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1 <HTML> 2 <HEAD> 3 <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"> 4 <TITLE>FAQ</TITLE> 5 <LINK TYPE="text/css" REL="stylesheet" HREF="fpdf.css"> 6 </HEAD> 7 <BODY> 8 <H2>FAQ</H2> 9 <B>1.</B> <A HREF='#1'>What's exactly the license of FPDF? Are there any usage restrictions?</A><BR> 10 <B>2.</B> <A HREF='#2'>When I try to create a PDF, a lot of weird characters show on the screen. Why?</A><BR> 11 <B>3.</B> <A HREF='#3'>I try to generate a PDF and IE displays a blank page. What happens?</A><BR> 12 <B>4.</B> <A HREF='#4'>I send parameters using the POST method and the values don't appear in the PDF.</A><BR> 13 <B>5.</B> <A HREF='#5'>When I use a PHP session, IE doesn't display my PDF any more but asks me to download it.</A><BR> 14 <B>6.</B> <A HREF='#6'>When I'm on SSL, IE can't open the PDF.</A><BR> 15 <B>7.</B> <A HREF='#7'>When I execute a script I get the message "FPDF error: Don't alter the locale before including class file".</A><BR> 16 <B>8.</B> <A HREF='#8'>I try to put a PNG and Acrobat says "There was an error processing a page. A drawing error occurred".</A><BR> 17 <B>9.</B> <A HREF='#9'>I encounter the following error when I try to generate a PDF: Warning: Cannot add header information - headers already sent by (output started at script.php:X)</A><BR> 18 <B>10.</B> <A HREF='#10'>I try to display a variable in the Header method but nothing prints.</A><BR> 19 <B>11.</B> <A HREF='#11'>I defined the Header and Footer methods in my PDF class but nothing appears.</A><BR> 20 <B>12.</B> <A HREF='#12'>I can't make line breaks work. I put \n in the string printed by MultiCell but it doesn't work.</A><BR> 21 <B>13.</B> <A HREF='#13'>I try to put the euro symbol but it doesn't work.</A><BR> 22 <B>14.</B> <A HREF='#14'>I draw a frame with very precise dimensions, but when printed I notice some differences.</A><BR> 23 <B>15.</B> <A HREF='#15'>I'd like to use the whole surface of the page, but when printed I always have some margins. How can I get rid of them?</A><BR> 24 <B>16.</B> <A HREF='#16'>What's the limit of the file sizes I can generate with FPDF?</A><BR> 25 <B>17.</B> <A HREF='#17'>Can I modify a PDF with FPDF?</A><BR> 26 <B>18.</B> <A HREF='#18'>I'd like to make a search engine in PHP and index PDF files. Can I do it with FPDF?</A><BR> 27 <B>19.</B> <A HREF='#19'>Can I convert an HTML page to PDF with FPDF?</A><BR> 28 <B>20.</B> <A HREF='#20'>Can I concatenate PDF files with FPDF?</A><BR> 29 <BR><BR> 30 <P><A NAME='1'></A><B>1.</B> <FONT CLASS='st'>What's exactly the license of FPDF? Are there any usage restrictions?</FONT></P> 31 FPDF is Freeware (it is stated at the beginning of the source file). There is no usage 32 restriction. You may embed it freely in your application (commercial or not), with or 33 without modification. You may redistribute it, too. 34 <P><A NAME='2'></A><B>2.</B> <FONT CLASS='st'>When I try to create a PDF, a lot of weird characters show on the screen. Why?</FONT></P> 35 These "weird" characters are in fact the actual content of your PDF. This behaviour is a bug of 36 IE. When it first receives an HTML page, then a PDF from the same URL, it displays it directly 37 without launching Acrobat. This happens frequently during the development stage: on the least 38 script error, an HTML page is sent, and after correction, the PDF arrives. 39 <BR> 40 To solve the problem, simply quit and restart IE. You can also go to another URL and come 41 back. 42 <BR> 43 To avoid this kind of inconvenience during the development, you can generate the PDF directly 44 to a file and open it through the explorer. 45 <P><A NAME='3'></A><B>3.</B> <FONT CLASS='st'>I try to generate a PDF and IE displays a blank page. What happens?</FONT></P> 46 First of all, check that you send nothing to the browser after the PDF (not even a space or a 47 carriage return). You can put an exit statement just after the call to the Output() method to 48 be sure. 49 <BR> 50 If it still doesn't work, it means you're a victim of the "blank page syndrome". IE used in 51 conjunction with the Acrobat plug-in suffers from numerous bugs, in all versions. You should 52 test your application with as many IE versions as possible (at least if you're on the Internet). 53 The problem occurs mostly with the POST method, so it is strongly advised to avoid it (all the 54 more that it causes other problems, see the next question). The GET works better but may fail 55 when the URL becomes too long: don't use a query string with more than 45 characters. However, a 56 tip exists to exceed this limit: end the URL with .pdf, which tricks IE. If you use a form, you 57 can add a hidden field at the last position: 58 <BR> 59 <BR> 60 <TABLE WIDTH="100%" BGCOLOR="#E0E0E0"><TR><TD> 61 <TT> 62 <INPUT TYPE="HIDDEN" NAME="ext" VALUE=".pdf"> 63 </TT> 64 </TD></TR></TABLE><BR> 65 The usage of PHP sessions also often causes trouble (avoid using HTTP headers preventing caching). 66 See question 5 for a workaround. 67 <BR> 68 <BR> 69 To avoid all these problems in a reliable manner, two main techniques exist: 70 <BR> 71 <BR> 72 - Disable the plug-in and use Acrobat as a helper application. To do this, launch Acrobat; in 73 the File menu, Preferences, General, uncheck the option "Web Browser Integration" (for Acrobat 74 5: Edit, Preferences, Options, "Display PDF in Browser"). Then, the next time you load a PDF in 75 IE, it displays the dialog box "Open it" or "Save it to disk". Uncheck the option "Always ask 76 before opening this type of file" and choose Open. From now on, PDF files will open 77 automatically in an external Acrobat window. 78 <BR> 79 The drawback of the method is that you need to alter the client configuration, which you can do 80 in an intranet environment but not for the Internet. 81 <BR> 82 <BR> 83 - Use a redirection technique. It consists in generating the PDF in a temporary file on the 84 server and redirect the client on it (by using JavaScript, not the Location HTTP header which 85 also causes trouble). For instance, at the end of the script, you can put the following: 86 <BR> 87 <BR> 88 <TABLE WIDTH="100%" BGCOLOR="#E0E0E0"><TR><TD> 89 <TT> 90 //Determine a temporary file name in the current directory<BR> 91 $file=basename(tempnam(getcwd(),'tmp'));<BR> 92 //Save PDF to file<BR> 93 $pdf->Output($file);<BR> 94 //JavaScript redirection<BR> 95 echo "<HTML><SCRIPT>document.location='getpdf.php?f=$file';</SCRIPT></HTML>"; 96 </TT> 97 </TD></TR></TABLE><BR> 98 Then create the getpdf.php file with this: 99 <BR> 100 <BR> 101 <TABLE WIDTH="100%" BGCOLOR="#E0E0E0"><TR><TD> 102 <TT> 103 <?php<BR> 104 $f=$HTTP_GET_VARS['f'];<BR> 105 //Check file (don't skip it!)<BR> 106 if(substr($f,0,3)!='tmp' or strpos($f,'/') or strpos($f,'\\'))<BR> 107 die('Incorrect file name');<BR> 108 if(!file_exists($f))<BR> 109 die('File does not exist');<BR> 110 //Handle special IE request if needed<BR> 111 if($HTTP_SERVER_VARS['HTTP_USER_AGENT']=='contype')<BR> 112 {<BR> 113 Header('Content-Type: application/pdf');<BR> 114 exit;<BR> 115 }<BR> 116 //Output PDF<BR> 117 Header('Content-Type: application/pdf');<BR> 118 Header('Content-Length: '.filesize($f));<BR> 119 readfile($f);<BR> 120 //Remove file<BR> 121 unlink($f);<BR> 122 exit;<BR> 123 ?> 124 </TT> 125 </TD></TR></TABLE><BR> 126 This method works in most cases but IE6 can still experience trouble. The "ultimate" method 127 consists in redirecting directly to the temporary file. The file name must therefore end with .pdf: 128 <BR> 129 <BR> 130 <TABLE WIDTH="100%" BGCOLOR="#E0E0E0"><TR><TD> 131 <TT> 132 //Determine a temporary file name in the current directory<BR> 133 $file=basename(tempnam(getcwd(),'tmp'));<BR> 134 rename($file,$file.'.pdf');<BR> 135 $file.='.pdf';<BR> 136 //Save PDF to file<BR> 137 $pdf->Output($file);<BR> 138 //JavaScript redirection<BR> 139 echo "<HTML><SCRIPT>document.location='$file';</SCRIPT></HTML>"; 140 </TT> 141 </TD></TR></TABLE><BR> 142 This method turns the dynamic PDF into a static one and avoids all troubles. But you have to do 143 some cleaning in order to delete the temporary files. For instance: 144 <BR> 145 <BR> 146 <TABLE WIDTH="100%" BGCOLOR="#E0E0E0"><TR><TD> 147 <TT> 148 function CleanFiles($dir)<BR> 149 {<BR> 150 //Delete temporary files<BR> 151 $t=time();<BR> 152 $h=opendir($dir);<BR> 153 while($file=readdir($h))<BR> 154 {<BR> 155 if(substr($file,0,3)=='tmp' and substr($file,-4)=='.pdf')<BR> 156 {<BR> 157 $path=$dir.'/'.$file;<BR> 158 if($t-filemtime($path)>3600)<BR> 159 @unlink($path);<BR> 160 }<BR> 161 }<BR> 162 closedir($h);<BR> 163 } 164 </TT> 165 </TD></TR></TABLE><BR> 166 This function deletes all files of the form tmp*.pdf older than an hour in the specified 167 directory. You may call it where you want, for instance in the script which generates the PDF. 168 <BR> 169 <BR> 170 Remark: it is necessary to open the PDF in a new window, as you can't go backwards due to the 171 redirection. 172 <P><A NAME='4'></A><B>4.</B> <FONT CLASS='st'>I send parameters using the POST method and the values don't appear in the PDF.</FONT></P> 173 It's a problem affecting some versions of IE (especially the first 5.5). See the previous 174 question for the ways to work around it. 175 <P><A NAME='5'></A><B>5.</B> <FONT CLASS='st'>When I use a PHP session, IE doesn't display my PDF any more but asks me to download it.</FONT></P> 176 It's a problem affecting some versions of IE. To work around it, add the following line before 177 session_start(): 178 <BR> 179 <BR> 180 <TABLE WIDTH="100%" BGCOLOR="#E0E0E0"><TR><TD> 181 <TT> 182 session_cache_limiter('private'); 183 </TT> 184 </TD></TR></TABLE><BR> 185 or do a redirection as explained in question 3. 186 <P><A NAME='6'></A><B>6.</B> <FONT CLASS='st'>When I'm on SSL, IE can't open the PDF.</FONT></P> 187 The problem may be fixed by adding this line:<BR> 188 <BR> 189 <TABLE WIDTH="100%" BGCOLOR="#E0E0E0"><TR><TD> 190 <TT> 191 Header('Pragma: public'); 192 </TT> 193 </TD></TR></TABLE><BR> 194 195 <P><A NAME='7'></A><B>7.</B> <FONT CLASS='st'>When I execute a script I get the message "FPDF error: Don't alter the locale before including class file".</FONT></P> 196 When the decimal separator is configured as a comma before including a file, there is a 197 <A HREF="http://bugs.php.net/bug.php?id=17105" TARGET="_blank">bug</A> in some PHP versions and decimal 198 numbers get truncated. Therefore you shouldn't make a call to setlocale() before including the class. 199 On Unix, you shouldn't set the LC_ALL environment variable neither, for it is equivalent to a 200 setlocale() call. 201 <P><A NAME='8'></A><B>8.</B> <FONT CLASS='st'>I try to put a PNG and Acrobat says "There was an error processing a page. A drawing error occurred".</FONT></P> 202 Acrobat 5 has a bug and is unable to display transparent monochrome images (i.e. with 1 bit per 203 pixel). Remove transparency or save your image in 16 colors (4 bits per pixel) or more. 204 <P><A NAME='9'></A><B>9.</B> <FONT CLASS='st'>I encounter the following error when I try to generate a PDF: Warning: Cannot add header information - headers already sent by (output started at script.php:X)</FONT></P> 205 You must send nothing to the browser except the PDF itself: no HTML, no space, no carriage return, 206 neither before nor after. The script outputs something at line X. 207 <P><A NAME='10'></A><B>10.</B> <FONT CLASS='st'>I try to display a variable in the Header method but nothing prints.</FONT></P> 208 You have to use the <TT>global</TT> keyword, for instance: 209 <BR> 210 <BR> 211 <TABLE WIDTH="100%" BGCOLOR="#E0E0E0"><TR><TD> 212 <TT> 213 function Header()<BR> 214 {<BR> 215 global $title;<BR> 216 <BR> 217 $this->SetFont('Arial','B',15);<BR> 218 $this->Cell(0,10,$title,1,1,'C');<BR> 219 } 220 </TT> 221 </TD></TR></TABLE><BR> 222 223 <P><A NAME='11'></A><B>11.</B> <FONT CLASS='st'>I defined the Header and Footer methods in my PDF class but nothing appears.</FONT></P> 224 You have to create an object from the PDF class, not FPDF:<BR> 225 <BR> 226 <TABLE WIDTH="100%" BGCOLOR="#E0E0E0"><TR><TD> 227 <TT> 228 $pdf=new PDF(); 229 </TT> 230 </TD></TR></TABLE><BR> 231 232 <P><A NAME='12'></A><B>12.</B> <FONT CLASS='st'>I can't make line breaks work. I put \n in the string printed by MultiCell but it doesn't work.</FONT></P> 233 You have to enclose your string with double quotes, not single ones. 234 <P><A NAME='13'></A><B>13.</B> <FONT CLASS='st'>I try to put the euro symbol but it doesn't work.</FONT></P> 235 The standard fonts have the euro character at position 128. You can define a constant like this 236 for convenience: 237 <BR> 238 <BR> 239 <TABLE WIDTH="100%" BGCOLOR="#E0E0E0"><TR><TD> 240 <TT> 241 define('EURO',chr(128)); 242 </TT> 243 </TD></TR></TABLE><BR> 244 Note: Acrobat 4 or higher is required to display euro. 245 <P><A NAME='14'></A><B>14.</B> <FONT CLASS='st'>I draw a frame with very precise dimensions, but when printed I notice some differences.</FONT></P> 246 To respect dimensions, you have to uncheck the option "Fit to page" in the print dialog box. 247 <P><A NAME='15'></A><B>15.</B> <FONT CLASS='st'>I'd like to use the whole surface of the page, but when printed I always have some margins. How can I get rid of them?</FONT></P> 248 All printers have physical margins (different depending on the model), it is therefore impossible 249 to remove them and print on the totality of the paper. 250 <P><A NAME='16'></A><B>16.</B> <FONT CLASS='st'>What's the limit of the file sizes I can generate with FPDF?</FONT></P> 251 There is no particular limit. There are some constraints however: 252 <BR> 253 <BR> 254 - The maximum memory size allocated to PHP scripts defaults to 8MB. For very big documents, 255 especially with images, this limit may be reached (the file being built into memory). The 256 parameter is configured in the php.ini file. 257 <BR> 258 <BR> 259 - The maximum execution time allocated defaults to 30 seconds. This limit can of course be easily 260 reached. It is configured in php.ini and may be altered dynamically with set_time_limit(). 261 <BR> 262 <BR> 263 - Browsers generally have a 5 minute time-out. If you send the PDF directly to the browser and 264 reach the limit, it will be lost. It is therefore advised for very big documents to 265 generate them in a file, and to send some data to the browser from time to time (for instance 266 page 1, page 2... with flush() to force the output). When the document is finished, you can send 267 a redirection on it with JavaScript or create a link. 268 <BR> 269 Remark: even when the browser goes in time-out, the script may continue to run on the server. 270 <P><A NAME='17'></A><B>17.</B> <FONT CLASS='st'>Can I modify a PDF with FPDF?</FONT></P> 271 No. 272 <P><A NAME='18'></A><B>18.</B> <FONT CLASS='st'>I'd like to make a search engine in PHP and index PDF files. Can I do it with FPDF?</FONT></P> 273 No. But a GPL C utility does exist, pdftotext, which is able to extract the textual content from 274 a PDF. It is provided with the Xpdf package:<BR> 275 <BR> 276 <A HREF="http://www.foolabs.com/xpdf/" TARGET="_blank">http://www.foolabs.com/xpdf/</A> 277 <P><A NAME='19'></A><B>19.</B> <FONT CLASS='st'>Can I convert an HTML page to PDF with FPDF?</FONT></P> 278 No. But a GPL C utility does exist, htmldoc, which allows to do it and gives good results:<BR> 279 <BR> 280 <A HREF="http://www.easysw.com/htmldoc/" TARGET="_blank">http://www.easysw.com/htmldoc/</A> 281 <P><A NAME='20'></A><B>20.</B> <FONT CLASS='st'>Can I concatenate PDF files with FPDF?</FONT></P> 282 No. But a free C utility exists to perform this task:<BR> 283 <BR> 284 <A HREF="http://thierry.schmit.free.fr/dev/mbtPdfAsm/enMbtPdfAsm2.html" TARGET="_blank">http://thierry.schmit.free.fr/dev/mbtPdfAsm/enMbtPdfAsm2.html</A> 285 </BODY> 286 </HTML>
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