Adding a custom image upload size and making it selected by default?

2 comments

1. There are a few steps to this, as I found out today. First, you add a custom image size (you can put this somewhere the functions.php file in your theme):

   add_theme_support( 'post-thumbnails' );
   add_image_size( 'my-size', 550, 550 ); // not sure what you want your height to
                                        // be, but this'll shrink it to 550px
                                        // wide *or* tall. If you want it to be
                                        // cropped to a 550px square, add true as
                                        // a fourth argument
   

   The unfortunate thing is that WordPress doesn’t actually show this new size in the media uploader. You’ll have to put a function that does this into your functions.php as well (source: http://kucrut.org/insert-image-with-custom-size-into-post/):

   function my_insert_custom_image_sizes( $sizes ) {
       // get the custom image sizes
       global $_wp_additional_image_sizes;
       // if there are none, just return the built-in sizes
       if ( empty( $_wp_additional_image_sizes ) )
           return $sizes;
   
       // add all the custom sizes to the built-in sizes
       foreach ( $_wp_additional_image_sizes as $id => $data ) {
           // take the size ID (e.g., 'my-name'), replace hyphens with spaces,
           // and capitalise the first letter of each word
           if ( !isset($sizes[$id]) )
               $sizes[$id] = ucfirst( str_replace( '-', ' ', $id ) );
       }
   
       return $sizes;
   }
   
   // apply the above function as a filter on the media uploader's list of
   // image sizes
   add_filter( 'image_size_names_choose', 'my_insert_custom_image_sizes' );
   

   Lastly, to set this size as the default, you’ll need to change a WordPress setting. Add a filter on the setting in question. This has the benefit of being portable with your theme in which you’ve defined all the above options.

   function my_set_default_image_size () {
       return 'my-size';
   }
   add_filter( 'pre_option_image_default_size', 'my_set_default_image_size' );
   

   I tested this all out on WordPress 3.4.2, and it seems to work great.

   Note: I’d recommend putting the above PHP code into an init function of some sort and attaching it to the 'after_setup_theme' hook:

   // define the functions first
   function my_insert_custom_image_sizes( $sizes ) {
       // not going to repeat the function body, for brevity's sake
   }
   
   function my_set_default_image_size() {
       // ditto
   }
   
   // define the init function next, which sets up all the necessary stuff
   function custom_image_setup () {
       add_theme_support( 'post-thumbnails' );
       add_image_size( 'my-size', 550, 550 );
       add_filter( 'image_size_names_choose', 'my_insert_custom_image_sizes' );
       add_filter( 'pre_option_image_default_size', 'my_set_default_image_size' );
   }
   
   // and attach that init function to the 'after_setup_theme' hook
   // so it runs on each page load once your theme's been loaded
   add_action( 'after_setup_theme', 'custom_image_setup' );
   

   Log in to Reply

2. Just set all other options to 0 in your Admin panel under “Settings” » “Media”. This will disable them.

   Log in to Reply