Image_GD::check PHP Method

    public static function check()
    {
        if (!function_exists('gd_info')) {
            throw new CException('GD is either not installed or not enabled, check your configuration');
        }
        if (defined('GD_VERSION')) {
            // Get the version via a constant, available in PHP 5.2.4+
            $version = GD_VERSION;
        } else {
            // Get the version information
            $info = gd_info();
            // Extract the version number
            preg_match('/\\d+\\.\\d+(?:\\.\\d+)?/', $info['GD Version'], $matches);
            // Get the major version
            $version = $matches[0];
        }
        if (!version_compare($version, '2.0.1', '>=')) {
            throw new CException('Image_GD requires GD version 2.0.1 or greater, you have ' . $version);
        }
        return Image_GD::$_checked = TRUE;
    }

 public function __construct($file)
 {
     if (!Image_GD::$_checked) {
         // Run the install check
         Image_GD::check();
     }
     parent::__construct($file);
     // Set the image creation function name
     switch ($this->type) {
         case IMAGETYPE_JPEG:
             $create = 'imagecreatefromjpeg';
             break;
         case IMAGETYPE_GIF:
             $create = 'imagecreatefromgif';
             break;
         case IMAGETYPE_PNG:
             $create = 'imagecreatefrompng';
             break;
     }
     if (!isset($create) or !function_exists($create)) {
         throw new Kohana_Exception('Installed GD does not support :type images', array(':type' => image_type_to_extension($this->type, FALSE)));
     }
     // Save function for future use
     $this->_create_function = $create;
     // Save filename for lazy loading
     $this->_image = $this->file;
 }