Memory optimization

Informations

Author: Olivier
License: FPDF

Description

The standard FPDF class builds the document entirely in memory, which can be problematic for large documents. This extension saves the pages to the destination file as soon as they are finished, which solves the issue.

After you have created the object, call Open() with the name of the file:

$pdf = new FPDF2File();
$pdf->Open('doc.pdf');

and when the document is finished, call Output():

$pdf->Output();

Note: you can't use the AliasNbPages() method with this extension.

Source

<?php
require('fpdf.php');

class FPDF2File extends FPDF
{
protected $f;

function Open($file='doc.pdf')
{
    if(FPDF_VERSION<'1.8')
        $this->Error('Version 1.8 or above is required by this extension');
    $this->f=fopen($file,'wb');
    if(!$this->f)
        $this->Error('Unable to create output file: '.$file);
    $this->_putheader();
}

function Image($file, $x=null, $y=null, $w=0, $h=0, $type='', $link='')
{
    if(!isset($this->images[$file]))
    {
        //Retrieve only meta-information
        $a=getimagesize($file);
        if($a===false)
            $this->Error('Missing or incorrect image file: '.$file);
        $this->images[$file]=array('w'=>$a[0],'h'=>$a[1],'type'=>$a[2],'i'=>count($this->images)+1);
    }
    parent::Image($file,$x,$y,$w,$h,$type,$link);
}

function Output($dest='', $name='', $isUTF8=false)
{
    if($this->state<3)
        $this->Close();
}

function _endpage()
{
    parent::_endpage();
    //Write page to file
    $this->_putstreamobject($this->pages[$this->page]);
    unset($this->pages[$this->page]);
}

function _getoffset()
{
    return ftell($this->f);
}

function _put($s)
{
    fwrite($this->f,$s."\n",strlen($s)+1);
}

function _putimages()
{
    foreach(array_keys($this->images) as $file)
    {
        $type=$this->images[$file]['type'];
        if($type==1)
            $info=$this->_parsegif($file);
        elseif($type==2)
            $info=$this->_parsejpg($file);
        elseif($type==3)
            $info=$this->_parsepng($file);
        else
            $this->Error('Unsupported image type: '.$file);
        $this->_putimage($info);
        $this->images[$file]['n']=$info['n'];
        unset($info);
    }
}

function _putpages()
{
    $nb=$this->page;
    for($n=1;$n<=$nb;$n++)
        $this->PageInfo[$n]['n']=$this->n+$n;
    if($this->DefOrientation=='P')
    {
        $wPt=$this->DefPageSize[0]*$this->k;
        $hPt=$this->DefPageSize[1]*$this->k;
    }
    else
    {
        $wPt=$this->DefPageSize[1]*$this->k;
        $hPt=$this->DefPageSize[0]*$this->k;
    }
    //Page objects
    for($n=1;$n<=$nb;$n++)
    {
        $this->_newobj();
        $this->_put('<</Type /Page');
        $this->_put('/Parent 1 0 R');
        if(isset($this->PageInfo[$n]['size']))
            $this->_put(sprintf('/MediaBox [0 0 %.2F %.2F]',$this->PageInfo[$n]['size'][0],$this->PageInfo[$n]['size'][1]));
        if(isset($this->PageInfo[$n]['rotation']))
            $this->_put('/Rotate '.$this->PageInfo[$n]['rotation']);
        $this->_put('/Resources 2 0 R');
        if(isset($this->PageLinks[$n]))
        {
            //Links
            $annots='/Annots [';
            foreach($this->PageLinks[$n] as $pl)
            {
                $rect=sprintf('%.2F %.2F %.2F %.2F',$pl[0],$pl[1],$pl[0]+$pl[2],$pl[1]-$pl[3]);
                $annots.='<</Type /Annot /Subtype /Link /Rect ['.$rect.'] /Border [0 0 0] ';
                if(is_string($pl[4]))
                    $annots.='/A <</S /URI /URI '.$this->_textstring($pl[4]).'>>>>';
                else
                {
                    $l=$this->links[$pl[4]];
                    if(isset($this->PageInfo[$l[0]]['size']))
                        $h=$this->PageInfo[$l[0]]['size'][1];
                    else
                        $h=$hpt;
                    $annots.=sprintf('/Dest [%d 0 R /XYZ 0 %.2F null]>>',$this->PageInfo[$l[0]]['n'],$h-$l[1]*$this->k);
                }
            }
            $this->_put($annots.']');
        }
        if($this->WithAlpha)
            $this->_put('/Group <</Type /Group /S /Transparency /CS /DeviceRGB>>');
        $this->_put('/Contents '.(2+$n).' 0 R>>');
        $this->_put('endobj');
    }
    //Pages root
    $this->offsets[1]=$this->_getoffset();
    $this->_put('1 0 obj');
    $this->_put('<</Type /Pages');
    $kids='/Kids [';
    for($n=1;$n<=$nb;$n++)
        $kids.=(2+$nb+$n).' 0 R ';
    $this->_put($kids.']');
    $this->_put('/Count '.$nb);
    $this->_put(sprintf('/MediaBox [0 0 %.2F %.2F]',$wPt,$hPt));
    $this->_put('>>');
    $this->_put('endobj');
}

function _putheader()
{
    if($this->_getoffset()==0)
        parent::_putheader();
}

function _enddoc()
{
    parent::_enddoc();
    fclose($this->f);
}
}
?>

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