Lock aspect ratio in WooCommerce Measurement Price Calculator

functions.php

<?php

function display_aspect_ratio() {
	global $post;
	if ($post) {
		$aspect = get_post_meta($post->ID, 'aspect_ratio', true);
		if ($aspect) {
			echo '<input type="hidden" id="aspect_ratio" name="aspect_ratio" value="' . esc_attr( $aspect ) . '" />';
		}
	}
}
add_action( 'woocommerce_single_product_summary', 'display_aspect_ratio', 5 );

add_action( 'wp_head', 'lock_aspect_ratio', 99 );
function lock_aspect_ratio() {
	if ( is_product() ) {
		?>
			<script>
				jQuery( document ).ready(function() {
					var update_width;
					var update_height;
					update_width = function() {
                        			jQuery( '#width_needed' ).unbind('keyup', update_height);
  						if ( parseFloat(jQuery( '#aspect_ratio' ).val()) && parseFloat(jQuery( '#length_needed' ).val()) ) {
                            				jQuery( '#width_needed' ).val( Math.round(parseFloat(jQuery( '#length_needed' ).val()) *  parseFloat(jQuery( '#aspect_ratio' ).val())) ).keyup();
			                        }
			                        jQuery( '#width_needed' ).bind('keyup', update_height);
  					};
                    			update_height = function() {
                        			jQuery( '#length_needed' ).unbind('keyup', update_width);
  						if ( parseFloat(jQuery( '#aspect_ratio' ).val()) && parseFloat(jQuery( '#width_needed' ).val()) ) {
                            				jQuery( '#length_needed' ).val( Math.round(parseFloat(jQuery( '#width_needed' ).val()) /  parseFloat(jQuery( '#aspect_ratio' ).val())) ).keyup();
                        			}
                        			jQuery( '#length_needed' ).bind('keyup', update_width);
  					};
  					jQuery( '#length_needed' ).bind('keyup', update_width);
  					jQuery( '#width_needed' ).bind('keyup', update_height);
				});
			</script>
		<?php
	}
}

?>