Make Sure Important Emails Reach Your Customers
Solve common email deliverability issues for good. Get WP Mail SMTP!
/** * Regenerate Thumbnails: Attachment regenerator class * * @package RegenerateThumbnails * @since 3.0.0 */ /** * Regenerates the thumbnails for a given attachment. * * @since 3.0.0 */ class RegenerateThumbnails_Regenerator { /** * The WP_Post object for the attachment that is being operated on. * * @since 3.0.0 * * @var WP_Post */ public $attachment; /** * The full path to the original image so that it can be passed between methods. * * @since 3.0.0 * * @var string */ public $fullsizepath; /** * An array of thumbnail size(s) that were skipped during regeneration due to already existing. * A class variable is used so that the data can later be used to merge the size(s) back in. * * @since 3.0.0 * * @var array */ public $skipped_thumbnails = array(); /** * The metadata for the attachment before the regeneration process starts. * * @since 3.1.6 * * @var array */ private $old_metadata = array(); /** * Generates an instance of this class after doing some setup. * * MIME type is purposefully not validated in order to be more future proof and * to avoid duplicating a ton of logic that already exists in WordPress core. * * @since 3.0.0 * * @param int $attachment_id Attachment ID to process. * * @return RegenerateThumbnails_Regenerator|WP_Error A new instance of RegenerateThumbnails_Regenerator on success, or WP_Error on error. */ public static function get_instance( $attachment_id ) { $attachment = get_post( $attachment_id ); if ( ! $attachment ) { return new WP_Error( 'regenerate_thumbnails_regenerator_attachment_doesnt_exist', __( 'No attachment exists with that ID.', 'regenerate-thumbnails' ), array( 'status' => 404, ) ); } // We can only regenerate thumbnails for attachments. if ( 'attachment' !== get_post_type( $attachment ) ) { return new WP_Error( 'regenerate_thumbnails_regenerator_not_attachment', __( 'This item is not an attachment.', 'regenerate-thumbnails' ), array( 'status' => 400, ) ); } // Don't touch any attachments that are being used as a site icon. Their thumbnails are usually custom cropped. if ( self::is_site_icon( $attachment ) ) { return new WP_Error( 'regenerate_thumbnails_regenerator_is_site_icon', __( "This attachment is a site icon and therefore the thumbnails shouldn't be touched.", 'regenerate-thumbnails' ), array( 'status' => 415, 'attachment' => $attachment, ) ); } return new RegenerateThumbnails_Regenerator( $attachment ); } /** * The constructor for this class. Don't call this directly, see get_instance() instead. * This is done so that WP_Error objects can be returned during class initiation. * * @since 3.0.0 * * @param WP_Post $attachment The WP_Post object for the attachment that is being operated on. */ private function __construct( WP_Post $attachment ) { $this->attachment = $attachment; } /** * Returns whether the attachment is or was a site icon. * * @since 3.0.0 * * @param WP_Post $attachment The WP_Post object for the attachment that is being operated on. * * @return bool Whether the attachment is or was a site icon. */ public static function is_site_icon( WP_Post $attachment ) { return ( 'site-icon' === get_post_meta( $attachment->ID, '_wp_attachment_context', true ) ); } /** * Get the path to the fullsize attachment. * * @return string|WP_Error The path to the fullsize attachment, or a WP_Error object on error. */ public function get_fullsizepath() { if ( $this->fullsizepath ) { return $this->fullsizepath; } if ( function_exists( 'wp_get_original_image_path' ) ) { $this->fullsizepath = wp_get_original_image_path( $this->attachment->ID ); } else { $this->fullsizepath = get_attached_file( $this->attachment->ID ); } if ( false === $this->fullsizepath || ! file_exists( $this->fullsizepath ) ) { $error = new WP_Error( 'regenerate_thumbnails_regenerator_file_not_found', sprintf( /* translators: The relative upload path to the attachment. */ __( "The fullsize image file cannot be found in your uploads directory at %s. Without it, new thumbnail images can't be generated.", 'regenerate-thumbnails' ), _wp_relative_upload_path( $this->fullsizepath ) ), array( 'status' => 404, 'fullsizepath' => _wp_relative_upload_path( $this->fullsizepath ), 'attachment' => $this->attachment, ) ); $this->fullsizepath = $error; } return $this->fullsizepath; } /** * Regenerate the thumbnails for this instance's attachment. * * @since 3.0.0 * * @param array|string $args { * Optional. Array or string of arguments for thumbnail regeneration. * * @type bool $only_regenerate_missing_thumbnails Skip regenerating existing thumbnail files. Default true. * @type bool $delete_unregistered_thumbnail_files Delete any thumbnail sizes that are no longer registered. Default false. * } * * @return mixed|WP_Error Metadata for attachment (see wp_generate_attachment_metadata()), or WP_Error on error. */ public function regenerate( $args = array() ) { global $wpdb; $args = wp_parse_args( $args, array( 'only_regenerate_missing_thumbnails' => true, 'delete_unregistered_thumbnail_files' => false, ) ); $fullsizepath = $this->get_fullsizepath(); if ( is_wp_error( $fullsizepath ) ) { $fullsizepath->add_data( array( 'attachment' => $this->attachment ) ); return $fullsizepath; } $this->old_metadata = wp_get_attachment_metadata( $this->attachment->ID ); if ( $args['only_regenerate_missing_thumbnails'] ) { add_filter( 'intermediate_image_sizes_advanced', array( $this, 'filter_image_sizes_to_only_missing_thumbnails' ), 10, 2 ); } require_once( ABSPATH . 'wp-admin/includes/admin.php' ); $new_metadata = wp_generate_attachment_metadata( $this->attachment->ID, $fullsizepath ); if ( $args['only_regenerate_missing_thumbnails'] ) { // Thumbnail sizes that existed were removed and need to be added back to the metadata. foreach ( $this->skipped_thumbnails as $skipped_thumbnail ) { if ( ! empty( $this->old_metadata['sizes'][ $skipped_thumbnail ] ) ) { $new_metadata['sizes'][ $skipped_thumbnail ] = $this->old_metadata['sizes'][ $skipped_thumbnail ]; } } $this->skipped_thumbnails = array(); remove_filter( 'intermediate_image_sizes_advanced', array( $this, 'filter_image_sizes_to_only_missing_thumbnails' ), 10 ); } $wp_upload_dir = dirname( $fullsizepath ) . DIRECTORY_SEPARATOR; if ( $args['delete_unregistered_thumbnail_files'] ) { // Delete old sizes that are still in the metadata. $intermediate_image_sizes = get_intermediate_image_sizes(); foreach ( $this->old_metadata['sizes'] as $old_size => $old_size_data ) { if ( in_array( $old_size, $intermediate_image_sizes ) ) { continue; } wp_delete_file( $wp_upload_dir . $old_size_data['file'] ); unset( $new_metadata['sizes'][ $old_size ] ); } $relative_path = dirname( $new_metadata['file'] ) . DIRECTORY_SEPARATOR; // It's possible to upload an image with a filename like image-123x456.jpg and it shouldn't be deleted. $whitelist = $wpdb->get_col( $wpdb->prepare( " SELECT meta_value FROM {$wpdb->postmeta} WHERE meta_key = '_wp_attached_file' AND meta_value REGEXP %s /* Regenerate Thumbnails */ ", '^' . preg_quote( $relative_path ) . '[^' . preg_quote( DIRECTORY_SEPARATOR ) . ']+-[0-9]+x[0-9]+\.' ) ); $whitelist = array_map( 'basename', $whitelist ); $filelist = array(); foreach ( scandir( $wp_upload_dir ) as $file ) { if ( '.' == $file || '..' == $file || ! is_file( $wp_upload_dir . $file ) ) { continue; } $filelist[] = $file; } $registered_thumbnails = array(); foreach ( $new_metadata['sizes'] as $size ) { $registered_thumbnails[] = $size['file']; } $fullsize_parts = pathinfo( $fullsizepath ); foreach ( $filelist as $file ) { if ( in_array( $file, $whitelist ) || in_array( $file, $registered_thumbnails ) ) { continue; } if ( ! preg_match( '#^' . preg_quote( $fullsize_parts['filename'], '#' ) . '-[0-9]+x[0-9]+\.' . preg_quote( $fullsize_parts['extension'], '#' ) . '$#', $file ) ) { continue; } wp_delete_file( $wp_upload_dir . $file ); } } elseif ( ! empty( $this->old_metadata ) && ! empty( $this->old_metadata['sizes'] ) && is_array( $this->old_metadata['sizes'] ) ) { // If not deleting, rename any size conflicts to avoid them being lost if the file still exists. foreach ( $this->old_metadata['sizes'] as $old_size => $old_size_data ) { if ( empty( $new_metadata['sizes'][ $old_size ] ) ) { $new_metadata['sizes'][ $old_size ] = $this->old_metadata['sizes'][ $old_size ]; continue; } $new_size_data = $new_metadata['sizes'][ $old_size ]; if ( $new_size_data['width'] !== $old_size_data['width'] && $new_size_data['height'] !== $old_size_data['height'] && file_exists( $wp_upload_dir . $old_size_data['file'] ) ) { $new_metadata['sizes'][ $old_size . '_old_' . $old_size_data['width'] . 'x' . $old_size_data['height'] ] = $old_size_data; } } } wp_update_attachment_metadata( $this->attachment->ID, $new_metadata ); return $new_metadata; } /** * Filters the list of thumbnail sizes to only include those which have missing files. * * @since 3.0.0 * * @param array $sizes An associative array of registered thumbnail image sizes. * @param array $fullsize_metadata An associative array of fullsize image metadata: width, height, file. * * @return array An associative array of image sizes. */ public function filter_image_sizes_to_only_missing_thumbnails( $sizes, $fullsize_metadata ) { if ( ! $sizes ) { return $sizes; } $fullsizepath = $this->get_fullsizepath(); if ( is_wp_error( $fullsizepath ) ) { return $sizes; } $editor = wp_get_image_editor( $fullsizepath ); if ( is_wp_error( $editor ) ) { return $sizes; } $metadata = $this->old_metadata; // This is based on WP_Image_Editor_GD::multi_resize() and others. foreach ( $sizes as $size => $size_data ) { if ( empty( $metadata['sizes'][ $size ] ) ) { continue; } if ( ! isset( $size_data['width'] ) && ! isset( $size_data['height'] ) ) { continue; } if ( ! isset( $size_data['width'] ) ) { $size_data['width'] = null; } if ( ! isset( $size_data['height'] ) ) { $size_data['height'] = null; } if ( ! isset( $size_data['crop'] ) ) { $size_data['crop'] = false; } $thumbnail = $this->get_thumbnail( $editor, $fullsize_metadata['width'], $fullsize_metadata['height'], $size_data['width'], $size_data['height'], $size_data['crop'] ); // The false check filters out thumbnails that would be larger than the fullsize image. // The size comparison makes sure that the size is also correct. if ( false === $thumbnail || ( $thumbnail['width'] === $metadata['sizes'][ $size ]['width'] && $thumbnail['height'] === $metadata['sizes'][ $size ]['height'] && file_exists( $thumbnail['filename'] ) ) ) { $this->skipped_thumbnails[] = $size; unset( $sizes[ $size ] ); } } /** * Filters the list of missing thumbnail sizes if you want to add/remove any. * * @since 3.1.0 * * @param array $sizes An associative array of image sizes that are missing. * @param array $fullsize_metadata An associative array of fullsize image metadata: width, height, file. * @param object $this The current instance of this class. * * @return array An associative array of image sizes. */ return apply_filters( 'regenerate_thumbnails_missing_thumbnails', $sizes, $fullsize_metadata, $this ); } /** * Generate the thumbnail filename and dimensions for a given set of constraint dimensions. * * @since 3.0.0 * * @param WP_Image_Editor|WP_Error $editor An instance of WP_Image_Editor, as returned by wp_get_image_editor(). * @param int $fullsize_width The width of the fullsize image. * @param int $fullsize_height The height of the fullsize image. * @param int $thumbnail_width The width of the thumbnail. * @param int $thumbnail_height The height of the thumbnail. * @param bool $crop Whether to crop or not. * * @return array|false An array of the filename, thumbnail width, and thumbnail height, * or false on failure to resize such as the thumbnail being larger than the fullsize image. */ public function get_thumbnail( $editor, $fullsize_width, $fullsize_height, $thumbnail_width, $thumbnail_height, $crop ) { $dims = image_resize_dimensions( $fullsize_width, $fullsize_height, $thumbnail_width, $thumbnail_height, $crop ); if ( ! $dims ) { return false; } list( , , , , $dst_w, $dst_h ) = $dims; $suffix = "{$dst_w}x{$dst_h}"; $file_ext = strtolower( pathinfo( $this->get_fullsizepath(), PATHINFO_EXTENSION ) ); return array( 'filename' => $editor->generate_filename( $suffix, null, $file_ext ), 'width' => $dst_w, 'height' => $dst_h, ); } /** * Update the post content of any public post types (posts and pages by default) * that make use of this attachment. * * @since 3.0.0 * * @param array|string $args { * Optional. Array or string of arguments for controlling the updating. * * @type array $post_type The post types to update. Defaults to public post types (posts and pages by default). * @type array $post_ids Specific post IDs to update as opposed to any that uses the attachment. * @type int $posts_per_loop How many posts to query at a time to keep memory usage down. You shouldn't need to modify this. * } * * @return array|WP_Error List of post IDs that were modified. The key is the post ID and the value is either the post ID again or a WP_Error object if wp_update_post() failed. */ public function update_usages_in_posts( $args = array() ) { // Temporarily disabled until it can be even better tested for edge cases return array(); $args = wp_parse_args( $args, array( 'post_type' => array(), 'post_ids' => array(), 'posts_per_loop' => 10, ) ); if ( empty( $args['post_type'] ) ) { $args['post_type'] = array_values( get_post_types( array( 'public' => true ) ) ); unset( $args['post_type']['attachment'] ); } $offset = 0; $posts_updated = array(); while ( true ) { $posts = get_posts( array( 'numberposts' => $args['posts_per_loop'], 'offset' => $offset, 'orderby' => 'ID', 'order' => 'ASC', 'include' => $args['post_ids'], 'post_type' => $args['post_type'], 's' => 'wp-image-' . $this->attachment->ID, // For faster queries. 'update_post_meta_cache' => false, 'update_post_term_cache' => false, ) ); if ( ! $posts ) { break; } $offset += $args['posts_per_loop']; foreach ( $posts as $post ) { $content = $post->post_content; $search = array(); $replace = array(); // Find all tags for this attachment and update them. preg_match_all( '#]+wp-image-' . $this->attachment->ID . '[^>]+/>#i', $content, $matches, PREG_SET_ORDER ); if ( $matches ) { foreach ( $matches as $img_tag ) { preg_match( '# class="([^"]+)?size-([^" ]+)#i', $img_tag[0], $thumbnail_size ); if ( $thumbnail_size ) { $thumbnail = image_downsize( $this->attachment->ID, $thumbnail_size[2] ); if ( ! $thumbnail ) { continue; } $search[] = $img_tag[0]; $img_tag[0] = preg_replace( '# src="[^"]+"#i', ' src="' . esc_url( $thumbnail[0] ) . '"', $img_tag[0] ); $img_tag[0] = preg_replace( '# width="[^"]+" height="[^"]+"#i', ' width="' . esc_attr( $thumbnail[1] ) . '" height="' . esc_attr( $thumbnail[2] ) . '"', $img_tag[0] ); $replace[] = $img_tag[0]; } } } $content = str_replace( $search, $replace, $content ); $search = array(); $replace = array(); // Update the width in any [caption] shortcodes. preg_match_all( '#\[caption id="attachment_' . $this->attachment->ID . '"([^\]]+)? width="[^"]+"\]([^\[]+)size-([^" ]+)([^\[]+)\[\/caption\]#i', $content, $matches, PREG_SET_ORDER ); if ( $matches ) { foreach ( $matches as $match ) { $thumbnail = image_downsize( $this->attachment->ID, $match[3] ); if ( ! $thumbnail ) { continue; } $search[] = $match[0]; $replace[] = '[caption id="attachment_' . $this->attachment->ID . '"' . $match[1] . ' width="' . esc_attr( $thumbnail[1] ) . '"]' . $match[2] . 'size-' . $match[3] . $match[4] . '[/caption]'; } } $content = str_replace( $search, $replace, $content ); $updated_post_object = (object) array( 'ID' => $post->ID, 'post_content' => $content, ); $posts_updated[ $post->ID ] = wp_update_post( $updated_post_object, true ); } } return $posts_updated; } /** * Returns information about the current attachment for use in the REST API. * * @since 3.0.0 * * @return array|WP_Error The attachment name, fullsize URL, registered thumbnail size status, and any unregistered sizes, or WP_Error on error. */ public function get_attachment_info() { $fullsizepath = $this->get_fullsizepath(); if ( is_wp_error( $fullsizepath ) ) { $fullsizepath->add_data( array( 'attachment' => $this->attachment ) ); return $fullsizepath; } $editor = wp_get_image_editor( $fullsizepath ); if ( is_wp_error( $editor ) ) { // Display a more helpful error message. if ( 'image_no_editor' === $editor->get_error_code() ) { $editor = new WP_Error( 'image_no_editor', __( 'The current image editor cannot process this file type.', 'regenerate-thumbnails' ) ); } $editor->add_data( array( 'attachment' => $this->attachment, 'status' => 415, ) ); return $editor; } $metadata = wp_get_attachment_metadata( $this->attachment->ID ); if ( false === $metadata || ! is_array( $metadata ) ) { return new WP_Error( 'regenerate_thumbnails_regenerator_no_metadata', __( 'Unable to load the metadata for this attachment.', 'regenerate-thumbnails' ), array( 'status' => 404, 'attachment' => $this->attachment, ) ); } if ( ! isset( $metadata['sizes'] ) ) { $metadata['sizes'] = array(); } // PDFs don't have width/height set. $width = ( isset( $metadata['width'] ) ) ? $metadata['width'] : null; $height = ( isset( $metadata['height'] ) ) ? $metadata['height'] : null; require_once( ABSPATH . '/wp-admin/includes/image.php' ); $preview = false; if ( file_is_displayable_image( $fullsizepath ) ) { $preview = wp_get_attachment_url( $this->attachment->ID ); } elseif ( is_array( $metadata['sizes'] ) && is_array( $metadata['sizes']['full'] ) && ! empty( $metadata['sizes']['full']['file'] ) ) { $preview = str_replace( wp_basename( $fullsizepath ), $metadata['sizes']['full']['file'], wp_get_attachment_url( $this->attachment->ID ) ); if ( ! file_exists( $preview ) ) { $preview = false; } } $response = array( 'name' => ( $this->attachment->post_title ) ? $this->attachment->post_title : sprintf( __( 'Attachment %d', 'regenerate-thumbnails' ), $this->attachment->ID ), 'preview' => $preview, 'relative_path' => _wp_get_attachment_relative_path( $fullsizepath ) . DIRECTORY_SEPARATOR . wp_basename( $fullsizepath ), 'edit_url' => get_edit_post_link( $this->attachment->ID, 'raw' ), 'width' => $width, 'height' => $height, 'registered_sizes' => array(), 'unregistered_sizes' => array(), ); $wp_upload_dir = dirname( $fullsizepath ) . DIRECTORY_SEPARATOR; $registered_sizes = RegenerateThumbnails()->get_thumbnail_sizes(); if ( 'application/pdf' === get_post_mime_type( $this->attachment ) ) { $registered_sizes = array_intersect_key( $registered_sizes, array( 'thumbnail' => true, 'medium' => true, 'large' => true, ) ); } // Check the status of all currently registered sizes. foreach ( $registered_sizes as $size ) { // Width and height are needed to generate the thumbnail filename. if ( $width && $height ) { $thumbnail = $this->get_thumbnail( $editor, $width, $height, $size['width'], $size['height'], $size['crop'] ); if ( $thumbnail ) { $size['filename'] = wp_basename( $thumbnail['filename'] ); $size['fileexists'] = file_exists( $thumbnail['filename'] ); } else { $size['filename'] = false; $size['fileexists'] = false; } } elseif ( ! empty( $metadata['sizes'][ $size['label'] ]['file'] ) ) { $size['filename'] = wp_basename( $metadata['sizes'][ $size['label'] ]['file'] ); $size['fileexists'] = file_exists( $wp_upload_dir . $metadata['sizes'][ $size['label'] ]['file'] ); } else { $size['filename'] = false; $size['fileexists'] = false; } $response['registered_sizes'][] = $size; } if ( ! $width && ! $height && is_array( $metadata['sizes']['full'] ) ) { $response['registered_sizes'][] = array( 'label' => 'full', 'width' => $metadata['sizes']['full']['width'], 'height' => $metadata['sizes']['full']['height'], 'filename' => $metadata['sizes']['full']['file'], 'fileexists' => file_exists( $wp_upload_dir . $metadata['sizes']['full']['file'] ), ); } // Look at the attachment metadata and see if we have any extra files from sizes that are no longer registered. foreach ( $metadata['sizes'] as $label => $size ) { if ( ! file_exists( $wp_upload_dir . $size['file'] ) ) { continue; } // An unregistered size could match a registered size's dimensions. Ignore these. foreach ( $response['registered_sizes'] as $registered_size ) { if ( $size['file'] === $registered_size['filename'] ) { continue 2; } } if ( ! empty( $registered_sizes[ $label ] ) ) { /* translators: Used for listing old sizes of currently registered thumbnails */ $label = sprintf( __( '%s (old)', 'regenerate-thumbnails' ), $label ); } $response['unregistered_sizes'][] = array( 'label' => $label, 'width' => $size['width'], 'height' => $size['height'], 'filename' => $size['file'], 'fileexists' => true, ); } return $response; } } Does Class Size Really Matters? – Skoop Singapore | One stop platform for kids education, enrichment and resources
  • You have no bookmark.

Your Wishlist : 0 listings

Sign In

Does Class Size Really Matters?

Class size matters more in early education, less so for teens.

 

When it comes to education, the topic of class size frequently pops up. Many has wondered why Singapore, a country known for its robust education system, hasn’t pushed for smaller class sizes.

 

You might not be aware, but in Singapore schools, the teacher-student ratio is about 1 teacher for every 14 to 15 students, which is similar to the average in many developed countries. While it might seem like classrooms are overcrowded, this ratio actually shows that we have a reasonable number of teachers compared to students. The situation is more balanced than it might appear at first glance.

 

But we might wonder why classes are not capped at, say, 20 students? It’s likely because it isn’t practical because teachers have many responsibilities beyond teaching, such as lesson planning, grading, and student progress monitoring. Smaller class sizes would require more teachers, and without increasing staff, existing teachers would be overburdened, leading to burnout and reduced teaching quality.

 

However, with larger class sizes of around 30 to 40 students, it becomes challenging for teachers to give personalized attention to each child. It’s tough to cater to every student’s unique learning pace and needs in such a setting. As a result, many parents turn to external enrichment classes to ensure their children receive the extra support they require.

 

Enrichment centres, in contrast, typically have an average class size of just 6 to 8 students. A survey of 50 parents revealed that 80% believe the ideal class size at these centres should be between 4 to 6 students, clearly showing that class size is a top priority for parents when selecting an educational centre for their children.


Benefits of small class size:

 

Individualized Attention: Smaller class sizes allow teachers to focus on each child’s unique learning style and needs, providing personalized support that can lead to better academic outcomes.

 

Increased Engagement & Participation: Students are more likely to engage actively in discussions and activities in smaller classes, which enhances their interest, understanding, and retention of the subject matter. In such settings, they often feel more comfortable asking questions and seeking clarification, resulting in higher levels of participation.

 

Better Classroom Management: Smaller classes usually make classroom management easier, minimizing distractions and disruptions, which leads to a more focused learning environment—especially for younger students who are more prone to getting distracted.

 

Tailored Instruction: Teachers can adapt their teaching methods and materials more effectively to suit the specific needs of their students making lessons more relevant and engaging.

 

Faster Feedback: With fewer students to assess, teachers are able to monitor students progress more closely and can provide immediate feedback on homework and assessments, helping students understand their progress and areas for improvement.

 


This targeted support is why many parents view outside school support as a vital supplement to their child’s education, helping them not only to keep up but also excel in their learning journey. However, research shows that smaller class sizes are more effective in early education but matter less as students grow older. For secondary and higher education levels, factors like teaching quality, curriculum, and student motivation may have a greater influence on learning outcomes.

Therefore, while smaller classes can provide certain advantages, they are not the sole determinant of a quality education. The overall learning environment, teacher quality, and access to resources can also have a significant impact on a child’s educational experience.

Prev Post
Every Family Needs a “Phone Contract”
Next Post
The real reasons why parents are turning to tuition for their kids

Add Comment

Your email is safe with us.

0
Close

Your cart

No products in the cart.