code: public function setGlowProperties($size, $color_value = null, $color_alpha = null, $color_type = null)
      {
          $this->setGlowSize($size)
              ->setGlowColor(
                  $color_value === null ? $this->glowProperties['color']['value'] : $color_value,
                  $color_alpha === null ? (int) $this->glowProperties['color']['alpha'] : $color_alpha,
                  $color_type === null ? $this->glowProperties['color']['type'] : $color_type
              );
      }
docs: Set Glow Properties.
  
  @param float $size
  @param string $color_value
  @param int $color_alpha
  @param string $color_type