MapBottomSheet

The MapBottomSheet is a custom bottom sheet built with AnchoredDraggable (not Material's BottomSheetScaffold) for full control over anchor positions and nested scroll behavior. For the rationale behind this choice, see the design decisions.

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SheetAnchor State Machine

enum class SheetAnchor {
    Collapsed,
    HalfExpanded,
    Expanded,
}

Anchor positions are computed from the available height:

Anchor	Offset (from top)	Description
Collapsed	availableHeight - dragHandleHeight	Only the drag handle visible (24dp)
HalfExpanded	availableHeight * (1 - 0.50)	50% of screen (or content-fitted for detail views)
Expanded	availableHeight * (1 - 0.90)	90% of screen

For fixed-height content (device info, notification info), HalfExpanded snaps to the actual content height instead of 50%:

val halfOffset = if (isFixedContent && measuredContentHeight > 0) {
    val contentSheetHeight = measuredContentHeight + collapsedHeightPx
    (availableHeightPx - contentSheetHeight).coerceAtLeast(expandedOffset)
} else {
    availableHeightPx * (1f - Dimensions.BottomSheet.HALF_FRACTION)
}

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BottomSheet Dimension Tokens

Token	Value
dragHandleHeight	24.dp
dragHandleWidth	28.dp
dragHandleThickness	3.dp
topCornerRadius	16.dp
headerHeight	40.dp
EXPANDED_FRACTION	0.90f
HALF_FRACTION	0.50f

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Nested Scroll Integration

The BottomSheetNestedScrollConnection coordinates between the sheet's drag and the inner LazyColumn scroll:

// Swiping up: only move sheet if Collapsed
dy < 0 -> sheetState.currentValue == SheetAnchor.Collapsed
// Swiping down: collapse sheet when list is at top
dy > 0 -> !lazyListState.canScrollBackward

Fling behavior:

• Fling up from Collapsed → animate to HalfExpanded
• Fling up at HalfExpanded (list can't scroll further) → animate to Expanded
• Fling down (list at top) → step down one anchor (Expanded → HalfExpanded → Collapsed)

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SheetContentMode

The sheet supports three content modes via a sealed class:

sealed class SheetContentMode {
    data object DeviceList : SheetContentMode()
    data class DeviceInfo(val device: DeviceWithPosition) : SheetContentMode()
    data class NotificationInfo(val detail: NotificationDetail, val deviceName: String) : SheetContentMode()
}

Content transitions use AnimatedContent with fadeIn togetherWith fadeOut. When switching to DeviceInfo or NotificationInfo, the sheet auto-animates to HalfExpanded.