Replace Images
An example that shows you how to replace images in an existing PDF document.
For demonstration purpose we change the image based on their orientation to a new image.
PHP
<?php
use setasign\SetaPDF2\Demos\ContentStreamProcessor\ImageProcessor;
use setasign\SetaPDF2\Core\Document;
use setasign\SetaPDF2\Core\Image\Image;
use setasign\SetaPDF2\Core\Writer\HttpWriter;
// load and register the autoload function
require_once '../../../../../bootstrap.php';
// prepare some files
$files = glob($assetsDirectory . '/pdfs/lenstown/products/*.pdf');
$path = displayFiles($files);
require_once $classesDirectory . '/ContentStreamProcessor/ImageProcessor.php';
// load a document instance
$document = Document::loadByFilename($path);
// get access to the pages object
$pages = $document->getCatalog()->getPages();
// define the replacement images
$portraitImage = Image::getByPath($assetsDirectory . '/images/portrait.jpg');
$portraitXObject = $portraitImage->toXObject($document);
$landscapeImage = Image::getByPath($assetsDirectory . '/images/landscape.jpg');
$landscapeXObject = $landscapeImage->toXObject($document);
// walk through the pages
for ($pageNo = 1; $pageNo <= $pages->count(); $pageNo++) {
$page = $pages->getPage($pageNo);
// create an image processor instance
$imageProcessor = new ImageProcessor($page->getCanvas(), ($page->getRotation() / 90) % 2 > 0);
// process the content stream
$images = $imageProcessor->process();
foreach ($images AS $image) {
// we've several pieces of information available but for demonstration purpose we just compare
// the width and height to define which new image will be used
if ($image['width'] > $image['height']) {
$image['objectReference']->setValue($landscapeXObject->getIndirectObject());
} else {
$image['objectReference']->setValue($portraitXObject->getIndirectObject());
}
}
}
// save and finish
$document->setWriter(new HttpWriter('replaced-images.pdf', true));
$document->save()->finish();
PHP
<?php
namespace setasign\SetaPDF2\Demos\ContentStreamProcessor;
use setasign\SetaPDF2\Core\Canvas\Canvas;
use setasign\SetaPDF2\Core\Canvas\GraphicState;
use setasign\SetaPDF2\Core\Filter\Exception as FilterException;
use setasign\SetaPDF2\Core\Geometry\Vector;
use setasign\SetaPDF2\Core\Parser\Content;
use setasign\SetaPDF2\Core\Resource\ResourceInterface;
use setasign\SetaPDF2\Core\Type\PdfIndirectReference;
use setasign\SetaPDF2\Core\XObject\XObject;
use setasign\SetaPDF2\Core\XObject\Form;
use setasign\SetaPDF2\NotImplementedException;
/**
* Class ImageProcessor
*/
class ImageProcessor
{
/**
* The content stream.
*
* @var string
*/
protected $_canvas;
/**
* The graphic state.
*
* @var GraphicState
*/
protected $_graphicState;
/**
* The content parser instance.
*
* @var Content
*/
protected $_contentParser;
/**
* The result data.
*
* @var array
*/
protected $_result = [];
/**
* Switch the width and height values.
*
* @var bool
*/
protected $_switchWidthAndHeight = false;
/**
* @var array All object ids of visited XObjects to prevent circular references
*/
protected $_xObjectObjectIds = [];
/**
* The constructor.
*
* The parameters are the content stream and its resource dictionary.
*
* @param Canvas $canvas
* @param bool $switchWidthAndHeight
* @param GraphicState|null $graphicState
*/
public function __construct(
Canvas $canvas,
bool $switchWidthAndHeight,
?GraphicState $graphicState = null
) {
$this->_canvas = $canvas;
$this->_switchWidthAndHeight = $switchWidthAndHeight;
$this->_graphicState = $graphicState === null ? new GraphicState() : $graphicState;
}
/**
* Get the graphic state.
*
* @return GraphicState
*/
public function getGraphicState(): GraphicState
{
return $this->_graphicState;
}
/**
* Process the content stream and return the resolved data.
*
* @return array
*/
public function process(): array
{
$parser = $this->_getContentParser();
$parser->process();
return $this->_result;
}
/**
* A method to receive the content parser instance.
*
* @return Content
*/
protected function _getContentParser()
{
if ($this->_contentParser === null) {
try {
$stream = $this->_canvas->getStream();
} catch (FilterException $e) {
// if a stream cannot be unfiltered, we ignore it
$stream = '';
}
$this->_contentParser = new Content($stream);
$this->_contentParser->registerOperator(['q', 'Q'], [$this, '_onGraphicStateChange']);
$this->_contentParser->registerOperator('cm', [$this, '_onCurrentTransformationMatrix']);
$this->_contentParser->registerOperator('Do', [$this, '_onFormXObject']);
$this->_contentParser->registerOperator('ID', [$this, '_onInlineImageData']);
}
return $this->_contentParser;
}
/**
* Callback for inline image data operator
*
* @param array $arguments
* @return bool
*/
public function _onInlineImageData(array $arguments): bool
{
$data = [];
for ($i = 0, $c = count($arguments); $i < $c; $i += 2) {
$data[$arguments[$i]->getValue()] = $arguments[$i + 1];
}
if (!(isset($data['W']) || isset($data['Width'])) || !(isset($data['H']) || isset($data['Height']))) {
return true;
}
$pixelWidth = isset($data['W']) ? $data['W']->getValue() : $data['Width']->getValue();
$pixelHeight = isset($data['H']) ? $data['H']->getValue() : $data['Height']->getValue();
$this->_result[] = $this->_getNewResult($pixelWidth, $pixelHeight);
$parser = $this->_contentParser->getParser();
$reader = $parser->getReader();
$pos = $reader->getPos();
$offset = $reader->getOffset();
while (
(\preg_match(
'/EI[\x00\x09\x0A\x0C\x0D\x20]/',
$reader->getBuffer(),
$m,
PREG_OFFSET_CAPTURE
)) === 0
) {
if ($reader->increaseLength(1000) === false) {
return false;
}
}
$parser->reset($pos + $offset + ((int) $m[0][1]) + strlen($m[0][0]));
return true;
}
/**
* Callback for the content parser which is called if a graphic state token (q/Q) is found.
*
* @param array $arguments
* @param string $operator
*/
public function _onGraphicStateChange(array $arguments, string $operator)
{
if ($operator === 'q') {
$this->getGraphicState()->save();
} else {
$this->getGraphicState()->restore();
}
}
/**
* Callback for the content parser which is called if a "cm" token is found.
*
* @param array $arguments
*/
public function _onCurrentTransformationMatrix(array $arguments)
{
$this->getGraphicState()->addCurrentTransformationMatrix(
$arguments[0]->getValue(), $arguments[1]->getValue(),
$arguments[2]->getValue(), $arguments[3]->getValue(),
$arguments[4]->getValue(), $arguments[5]->getValue()
);
}
/**
* Callback for the content parser which is called if a "Do" operator/token is found.
*
* @param array $arguments
* @throws NotImplementedException
*/
public function _onFormXObject(array $arguments)
{
$xObjects = $this->_canvas->getResources(true, false, ResourceInterface::TYPE_X_OBJECT);
if ($xObjects === null) {
return;
}
$xObjects = $xObjects->ensure();
$xObject = $xObjects->getValue($arguments[0]->getValue());
if (!($xObject instanceof PdfIndirectReference)) {
return;
}
$xObjectReference = $xObject;
$xObject = XObject::get($xObject);
if ($xObject instanceof Form) {
/* In that case we need to create a new instance of the processor and process
* the form xobjects stream.
*/
if (isset($this->_xObjectObjectIds[$xObject->getIndirectObject()->getObjectId()])) {
// recursion
return;
}
$this->_xObjectObjectIds[$xObject->getIndirectObject()->getObjectId()] = true;
$gs = $this->getGraphicState();
$gs->save();
$dict = $xObject->getIndirectObject()->ensure()->getValue();
$matrix = $dict->getValue('Matrix');
if ($matrix) {
$matrix = $matrix->ensure()->toPhp();
$gs->addCurrentTransformationMatrix(
$matrix[0], $matrix[1], $matrix[2], $matrix[3], $matrix[4], $matrix[5]
);
}
$processor = new self(
$xObject->getCanvas(),
$this->_switchWidthAndHeight,
$gs
);
$processor->_xObjectObjectIds =& $this->_xObjectObjectIds;
foreach ($processor->process() AS $image) {
$this->_result[] = $image;
}
$gs->restore();
unset($this->_xObjectObjectIds[$xObject->getIndirectObject()->getObjectId()]);
} else {
$newResult = $this->_getNewResult($xObject->getWidth(), $xObject->getHeight());
$newResult['objectReference'] = $xObjectReference;
$this->_result[] = $newResult;
}
}
/**
* Helper method to create a result entry.
*
* @param numeric $pixelWidth
* @param numeric $pixelHeight
* @return array
*/
protected function _getNewResult($pixelWidth, $pixelHeight)
{
// we have an image object, calculate it's outer points in user space
$gs = $this->getGraphicState();
$ll = $gs->toUserSpace(new Vector(0, 0, 1));
$ul = $gs->toUserSpace(new Vector(0, 1, 1));
$ur = $gs->toUserSpace(new Vector(1, 1, 1));
$lr = $gs->toUserSpace(new Vector(1, 0, 1));
// ...and match some further information
$width = \abs($this->_switchWidthAndHeight ? $ur->subtract($ll)->getY() : $ur->subtract($ll)->getX());
$height = \abs($this->_switchWidthAndHeight ? $ur->subtract($ll)->getX() : $ur->subtract($ll)->getY());
return [
'll' => $ll->toPoint(),
'ul' => $ul->toPoint(),
'ur' => $ur->toPoint(),
'lr' => $lr->toPoint(),
'width' => $width,
'height' => $height,
'resolutionX' => $pixelWidth / $width * 72,
'resolutionY' => $pixelHeight / $height * 72,
'pixelWidth' => $pixelWidth,
'pixelHeight' => $pixelHeight
];
}
}