LayoutStyle

Rules a parent uses to measure and place a widget: size, spacing, flex, grid, position, and overflow.

Overview

Configure a widget's geometry using widget.layout(style -> ...). Never manually calculate screen coordinates. Every size is a request: the parent container, flex/grid rules, and min/max constraints determine final bounds.

Concept	Meaning
Parent / Child	The parent container measures and places widgets; children configure their layout behavior.
Preferred Size	Requested dimensions (width, height, size). May be clamped or redistributed by layout rules.
SizeValue.auto()	Automatically computes size from widget content or available space. Not synonymous with 100%.
Main Axis	Primary flex direction: width for ROW, height for COLUMN.
Cross Axis	Perpendicular axis to the main axis (height for ROW, width for COLUMN).
Free Space	Remaining space after placing base sizes and margins. Distributed via flexGrow and flexShrink.

UniGUI Layout vs. Full Web CSS

While naming mirrors CSS properties, UniGUI implements a predictable, desktop-optimized layout engine. PositionType.FIXED is anchored relative to the nearest layout host (window or dialog), not the entire physical screen.

Size and positioning

Request dimensions using width, height, size, or sizePercent. Dimensions can be specified in UI pixels, parent percentages, or auto. minWidth / minHeight and maxWidth / maxHeight enforce strict bounds.

Method / Helper	Type	Description
width(w) / height(h)	Dimensions	Sets width or height (px, percent, or auto).
size(w, h)	Shortcut	Sets both width and height in UI pixels simultaneously.
sizePercent(w, h)	Percentage	Requests percentages of the parent's available size.
fixed(w, h)	Fixed Bounds	Sets pixel size and disables flex growth and shrink (0 0 auto).
fill()	100% Parent	Requests 100% width and 100% height (sizePercent(100, 100)).
expand()	Flex Remainder	Consumes remaining free space along the flex parent's main axis (1 1 0px).
position(ABSOLUTE)	Out-of-Flow	Removes widget from normal flow; position with left, top, right, bottom, or inset.

Choosing between fill() and expand()

Use fill() when a widget must occupy 100% of both parent dimensions regardless of siblings. Use expand() when a flex child (such as a scrollable body) should absorb whatever free space remains after fixed elements (such as headers and footers).

Spacing and overflow

Spacing governs margins around the widget, padding inside the border, and content clipping when elements exceed bounds.

Spacing Property	Placement	Purpose
margin(...)	Exterior	Separates the widget from adjacent siblings without affecting internal layout.
marginAutoHorizontal() / Vertical()	Exterior	Absorbs available free space, centering or pushing the widget against edges.
padding(...)	Interior	Insets children away from the widget's outer boundary.
gap(row, col)	Between Items	Uniform or independent spacing between flex lines/items or grid tracks.

Overflow Mode	Visual Behavior
Overflow.VISIBLE	Content renders beyond widget boundaries without clipping (default).
Overflow.HIDDEN	Content extending past boundaries is clipped.
Overflow.AUTO	Flags the axis as scrollable. Actual scrolling interactions are handled by ScrollView.

Scrolling Architecture

Setting overflowY(Overflow.AUTO) communicates intent to the layout engine, but scrolling interaction and scrollbars are provided by wrapping widgets in a ScrollView.

Flex layout

Flexbox arranges children sequentially along a primary main axis (ROW or COLUMN).

Container Configuration

Property	Axis / Scope	Values	Effect
flexDirection	Main Axis	ROW, COLUMN, ROW_REVERSE, COLUMN_REVERSE	Direction in which children are placed.
flexWrap	Wrapping	NOWRAP, WRAP, WRAP_REVERSE	Keeps children on one line or wraps to multiple lines.
justifyContent	Main Axis	START, CENTER, END, SPACE_BETWEEN, SPACE_AROUND, SPACE_EVENLY	Distributes children along the main axis.
alignItems	Cross Axis	STRETCH, START, CENTER, END, BASELINE	Aligns children perpendicular to the main axis.
alignContent	Multi-line	START, CENTER, END, STRETCH, SPACE_BETWEEN	Distributes wrapped lines (only active with WRAP).
gap(row, col)	Spacing	UI pixels (e.g. gap(8.0f))	Space between items and between wrapped lines.

Child Item Weights & Presets

Preset / Helper	Equivalent	Behavior
flexNone()	0 0 auto	Rigid: keeps requested/content size; never grows or shrinks.
expand()	1 1 0px	Greedy: consumes all remaining free space on the parent's main axis.
flexAuto()	1 1 auto	Flexible: sizes to content, grows if space is free, shrinks if squeezed.
flexInitial()	0 1 auto	Shrink-only: keeps requested size, shrinks when crowded, does not grow.
flex(grow, shrink, basis)	Explicit	Custom weights for growth and shrinkage; basis is the starting size.
alignSelf(Align)	Override	Overrides parent's alignItems for this specific child.

Grid and alignment

Grid layout arranges widgets into a 2D matrix of columns and rows defined by GridTrack track specifications.

Track Definitions (GridTrack)

Track Builder	Type	Description	Example
GridTrack.px(n)	Fixed	Exact track size in UI pixels.	GridTrack.px(96.0f)
GridTrack.fr(n)	Fractional	Proportional share of leftover free space.	GridTrack.fr(1.0f)
GridTrack.percent(n)	Percentage	Percentage of the grid container's dimension.	GridTrack.percent(33.3f)
GridTrack.auto()	Automatic	Sized automatically to fit largest cell content.	GridTrack.auto()
GridTrack.minmax(min, max)	Constrained	Clamps track size within minimum and maximum limits.	GridTrack.minmax(px(50), fr(1))

Grid Properties & Placement

Method	Target	Description
gridTemplateColumns(...)	Container	Explicit list of column tracks.
gridTemplateRows(...)	Container	Explicit list of row tracks.
gridAutoColumns(...) / gridAutoRows(...)	Container	Track sizes applied automatically beyond explicit templates.
gridAutoFlow(GridAutoFlow)	Container	Traversal direction for auto-placement: ROW, COLUMN, ROW_DENSE, COLUMN_DENSE.
gridColumn(start, span)	Child	1-based column start index and span width (<= 0 requests auto-placement).
gridRow(start, span)	Child	1-based row start index and span height (<= 0 requests auto-placement).
alignSelf / centerSelf	Child	Aligns this individual child inside its grid cell.
zIndex(int)	Child	Layering order among siblings (higher values render on top).

Batching and copies

A widget's live LayoutStyle automatically triggers layout reflow whenever a property changes. When applying several properties together, group mutations within update(...) to recalculate layout only once after the block finishes.

style.update(s -> s
        .width(240.0f)
        .padding(12.0f)
        .flexNone());

Lifecycle Method	Preserves Callback	When to Use
update(Consumer<LayoutStyle>)	Yes	Batch multiple modifications; triggers exactly one recalculation. Safe to nest.
copy()	No	Creates a detached snapshot of all values with no widget callback attached.
copyFrom(LayoutStyle other)	Yes	Overwrites all property values from another style, keeping the existing owner callback.

Fixed header, expanding body

VBox root = new VBox();
Label header = new Label("Files");
VBox content = new VBox();

header.layout(style -> style.height(24.0f).flexNone());
content.layout(style -> style.expand().padding(12.0f));
root.addChild(header);
root.addChild(content);

Fixed column plus a flexible column

LayoutStyle grid = new LayoutStyle()
        .gridTemplateColumns(GridTrack.px(96.0f), GridTrack.fr(1.0f))
        .gridAutoRowsOf(GridTrack.auto())
        .gap(8.0f, 12.0f);

API

Size & Position

Method	Description
position(PositionType)	Selects normal-flow participation (RELATIVE/STATIC) or out-of-flow positioning (ABSOLUTE/FIXED).
width(SizeValue)	Requests desired width as auto, UI pixels, or a percentage of the parent.
width(float)	Requests desired width in UI pixels.
height(SizeValue)	Requests desired height as auto, UI pixels, or a percentage of the parent.
height(float)	Requests desired height in UI pixels.
size(SizeValue, SizeValue)	Sets both width and height using SizeValue instances.
size(float, float)	Requests width and height in UI pixels. The legacy LayoutConstraints.AUTO value becomes auto.
sizePercent(float, float)	Requests width and height as percentages of the parent container.
fixed(float, float)	Sets exact pixel width and height, completely disabling flex growth and shrinkage (0 0 auto).
fill()	Requests 100% width and 100% height of the parent container.
minWidth(SizeValue)	Sets the minimum allowable width to prevent unwanted collapsing.
maxWidth(SizeValue)	Sets the upper allowable width constraint.
minHeight(SizeValue)	Sets the minimum allowable height.
maxHeight(SizeValue)	Sets the upper allowable height constraint.
inset(SizeValue, SizeValue, SizeValue, SizeValue)	Sets distances to all parent edges, typically used for ABSOLUTE positioning.

LayoutStyle::position(PositionType)

Position mode

Selects normal-flow participation (RELATIVE/STATIC) or out-of-flow positioning (ABSOLUTE/FIXED).

Parameter	Type	Description
position	PositionType	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::width(SizeValue)

Set width (SizeValue)

Requests desired width as auto, UI pixels, or a percentage of the parent.

Parameter	Type	Description
width	SizeValue	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::width(float)

Set width in pixels

Requests desired width in UI pixels.

Parameter	Type	Description
pixels	float	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::height(SizeValue)

Set height (SizeValue)

Requests desired height as auto, UI pixels, or a percentage of the parent.

Parameter	Type	Description
height	SizeValue	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::height(float)

Set height in pixels

Requests desired height in UI pixels.

Parameter	Type	Description
pixels	float	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::size(SizeValue, SizeValue)

Set size (SizeValue)

Sets both width and height using SizeValue instances.

Parameter	Type	Description
width	SizeValue	—
height	SizeValue	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::size(float, float)

Set pixel size

Requests width and height in UI pixels. The legacy LayoutConstraints.AUTO value becomes auto.

This is a size request, not a guaranteed final size. Flex, grid, min/max, and the parent can still change the result. It does not disable flex grow or shrink; use fixed for that.

Parameter	Type	Description
width	float	Width in UI pixels, or LayoutConstraints.AUTO for content-based sizing.
height	float	Height in UI pixels, or LayoutConstraints.AUTO for content-based sizing.

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::sizePercent(float, float)

Set size percent

Requests width and height as percentages of the parent container.

Parameter	Type	Description
widthPercent	float	—
heightPercent	float	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::fixed(float, float)

Fixed size

Sets exact pixel width and height, completely disabling flex growth and shrinkage (0 0 auto).

Parameter	Type	Description
width	float	—
height	float	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::fill()

Fill parent

Requests 100% width and 100% height of the parent container.

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::minWidth(SizeValue)

Minimum width

Sets the minimum allowable width to prevent unwanted collapsing.

Parameter	Type	Description
minWidth	SizeValue	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::maxWidth(SizeValue)

Maximum width

Sets the upper allowable width constraint.

Parameter	Type	Description
maxWidth	SizeValue	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::minHeight(SizeValue)

Minimum height

Sets the minimum allowable height.

Parameter	Type	Description
minHeight	SizeValue	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::maxHeight(SizeValue)

Maximum height

Sets the upper allowable height constraint.

Parameter	Type	Description
maxHeight	SizeValue	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::inset(SizeValue, SizeValue, SizeValue, SizeValue)

Edge insets

Sets distances to all parent edges, typically used for ABSOLUTE positioning.

Parameter	Type	Description
left	SizeValue	—
top	SizeValue	—
right	SizeValue	—
bottom	SizeValue	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

Spacing & Overflow

Method	Description
margin(EdgeInsets)	Sets exterior spacing separating the widget from siblings.
margin(float)	Sets the same exterior spacing on all four sides in UI pixels.
margin(float, float)	Sets horizontal and vertical exterior margins in UI pixels.
marginAutoHorizontal()	Enables left and right auto-margins to absorb remaining horizontal space.
marginAutoVertical()	Enables top and bottom auto-margins to absorb remaining vertical space.
padding(EdgeInsets)	Sets interior spacing between widget boundaries and its children.
padding(float)	Sets the same inner padding on all four sides, in UI pixels.
padding(float, float)	Sets horizontal and vertical inner paddings in UI pixels.
overflowX(Overflow)	Controls content extending past the left and right boundaries (VISIBLE, HIDDEN, AUTO).
overflowY(Overflow)	Controls content extending past the top and bottom boundaries; scrolling handled by ScrollView.
overflow(Overflow)	Sets overflow behavior simultaneously for both horizontal and vertical axes.

LayoutStyle::margin(EdgeInsets)

Margin (EdgeInsets)

Sets exterior spacing separating the widget from siblings.

Parameter	Type	Description
margin	EdgeInsets	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::margin(float)

Uniform margin

Sets the same exterior spacing on all four sides in UI pixels.

Parameter	Type	Description
all	float	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::margin(float, float)

Margin by axes

Sets horizontal and vertical exterior margins in UI pixels.

Parameter	Type	Description
horizontal	float	—
vertical	float	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::marginAutoHorizontal()

Auto horizontal margins

Enables left and right auto-margins to absorb remaining horizontal space.

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::marginAutoVertical()

Auto vertical margins

Enables top and bottom auto-margins to absorb remaining vertical space.

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::padding(EdgeInsets)

Padding (EdgeInsets)

Sets interior spacing between widget boundaries and its children.

Parameter	Type	Description
padding	EdgeInsets	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::padding(float)

Uniform padding

Sets the same inner padding on all four sides, in UI pixels.

Parameter	Type	Description
all	float	Padding applied to the left, top, right, and bottom edges.

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::padding(float, float)

Padding by axes

Sets horizontal and vertical inner paddings in UI pixels.

Parameter	Type	Description
horizontal	float	—
vertical	float	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::overflowX(Overflow)

Horizontal overflow

Controls content extending past the left and right boundaries (VISIBLE, HIDDEN, AUTO).

Parameter	Type	Description
overflowX	Overflow	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::overflowY(Overflow)

Vertical overflow

Controls content extending past the top and bottom boundaries; scrolling handled by ScrollView.

Parameter	Type	Description
overflowY	Overflow	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::overflow(Overflow)

Uniform overflow

Sets overflow behavior simultaneously for both horizontal and vertical axes.

Parameter	Type	Description
overflow	Overflow	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

Flex Layout

Method	Description
flexDirection(FlexDirection)	Sets the main layout axis of the flex container (ROW or COLUMN).
flexWrap(FlexWrap)	Controls single-line (NOWRAP) vs multi-line (WRAP) item flow.
flexFlow(FlexDirection, FlexWrap)	Sets flex container direction and wrap mode together.
gap(float)	Sets uniform spacing between rows and between columns in UI pixels.
gap(float, float)	Sets row gap and column gap independently in UI pixels.
flex(float, float, SizeValue)	Sets grow weight, shrink weight, and the base size before free-space distribution.
flexNone()	Disables flex growth and shrinkage, preserving exact requested/content size (0 0 auto).
expand()	Greedily consumes all remaining free space along the flex parent's main axis (1 1 0px).
flexAuto()	Sizes widget from content, growing to absorb leftover space or shrinking if crowded (1 1 auto).
flexInitial()	Sizes widget from base dimensions; shrinks when crowded but never grows (0 1 auto).
justifyContent(Justify)	Distributes children along the container's main axis (START, CENTER, END, SPACE_BETWEEN).
alignItems(Align)	Aligns children along the container's cross axis (STRETCH, START, CENTER, END).
alignSelf(Align)	Overrides the parent's alignItems alignment rule for this specific child widget.
alignContent(AlignContent)	Distributes wrapped lines along the cross axis when flexWrap creates multiple rows.

LayoutStyle::flexDirection(FlexDirection)

Flex direction

Sets the main layout axis of the flex container (ROW or COLUMN).

Parameter	Type	Description
flexDirection	FlexDirection	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::flexWrap(FlexWrap)

Flex wrap

Controls single-line (NOWRAP) vs multi-line (WRAP) item flow.

Parameter	Type	Description
flexWrap	FlexWrap	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::flexFlow(FlexDirection, FlexWrap)

Flex flow

Sets flex container direction and wrap mode together.

Parameter	Type	Description
direction	FlexDirection	—
wrap	FlexWrap	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::gap(float)

Uniform gap

Sets uniform spacing between rows and between columns in UI pixels.

Parameter	Type	Description
gap	float	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::gap(float, float)

Gap by axes

Sets row gap and column gap independently in UI pixels.

Parameter	Type	Description
rowGap	float	—
columnGap	float	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::flex(float, float, SizeValue)

Flex shorthand

Sets grow weight, shrink weight, and the base size before free-space distribution.

Grow and shrink are weights, not percentages. basis is the starting main-axis size; auto uses the width or height request. The parent may still change the final size.

Parameter	Type	Description
grow	float	Share of leftover main-axis space. 0 does not grow.
shrink	float	Share of the deficit when children do not fit. 0 does not shrink.
basis	SizeValue	Base main-axis size (auto, pixels, or percent). Null becomes auto.

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::flexNone()

Flex none

Disables flex growth and shrinkage, preserving exact requested/content size (0 0 auto).

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::expand()

Expand on main axis

Greedily consumes all remaining free space along the flex parent's main axis (1 1 0px).

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::flexAuto()

Flex auto

Sizes widget from content, growing to absorb leftover space or shrinking if crowded (1 1 auto).

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::flexInitial()

Flex initial

Sizes widget from base dimensions; shrinks when crowded but never grows (0 1 auto).

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::justifyContent(Justify)

Justify content

Distributes children along the container's main axis (START, CENTER, END, SPACE_BETWEEN).

Parameter	Type	Description
justifyContent	Justify	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::alignItems(Align)

Align items

Aligns children along the container's cross axis (STRETCH, START, CENTER, END).

Parameter	Type	Description
alignItems	Align	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::alignSelf(Align)

Align self

Overrides the parent's alignItems alignment rule for this specific child widget.

Parameter	Type	Description
alignSelf	Align	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::alignContent(AlignContent)

Align content

Distributes wrapped lines along the cross axis when flexWrap creates multiple rows.

Parameter	Type	Description
alignContent	AlignContent	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

Grid & Alignment

Method	Description
gridTemplateColumns(List)	Sets the explicit column template. An empty or null list keeps automatic columns.
gridTemplateColumns(GridTrack[])	Sets explicit column template tracks using varargs.
gridTemplateRows(List)	Sets explicit row template tracks.
gridTemplateRows(GridTrack[])	Sets explicit row template tracks using varargs.
gridAutoColumns(List)	Defines track sizes for implicit columns created beyond the explicit template.
gridAutoRows(List)	Defines track sizes for implicit rows created beyond the explicit template.
gridAutoFlow(GridAutoFlow)	Controls placement direction during auto-placement (ROW, COLUMN, ROW_DENSE, COLUMN_DENSE).
gridColumn(int, int)	Pins child to 1-based column start index and sets column span (<= 0 requests auto-placement).
gridRow(int, int)	Pins child to 1-based row start index and sets row span (<= 0 requests auto-placement).
aspectRatio(float)	Sets desired width-to-height ratio when one dimension remains auto.
zIndex(int)	Sets drawing layer order among siblings; higher integers render on top.
center()	Centers the container's children on both the main and cross axes.
centerSelf()	Centers this flex item on its parent's cross axis (alignSelf(CENTER)).

LayoutStyle::gridTemplateColumns(List)

Grid columns

Sets the explicit column template. An empty or null list keeps automatic columns.

Each GridTrack is one column: px, percent, fr, auto, or minmax. Tracks created beyond this template come from gridAutoColumns.

Parameter	Type	Description
tracks	List	Column tracks in order. Null or an empty list clears the template.

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::gridTemplateColumns(GridTrack[])

Grid columns (varargs)

Sets explicit column template tracks using varargs.

Parameter	Type	Description
tracks	GridTrack[]	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::gridTemplateRows(List)

Grid rows

Sets explicit row template tracks.

Parameter	Type	Description
tracks	List	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::gridTemplateRows(GridTrack[])

Grid rows (varargs)

Sets explicit row template tracks using varargs.

Parameter	Type	Description
tracks	GridTrack[]	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::gridAutoColumns(List)

Auto columns

Defines track sizes for implicit columns created beyond the explicit template.

Parameter	Type	Description
tracks	List	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::gridAutoRows(List)

Auto rows

Defines track sizes for implicit rows created beyond the explicit template.

Parameter	Type	Description
tracks	List	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::gridAutoFlow(GridAutoFlow)

Grid auto flow

Controls placement direction during auto-placement (ROW, COLUMN, ROW_DENSE, COLUMN_DENSE).

Parameter	Type	Description
flow	GridAutoFlow	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::gridColumn(int, int)

Grid column placement

Pins child to 1-based column start index and sets column span (<= 0 requests auto-placement).

Parameter	Type	Description
start	int	—
span	int	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::gridRow(int, int)

Grid row placement

Pins child to 1-based row start index and sets row span (<= 0 requests auto-placement).

Parameter	Type	Description
start	int	—
span	int	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::aspectRatio(float)

Aspect ratio

Sets desired width-to-height ratio when one dimension remains auto.

Parameter	Type	Description
ratio	float	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::zIndex(int)

Z-Index

Sets drawing layer order among siblings; higher integers render on top.

Parameter	Type	Description
zIndex	int	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::center()

Center children

Centers the container's children on both the main and cross axes.

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::centerSelf()

Center self

Centers this flex item on its parent's cross axis (alignSelf(CENTER)).

Returns LayoutStyle: this LayoutStyle for fluent configuration.

Batching & Lifecycle

Method	Description
update(Consumer)	Applies several layout changes and notifies the owner once after the outer block finishes.
copy()	Creates an independent detached copy of all layout properties with no widget callback attached.
copyFrom(LayoutStyle)	Copies all layout values from another style, retaining this object's change callback.
onChanged(Runnable)	Registers a callback notified whenever any layout property mutates.

LayoutStyle::update(Consumer)

Batch updates

Applies several layout changes and notifies the owner once after the outer block finishes.

Nested update calls are safe. The change callback runs only after the outermost block, and only if a property actually changed. A null consumer is ignored.

Parameter	Type	Description
update	Consumer	Callback that mutates this style; null is a no-op.

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::copy()

Copy snapshot

Creates an independent detached copy of all layout properties with no widget callback attached.

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::copyFrom(LayoutStyle)

Copy from another style

Copies all layout values from another style, retaining this object's change callback.

Parameter	Type	Description
other	LayoutStyle	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.

LayoutStyle::onChanged(Runnable)

Change callback

Registers a callback notified whenever any layout property mutates.

Parameter	Type	Description
onChanged	Runnable	—

Returns LayoutStyle: this LayoutStyle for fluent configuration.