[#ZF-3392] Png with transparency makes pdf generation performance collapse - Zend Framework Issue Tracker

Zend Framework

Png with transparency makes pdf generation performance collapse

Created: 05/Jun/08 04:27 AM Updated: 27/Jan/10 09:44 AM

Return to search "Fixed in 1.5.1"

Component/s:

Zend_Pdf

Affects Version/s:

1.5.2

Fix Version/s:

Next Minor Release

Time Tracking:

Not Specified

Fix Version Priority:

Should Have

Description

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here is my test code :

public function printtestAction()
    {
        require_once 'Zend/Pdf.php';
        $pdf = new Zend_Pdf() ;
        $pdf->pages[] = ($page1 = $pdf->newPage('A4')) ;
        $style = new Zend_Pdf_Style() ;
        $style->setFont(Zend_Pdf_Font::fontWithName(Zend_Pdf_Font::FONT_HELVETICA));
        $style->setFontSize(12);
        $style->setFillColor(new Zend_Pdf_Color_Html('black'));
        $page1->setStyle($style);
        $page1->drawText('Test',50,50,'UTF-8') ;
        $background = Zend_Pdf_Image::imageWithPath('pdf_ressources/fond.png');
        $page1->drawImage($background, 0, 0, 597, 841);
        
        $response = $this->getResponse(); 
        $response->setHeader('Cache-Control', 'public', true) 
            ->setHeader('Content-Description', 'File Transfer', true) 
            ->setHeader('Content-Type', 'application/pdf', true) 
            ->setHeader('Content-Disposition', 'attachment;filename=test.pdf', true) 
            ->setHeader('Content-Transfer-Encoding', 'binary', true) 
            ->appendBody($pdf->render());
        
        $this->_helper->layout->disableLayout();
        $this->_helper->viewRenderer->setNoRender(true) ;
    }

The image is 597x841. With transparency, it takes about 20 sec, without it's immediate. The image is about 120kB with transparency and about 70kB without.

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Francois Gaudin added a comment - 09/Jun/08 07:18 AM

Alexander, related to your comment on my blog, I can't attach the image since it's a copyrighted one but I think any A4 image with a lot of transparency may cause the problem. I'll test during the week with an other (home made) image to check.

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Kevin McArthur added a comment - 15/Jul/08 02:16 PM

This is unfortunatly a technical limitation to the way the PNG parser works. I assume this is a RGB + Alpha channel image.

The way PDF works is to create two images from one and overlay them as two data streams. PNG is an integrated format. As a result putting out a transparent alpha png requires looping the entire thing and copying out the transparency data.

The key bit of code is...

//Iterate every pixel and copy out rgb data and alpha channel (this will be slow)
for($pixel = 0, $pixelcount = ($width * $height); $pixel < $pixelcount; $pixel++) { $imageDataTmp .= $pngDataRawDecoded[($pixel*4)+0] . $pngDataRawDecoded[($pixel*4)+1] . $pngDataRawDecoded[($pixel*4)+2]; $smaskData .= $pngDataRawDecoded[($pixel*4)+3]; }

However, this peice of code is being upgraded to the new fileparsers so, any improvement to this should occur after the fileparser upgrades are done. (Which is being worked on in the community, but not at zend afaik)

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Willie Alberty added a comment - 31/Jul/08 11:20 AM

Alexander - are you actively working on this? If not, I have a newer parser half-finished that should help address this; please assign to me.

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Alexander Veremyev added a comment - 01/Aug/08 03:39 AM

Hi Willie!

No. I don't touch these things now.
The only thing I would like to add before ZF 1.6 is transparency handling.

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Willie Alberty added a comment - 04/Dec/08 10:34 PM

Unassigning Zend_Pdf issues currently assigned to me pending decision on ZF 2.0 release timeframe and potential contribution of comprehensive changeset.