PHPePub\Core\EPub::setViewport PHP Method

    public function setViewport($width = null, $height = null)
    {
        if ($width == null) {
            unset($this->viewport);
        }
        if (is_string($width) && in_array($width, $this->viewportMap)) {
            $vp = $this->viewportMap[$width];
            $width = $vp['width'];
            $height = $vp['height'];
        }
        $this->viewport = array('width' => $width, 'height' => $height);
    }