The Zend_Pdf class represents PDF documents and provides document-level operations.

To create a new document, a new Zend_Pdf object should first be created.

Zend_Pdf class also provides two static methods to load an existing PDF document. These are the Zend_Pdf::load() and Zend_Pdf::parse() methods. Both of them return Zend_Pdf objects as a result or throw an exception if an error occurs.

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// Create a new PDF document
$pdf1 = new Zend_Pdf();

// Load a PDF document from a file
$pdf2 = Zend_Pdf::load($fileName);

// Load a PDF document from a string
$pdf3 = Zend_Pdf::parse($pdfString);
...

The PDF file format supports incremental document update. Thus each time a document is updated, then a new revision of the document is created. Zend_Pdf component supports the retrieval of a specified revision.

A revision can be specified as a second parameter to the Zend_Pdf::load() and Zend_Pdf::parse() methods or requested by calling the Zend_Pdf::rollback() method. ^[9] call.

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// Load the previous revision of the PDF document
$pdf1 = Zend_Pdf::load($fileName, 1);

// Load the previous revision of the PDF document
$pdf2 = Zend_Pdf::parse($pdfString, 1);

// Load the first revision of the PDF document
$pdf3 = Zend_Pdf::load($fileName);
$revisions = $pdf3->revisions();
$pdf3->rollback($revisions - 1);
...