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wear: fix dock/undock flapping when scrolling up from bottom - undocking collapsed the 48dp bottom clearance which clamped scroll back to the end and re-docked in a loop; buttons now toggle on a fast 12dp overlay-only channel while the geometry-changing docked state requires 60dp of upward scroll (> 48dp padding delta)

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callebtc 2026-07-29 00:52:07 +02:00
parent 8f4c937e92
commit 80342a74e8
1 changed files with 18 additions and 15 deletions
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33
wear/src/main/java/com/bitchat/watch/ui/ChatScaffold.kt
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@ -72,36 +72,39 @@ fun ChatScaffold(
// "Docked at newest" is the single source of truth for the chat's resting state:
// bottom clearance expanded (newest message sits above the floating buttons), action
// bar visible, header at full size. It is driven by scroll intent, not layout geometry:
// reaching the end of the list docks; deliberately scrolling away undocks. Geometry-based
// detection (distance-to-last-item) was unreliable here because expanding the bottom
// clearance grows the scroll range, which read as "left the bottom", and the edge-scaled
// last item skewed the measurement further.
// bar visible, header at full size. It is driven by scroll intent, not layout geometry.
var dockedAtNewest by remember { mutableStateOf(true) }
// Action bar: ALWAYS visible while the list is scrolled to the bottom; hides when
// scrolling up into history and reappears as soon as the user scrolls back down, so
// replying is one short flick away even from the very top.
// Action bar: ALWAYS visible while the list is scrolled to the bottom; hides quickly
// when scrolling up into history and reappears as soon as the user scrolls back down,
// so replying is one short flick away even from the very top. The bar is an overlay,
// so its fast 12dp threshold cannot feed back into the scroll geometry.
val buttonsVisible = remember { mutableStateOf(true) }
// The docked state, by contrast, changes the geometry: collapsing the bottom clearance
// shrinks the scroll range by the 48dp padding delta. Undocking near the bottom would
// clamp the scroll position back to the end and instantly re-dock — the hide/show
// flapping loop. So undocking requires scrolling well clear of the bottom (60dp > 48dp).
val undockThresholdPx = with(androidx.compose.ui.platform.LocalDensity.current) {
60.dp.roundToPx()
}
LaunchedEffect(columnState) {
var lastPosition = -1
var bottomPosition = 0
snapshotFlow {
val first = columnState.layoutInfo.visibleItems.firstOrNull()
Triple(columnState.canScrollForward, first?.index ?: 0, first?.offset ?: 0)
}.collect { (canScrollForward, index, offset) ->
val atBottom = !canScrollForward
val position = index * 100_000 + offset
if (atBottom) {
bottomPosition = position
dockedAtNewest = true
buttonsVisible.value = true
}
val position = index * 100_000 + offset
if (lastPosition >= 0) {
} else if (lastPosition >= 0) {
when {
position > lastPosition + 24 -> buttonsVisible.value = true
position < lastPosition - 24 -> {
buttonsVisible.value = false
if (!atBottom) dockedAtNewest = false
}
position < lastPosition - 24 -> buttonsVisible.value = false
}
if (bottomPosition - position > undockThresholdPx) dockedAtNewest = false
}
lastPosition = position
}