images - How to implement add_image_size in a plugin

I created a plugin and I need to use add_image_size in it.

I know how it works in the functions.php file and for a theme, but how can I implement this in a plugin?

I want new images uploaded by WordPress users to be smaller for mobile screens by

add_image_size( 'wp_small', 60, 75, true ); // mobile

I read that you need to use init or admin_init but I don't know how to implement this.

I created a plugin and I need to use add_image_size in it.

I know how it works in the functions.php file and for a theme, but how can I implement this in a plugin?

I want new images uploaded by WordPress users to be smaller for mobile screens by

add_image_size( 'wp_small', 60, 75, true ); // mobile

I read that you need to use init or admin_init but I don't know how to implement this.

• plugin-development
• images

Share Improve this question edited Mar 4, 2019 at 10:05 norman.lol 3,26133 gold badges3030 silver badges3535 bronze badges asked Jun 7, 2012 at 1:40 GinoGino 20233 silver badges1010 bronze badges 1

• Did you finish your plugin yet? And did you release it by any chance? I'm searching for one currently, can't be bothered to code something... :D – Julian F. Weinert Commented Feb 8, 2021 at 13:00

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2 Answers 2

Sorted by: Reset to default 6

Just call this function in the init action. This action is fired for both frontend and backend. So it should look like this:

add_action( 'init', 'wpse4378_add_new_image_size' );
function wpse4378_add_new_image_size() {
    add_image_size( 'wp_small', 60, 75, true ); //mobile
}

It's better to call it in after_setup_theme instead of init action:

Codex says you should call add_image_size in functions.php so the closest action is after_setup_theme. Then you have:

add_action( 'after_setup_theme', 'your_theme_setup' );
function your_theme_setup() {
    add_image_size( 'wp_small', 60, 75, true ); //mobile
}

(Also explained in user contributed notes)