get_adjacent_image_link

WordPress Version: 5.8

/**
 * Gets the next or previous image link that has the same post parent.
 *
 * Retrieves the current attachment object from the $post global.
 *
 * @since 5.8.0
 *
 * @param bool         $prev Optional. Whether to display the next (false) or previous (true) link. Default true.
 * @param string|int[] $size Optional. Image size. Accepts any registered image size name, or an array
 *                           of width and height values in pixels (in that order). Default 'thumbnail'.
 * @param bool         $text Optional. Link text. Default false.
 * @return string Markup for image link.
 */
function get_adjacent_image_link($prev = true, $size = 'thumbnail', $text = false)
{
    $post = get_post();
    $attachments = array_values(get_children(array('post_parent' => $post->post_parent, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => 'ASC', 'orderby' => 'menu_order ID')));
    foreach ($attachments as $k => $attachment) {
        if ((int) $attachment->ID === (int) $post->ID) {
            break;
        }
    }
    $output = '';
    $attachment_id = 0;
    if ($attachments) {
        $k = $prev ? $k - 1 : ($k + 1);
        if (isset($attachments[$k])) {
            $attachment_id = $attachments[$k]->ID;
            $attr = array('alt' => get_the_title($attachment_id));
            $output = wp_get_attachment_link($attachment_id, $size, true, false, $text, $attr);
        }
    }
    $adjacent = $prev ? 'previous' : 'next';
    /**
     * Filters the adjacent image link.
     *
     * The dynamic portion of the hook name, `$adjacent`, refers to the type of adjacency,
     * either 'next', or 'previous'.
     *
     * Possible hook names include:
     *
     *  - `next_image_link`
     *  - `previous_image_link`
     *
     * @since 3.5.0
     *
     * @param string $output        Adjacent image HTML markup.
     * @param int    $attachment_id Attachment ID
     * @param string|int[] $size    Requested image size. Can be any registered image size name, or
     *                              an array of width and height values in pixels (in that order).
     * @param string $text          Link text.
     */
    return apply_filters("{$adjacent}_image_link", $output, $attachment_id, $size, $text);
}