size }
         val syncState = rememberSliderPagerDoubleSyncState(lazyListState, pagerState, pageLoader)
-        syncState.Sync(ReadingModeType.isWebtoon(readingMode))
         Box {
             var appbarVisible by remember { mutableStateOf(false) }
             val bgColor by collectBackgroundColorAsState()
+            syncState.Sync(ReadingModeType.isWebtoon(readingMode)) { appbarVisible = false }
             if (fullscreen) {
                 LaunchedEffect(Unit) {
                     snapshotFlow { appbarVisible }.collect {

app/src/main/kotlin/com/hippo/ehviewer/ui/reader/SliderPagerDoubleSync.kt

@@ -8,12 +8,11 @@ import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.Stable
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableIntStateOf
+import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.runtime.snapshotFlow
-import com.hippo.ehviewer.Settings
 import com.hippo.ehviewer.gallery.PageLoader2
-import kotlin.math.absoluteValue
 import kotlinx.coroutines.flow.collectLatest
 import kotlinx.coroutines.flow.filterNotNull
 
@@ -23,8 +22,7 @@ class SliderPagerDoubleSync(
     private val pagerState: PagerState,
     private val pageLoader: PageLoader2,
 ) {
-    private var requestScroll = true
-    private var sliderFollowPager = true
+    private var sliderFollowPager by mutableStateOf(false)
     var sliderValue by mutableIntStateOf(pageLoader.startPage + 1)
         private set
 
@@ -34,12 +32,12 @@ class SliderPagerDoubleSync(
     }
 
     @Composable
-    fun Sync(webtoon: Boolean) {
+    fun Sync(webtoon: Boolean, onPageSelected: () -> Unit) {
         val fling by lazyListState.interactionSource.collectIsDraggedAsState()
         val pagerFling by pagerState.interactionSource.collectIsDraggedAsState()
         if (fling || pagerFling) sliderFollowPager = true
         val currentIndexFlow = remember(webtoon) {
-            requestScroll = true
+            sliderFollowPager = false
             if (webtoon) {
                 snapshotFlow {
                     with(lazyListState.layoutInfo) {
@@ -52,41 +50,24 @@ class SliderPagerDoubleSync(
                 snapshotFlow { pagerState.currentPage }
             }
         }
-        LaunchedEffect(currentIndexFlow) {
-            currentIndexFlow.collect { index ->
-                if (sliderFollowPager && !requestScroll) {
+        if (sliderFollowPager) {
+            LaunchedEffect(currentIndexFlow) {
+                currentIndexFlow.collect { index ->
                     sliderValue = index + 1
                     pageLoader.startPage = index
+                    onPageSelected()
                 }
             }
-        }
-        LaunchedEffect(webtoon) {
-            snapshotFlow { sliderValue - 1 }.collectLatest { index ->
-                if (sliderFollowPager && !requestScroll) return@collectLatest
-                if (webtoon) {
-                    if (requestScroll) {
-                        lazyListState.requestScrollToItem(index)
-                        requestScroll = false
+        } else {
+            LaunchedEffect(webtoon) {
+                snapshotFlow { sliderValue - 1 }.collectLatest { index ->
+                    if (webtoon) {
+                        lazyListState.scrollToItem(index)
                     } else {
-                        if (smoothScroll((index - lazyListState.firstVisibleItemIndex))) {
-                            lazyListState.animateScrollToItem(index)
-                        } else {
-                            lazyListState.scrollToItem(index)
-                        }
-                    }
-                } else {
-                    if (requestScroll) {
-                        pagerState.requestScrollToPage(index)
-                        requestScroll = false
-                    } else {
-                        if (smoothScroll((index - pagerState.currentPage))) {
-                            pagerState.animateScrollToPage(index)
-                        } else {
-                            pagerState.scrollToPage(index)
-                        }
+                        pagerState.animateScrollToPage(index)
                     }
+                    pageLoader.startPage = index
                 }
-                pageLoader.startPage = index
             }
         }
     }
@@ -101,8 +82,3 @@ fun rememberSliderPagerDoubleSyncState(
 ): SliderPagerDoubleSync = remember {
     SliderPagerDoubleSync(lazyListState, pagerState, pageLoader)
 }
-
-private fun smoothScroll(distance: Int) =
-    distance.absoluteValue < SMOOTH_SCROLL_THRESHOLD && Settings.pageTransitions.value
-
-private const val SMOOTH_SCROLL_THRESHOLD = 50