SetaPDF-LinkReplacer Implement identical functionality as the SetaPDF-LinkReplacer offered

Introduction

As of SetaPDF 2 the so called SetaPDF-LinkReplacer API is obsolete, because all features are available in the Core component.

This article will show replacement code for specific methods of the old API. 

Error Handling

While in version 1 error objects were returned, version 2 uses Exceptions throughout. More details can be found here

Loading and Saving PDF Documents

The SetaPDF-LinkReplacer offered only the possibility to load a PDF file from a file. The new system allows a PDF document to be read from various sources through so called Reader objects.

Nearly same things exists for the resulting document: SetaPDF_Core_Writer_WriterInterface

PHP
$filename = 'a/path/to/a/pdf/file.pdf';
$target = 'a/path/to/the/resulting/file.pdf';

// old version
$linkReplacer = SetaPDF_LinkReplacer::factory($filename);
// ...
$linkReplacer->replaceLinks($target);

// will become:
$reader = new SetaPDF_Core_Reader_File($filename);
$writer = new SetaPDF_Core_Writer_File($target);
$document = SetaPDF_Core_Document::load($reader, $writer);
// ...
$document->save()->finish();

In the new version it is possible to define separate readers or writers, which was impossible for the old version.  

Equivalent Code of Methods

The old methods can be refactored to the new version as follows:  

setUseUpdate()

The behavior of the setUseUpdate() method is identical to the $update parameter of the SetaPDF_Core_Document::save() method. 

PHP
$update = false;
// old
$linkReplacer->setUseUpdate($update);
// new
$document->save($update);

getPageCount()

In the new version a helper class has to be used: 

PHP
// old:
$pageCount = $linkReplacer->getPageCount();
// new:
$pageCount = $document->getCatalog()->getPages()->count();

getLinks()

In the new version links are represented through annotation objects with specific destinations or actions attached.

These annotations are available through an annotation helper class of individual page objects. The LinkReplacer handled only Uri actions which are represented by the SetaPDF_Core_Document_Action_Uri class. 

PHP
$pages = $document->getCatalog()->getPages();
for ($pageNo = 1, $pageCount = $pages->count(); $pageNo <= $pageCount; $pageNo++) {
    $page = $pages->getPage($pageNo);
    $annotationsHelper = $page->getAnnotations();
    $linkAnnotations = $annotationsHelper->getAll(SetaPDF_Core_Document_Page_Annotation::TYPE_LINK);
    foreach ($linkAnnotations AS $linkAnnotation) {
        // $linkAnnotation is an instance of SetaPDF_Core_Document_Page_Annotation_Link 
        $action = $linkAnnotation->getAction();
        if ($action && $action instanceof SetaPDF_Core_Document_Action_Uri) {
            // Here we have access to the Uri action
            // ...
        }
    }
}

getValue()

The object type SetaPDF_Link is not available anymore but the access to the URI is possible through an Uri action instance as resolved in the previous example.  

PHP
// old
$uri = $link->getValue();
// new
$uri = $action->getUri();

setValue()

Also setting a new URI is possible through an Uri action instance. 

PHP
$uri = 'http://www.setasign.com';
// old
$link->setValue($uri);
// new
$action->setUri($uri);