13.2. Creating and loading PDF documents.
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## 13.2. Creating and loading PDF documents.

`Zend_Pdf` class represents PDF document itself and provides document level functionality.

To create new document new `Zend_Pdf` object should be created.

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

例 13.1. Create new or load existing PDF document.

    <?php
    ...
    // Create new PDF document.
    $pdf1 = new Zend_Pdf();

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

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

PDF file format supports incremental document update. Thus each time when document is updated, then new revision of the document is created. Zend_Pdf module supports retrieving of specified revision.

Revision can be specified as a second parameter for `Zend_Pdf::load()` and `Zend_Pdf::parse()` methods or requested by `Zend_Pdf::rollback()` [3] call.

例 13.2. Requesting specified revision of the PDF document.

    <?php
    ...
    // Load PDF previouse revision of the document.
    $pdf1 = Zend_Pdf::load($fileName, 1);

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

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

[3] `Zend_Pdf::rollback()` method must be invoked before any changes, applied to the document. Otherwise behavior is undefined.

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第 13 章 Zend_Pdf | 起始页 | 13.3. Save changes to the PDF document.