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The best way to understand what a hook does is to look at where it occurs in the source code.
do_action( "hook_name" )apply_filters( "hook_name", "what_to_filter" ).Remember, this hook may occur in more than one file. Moreover, the hook's context may change from version to version.
This hook occurs 5 times in this file.
| Line | Code |
|---|---|
| 5653 | |
| 5654 | $loading_attrs = array(); |
| 5655 | |
| 5656 | /* |
| 5657 | * Skip lazy-loading for the overall block template, as it is handled more granularly. |
| 5658 | * The skip is also applicable for `fetchpriority`. |
| 5659 | */ |
| 5660 | if ( 'template' === $context ) { |
| 5661 | /** This filter is documented in wp-includes/media.php */ |
| 5662 | return apply_filters( 'wp_get_loading_optimization_attributes', $loading_attrs, $tag_name, $attr, $context ); |
| 5663 | } |
| 5664 | |
| 5665 | // For now this function only supports images and iframes. |
| 5666 | if ( 'img' !== $tag_name && 'iframe' !== $tag_name ) { |
| 5667 | /** This filter is documented in wp-includes/media.php */ |
| 5668 | return apply_filters( 'wp_get_loading_optimization_attributes', $loading_attrs, $tag_name, $attr, $context ); |
| 5669 | } |
| 5670 | |
| 5671 | /* |
| 5672 | * Skip programmatically created images within content blobs as they need to be handled together with the other |
| 5673 | * images within the post content or widget content. |
| 5674 | * Without this clause, they would already be considered within their own context which skews the image count and |
| 5675 | * can result in the first post content image being lazy-loaded or an image further down the page being marked as a |
| 5676 | * high priority. |
| 5677 | */ |
| 5678 | if ( |
| 5679 | 'the_content' !== $context && doing_filter( 'the_content' ) || |
| 5680 | 'widget_text_content' !== $context && doing_filter( 'widget_text_content' ) || |
| 5681 | 'widget_block_content' !== $context && doing_filter( 'widget_block_content' ) |
| 5682 | ) { |
| 5683 | /** This filter is documented in wp-includes/media.php */ |
| 5684 | return apply_filters( 'wp_get_loading_optimization_attributes', $loading_attrs, $tag_name, $attr, $context ); |
| 5685 | |
| 5686 | } |
| 5687 | |
| 5688 | /* |
| 5689 | * Add `decoding` with a value of "async" for every image unless it has a |
| 5690 | * conflicting `decoding` attribute already present. |
| 5691 | */ |
| 5692 | if ( 'img' === $tag_name ) { |
| 5693 | if ( isset( $attr['decoding'] ) ) { |
| 5694 | $loading_attrs['decoding'] = $attr['decoding']; |
| 5695 | } else { |
| 5696 | $loading_attrs['decoding'] = 'async'; |
| 5697 | } |
| 5698 | } |
| 5699 | |
| 5700 | // For any resources, width and height must be provided, to avoid layout shifts. |
| 5701 | if ( ! isset( $attr['width'], $attr['height'] ) ) { |
| 5702 | /** This filter is documented in wp-includes/media.php */ |
| 5703 | return apply_filters( 'wp_get_loading_optimization_attributes', $loading_attrs, $tag_name, $attr, $context ); |
| 5704 | } |
| 5705 | |
| 5706 | /* |
| 5707 | * The key function logic starts here. |
| 5708 | */ |
| 5709 | $maybe_in_viewport = null; |
| 5710 | $increase_count = false; |
| 5711 | $maybe_increase_count = false; |
| 5712 | |
| Line | Code |
| 5839 | * Filters the loading optimization attributes. |
| 5840 | * |
| 5841 | * @since 6.4.0 |
| 5842 | * |
| 5843 | * @param array $loading_attrs The loading optimization attributes. |
| 5844 | * @param string $tag_name The tag name. |
| 5845 | * @param array $attr Array of the attributes for the tag. |
| 5846 | * @param string $context Context for the element for which the loading optimization attribute is requested. |
| 5847 | */ |
| 5848 | return apply_filters( 'wp_get_loading_optimization_attributes', $loading_attrs, $tag_name, $attr, $context ); |
| 5849 | } |
| 5850 | |
| 5851 | /** |
| 5852 | * Gets the threshold for how many of the first content media elements to not lazy-load. |
| 5853 | * |
| 5854 | * This function runs the {@see 'wp_omit_loading_attr_threshold'} filter, which uses a default threshold value of 3. |
| 5855 | * The filter is only run once per page load, unless the `$force` parameter is used. |
| 5856 | * |
| 5857 | * @since 5.9.0 |