The largest and most complex block support. Handles layout types (flow, constrained, flex, grid), gap/spacing styles, child layout positioning, and classic theme compatibility.

Source: wp-includes/block-supports/layout.php
Since: 5.8.0

Support Keys

• supports.layout
• supports.__experimentalLayout (legacy fallback)

Registered Attribute

Layout Types

wp_get_layout_definitions()

function wp_get_layout_definitions(): array

Since: 6.3.0
Since: 6.6.0 Updated specificity for 0-1-0 global styles compatibility.
Access: private

Returns definitions for four layout types:

Each definition includes baseStyles and spacingStyles arrays with selector/rules pairs.

Flow/Constrained Base Styles

• .alignleft: float left with inline margins
• .alignright: float right with inline margins
• .aligncenter: auto left/right margins

Constrained Additional Base Styles

• Non-aligned children: max-width: var(--wp--style--global--content-size), auto margins
• .alignwide: max-width: var(--wp--style--global--wide-size)

Flex Base Styles

• flex-wrap: wrap, align-items: center
• Children: margin: 0 (with :is(*, div) for +001 specificity)

Grid Base Styles

• Children: margin: 0 (with :is(*, div) for +001 specificity)

Functions

wp_register_layout_support()

function wp_register_layout_support( WP_Block_Type $block_type )

Since: 5.8.0
Since: 6.3.0 Check for layout support via layout key with fallback to __experimentalLayout.
Access: private

wp_get_layout_style()

function wp_get_layout_style(
    string $selector,
    array $layout,
    bool $has_block_gap_support = false,
    string|array|null $gap_value = null,
    bool $should_skip_gap_serialization = false,
    string $fallback_gap_value = '0.5em',
    ?array $block_spacing = null
): string

Since: 5.9.0
Since: 6.1.0 Added $block_spacing param, use style engine to enqueue styles.
Since: 6.3.0 Added grid layout type.
Since: 6.6.0 Removed duplicated selector; enabled negative margins for alignfull children.
Access: private

Generates CSS rules based on layout type:

Flow (default):

• Block gap via margin-block-start/margin-block-end on > * and > * + *

Constrained:

• contentSize → max-width on non-aligned children
• wideSize → max-width on .alignwide
• .alignfull → max-width: none
• justifyContent → margin-left/margin-right adjustments (left, right, center)
• Negative margins for .alignfull when block has custom padding
• Block gap same as flow

Flex:

• orientation → horizontal (default) or vertical (flex-direction: column)
• justifyContent → maps to justify-content or align-items depending on orientation
• verticalAlignment → maps to align-items or justify-content
• flexWrap: nowrap → flex-wrap: nowrap
• Gap: row and column gap support (array or single value)

Grid:

• columnCount → grid-template-columns: repeat(N, minmax(0, 1fr))
• minimumColumnWidth → grid-template-columns: repeat(auto-fill, minmax(min(W, 100%), 1fr)) + container-type: inline-size
• Gap support same as flex

All styles stored in style engine block-supports context.

wp_render_layout_support_flag()

function wp_render_layout_support_flag( string $block_content, array $block ): string

Since: 5.8.0
Since: 6.3.0 Adds compound class for global spacing; checks layout with __experimentalLayout fallback.
Since: 6.6.0 Removed duplicate container class.
Access: private

Processing:

1. Child layout: Handles $block['attrs']['style']['layout'] (selfStretch, flexSize, columnSpan, rowSpan) and $block['parentLayout']

   • Generates deterministic class via wp_unique_id_from_values()
   • fixed selfStretch → flex-basis + box-sizing: border-box
   • fill selfStretch → flex-grow: 1
   • columnSpan → grid-column: span N
   • rowSpan → grid-row: span N
   • Responsive column span: @container query resets to 1/-1 when grid is too narrow

2. Parent layout: Reads $used_layout from block attributes or fallback

   • Legacy inherit: true or contentSize → sets type to constrained
   • useRootPaddingAwareAlignments + constrained → adds has-global-padding
   • Adds orientation, justification, and nowrap classes
   • Generates layout CSS via wp_get_layout_style() (skipped if theme supports disable-layout-styles)
   • Adds compound class: wp-block-{name}-{layout-class}

3. Inner block wrapper detection: Searches for the inner wrapper tag by matching original class attribute from $block['innerContent'][0]

wp_add_parent_layout_to_parsed_block()

function wp_add_parent_layout_to_parsed_block( array $parsed_block, array $source_block, WP_Block $parent_block ): array

Child layout: Handles $block['attrs']['style']['layout'] (selfStretch, flexSize, columnSpan, rowSpan) and $block['parentLayout']

Parent layout: Reads $used_layout from block attributes or fallback

wp_restore_group_inner_container()

function wp_restore_group_inner_container( string $block_content, array $block ): string

Inner block wrapper detection: Searches for the inner wrapper tag by matching original class attribute from $block['innerContent'][0]

Child layout: Handles $block['attrs']['style']['layout'] (selfStretch, flexSize, columnSpan, rowSpan) and $block['parentLayout']

wp_restore_image_outer_container()

function wp_restore_image_outer_container( string $block_content, array $block ): string

Parent layout: Reads $used_layout from block attributes or fallback

Inner block wrapper detection: Searches for the inner wrapper tag by matching original class attribute from $block['innerContent'][0]

Generated CSS Classes

Hooks

Registration

WP_Block_Supports::get_instance()->register(
    'layout',
    array(
        'register_attribute' => 'wp_register_layout_support',
    )
);

Since: 6.6.0
Access: private