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Deduplicate position block support container classes #13792

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7192eb8
Deduplicate position block support container classes
mukeshpanchal27 Sep 28, 2026
6d4fae4
Add tests for block position style sharing behaviour
mukeshpanchal27 Sep 28, 2026
1b634ad
Merge branch 'trunk' into fix/66200
mukeshpanchal27 Sep 28, 2026
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18 changes: 16 additions & 2 deletions src/wp-includes/block-supports/position.php
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Original file line number Diff line number Diff line change
Expand Up @@ -148,12 +148,26 @@ function wp_render_position_support( $block_content, $block ) {

$viewport_settings = $global_settings['viewport'] ?? null;
$responsive_media_queries = WP_Theme_JSON::get_viewport_media_queries( $viewport_settings );
$class_name = wp_unique_id( 'wp-container-' );
$selector = ".$class_name";
$position_styles = array();
$wrapper_classes = array();
$base_position = $style_attribute['position'] ?? null;

/*
* Derive the container class from the position styles rather than from a
* counter, so that blocks resolving to the same CSS share a single rule in
* the style engine store instead of emitting one rule per block instance.
*
* The hash covers the default state and every viewport state, since each
* contributes rules scoped to this class.
*/
$position_hash_input = array( $base_position );
foreach ( array_keys( $responsive_media_queries ) as $breakpoint ) {
$position_hash_input[ $breakpoint ] = $style_attribute[ $breakpoint ]['position'] ?? null;
}

$class_name = wp_unique_id_from_values( $position_hash_input, 'wp-container-' );
$selector = ".$class_name";

// Default viewport (base) position styles.
$base_styles = wp_get_position_support_styles(
$selector,
Expand Down
201 changes: 193 additions & 8 deletions tests/phpunit/tests/block-supports/wpRenderPositionSupport.php
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Original file line number Diff line number Diff line change
Expand Up @@ -127,6 +127,191 @@ public function test_position_block_support( $theme_name, $block_name, $position
);
}

/**
* Tests that blocks resolving to the same position styles share a single CSS rule.
*
* The container class is derived from the position styles, so repeating a block
* with the same position does not add a rule per instance to the style engine store.
*
* @ticket 66200
*
* @covers ::wp_render_position_support
*/
public function test_identical_position_styles_share_one_rule() {
switch_theme( 'block-theme-child-with-fluid-typography' );
$this->test_block_name = 'test/position-rules-are-deduplicated';

register_block_type(
$this->test_block_name,
array(
'api_version' => 2,
'attributes' => array(
'style' => array(
'type' => 'object',
),
),
'supports' => array(
'position' => true,
),
)
);

$block = array(
'blockName' => $this->test_block_name,
'attrs' => array(
'style' => array(
'position' => array(
'type' => 'sticky',
'top' => '0px',
),
),
),
);

$first = wp_render_position_support( '<div>One</div>', $block );
$second = wp_render_position_support( '<div>Two</div>', $block );

$this->assertSame(
1,
preg_match( '/class="(wp-container-[0-9a-f]{8}) is-position-sticky"/', $first, $first_match ),
'First block should receive a hashed position container class.'
);
$this->assertSame(
1,
preg_match( '/class="(wp-container-[0-9a-f]{8}) is-position-sticky"/', $second, $second_match ),
'Second block should receive a hashed position container class.'
);
$this->assertSame(
$first_match[1],
$second_match[1],
'Blocks with identical position styles should share a container class.'
);

$stylesheet = wp_style_engine_get_stylesheet_from_context(
'block-supports',
array(
'prettify' => false,
)
);

$this->assertSame(
1,
substr_count( $stylesheet, '.' . $first_match[1] . '{' ),
'Identical position styles should produce a single CSS rule.'
);
}

/**
* Tests that blocks with different position styles do not share a CSS rule.
*
* @ticket 66200
*
* @covers ::wp_render_position_support
*/
public function test_differing_position_styles_do_not_share_a_rule() {
switch_theme( 'block-theme-child-with-fluid-typography' );
$this->test_block_name = 'test/position-rules-differ';

register_block_type(
$this->test_block_name,
array(
'api_version' => 2,
'attributes' => array(
'style' => array(
'type' => 'object',
),
),
'supports' => array(
'position' => true,
),
)
);

$make_block = static function ( $top ) {
return array(
'blockName' => 'test/position-rules-differ',
'attrs' => array(
'style' => array(
'position' => array(
'type' => 'sticky',
'top' => $top,
),
),
),
);
};

$first = wp_render_position_support( '<div>One</div>', $make_block( '0px' ) );
$second = wp_render_position_support( '<div>Two</div>', $make_block( '10px' ) );

preg_match( '/class="(wp-container-[0-9a-f]{8}) /', $first, $first_match );
preg_match( '/class="(wp-container-[0-9a-f]{8}) /', $second, $second_match );

$this->assertNotSame(
$first_match[1],
$second_match[1],
'Blocks with different position styles should not share a container class.'
);
}

/**
* Tests that blocks differing only in a viewport state position do not share a CSS rule.
*
* @ticket 66200
*
* @covers ::wp_render_position_support
*/
public function test_differing_viewport_position_styles_do_not_share_a_rule() {
switch_theme( 'block-theme-child-with-fluid-typography' );
$this->test_block_name = 'test/position-viewport-rules-differ';

register_block_type(
$this->test_block_name,
array(
'api_version' => 2,
'attributes' => array(
'style' => array(
'type' => 'object',
),
),
'supports' => array(
'position' => true,
),
)
);

$make_block = static function ( $tablet_top ) {
return array(
'blockName' => 'test/position-viewport-rules-differ',
'attrs' => array(
'style' => array(
'position' => array(
'type' => 'sticky',
'top' => '0px',
),
'@tablet' => array(
'position' => array(
'top' => $tablet_top,
),
),
),
),
);
};

$first = wp_render_position_support( '<div>One</div>', $make_block( '1rem' ) );
$second = wp_render_position_support( '<div>Two</div>', $make_block( '2rem' ) );

preg_match( '/class="(wp-container-[0-9a-f]{8}) /', $first, $first_match );
preg_match( '/class="(wp-container-[0-9a-f]{8}) /', $second, $second_match );

$this->assertNotSame(
$first_match[1],
$second_match[1],
'Blocks with different viewport position styles should not share a container class.'
);
}

/**
* Data provider.
*
Expand All @@ -144,8 +329,8 @@ public function data_position_block_support() {
'top' => '0px',
),
),
'expected_wrapper' => '/^<div class="wp-container-\d+ is-position-sticky">Content<\/div>$/',
'expected_styles' => '/^.wp-container-\d+' . preg_quote( '{top:calc(0px + var(--wp-admin--admin-bar--position-offset, 0px));position:sticky;z-index:10;}' ) . '$/',
'expected_wrapper' => '/^<div class="wp-container-[0-9a-f]{8} is-position-sticky">Content<\/div>$/',
'expected_styles' => '/^.wp-container-[0-9a-f]{8}' . preg_quote( '{top:calc(0px + var(--wp-admin--admin-bar--position-offset, 0px));position:sticky;z-index:10;}' ) . '$/',
),
'sticky position style is not applied if theme does not support it' => array(
'theme_name' => 'default',
Expand Down Expand Up @@ -198,8 +383,8 @@ public function data_position_block_support() {
),
),
),
'expected_wrapper' => '/^<div class="wp-container-\d+ is-position-sticky">Content<\/div>$/',
'expected_styles' => '/^' . preg_quote( '@media (width <= 480px){.wp-container-' ) . '\d+' . preg_quote( '{top:calc(0px + var(--wp-admin--admin-bar--position-offset, 0px));position:sticky;z-index:10;}}' ) . '$/',
'expected_wrapper' => '/^<div class="wp-container-[0-9a-f]{8} is-position-sticky">Content<\/div>$/',
'expected_styles' => '/^' . preg_quote( '@media (width <= 480px){.wp-container-' ) . '[0-9a-f]{8}' . preg_quote( '{top:calc(0px + var(--wp-admin--admin-bar--position-offset, 0px));position:sticky;z-index:10;}}' ) . '$/',
),
'viewport position style inherits the default state position type' => array(
'theme_name' => 'block-theme-child-with-fluid-typography',
Expand All @@ -216,8 +401,8 @@ public function data_position_block_support() {
),
),
),
'expected_wrapper' => '/^<div class="wp-container-\d+ is-position-sticky">Content<\/div>$/',
'expected_styles' => '/^' . preg_quote( '.wp-container-' ) . '\d+' . preg_quote( '{top:calc(0px + var(--wp-admin--admin-bar--position-offset, 0px));position:sticky;z-index:10;}' ) . preg_quote( '@media (480px < width <= 782px){.wp-container-' ) . '\d+' . preg_quote( '{top:calc(2rem + var(--wp-admin--admin-bar--position-offset, 0px));position:sticky;z-index:10;}}' ) . '$/',
'expected_wrapper' => '/^<div class="wp-container-[0-9a-f]{8} is-position-sticky">Content<\/div>$/',
'expected_styles' => '/^' . preg_quote( '.wp-container-' ) . '[0-9a-f]{8}' . preg_quote( '{top:calc(0px + var(--wp-admin--admin-bar--position-offset, 0px));position:sticky;z-index:10;}' ) . preg_quote( '@media (480px < width <= 782px){.wp-container-' ) . '[0-9a-f]{8}' . preg_quote( '{top:calc(2rem + var(--wp-admin--admin-bar--position-offset, 0px));position:sticky;z-index:10;}}' ) . '$/',
),
'viewport position style is not applied if theme does not support it' => array(
'theme_name' => 'default',
Expand Down Expand Up @@ -249,8 +434,8 @@ public function data_position_block_support() {
),
),
),
'expected_wrapper' => '/^<div class="wp-container-\d+ is-position-sticky">Content<\/div>$/',
'expected_styles' => '/^' . preg_quote( '.wp-container-' ) . '\d+' . preg_quote( '{top:calc(0px + var(--wp-admin--admin-bar--position-offset, 0px));position:sticky;z-index:10;}' ) . preg_quote( '@media (width <= 480px){.wp-container-' ) . '\d+' . preg_quote( '{position:static;}}' ) . '$/',
'expected_wrapper' => '/^<div class="wp-container-[0-9a-f]{8} is-position-sticky">Content<\/div>$/',
'expected_styles' => '/^' . preg_quote( '.wp-container-' ) . '[0-9a-f]{8}' . preg_quote( '{top:calc(0px + var(--wp-admin--admin-bar--position-offset, 0px));position:sticky;z-index:10;}' ) . preg_quote( '@media (width <= 480px){.wp-container-' ) . '[0-9a-f]{8}' . preg_quote( '{position:static;}}' ) . '$/',
),
);
}
Expand Down
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