WordPress image resize functon

image-resize.php

/**
 * Resize an image to the specified dimensions
 * http://codex.wordpress.org/Class_Reference/WP_Image_Editor
 *
 * Returns the new image file path
 *
 * @param image_url
 * @param width
 * @param width
 * @return resized image file path
 
 function image_resize( $image_url=null, $width=null, $height=null ){
    $img = wp_get_image_editor( $image_url );
    if ( ! is_wp_error( $img ) ) {
        // resize if height and width supplied
        if ( $width || $height ) {
            if ( $width >= $height ) {
                $max = $width;
            } else {
                $max = $height;
            }
            $img->resize( $max, $max, false );
            $img->set_quality( 100 );
        }
        $img->stream();
    }
}