Handles sticky and fixed positioning for blocks.

Source: wp-includes/block-supports/position.php
Since: 6.2.0

Support Key

supports.position

Position types are gated by global theme settings (not just block support):

• settings.position.sticky must be true for sticky
• settings.position.fixed must be true for fixed

Registered Attribute

Block Attributes Read

From $block['attrs']['style']['position']:

Functions

wp_register_position_support()

function wp_register_position_support( WP_Block_Type $block_type )

Since: 6.2.0
Access: private

wp_render_position_support()

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

Since: 6.2.0
Access: private

Processing:

1. Checks block support and non-empty style.position
2. Reads global settings to determine allowed position types
3. For each side (top, right, bottom, left):
   • If value is 0 or '0', converts to '0px' for calc() compatibility
   • For top with fixed or sticky: wraps in calc({value} + var(--wp-admin--admin-bar--position-offset, 0px)) to account for the admin bar
4. Sets position: {type} and z-index: 10
5. Stores CSS in style engine block-supports context
6. Adds unique class and is-position-{type} class via WP_HTML_Tag_Processor

Generated CSS Classes

Generated Inline Styles

• If value is 0 or '0', converts to '0px' for calc() compatibility
• For top with fixed or sticky: wraps in calc({value} + var(--wp-admin--admin-bar--position-offset, 0px)) to account for the admin bar

Hooks

Registration

WP_Block_Supports::get_instance()->register(
    'position',
    array(
        'register_attribute' => 'wp_register_position_support',
    )
);