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class-amp-img-sanitizer.php
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class-amp-img-sanitizer.php
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<?php
/**
* Class AMP_Img_Sanitizer.
*
* @package AMP
*/
/**
* Class AMP_Img_Sanitizer
*
* Converts <img> tags to <amp-img> or <amp-anim>
*/
class AMP_Img_Sanitizer extends AMP_Base_Sanitizer {
/**
* Value used for width attribute when $attributes['width'] is empty.
*
* @since 0.2
*
* @const int
*/
const FALLBACK_WIDTH = 600;
/**
* Value used for height attribute when $attributes['height'] is empty.
*
* @since 0.2
*
* @const int
*/
const FALLBACK_HEIGHT = 400;
/**
* Tag.
*
* @var string HTML <img> tag to identify and replace with AMP version.
*
* @since 0.2
*/
public static $tag = 'img';
/**
* Animation extension.
*
* @var string
*/
private static $anim_extension = '.gif';
/**
* Sanitize the <img> elements from the HTML contained in this instance's DOMDocument.
*
* @since 0.2
*/
public function sanitize() {
/**
* Node list.
*
* @var DOMNodeList $node
*/
$nodes = $this->dom->getElementsByTagName( self::$tag );
$need_dimensions = array();
$num_nodes = $nodes->length;
if ( 0 === $num_nodes ) {
return;
}
for ( $i = $num_nodes - 1; $i >= 0; $i-- ) {
$node = $nodes->item( $i );
if ( ! $node instanceof DOMElement ) {
continue;
}
if ( ! $node->hasAttribute( 'src' ) || '' === $node->getAttribute( 'src' ) ) {
$this->remove_invalid_child( $node );
continue;
}
// Determine which images need their dimensions determined/extracted.
if ( ! is_numeric( $node->getAttribute( 'width' ) ) || ! is_numeric( $node->getAttribute( 'height' ) ) ) {
$need_dimensions[ $node->getAttribute( 'src' ) ][] = $node;
} else {
$this->adjust_and_replace_node( $node );
}
}
$this->determine_dimensions( $need_dimensions );
$this->adjust_and_replace_nodes_in_array_map( $need_dimensions );
}
/**
* "Filter" HTML attributes for <amp-anim> elements.
*
* @since 0.2
*
* @param string[] $attributes {
* Attributes.
*
* @type string $src Image URL - Pass along if found
* @type string $alt <img> `alt` attribute - Pass along if found
* @type string $class <img> `class` attribute - Pass along if found
* @type string $srcset <img> `srcset` attribute - Pass along if found
* @type string $sizes <img> `sizes` attribute - Pass along if found
* @type string $on <img> `on` attribute - Pass along if found
* @type string $attribution <img> `attribution` attribute - Pass along if found
* @type int $width <img> width attribute - Set to numeric value if px or %
* @type int $height <img> width attribute - Set to numeric value if px or %
* }
* @return array Returns HTML attributes; removes any not specifically declared above from input.
*/
private function filter_attributes( $attributes ) {
$out = array();
foreach ( $attributes as $name => $value ) {
switch ( $name ) {
case 'src':
case 'alt':
case 'class':
case 'srcset':
case 'sizes':
case 'on':
case 'attribution':
$out[ $name ] = $value;
break;
case 'width':
case 'height':
$out[ $name ] = $this->sanitize_dimension( $value, $name );
break;
default:
break;
}
}
return $out;
}
/**
* Determine width and height attribute values for images without them.
*
* Attempt to determine actual dimensions, otherwise set reasonable defaults.
*
* @param DOMElement[][] $need_dimensions Map <img> @src URLs to node for images with missing dimensions.
*/
private function determine_dimensions( $need_dimensions ) {
$dimensions_by_url = AMP_Image_Dimension_Extractor::extract( array_keys( $need_dimensions ) );
foreach ( $dimensions_by_url as $url => $dimensions ) {
foreach ( $need_dimensions[ $url ] as $node ) {
if ( ! $node instanceof DOMElement ) {
continue;
}
if (
! is_numeric( $node->getAttribute( 'width' ) ) &&
! is_numeric( $node->getAttribute( 'height' ) )
) {
$height = self::FALLBACK_HEIGHT;
$width = self::FALLBACK_WIDTH;
$node->setAttribute( 'width', $width );
$node->setAttribute( 'height', $height );
$class = $node->hasAttribute( 'class' ) ? $node->getAttribute( 'class' ) . ' amp-wp-unknown-size' : 'amp-wp-unknown-size';
$node->setAttribute( 'class', $class );
} elseif (
! is_numeric( $node->getAttribute( 'height' ) )
) {
$height = self::FALLBACK_HEIGHT;
$node->setAttribute( 'height', $height );
$class = $node->hasAttribute( 'class' ) ? $node->getAttribute( 'class' ) . ' amp-wp-unknown-size amp-wp-unknown-height' : 'amp-wp-unknown-size amp-wp-unknown-height';
$node->setAttribute( 'class', $class );
} elseif (
! is_numeric( $node->getAttribute( 'width' ) )
) {
$width = self::FALLBACK_WIDTH;
$node->setAttribute( 'width', $width );
$class = $node->hasAttribute( 'class' ) ? $node->getAttribute( 'class' ) . ' amp-wp-unknown-size amp-wp-unknown-width' : 'amp-wp-unknown-size amp-wp-unknown-width';
$node->setAttribute( 'class', $class );
}
}
}
}
/**
* Now that all images have width and height attributes, make final tweaks and replace original image nodes
*
* @param DOMNodeList[] $node_lists Img DOM nodes (now with width and height attributes).
*/
private function adjust_and_replace_nodes_in_array_map( $node_lists ) {
foreach ( $node_lists as $node_list ) {
foreach ( $node_list as $node ) {
$this->adjust_and_replace_node( $node );
}
}
}
/**
* Make final modifications to DOMNode
*
* @param DOMNode $node The DOMNode to adjust and replace.
*/
private function adjust_and_replace_node( $node ) {
$old_attributes = AMP_DOM_Utils::get_node_attributes_as_assoc_array( $node );
$new_attributes = $this->filter_attributes( $old_attributes );
$new_attributes = $this->enforce_sizes_attribute( $new_attributes );
if ( $this->is_gif_url( $new_attributes['src'] ) ) {
$this->did_convert_elements = true;
$new_tag = 'amp-anim';
} else {
$new_tag = 'amp-img';
}
$new_node = AMP_DOM_Utils::create_node( $this->dom, $new_tag, $new_attributes );
$node->parentNode->replaceChild( $new_node, $node );
}
/**
* Determines is a URL is considered a GIF URL
*
* @since 0.2
*
* @param string $url URL to inspect for GIF vs. JPEG or PNG.
*
* @return bool Returns true if $url ends in `.gif`
*/
private function is_gif_url( $url ) {
$ext = self::$anim_extension;
$path = AMP_WP_Utils::parse_url( $url, PHP_URL_PATH );
return substr( $path, -strlen( $ext ) ) === $ext;
}
}