Force resizes and caches images without needing to add_image_size() and bloat the /upoads/ dir

iso-get-resized-attachment-src.php

<?php
/**
 * Force resizes and caches images without needing to add_image_size() and bloat the /upoads/ dir
 *
 * Most code is completely based on Konstantin Kovshenin's image-shortcode.php
 * https://gist.github.com/kovshenin/1984363
 *
 * Expects the params similar to wp_get_attachment_image_src()
 * http://codex.wordpress.org/Function_Reference/wp_get_attachment_image_src
 *
 * @uses image_make_intermediate_size
 *
 * @param int   $attachment_id
 * @param array $size
 *
 * @return array|string
 */
function iso_get_resized_attachment_src( $attachment_id, $size = array( 150, 150 ), $cropped = true ) {

	global $wpdb;


	// Sanitize
	$width        = absint( $size[0] );
	$height       = absint( $size[1] );
	$needs_resize = true;

	$desired_image_size = sprintf( 'resized-%dx%d', $width, $height );

	$upload_dir = wp_upload_dir();
	$src        = wp_get_attachment_url( $attachment_id );

	// If an attachment record was not found.
	if ( false === $src ) {
		return "Error: attachment not found.";
	}


	// Get the attachment's meta information
	$meta = wp_get_attachment_metadata( $attachment_id );

	if ( ! empty( $meta['sizes'][ $desired_image_size ] ) && ! empty( $meta['sizes'][ $desired_image_size ]['file'] ) ) {
		$src          = str_replace( basename( $src ), $meta['sizes'][ $desired_image_size ]['file'], $src );
		$needs_resize = false;
	}

	// Too small to resize
	if ( $meta['width'] < $width && $meta['height'] < $height ) {
		if ( empty( $meta['sizes'][ $desired_image_size ] ) || empty( $meta['sizes'][ $desired_image_size ]['file'] ) ) {
			$key       = $desired_image_size;
			$mime_type = wp_check_filetype( $src );

			$meta['sizes'][ $key ] = array(
				'file'      => basename( $src ),
				'width'     => $meta['width'],
				'height'    => $meta['height'],
				'mime-type' => $mime_type['type'],
			);
			wp_update_attachment_metadata( $attachment_id, $meta );
		}

		$needs_resize = false;
	}


	// If an image of such size was not found, we can create one.
	if ( $needs_resize ) {
		$attached_file = get_attached_file( $attachment_id );
		$resized       = image_make_intermediate_size( $attached_file, $width, $height, $cropped );
		if ( ! is_wp_error( $resized ) ) {

			// Let metadata know about our new size.
			$key                   = $desired_image_size;
			$meta['sizes'][ $key ] = $resized;
			$src                   = str_replace( basename( $src ), $resized['file'], $src );
			wp_update_attachment_metadata( $attachment_id, $meta );

			// Record in backup sizes so everything's cleaned up when attachment is deleted.
			$backup_sizes = get_post_meta( $attachment_id, '_wp_attachment_backup_sizes', true );
			if ( ! is_array( $backup_sizes ) ) {
				$backup_sizes = array();
			}
			$backup_sizes[ $key ] = $resized;
			update_post_meta( $attachment_id, '_wp_attachment_backup_sizes', $backup_sizes );
		}
	}

	return array( esc_url( $src ), $width, $height );
}