Value 1 provided is not a const in enum Cairo\Antialias

[adamdyson]

I'm in the process of working through the examples and re-factoring them to work with PHP 7. After updating the first example I believe I've encountered a bug.

The updated example can be found here and the error message after execution is:

PHP Fatal error:  Uncaught TypeError: Value 1 provided is not a const in enum Cairo\Antialias in /home/adam/cairo/examples/a1-image-sample.php:21
Stack trace:
#0 /home/adam/cairo/examples/a1-image-sample.php(21): Cairo\Context->setAntialias(1)
#1 {main}
  thrown in /home/adam/cairo/examples/a1-image-sample.php on line 21