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wp_print_auto_sizes_contain_css_fix()

Since
6.7.1
Source
wp-includes/media.php:2068
Prints a CSS rule to fix potential visual issues with images using sizes=auto.

Description

This rule overrides the similar rule in the default user agent stylesheet, to avoid images that use e.g.
width: auto or width: fit-content to appear smaller.

Compatibility

WordPress
since 6.7.1
PHP
7.4–8.6-dev
  • 6.7.10
  • 6.8.11
  • 6.9.10
  • 7.0.7
  • 7.1.3

Present in every tracked release (6.7.10 to 7.1.3), and compiles on PHP 7.4 through 8.6-dev.

Performance profile

How much work a call to wp_print_auto_sizes_contain_css_fix() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class
Trivial

Touches nothing outside its own arguments.

Scaling
Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions
7–8

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 9.

Plugin surface
1 hook

Third-party callbacks on 'wp_img_tag_add_auto_sizes' run inside this call, and their cost is not bounded by anything here.

Called by
0

Nothing in core calls this; the cost is only what you spend yourself.

What it touches

  • hookthird-party callbacksapply_filters()called directly

What one call costs · 1 distinct outcome

One number would be a lie: the work depends on which branch runs. These are every distinct cost wp_print_auto_sizes_contain_css_fix() can have, taken from its control-flow graph on PHP 8.5.

WhenInstructionsCalls it makes
always7–8apply_filters()

Across PHP versions

Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 9 instructions, 7–8 executed per call, 1 branch. The work does not change between versions.

An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.

Hooks and filters fired · 1

One hook fires while wp_print_auto_sizes_contain_css_fix() runs, in this order:

  1. apply_filters( wp_img_tag_add_auto_sizes )filterline 2070 (+2 into the body)

    Filters whether auto-sizes for lazy loaded images is enabled.

Uses · 1

  • apply_filters()Calls the callback functions that have been added to a filter hook.

Source code

View on Trac View on GitHub 

function wp_print_auto_sizes_contain_css_fix() {	/** This filter is documented in wp-includes/media.php */	$add_auto_sizes = apply_filters( 'wp_img_tag_add_auto_sizes', true );	if ( ! $add_auto_sizes ) {		return;	} 	?>	<style>img:is([sizes="auto" i], [sizes^="auto," i]) { contain-intrinsic-size: 3000px 1500px }</style>	<?php}

Changelog

Introduced in 6.7.1. Unchanged from 6.7.10 through 7.1.3.

  1. 6.7.10
  2. 6.8.11
  3. 6.9.10
  4. 7.0.7
  5. 7.1.3

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data
Generated from the wordpress-develop 6.7.10 tag, from src/wp-includes/media.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
Corrections
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