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Description

Gets loading optimization attributes.

This function returns an array of attributes that should be merged into the given attributes array to optimize loading performance. Potential attributes returned by this function are:

• `loading` attribute with a value of "lazy"
• `fetchpriority` attribute with a value of "high"
• `decoding` attribute with a value of "async"

If any of these attributes are already present in the given attributes, they will not be modified. Note that no element should have both loading="lazy" and `fetchpriority="high"`, so the function will trigger a warning in case both attributes are present with those values.

Usage

$array = wp_get_loading_optimization_attributes( $tag_name, $attr, $context );

Parameters

$tag_name

( string ) required – The tag name.

$attr

( array ) required – Array of the attributes for the tag.

$context

( string ) required – Context for the element for which the loading optimization attribute is requested.

Returns

array Loading optimization attributes.

Source

File name: wordpress/wp-includes/media.php
Lines:

     * Otherwise, the value can be interpreted as in viewport, since only
     * the most important in-viewport image should have `fetchpriority` set
     * to "high".
     */
    if ( false === $maybe_in_viewport ) {
      _doing_it_wrong(
        __FUNCTION__,
        __( 'An image should not be lazy-loaded and marked as high priority at the same time.' ),
        '6.3.0'
      );
      /*
			 * Set `fetchpriority` here for backward-compatibility as we should
			 * not override what a developer decided, even though it seems
			 * incorrect.
			 */
      $loading_attrs['fetchpriority'] = 'high';
    } else {
      $maybe_in_viewport = true;
    }
  }

  if ( null === $maybe_in_viewport ) {
    $header_enforced_contexts = array(
      'template_part_' . WP_TEMPLATE_PART_AREA_HEADER => true,
      'get_header_image_tag' => true,
    );

    
/**
 * Filters the header-specific contexts.
 *
 * @since 6.4.0
 *
 * @param array $default_header_enforced_contexts Map of contexts for which elements should be considered
 *                                                in the header of the page, as $context => $enabled
 *                                                pairs. The $enabled should always be true.
 */
    $header_enforced_contexts = apply_filters( 'wp_loading_optimization_force_header_contexts', $header_enforced_contexts );

    // Consider elements with these header-specific contexts to be in viewport.
    if ( isset( $header_enforced_contexts[ $context ] ) ) {
      $maybe_in_viewport    = true;
      $maybe_increase_count = true;
    } elseif ( ! is_admin() && in_the_loop() && is_main_query() ) {
      /*
			 * Get the content media count, since this is a main query
			 * content element. This is accomplished by "increasing"
			 * the count by zero, as the only way to get the count is
			 * to call this function.
			 * The actual count increase happens further below, based
			 * on the `$increase_count` flag set here.
			 */
      $content_media_count = wp_increase_content_media_count( 0 );
      $increase_count      = true;

      // If the count so far is below the threshold, `loading` attribute is omitted.
      if ( $content_media_count < wp_omit_loading_attr_threshold() ) {
        $maybe_in_viewport = true;
      } else {
        $maybe_in_viewport = false;
      }
    } elseif (
      // Only apply for main query but before the loop.
      $wp_query->before_loop && $wp_query->is_main_query()
      /*
			 * Any image before the loop, but after the header has started should not be lazy-loaded,
			 * except when the footer has already started which can happen when the current template
			 * does not include any loop.
			 */
      && did_action( 'get_header' ) && ! did_action( 'get_footer' )
      ) {
      $maybe_in_viewport    = true;
      $maybe_increase_count = true;
    }
  }

  /*
	 * If the element is in the viewport (`true`), potentially add
	 * `fetchpriority` with a value of "high". Otherwise, i.e. if the element
	 * is not not in the viewport (`false`) or it is unknown (`null`), add
	 * `loading` with a value of "lazy".
	 */
  if ( $maybe_in_viewport ) {
    $loading_attrs = wp_maybe_add_fetchpriority_high_attr( $loading_attrs, $tag_name, $attr );
  } else {
    // Only add `loading="lazy"` if the feature is enabled.
    if ( wp_lazy_loading_enabled( $tag_name, $context ) ) {
      $loading_attrs['loading'] = 'lazy';
    }
  }

  /*
	 * If flag was set based on contextual logic above, increase the content
	 * media count, either unconditionally, or based on whether the image size
	 * is larger than the threshold.
	 */
  if ( $increase_count ) {
    wp_increase_content_media_count();
  } elseif ( $maybe_increase_count ) {
    
/** This filter is documented in wp-includes/media.php */
    $wp_min_priority_img_pixels = apply_filters( 'wp_min_priority_img_pixels', 50000 );
 

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