layout

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 Go to latest Published: Oct 16, 2026 License: BSD-3-Clause Imports: 8 Imported by: 0

Documentation

Overview

Package layout defines the various layouts available to Bellui apps.

Index

Constants

This section is empty.

Variables

View Source 
var DefaultResponsiveBreakpoints = []float32{600, 840, 1200, 1600}

DefaultResponsiveBreakpoints are the Material Design 3 window size class boundaries, in dp: compact <600, medium <840, expanded <1200, large <1600, extra-large >=1600. Each value is the exclusive upper bound of one size class; widths at or beyond the last bound fall in the final class. Assign a custom ascending table to ResponsiveLayout.Breakpoints to use different classes — e.g. Bootstrap's 576, 768, 992, 1200.

Functions

func MirrorChildren 

func MirrorChildren(objects []core.CanvasObject, totalWidth float32)

MirrorChildren reflects every visible child horizontally within totalWidth so that a left-to-right arrangement becomes its right-to-left mirror. A child occupying [x, x+width) on the left is moved to the equivalent span measured from the right edge; vertical positions and all sizes are preserved. Full-width children (such as VBox rows or Border top/bottom bars) map onto themselves, so the reflection is a no-op for them.

It is applied as a post-pass after a layout has positioned its children, keeping the original (left-to-right) positioning code untouched. The standard layouts call it directly; custom-renderer widgets reach it via the widget package's mirrorIfRTL helper.

func NewAdaptiveGridLayout 

func NewAdaptiveGridLayout(rowcols int) core.Layout

NewAdaptiveGridLayout returns a new grid layout which uses columns when horizontal but rows when vertical.

func NewBorderLayout 

func NewBorderLayout(top, bottom, left, right core.CanvasObject) core.Layout

NewBorderLayout creates a new BorderLayout instance with top, bottom, left and right objects set. All other items in the container will fill the remaining space in the middle. Multiple extra items will be stacked in the specified order as a Stack container.

func NewCenterLayout 

func NewCenterLayout() core.Layout

NewCenterLayout creates a new CenterLayout instance

func NewCustomPaddedHBoxLayout 

func NewCustomPaddedHBoxLayout(padding float32) core.Layout

NewCustomPaddedHBoxLayout returns a layout similar to HBoxLayout that uses a custom amount of padding in between objects instead of the theme.Padding value.

Since: 1.0

func NewCustomPaddedLayout 

func NewCustomPaddedLayout(padTop, padBottom, padLeft, padRight float32) core.Layout

NewCustomPaddedLayout creates a new CustomPaddedLayout instance with the specified paddings.

Since: 1.0

func NewCustomPaddedVBoxLayout 

func NewCustomPaddedVBoxLayout(padding float32) core.Layout

NewCustomPaddedVBoxLayout returns a layout similar to VBoxLayout that uses a custom amount of padding in between objects instead of the theme.Padding value.

Since: 1.0

func NewFormLayout 

func NewFormLayout() core.Layout

NewFormLayout returns a new FormLayout instance

func NewGridLayout 

func NewGridLayout(cols int) core.Layout

NewGridLayout returns a grid layout arranged in a specified number of columns. The number of rows will depend on how many children are in the container that uses this layout.

func NewGridLayoutWithColumns 

func NewGridLayoutWithColumns(cols int) core.Layout

NewGridLayoutWithColumns returns a new grid layout that specifies a column count and wrap to new rows when needed.

func NewGridLayoutWithRows 

func NewGridLayoutWithRows(rows int) core.Layout

NewGridLayoutWithRows returns a new grid layout that specifies a row count that creates new rows as required.

func NewGridWrapLayout 

func NewGridWrapLayout(size geo.Size) core.Layout

NewGridWrapLayout returns a new GridWrapLayout instance

func NewHBoxLayout 

func NewHBoxLayout() core.Layout

NewHBoxLayout returns a horizontal box layout for stacking a number of child canvas objects or widgets left to right. The objects are always displayed at their horizontal MinSize. Use a different layout if the objects are intended to be larger than their horizontal MinSize.

func NewPaddedLayout 

func NewPaddedLayout() core.Layout

NewPaddedLayout creates a new PaddedLayout instance

Since: 1.0

func NewResponsiveLayout 

func NewResponsiveLayout(objects ...core.CanvasObject) *bellui.Container

NewResponsiveLayout returns a container with a ResponsiveLayout using the MD3 window size classes. Each object may declare per-class width ratios by being wrapped with Responsive; a plain object occupies a full row in every class.

Example: 

container := layout.NewResponsiveLayout(
    layout.Responsive(label, 1, .5, .25),  // full width when compact, half when medium, quarter beyond
    layout.Responsive(button, 1, .5, .25),
    label2,                                // full row in every class
)

Since: 1.0

func NewRowWrapLayout 

func NewRowWrapLayout() core.Layout

NewRowWrapLayout returns a layout that dynamically arranges objects of similar height in rows and wraps them dynamically. Objects are separated with horizontal and vertical padding.

Since: 1.0

func NewRowWrapLayoutWithCustomPadding 

func NewRowWrapLayoutWithCustomPadding(horizontal, vertical float32) core.Layout

NewRowWrapLayoutWithCustomPadding returns a new RowWrapLayout instance with custom horizontal and inner padding.

Since: 1.0

func NewShrinkLayout 

func NewShrinkLayout() core.Layout

NewShrinkLayout creates a layout that reports MinSize (0, 0) and positions every child at position (0, 0) with the full container size. This is useful when a resizable parent (Split, Scroll, AppTabs) must be able to shrink below the natural minimum size of its content.

Since: 1.0

func NewSpacer 

func NewSpacer() core.CanvasObject

NewSpacer returns a spacer object which can fill vertical and horizontal space. This is primarily used with a box layout.

func NewStackLayout 

func NewStackLayout() core.Layout

NewStackLayout returns a new StackLayout instance. Objects are stacked on top of each other with later objects on top of those before. Having only a single object has no impact as CanvasObjects will fill the available space even without a Stack.

Since: 1.0

func NewVBoxLayout 

func NewVBoxLayout() core.Layout

NewVBoxLayout returns a vertical box layout for stacking a number of child canvas objects or widgets top to bottom. The objects are always displayed at their vertical MinSize. Use a different layout if the objects are intended to be larger than their vertical MinSize.

func Responsive 

func Responsive(object core.CanvasObject, ratios ...float32) core.CanvasObject

Responsive wraps the given object with a responsive width configuration for use inside NewResponsiveLayout. The optional ratios must satisfy 0 < ratio <= 1 (out-of-range values are logged and treated as 1) and apply to the size classes in ascending order: 

Responsive(object, compact, medium, expanded, large, extraLarge)

A class without a ratio inherits the previous one, or 1.0 when none was given at all.

Since: 1.0

Types

type CustomPaddedLayout 

type CustomPaddedLayout struct {
	TopPadding    float32
	BottomPadding float32
	LeftPadding   float32
	RightPadding  float32
}

CustomPaddedLayout is a layout similar to PaddedLayout, but uses custom values for padding on each side, rather than the theme padding value.

Since: 1.0

func (CustomPaddedLayout) Layout 

func (c CustomPaddedLayout) Layout(objects []core.CanvasObject, size geo.Size)

Layout is called to pack all child objects into a specified size. For CustomPaddedLayout this sets all children to the full size passed minus the given paddings all around.

func (CustomPaddedLayout) MinSize 

func (c CustomPaddedLayout) MinSize(objects []core.CanvasObject) (min geo.Size)

MinSize finds the smallest size that satisfies all the child objects. For CustomPaddedLayout this is determined simply as the MinSize of the largest child plus the given paddings all around.

type FlexHBoxLayout 

type FlexHBoxLayout struct {
	Flex      []float32 // flex grow factor per child (0 = fixed size)
	MinWidth  []float32 // minimum width per child (0 = use MinSize)
	MaxWidth  []float32 // maximum width per child (0 = no limit)
	MinHeight []float32 // cross-axis minimum height per child (0 = unset); Since: 1.0
	MaxHeight []float32 // cross-axis maximum height per child (0 = no limit, full stretch); Since: 1.0
	Padding   float32   // spacing between children (0 = theme default)
}

FlexHBoxLayout is a horizontal layout where children can have flex grow factors and min/max width constraints. Children with flex=0 get their natural MinSize. Remaining space is distributed proportionally among children with flex>0.

The main axis is horizontal: Flex/MinWidth/MaxWidth constrain width. The cross axis is vertical and children are stretched to the container height by default; the optional MinHeight/MaxHeight arrays clamp a child's height instead (start/top-aligned within the freed space).

Since: 1.0

func NewFlexHBoxLayout 

func NewFlexHBoxLayout(flex []float32) *FlexHBoxLayout

NewFlexHBoxLayout creates a horizontal flex layout with the given per-child grow factors. Children with flex=0 use their natural MinSize; remaining space is split proportionally among children with flex>0.

func (*FlexHBoxLayout) Layout 

func (l *FlexHBoxLayout) Layout(objects []core.CanvasObject, size geo.Size)

func (*FlexHBoxLayout) MinSize 

func (l *FlexHBoxLayout) MinSize(objects []core.CanvasObject) geo.Size

type FlexVBoxLayout 

type FlexVBoxLayout struct {
	Flex      []float32 // flex grow factor per child
	MinHeight []float32 // minimum height per child
	MaxHeight []float32 // maximum height per child
	MinWidth  []float32 // cross-axis minimum width per child (0 = unset); Since: 1.0
	MaxWidth  []float32 // cross-axis maximum width per child (0 = no limit, full stretch); Since: 1.0
	Padding   float32   // spacing between children (0 = theme default)
}

FlexVBoxLayout is the vertical equivalent of FlexHBoxLayout. Children with flex>0 share remaining vertical space proportionally.

The main axis is vertical: Flex/MinHeight/MaxHeight constrain height. The cross axis is horizontal and children are stretched to the container width by default; the optional MinWidth/MaxWidth arrays clamp a child's width instead (start/left-aligned within the freed space).

Since: 1.0

func NewFlexVBoxLayout 

func NewFlexVBoxLayout(flex []float32) *FlexVBoxLayout

NewFlexVBoxLayout creates a vertical flex layout with the given per-child grow factors.

func (*FlexVBoxLayout) Layout 

func (l *FlexVBoxLayout) Layout(objects []core.CanvasObject, size geo.Size)

func (*FlexVBoxLayout) MinSize 

func (l *FlexVBoxLayout) MinSize(objects []core.CanvasObject) geo.Size

type ResponsiveLayout 

type ResponsiveLayout struct {
	// Breakpoints are the ascending, exclusive upper bounds (in dp) of each
	// size class except the last. When nil, [DefaultResponsiveBreakpoints]
	// (the MD3 window size classes) apply. A ratio configuration always
	// holds five entries; with a shorter table the trailing entries are
	// unused, with a longer one the last entry repeats.
	Breakpoints []float32
	// contains filtered or unexported fields
}

ResponsiveLayout lays out objects in rows, giving each object a width that is its configured ratio of the container width for the active size class (see Responsive) and wrapping to a new row when a row's ratios would exceed the full width. Rows are as tall as their tallest member and mirror under a right-to-left layout direction.

Since: 1.0

func (*ResponsiveLayout) Layout 

func (r *ResponsiveLayout) Layout(objects []core.CanvasObject, containerSize geo.Size)

Layout is called to pack all child objects into a specified size.

Implements: core.Layout

func (*ResponsiveLayout) MinSize 

func (r *ResponsiveLayout) MinSize(objects []core.CanvasObject) geo.Size

MinSize returns the smallest size this layout needs: the widest child's minimum width (rows reflow, so no row is forced wider than one child) and the height of the current arrangement. Before the first layout pass it estimates a single-column stack.

Implements: core.Layout

type Spacer 

type Spacer struct {
	FixHorizontal bool
	FixVertical   bool
	// contains filtered or unexported fields
}

Spacer is any simple object that can be used in a box layout to space out child objects

func (*Spacer) ExpandHorizontal 

func (s *Spacer) ExpandHorizontal() bool

ExpandHorizontal returns whether or not this spacer expands on the horizontal axis

func (*Spacer) ExpandVertical 

func (s *Spacer) ExpandVertical() bool

ExpandVertical returns whether or not this spacer expands on the vertical axis

func (*Spacer) Hide 

func (s *Spacer) Hide()

Hide removes this Spacer from layout calculations

func (*Spacer) MinSize 

func (s *Spacer) MinSize() geo.Size

MinSize returns a 0 size as a Spacer can shrink to no actual size

func (*Spacer) Move 

func (s *Spacer) Move(pos geo.Position)

Move sets a new position for the Spacer - this will be called by the layout

func (*Spacer) Position 

func (s *Spacer) Position() geo.Position

Position returns the current position of this Spacer

func (*Spacer) Refresh 

func (s *Spacer) Refresh()

Refresh does nothing for a spacer but is part of the CanvasObject definition

func (*Spacer) Resize 

func (s *Spacer) Resize(size geo.Size)

Resize sets a new size for the Spacer - this will be called by the layout

func (*Spacer) Show 

func (s *Spacer) Show()

Show sets the Spacer to be part of the layout calculations

func (*Spacer) Size 

func (s *Spacer) Size() geo.Size

Size returns the current size of this Spacer

func (*Spacer) Visible 

func (s *Spacer) Visible() bool

Visible returns true if this spacer should affect the layout

type SpacerObject 

type SpacerObject interface {
	ExpandVertical() bool
	ExpandHorizontal() bool
}

SpacerObject is any object that can be used to space out child objects

Source Files

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