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<?php
/**
* File: UserExperience_LazyLoad_Mutator.php
*
* @package W3TC
*/
namespace W3TC;
/**
* Class UserExperience_LazyLoad_Mutator
*/
class UserExperience_LazyLoad_Mutator {
/**
* Configuration settings for lazy loading.
*
* @var Config
*/
private $config;
/**
* Tracks whether the content was modified during processing.
*
* @var bool
*/
private $modified = false;
/**
* List of content patterns to exclude from lazy loading.
*
* @var array
*/
private $excludes;
/**
* Map of post URLs to their corresponding post IDs.
*
* @var array
*/
private $posts_by_url;
/**
* Constructor for UserExperience_LazyLoad_Mutator.
*
* @param array $config Configuration settings for lazy loading.
* @param array $posts_by_url Map of post URLs to their corresponding post IDs.
*
* @return void
*/
public function __construct( $config, $posts_by_url ) {
$this->config = $config;
$this->posts_by_url = $posts_by_url;
}
/**
* Runs the lazy loading mutator process on the provided buffer.
*
* @param string $buffer The HTML content to process for lazy loading.
*
* @return string The modified buffer with lazy loading applied.
*/
public function run( $buffer ) {
$this->excludes = apply_filters( 'w3tc_lazyload_excludes', $this->config->get_array( 'lazyload.exclude' ) );
$r = apply_filters(
'w3tc_lazyload_mutator_before',
array(
'buffer' => $buffer,
'modified' => $this->modified,
)
);
$buffer = $r['buffer'];
$this->modified = $r['modified'];
$unmutable = new UserExperience_LazyLoad_Mutator_Unmutable();
$buffer = $unmutable->remove_unmutable( $buffer );
if ( $this->config->get_boolean( 'lazyload.process_img' ) ) {
$buffer = preg_replace_callback(
'~<picture(\s[^>]+)*>(.*?)</picture>~is',
array( $this, 'tag_picture' ),
$buffer
);
$buffer = preg_replace_callback(
'~<img\s[^>]+>~is',
array( $this, 'tag_img' ),
$buffer
);
}
if ( $this->config->get_boolean( 'lazyload.process_background' ) ) {
$buffer = preg_replace_callback(
'~<[^>]+background(-image)?:\s*url[^>]+>~is',
array( $this, 'tag_with_background' ),
$buffer
);
}
$buffer = $unmutable->restore_unmutable( $buffer );
return $buffer;
}
/**
* Checks if the content has been modified during processing.
*
* @return bool True if the content was modified; otherwise, false.
*/
public function content_modified() {
return $this->modified;
}
/**
* Processes <picture> tags for lazy loading.
*
* @param array $matches Regex matches for the <picture> tag.
*
* @return string The modified <picture> tag with lazy loading applied.
*/
public function tag_picture( $matches ) {
$content = $matches[0];
if ( $this->is_content_excluded( $content ) ) {
return $content;
}
$m = new UserExperience_LazyLoad_Mutator_Picture( $this );
return $m->run( $content );
}
/**
* Processes <img> tags for lazy loading.
*
* @param array $matches Regex matches for the <img> tag.
*
* @return string The modified <img> tag with lazy loading applied.
*/
public function tag_img( $matches ) {
$content = $matches[0];
if ( $this->is_content_excluded( $content ) ) {
return $content;
}
// get image dimensions.
$dim = $this->tag_get_dimensions( $content );
return $this->tag_img_content_replace( $content, $dim );
}
/**
* Replaces <img> content with placeholders and adds lazy loading attributes.
*
* @param string $content The <img> tag content.
* @param array $dim The dimensions of the image (width and height).
*
* @return string The modified <img> tag.
*/
public function tag_img_content_replace( $content, $dim ) {
// do replace.
$count = 0;
$content = preg_replace(
'~(\s)src=~is',
'$1src="' . $this->placeholder( $dim['w'], $dim['h'] ) . '" data-src=',
$content,
-1,
$count
);
if ( $count > 0 ) {
$content = preg_replace(
'~(\s)(srcset|sizes)=~is',
'$1data-$2=',
$content
);
$content = $this->add_class_lazy( $content );
$content = $this->remove_native_lazy( $content );
$this->modified = true;
}
return $content;
}
/**
* Extracts image dimensions from <img> content or associated metadata.
*
* @param string $content The <img> tag content.
*
* @return array The dimensions of the image (width and height).
*/
public function tag_get_dimensions( $content ) {
$dim = array(
'w' => 1,
'h' => 1,
);
$m = null;
if ( preg_match( '~\swidth=[\s\'"]*([0-9]+)~is', $content, $m ) ) {
$dim['w'] = (int) $m[1];
$dim['h'] = $dim['w'];
if ( preg_match( '~\sheight=[\s\'"]*([0-9]+)~is', $content, $m ) ) {
$dim['h'] = (int) $m[1];
return $dim;
}
}
// if not in attributes - try to find via url.
if (
! preg_match(
'~\ssrc=(\'([^\']*)\'|"([^"]*)"|([^\'"][^\\s]*))~is',
$content,
$m
)
) {
return $dim;
}
$url = ( ! empty( $m[4] ) ? $m[4] : ( ( ! empty( $m[3] ) ? $m[3] : $m[2] ) ) );
// full url found.
if ( isset( $this->posts_by_url[ $url ] ) ) {
$post_id = $this->posts_by_url[ $url ];
$image = wp_get_attachment_image_src( $post_id, 'full' );
if ( $image ) {
$dim['w'] = $image[1];
$dim['h'] = $image[2];
}
return $dim;
}
// try resized url by format.
static $base_url = null;
if ( is_null( $base_url ) ) {
$base_url = wp_get_upload_dir()['baseurl'];
}
if (
substr( $url, 0, strlen( $base_url ) ) === $base_url &&
preg_match( '~(.+)-(\\d+)x(\\d+)(\\.[a-z0-9]+)$~is', $url, $m )
) {
$dim['w'] = (int) $m[2];
$dim['h'] = (int) $m[3];
}
return $dim;
}
/**
* Processes elements with background styles for lazy loading.
*
* @param array $matches Regex matches for elements with background styles.
*
* @return string The modified element with lazy loading applied.
*/
public function tag_with_background( $matches ) {
$content = $matches[0];
if ( $this->is_content_excluded( $content ) ) {
return $content;
}
$quote_match = null;
if ( ! preg_match( '~\s+style\s*=\s*([\"\'])~is', $content, $quote_match ) ) {
return $content;
}
$quote = $quote_match[1];
$count = 0;
$content = preg_replace_callback(
'~(\s+)(style\s*=\s*[' . $quote . '])(.*?)([' . $quote . '])~is',
array( $this, 'style_offload_background' ),
$content,
-1,
$count
);
if ( $count > 0 ) {
$content = $this->add_class_lazy( $content );
$this->modified = true;
}
return $content;
}
/**
* Offloads background styles for lazy loading.
*
* @param array $matches Regex matches for background styles.
*
* @return string The modified style attribute with lazy loading applied.
*/
public function style_offload_background( $matches ) {
list( $match, $v1, $v2, $v, $quote ) = $matches;
$url_match = null;
preg_match( '~background(-image)?:\s*(url\([^>]+\))~is', $v, $url_match );
$v = preg_replace( '~background(-image)?:\s*url\([^>]+\)[;]?\s*~is', '', $v );
return $v1 . $v2 . $v . $quote . ' data-bg=' . $quote . ( isset( $url_match[2] ) ? $url_match[2] : '' ) . $quote;
}
/**
* Adds the "lazy" class to the provided content if not already present.
*
* @param string $content The content to modify.
*
* @return string The modified content with the "lazy" class applied.
*/
private function add_class_lazy( $content ) {
$count = 0;
$content = preg_replace_callback(
'~(\s+)(class=)([\"\'])(.*?)([\"\'])~is',
array( $this, 'class_process' ),
$content,
-1,
$count
);
if ( $count <= 0 ) {
$content = preg_replace(
'~<(\S+)(\s+)~is',
'<$1$2class="lazy" ',
$content
);
}
return $content;
}
/**
* Removes native lazy loading attributes from the content.
*
* @param string $content The content to modify.
*
* @return string The modified content with native lazy loading removed.
*/
public function remove_native_lazy( $content ) {
return preg_replace(
'~(\s+)loading=[\'"]lazy[\'"]~is',
'',
$content
);
}
/**
* Processes class attributes to include the "lazy" class.
*
* @param array $matches Regex matches for class attributes.
*
* @return string The modified class attribute.
*/
public function class_process( $matches ) {
list( $match, $v1, $v2, $quote, $v ) = $matches;
if ( preg_match( '~(^|\\s)lazy(\\s|$)~is', $v ) ) {
return $match;
}
$v .= ' lazy';
return $v1 . $v2 . $quote . $v . $quote;
}
/**
* Determines if the content should be excluded from lazy loading.
*
* @param string $content The content to check.
*
* @return bool True if the content is excluded; otherwise, false.
*/
private function is_content_excluded( $content ) {
foreach ( $this->excludes as $w ) {
if ( ! empty( $w ) ) {
if ( strpos( $content, $w ) !== false ) {
return true;
}
}
}
return false;
}
/**
* Generates a placeholder SVG for an image with the given dimensions.
*
* @param int $w The width of the image.
* @param int $h The height of the image.
*
* @return string The SVG placeholder.
*/
public function placeholder( $w, $h ) {
return 'data:image/svg+xml,%3Csvg%20xmlns=\'http://www.w3.org/2000/svg\'%20viewBox=\'0%200%20' .
$w . '%20' . $h . '\'%3E%3C/svg%3E';
}
}