To update a sticky header in LazyColumn while scrolling, you can use the LazyColumn
's onScroll
callback. The onScroll
callback provides information about the scroll position, including the offset in pixels and the first visible item position.
You can use this information to determine when the sticky header should be updated. For example, you can set a threshold value such that if the offset is greater than the threshold, you update the sticky header with the appropriate text or content.
Here's an example of how you can update the sticky header in a LazyColumn
:
val items = listOf("Item 1", "Item 2", "Item 3", "Item 4")
var stickyHeader: String? = null
LazyColumn(
modifier = Modifier.fillMaxSize(),
contentPadding = PaddingValues(horizontal = 16.dp, vertical = 8.dp),
verticalArrangement = Arrangement.spacedBy(8.dp),
state = lazyListState,
onScroll = { scrollState ->
val firstVisibleItem = lazyListState.firstVisibleItemIndex
if (firstVisibleItem == 0 && scrollState.firstVisibleItemScrollOffset > 0) {
stickyHeader = items[firstVisibleItem]
} else {
stickyHeader = null
}
}
) {
items(items) { item ->
Text(item)
}
if (stickyHeader != null) {
val modifier = Modifier
.fillMaxWidth()
.background(Color.White)
.padding(vertical = 8.dp)
.stickyHeader {
Text(
text = stickyHeader!!,
fontWeight = FontWeight.Bold,
fontSize = 16.sp,
)
}
Spacer(modifier = modifier)
}
}
In this example, we set the onScroll
callback to update the stickyHeader
variable whenever the first visible item changes. If the first visible item is the first item (index 0) and the offset is greater than 0, we update the stickyHeader
variable with the appropriate text. Otherwise, we set it to null.
We then use this stickyHeader
variable to conditionally render a Spacer
with a stickyHeader
modifier. The stickyHeader
modifier sets the background color, padding, and content of the sticky header. We pass in the Text
component with the stickyHeader!!
text to render the updated header text.
Note that in this example, we've hard-coded the items
array for simplicity, but in practice, you would likely want to pass in a dynamic list of items.
Asked: 2022-05-19 11:00:00 +0000
Seen: 12 times
Last updated: Oct 18 '21