Check For Text
This demo shows how to check for text on pages in a pdf document. We use a helper class that analyses the document for us:
PHP
<?php
/**
* Class TextFoundException
*/
class TextFoundException extends Exception {}
/**
* Class TextProcessor
*/
class TextProcessor
{
/**
* The content stream.
*
* @var string
*/
protected $_stream;
/**
* The stream ressources dictionary.
*
* @var SetaPDF_Core_Type_Dictionary $_resources
*/
protected $_resources;
/**
* The content parser instance.
*
* @var SetaPDF_Core_Parser_Content
*/
protected $_contentParser;
/**
* The constructor
*
* The parameter are the content stream and its resources dictionary.
*
* DocumentProcessor constructor.
* @param string $stream
* @param SetaPDF_Core_Type_Dictionary $resources
*/
function __construct($stream, SetaPDF_Core_Type_Dictionary $resources)
{
$this->_stream = $stream;
$this->_resources = $resources;
}
/**
* Processes the content stream.
*
* Returns true if there is any text in the stream, otherwise false
*
* @return bool
*/
public function hasText()
{
try {
$this->_processStream();
return false;
} catch (TextFoundException $e) {
return true;
}
}
/**
* Process the content stream internal.
*
* @return void
*/
protected function _processStream()
{
$parser = $this->_getContentParser();
$parser->process();
}
/**
* A method to receive the content parser instance.
*
* @return SetaPDF_Core_Parser_Content
*/
protected function _getContentParser()
{
if (null === $this->_contentParser) {
$this->_contentParser = new SetaPDF_Core_Parser_Content($this->_stream);
$this->_contentParser->registerOperator(array('Tj', 'TJ', '"', "'"), array($this, '_onTextFound'));
$this->_contentParser->registerOperator('Do', array($this, '_onFormXObject'));
}
return $this->_contentParser;
}
/**
* Callback for the content parser which is called if a "Do" operator/token is found.
*
* @param $arguments
* @param $operator
*/
public function _onFormXObject($arguments, $operator)
{
$xObjects = $this->_resources->getValue(SetaPDF_Core_Resource::TYPE_X_OBJECT);
if (null === $xObjects) {
return;
}
$xObjects = $xObjects->ensure();
$xObject = $xObjects->getValue($arguments[0]->getValue());
$xObject = SetaPDF_Core_XObject::get($xObject);
if ($xObject instanceof SetaPDF_Core_XObject_Form) {
/* In that case we need to create a new instance of the processor and process
* the form xobjects stream.
*/
$stream = $xObject->getStreamProxy()->getStream();
$resources = $xObject->getCanvas()->getResources(false);
if (false === $resources) {
return;
}
$processor = new self($stream, $resources);
$processor->_processStream();
}
}
/**
* Callback for the content parser which is called if any text token was found.
*
* @param array $arguments
* @param string $operator
*
* @throws TextFoundException
*/
public function _onTextFound($arguments, $operator)
{
throw new TextFoundException();
}
}