Overwrite add_image_size defined by theme

Question

I bought a WP-Theme which defines a custom image-size in his theme-functions.php like this:

if ( function_exists( 'add_image_size' ) ){
    add_image_size( 'tie-small', 70, 70, true );
}

As you can see the third-parameter is true, which results in hard crop mode (see Wordpress Documentation for add_image_size). This mode isn't taking care of the proportions so some of my thumbnails are resized very badly. I did some tests and changing the crop-Parameter to FALSE will create better results.

I want to overwrite this image-size by using a plugin so that I can update my theme without changing the value above to FALSE on every update. The add_image_size function storing his data in a array with $name as key. So multiplice calls of this function will overwrite the values up to the last call.

My plugin is very simple and looks like the following:

class My_Plugin {
    public function __construct() {
        add_action( 'after_setup_theme', array( $this, 'overwrite_wptheme_settings' ) );
    }

    public function overwrite_wptheme_settings() {
        add_image_size( 'tie-small', 70, 70, false );
    }
}

Its not working, I reuploaded a test-image and it looks like crop is set to true. I cant figure out why because the value was overwritten! I could verify this by going to the function tie_last_posts in the theme-functions.php of the theme. This function is generating the widget with the post-thumbnail image:

[...]
function tie_last_posts($numberOfPosts = 5 , $thumb = true) {
    // [...]
    <?php global $_wp_additional_image_sizes; 
          var_dump($_wp_additional_image_sizes);
    ?>
    <?php the_post_thumbnail( 'tie-small' ) ; ?>

This will output the following before the widget:

array(3) {
  ["tie-small"]=>
  array(3) {
    ["width"]=>
    int(70)
    ["height"]=>
    int(70)
    ["crop"]=>
    bool(false)
  }
  ["tie-large"]=>
  array(3) {
    ["width"]=>
    int(300)
    ["height"]=>
    int(160)
    ["crop"]=>
    bool(true)
  }
  ["slider"]=>
  array(3) {
    ["width"]=>
    int(620)
    ["height"]=>
    int(330)
    ["crop"]=>
    bool(true)
  }
}

As you can see, the attribute crop is set to false in the index tie-small. So it was overwritten by my plugin. But the thumbnail get cropped. I verified this by using a testimage which is getting clearly bad when it gets cropped by wordpress. I always reuploaded the image in the article. AND I have verified that the overwriting itself is working: I inserted add_image_size( 'tie-small', 70, 70, false ); at the end of the theme-functions.php and it worked, but in my plugin it isnt. Whats wrong here?

Answer 1

Change the action to 'init':

class My_Plugin {
    public function __construct() {
        add_action( 'init', array( $this, 'overwrite_wptheme_settings' ) );
    }

    public function overwrite_wptheme_settings() {
        add_image_size( 'tie-small', 70, 70, false );
    }
}

Answer 2

Solved this by creating a child-theme. In the action after_setup_theme I overwrite the image-size and it works, thumbnails aren't cropped anymore. Not sure why it isn't possible to do this in a plugin, but for me it seems that creating a childtheme instead of a plugin is the better solution anyway. The WP-Doc itself says that this is the recommended way to modify a theme, so I will move my changes made by my plugin to the child-theme I created.