捕捉指数lazyrow

Question

我在Lazyrow的帮助下制作日历。我现在有一个问题，我希望该行在一定的滚动量后捕捉到索引，以便在索引之间不可能粘在索引中。有办法做到吗？

    LazyRow(state = calendarViewModel.listState, modifier = Modifier.fillMaxWidth()) {
        calendarYears.forEach {
            items(it.months.count()) { index ->
                calendarViewModel.onEvent(CalendarEvent.ClickedMenuItem(index))
                CalendarRowItem(
                    modifier = Modifier.fillParentMaxWidth(),
                    calendarSize = it.months[index].amountOfDays,
                    initWeekday = it.months[index].startDayOfMonth.ordinal,
                    textColor = MaterialTheme.colors.secondaryVariant,
                    clickedColor = MaterialTheme.colors.primary,
                    textStyle = MaterialTheme.typography.body1
                )
            }
        }
    }

Answer 1

首先要组合 1.3.0 您可以使用 将项目捕捉到给定位置：

val state = rememberLazyListState()

LazyRow(
    modifier = Modifier.fillMaxSize(),
    verticalAlignment = Alignment.CenterVertically,
    state = state,
    flingBehavior = rememberSnapFlingBehavior(lazyListState = state)
) {
  //item content
}

Answer 2

您可以从 canceranist Libraral 提供提供提供的提供的提供的提供的提供的提供的提供者这种爆炸行为在框外，并在内部使用lazyrow。

可以使用 snapper库创建的另一个选项。 /users/474997/chris-banes“>@chris-banes

在build.gradle.gradle中添加依赖关系。

dependencies {
    implementation "dev.chrisbanes.snapper:snapper:<version>"
}

并在您的lazyrow中使用它。

val lazyListState = rememberLazyListState()

LazyRow(
    state = lazyListState,
    flingBehavior = rememberSnapperFlingBehavior(lazyListState),
) {
    // content
}

结果：

Answer 3

在Gabriele的答案之上构建，以基于第一个可见项目（侧扣至开始）来捕捉，我们需要执行以下操作：

val scrollState = rememberLazyListState()
val positionInLayout: Density.(Float, Float) -> Float = { _, _ ->
    // This value tells where to snap on the x axis within the viewport
    // Setting it to 0 results in snapping of the first visible item to the left side (or right side if RTL)
    0f
}
val snappingLayout = remember(scrollState) { SnapLayoutInfoProvider(scrollState, positionInLayout) }
val flingBehavior = rememberSnapFlingBehavior(snappingLayout)
LazyRow(
    modifier = modifier,
    state = scrollState,
    contentPadding = PaddingValues(horizontal = 1.5f.u()),
    flingBehavior = flingBehavior,
    content = {}
)

Answer 4

val centerItemIndex by remember {
    derivedStateOf {
        val layoutInfo = listState.layoutInfo
        val visibleItems = layoutInfo.visibleItemsInfo
        val viewportCenter = (layoutInfo.viewportStartOffset + layoutInfo.viewportEndOffset) / 2

        visibleItems.minByOrNull { abs((it.offset + it.size / 2) - viewportCenter) }?.index ?: 0
    }
}