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Fix authored zero insets in absolute stack positioning (iOS) #39

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Merged
shanerbaner82 merged 2 commits into from
Aug 4, 2026
Merged

Fix authored zero insets in absolute stack positioning (iOS) #39

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bb7888e
fix: honour an authored zero inset in absolute stack positioning (iOS)
shanerbaner82 Aug 4, 2026
ff9962b
fix: honour authored zero insets in absolute stack positioning (Android)
shanerbaner82 Aug 4, 2026
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27 changes: 16 additions & 11 deletions resources/android/ContainerRenderers.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -78,24 +78,29 @@ object StackRenderer {

// Absolute children pin to the stack's edges by inset —
// the docs-blessed "layer a badge over an icon" pattern.
// Same anchor convention as ComposeFlexLayout / the iOS
// FlexContainer: a NON-ZERO right/bottom inset anchors to
// that edge; otherwise offset from top-left. Non-zero (not
// positive) so NEGATIVE insets overhang the edge, matching
// Tailwind's `-right-8` bleed.
// Same anchor convention as the iOS stack renderer: +0.0
// means unset, non-zero anchors (negatives overhang —
// `-right-8` bleed), and IEEE -0.0 is an authored explicit
// zero (`bottom-0`), which anchors to that edge too. When
// both edges are authored, left/top win (CSS precedence).
if (layout.positionType == PositionType.ABSOLUTE) {
val left = layout.positionLeft
val top = layout.positionTop
val right = layout.positionRight
val bottom = layout.positionBottom
// -0.0f == 0f in Kotlin, so authored zeros need the
// raw sign bit.
fun isSet(v: Float) = v != 0f || v.toRawBits() != 0
val anchorEnd = isSet(right) && !isSet(left)
val anchorBottom = isSet(bottom) && !isSet(top)
val anchor = when {
right != 0f && bottom != 0f -> Alignment.BottomEnd
right != 0f -> Alignment.TopEnd
bottom != 0f -> Alignment.BottomStart
else -> Alignment.TopStart
anchorEnd && anchorBottom -> Alignment.BottomEnd
anchorEnd -> Alignment.TopEnd
anchorBottom -> Alignment.BottomStart
else -> Alignment.TopStart
}
val offsetX = if (right != 0f) (-right).dp else left.dp
val offsetY = if (bottom != 0f) (-bottom).dp else top.dp
val offsetX = if (anchorEnd) (-right).dp else left.dp
val offsetY = if (anchorBottom) (-bottom).dp else top.dp
childMod = childMod.align(anchor).offset(x = offsetX, y = offsetY)
}
}
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16 changes: 9 additions & 7 deletions resources/ios/NativeUIStackRenderer.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -86,21 +86,23 @@ struct NativeUIStackLayout: Layout {

// Absolute children pin to the stack's edges by inset — the
// docs-blessed "layer a badge over an icon" pattern. Same anchor
// convention as FlexContainer.placeAbsolute: a NON-ZERO right /
// bottom inset (with zero left/top) anchors to that edge, and a
// negative one deliberately overhangs it (`-right-8` bleed).
// convention as FlexContainer.placeAbsolute: +0.0 means unset,
// non-zero anchors (negatives overhang — `-right-8` bleed), and
// IEEE -0.0 is an authored explicit zero (`bottom-0`), which
// anchors to that edge too.
if layout?.positionType == PositionType.absolute {
let top = CGFloat(layout?.positionTop ?? 0)
let right = CGFloat(layout?.positionRight ?? 0)
let bottom = CGFloat(layout?.positionBottom ?? 0)
let left = CGFloat(layout?.positionLeft ?? 0)
let isSet: (CGFloat) -> Bool = { $0 != 0 || $0.sign == .minus }

var x = bounds.minX + left
if right != 0 && left == 0 {
var x = bounds.minX + (isSet(left) ? left : 0)
if isSet(right) && !isSet(left) {
x = bounds.maxX - width - right
}
var y = bounds.minY + top
if bottom != 0 && top == 0 {
var y = bounds.minY + (isSet(top) ? top : 0)
if isSet(bottom) && !isSet(top) {
y = bounds.maxY - height - bottom
}

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