WordPress: Page Post Screen Columns

_page-post-screen-columns.php

<?php
/*
 * WordPress: Page Post Screen Columns
 * 
 * To add a custom column for pages, hook the manage_pages_columns filter.
 */

define("SHOW_ICON", true);
if (SHOW_ICON) {
    /*
     * image icon
     */
    $sizes = get_intermediate_image_sizes();
    $icon_size = 'icon';
    if (!in_array($icon_size, $sizes)) {
        add_image_size( 'icon', 30, 30, true );// 30x30 pixels, hard crop mode
    }

}

/*
 * Custom Columns for page
 *
 * Manage the columns of the `page` post type
 */
function manage_columns_for_page($columns){
    //remove columns
    unset($columns['title']);
    unset($columns['date']);
    unset($columns['comments']);
    unset($columns['author']);
     
    $columns['title'] = _x('Page Title', 'column name');
    $columns['page-template'] = 'Page Template'; 
    $columns['author'] = __('Author');
    $columns['date'] = _x('Date', 'column name');
    if (SHOW_ICON) {
        $columns['page-featured-image'] = 'Image';
    }
    return $columns;
}
add_action('manage_page_posts_columns','manage_columns_for_page');


/*
 * Populate custom columns for `page` post type
 */
function populate_page_columns($column,$post_id){

    //page template column
    if($column == 'page-template'){
        //get the current page template being used for the page 
        $page_template_name = get_post_meta( $post_id, '_wp_page_template', true ); 
        //get a listing of all of the page templates for our site
        $page_templates = get_page_templates();
        if(in_array($page_template_name,$page_templates)){
            //search through each template
            foreach($page_templates as $key => $value){
                //if the template matches our current template, we found it
                if($page_template_name == $value){
                    echo $key . '';    
                }
            }   
        }else{
            echo 'Default';
        }   
    }

    if (SHOW_ICON) {
        //featured image column
        if($column == 'page-featured-image'){
            //if this page has a featured image
            if(has_post_thumbnail($post_id)){
                $page_featured_image = get_the_post_thumbnail($post_id,'icon');
                echo $page_featured_image;
            }else{
                echo '—';
            }
        }
    }

}
add_action('manage_page_posts_custom_column','populate_page_columns',10,2);


/*
 * Quick and dirty way to add style to the head
 */
function page_post_screen_columns_css() {
    echo '<style type="text/css">';
    echo 'th.column-page-featured-image{width: 3em;}';
    echo 'td.page-featured-image {vertical-align: middle;text-align: center;width: 3em;}';
    echo 'th.column-page-template, td.page-template {width: 160px}';
    echo '</style>';
}
add_action('admin_head', 'page_post_screen_columns_css');