To rotate a page in a PDF document.

$doc = new PDFDoc($filename);

// Rotate the first page 90 degrees clockwise.
$page = $doc->GetPage(1);
$originalRotation = $page->GetRotation();
$rotation = NULL;
switch ($originalRotation)
{
  case Page::e_0:   $rotation = Page::e_90;  break;
  case Page::e_90:  $rotation = Page::e_180; break;
  case Page::e_180: $rotation = Page::e_270; break;
  case Page::e_270: $rotation = Page::e_0;   break;
  default:          $rotation = Page.Rotate.e_0;   break;
}
$page->SetRotation($rotation);

A page can be rotated clockwise, by 90 degrees, when displayed or printed. The Page.GetRotation() method returns the Page.Rotate enum specifying the current rotation. Similarly, Page.SetRotation() sets the current rotation.