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Add fast scroller to extensions screen (#7340)
This commit is contained in:
Ivan Iskandar
GitHub
@@ -40,7 +40,7 @@ import com.google.accompanist.swiperefresh.SwipeRefresh
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import com.google.accompanist.swiperefresh.rememberSwipeRefreshState
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import eu.kanade.presentation.browse.components.BaseBrowseItem
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import eu.kanade.presentation.browse.components.ExtensionIcon
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import eu.kanade.presentation.components.ScrollbarLazyColumn
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import eu.kanade.presentation.components.FastScrollLazyColumn
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import eu.kanade.presentation.components.SwipeRefreshIndicator
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import eu.kanade.presentation.theme.header
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import eu.kanade.presentation.util.horizontalPadding
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@@ -113,7 +113,7 @@ fun ExtensionContent(
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) {
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var trustState by remember { mutableStateOf<Extension.Untrusted?>(null) }
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ScrollbarLazyColumn(
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FastScrollLazyColumn(
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contentPadding = WindowInsets.navigationBars.asPaddingValues() + topPaddingValues,
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) {
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items(
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@@ -56,3 +56,38 @@ fun ScrollbarLazyColumn(
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content = content,
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)
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}
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/**
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* LazyColumn with fast scroller.
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*/
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@Composable
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fun FastScrollLazyColumn(
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modifier: Modifier = Modifier,
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state: LazyListState = rememberLazyListState(),
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contentPadding: PaddingValues = PaddingValues(0.dp),
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reverseLayout: Boolean = false,
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verticalArrangement: Arrangement.Vertical =
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if (!reverseLayout) Arrangement.Top else Arrangement.Bottom,
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horizontalAlignment: Alignment.Horizontal = Alignment.Start,
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flingBehavior: FlingBehavior = ScrollableDefaults.flingBehavior(),
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userScrollEnabled: Boolean = true,
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content: LazyListScope.() -> Unit,
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) {
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VerticalFastScroller(
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listState = state,
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modifier = modifier,
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topContentPadding = contentPadding.calculateTopPadding(),
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endContentPadding = contentPadding.calculateEndPadding(LocalLayoutDirection.current),
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) {
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LazyColumn(
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state = state,
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contentPadding = contentPadding,
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reverseLayout = reverseLayout,
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verticalArrangement = verticalArrangement,
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horizontalAlignment = horizontalAlignment,
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flingBehavior = flingBehavior,
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userScrollEnabled = userScrollEnabled,
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content = content,
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)
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}
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}
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@@ -0,0 +1,195 @@
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package eu.kanade.presentation.components
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import android.view.ViewConfiguration
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import androidx.compose.animation.core.Animatable
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import androidx.compose.animation.core.tween
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import androidx.compose.foundation.background
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import androidx.compose.foundation.gestures.Orientation
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import androidx.compose.foundation.gestures.draggable
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import androidx.compose.foundation.gestures.rememberDraggableState
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import androidx.compose.foundation.interaction.MutableInteractionSource
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import androidx.compose.foundation.interaction.collectIsDraggedAsState
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import androidx.compose.foundation.layout.Box
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import androidx.compose.foundation.layout.height
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import androidx.compose.foundation.layout.offset
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import androidx.compose.foundation.layout.padding
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import androidx.compose.foundation.layout.width
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import androidx.compose.foundation.lazy.LazyListItemInfo
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import androidx.compose.foundation.lazy.LazyListState
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import androidx.compose.foundation.shape.RoundedCornerShape
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import androidx.compose.foundation.systemGestureExclusion
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import androidx.compose.material3.MaterialTheme
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import androidx.compose.runtime.Composable
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import androidx.compose.runtime.LaunchedEffect
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import androidx.compose.runtime.getValue
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import androidx.compose.runtime.mutableStateOf
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import androidx.compose.runtime.remember
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import androidx.compose.runtime.setValue
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import androidx.compose.ui.Modifier
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import androidx.compose.ui.draw.alpha
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import androidx.compose.ui.graphics.Color
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import androidx.compose.ui.layout.SubcomposeLayout
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import androidx.compose.ui.platform.LocalDensity
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import androidx.compose.ui.unit.Dp
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import androidx.compose.ui.unit.IntOffset
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import androidx.compose.ui.unit.dp
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import androidx.compose.ui.util.fastForEach
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import androidx.compose.ui.util.fastMaxBy
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import kotlinx.coroutines.channels.BufferOverflow
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import kotlinx.coroutines.flow.MutableSharedFlow
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import kotlinx.coroutines.flow.collectLatest
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import kotlin.math.abs
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import kotlin.math.max
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import kotlin.math.min
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import kotlin.math.roundToInt
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@Composable
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fun VerticalFastScroller(
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listState: LazyListState,
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modifier: Modifier = Modifier,
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thumbColor: Color = MaterialTheme.colorScheme.primary,
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topContentPadding: Dp = Dp.Hairline,
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endContentPadding: Dp = Dp.Hairline,
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content: @Composable () -> Unit,
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) {
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SubcomposeLayout(modifier = modifier) { constraints ->
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val contentPlaceable = subcompose("content", content).map { it.measure(constraints) }
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val contentHeight = contentPlaceable.fastMaxBy { it.height }?.height ?: 0
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val contentWidth = contentPlaceable.fastMaxBy { it.width }?.width ?: 0
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val scrollerConstraints = constraints.copy(minWidth = 0, minHeight = 0)
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val scrollerPlaceable = subcompose("scroller") {
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val layoutInfo = listState.layoutInfo
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val showScroller = layoutInfo.visibleItemsInfo.size < layoutInfo.totalItemsCount
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if (!showScroller) return@subcompose
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val thumbTopPadding = with(LocalDensity.current) { topContentPadding.toPx() }
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var thumbOffsetY by remember(thumbTopPadding) { mutableStateOf(thumbTopPadding) }
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val dragInteractionSource = remember { MutableInteractionSource() }
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val isThumbDragged by dragInteractionSource.collectIsDraggedAsState()
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val scrolled = remember {
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MutableSharedFlow<Unit>(
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extraBufferCapacity = 1,
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onBufferOverflow = BufferOverflow.DROP_OLDEST,
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)
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}
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val heightPx = contentHeight.toFloat() - thumbTopPadding - listState.layoutInfo.afterContentPadding
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val thumbHeightPx = with(LocalDensity.current) { ThumbLength.toPx() }
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val trackHeightPx = heightPx - thumbHeightPx
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// When thumb dragged
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LaunchedEffect(thumbOffsetY) {
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if (layoutInfo.totalItemsCount == 0 || !isThumbDragged) return@LaunchedEffect
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val scrollRatio = (thumbOffsetY - thumbTopPadding) / trackHeightPx
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val scrollItem = layoutInfo.totalItemsCount * scrollRatio
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val scrollItemRounded = scrollItem.roundToInt()
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val scrollItemSize = layoutInfo.visibleItemsInfo.find { it.index == scrollItemRounded }?.size ?: 0
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val scrollItemOffset = scrollItemSize * (scrollItem - scrollItemRounded)
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listState.scrollToItem(index = scrollItemRounded, scrollOffset = scrollItemOffset.roundToInt())
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scrolled.tryEmit(Unit)
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}
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// When list scrolled
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LaunchedEffect(listState.firstVisibleItemScrollOffset) {
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if (listState.layoutInfo.totalItemsCount == 0 || isThumbDragged) return@LaunchedEffect
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val scrollOffset = computeScrollOffset(state = listState)
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val scrollRange = computeScrollRange(state = listState)
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val proportion = scrollOffset.toFloat() / (scrollRange.toFloat() - heightPx)
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thumbOffsetY = trackHeightPx * proportion + thumbTopPadding
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scrolled.tryEmit(Unit)
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}
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// Thumb alpha
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val alpha = remember { Animatable(0f) }
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val isThumbVisible = alpha.value > 0f
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LaunchedEffect(scrolled, alpha) {
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scrolled.collectLatest {
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alpha.snapTo(1f)
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alpha.animateTo(0f, animationSpec = FadeOutAnimationSpec)
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}
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}
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Box(
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modifier = Modifier
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.offset { IntOffset(0, thumbOffsetY.roundToInt()) }
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.height(ThumbLength)
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.then(
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// Exclude thumb from gesture area only when needed
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if (isThumbVisible && !isThumbDragged && !listState.isScrollInProgress) {
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Modifier.systemGestureExclusion()
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} else Modifier,
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)
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.padding(horizontal = 8.dp)
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.padding(end = endContentPadding)
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.width(ThumbThickness)
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.alpha(alpha.value)
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.background(color = thumbColor, shape = ThumbShape)
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.then(
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// Recompose opts
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if (!listState.isScrollInProgress) {
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Modifier.draggable(
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interactionSource = dragInteractionSource,
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orientation = Orientation.Vertical,
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enabled = isThumbVisible,
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state = rememberDraggableState { delta ->
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val newOffsetY = thumbOffsetY + delta
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thumbOffsetY = newOffsetY.coerceIn(thumbTopPadding, thumbTopPadding + trackHeightPx)
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},
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)
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} else Modifier,
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),
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)
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}.map { it.measure(scrollerConstraints) }
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val scrollerWidth = scrollerPlaceable.fastMaxBy { it.width }?.width ?: 0
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layout(contentWidth, contentHeight) {
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contentPlaceable.fastForEach {
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it.place(0, 0)
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}
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scrollerPlaceable.fastForEach {
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it.placeRelative(contentWidth - scrollerWidth, 0)
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}
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}
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}
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}
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private fun computeScrollOffset(state: LazyListState): Int {
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if (state.layoutInfo.totalItemsCount == 0) return 0
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val visibleItems = state.layoutInfo.visibleItemsInfo
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val startChild = visibleItems.first()
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val endChild = visibleItems.last()
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val minPosition = min(startChild.index, endChild.index)
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val maxPosition = max(startChild.index, endChild.index)
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val itemsBefore = minPosition.coerceAtLeast(0)
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val startDecoratedTop = startChild.top
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val laidOutArea = abs(endChild.bottom - startDecoratedTop)
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val itemRange = abs(minPosition - maxPosition) + 1
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val avgSizePerRow = laidOutArea.toFloat() / itemRange
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return (itemsBefore * avgSizePerRow + (0 - startDecoratedTop)).roundToInt()
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}
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private fun computeScrollRange(state: LazyListState): Int {
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if (state.layoutInfo.totalItemsCount == 0) return 0
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val visibleItems = state.layoutInfo.visibleItemsInfo
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val startChild = visibleItems.first()
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val endChild = visibleItems.last()
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val laidOutArea = endChild.bottom - startChild.top
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val laidOutRange = abs(startChild.index - endChild.index) + 1
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return (laidOutArea.toFloat() / laidOutRange * state.layoutInfo.totalItemsCount).roundToInt()
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}
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private val ThumbLength = 48.dp
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private val ThumbThickness = 8.dp
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private val ThumbShape = RoundedCornerShape(ThumbThickness / 2)
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private val FadeOutAnimationSpec = tween<Float>(
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durationMillis = ViewConfiguration.getScrollBarFadeDuration(),
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delayMillis = 2000,
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)
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private val LazyListItemInfo.top: Int
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get() = offset
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private val LazyListItemInfo.bottom: Int
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get() = offset + size
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