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123 lines
13 KiB
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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Troubleshooting the installation</title><link rel="stylesheet" type="text/css" href="manual.css"><meta name="generator" content="DocBook XSL Stylesheets V1.76.0"><link rel="home" href="index.html" title="JpGraph Manual"><link rel="up" href="ch03.html" title="Chapter 3. The Long Version: Installing the Library"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Troubleshooting the installation</th></tr><tr><td width="20%" align="left"> </td><th width="60%" align="center">Chapter 3. The Long Version: Installing the Library</th><td width="20%" align="right"> </td></tr></table><hr></div><div class="sect1" title="Troubleshooting the installation"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2492535"></a>Troubleshooting the installation</h2></div></div></div>
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<p>Unfortunately there are many parameters in a server installation that may affect
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the execution of PHP so the steps below can only give some indications of how to
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further investigate some potential problems.</p>
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<p>Experience shows that most of the trouble are caused by either an old buggy
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version of the free-type TTF library or using an old antiquated version of the GD
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library. So before starting trouble shooting the scripts please make sure that you
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have an up to date PHP installation with the bundled version of the GD library (as
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describe in the previous sections) and a working FreeType library installed.</p>
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<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
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<p><span class="bold"><strong>No image is displayed.</strong></span></p>
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<p>The first thing you should do is to isolate the problem by calling
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your graph script directly in the browser. There are then two variants
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of this problem. </p>
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<p>
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</p><div class="orderedlist"><ol class="orderedlist" type="a"><li class="listitem">
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<p>No data is sent back from the server.</p>
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<p>You can verify this by calling your graph script directly
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in the browser and then check the source (click "view
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source" menu item in the browser). If this is a truly blank
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image then no data was sent back from the browser.</p>
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<p>This means that the PHP process has been terminated
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prematurely before it could send any data back. This could
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be caused by either the PHP process crashing (due to a bug
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in either PHP or your HTTP server) or the HTTP server
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crashed. This is often due to a broken PHP installation and
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more than often a problem with the True Type libraries. </p>
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<p>It could also be caused by the PHP script running longer
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than the maximum allowed execution time (as specified in
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<code class="filename">php.ini</code>). The first thing you
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should do is to increase the maximum allowed execution time.
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If this does not solve the problem you should look in the
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log files for both your HTTP server and PHP to try to find
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clues to if the PHP process really crashed. Another
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possibility is that the PHP process uses more than the
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maximum allowed memory (as set in
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<code class="filename">php.ini</code>) and then it is terminated.
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So a good first step is to put some really high values for
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memory and time just to take away these parameters.</p>
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</li><li class="listitem">
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<p>The data sent back is corrupt.</p>
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<p>Depending on your browser this can show up differently but
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a common symptom is a "red X" in the browser. In order to
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debug this you should make sure that you have followed the
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steps in <a class="xref" href="ch03s03.html#sec2.config-dev-server" title="Configuring JpGraph/PHP on a development server">Configuring JpGraph/PHP on a development server</a> to make sure you
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have output buffering disabled and have maximum error
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checking enabled in PHP. The most common cases for this type
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of problem is having enabled output buffering and some minor
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errors in the script which causes PHP to emit warnings which
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gets included in the image data. </p>
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<p>A very common mistake is to have some white spaces in the
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script before the opening "<code class="code"><?php</code>". This
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white space will be added to the output buffer and then get
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mixed up with the image data causing the image data to be
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corrupt. A similar problem can occur if multiple newlines
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are added after the final <code class="code">"?>"</code>
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</p>
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</li></ol></div><p>
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</p>
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</li><li class="listitem">
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<p><span class="bold"><strong>An error message saying "Fonts are not available or not
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readable" </strong></span></p>
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<p>When an image contains TTF fonts you might get an error message saying
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that the fonts are not available or not readable. If this is the case it
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is first necessary to check that the font files really exist in the
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directory that is specified in <code class="filename">jpg-config.inc.php</code>
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and that they are also readable by the HTTP/PHP process. If this is the
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case then it is necessary to check that the names of the font files are
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the one that JpGraph assumes, see <a class="xref" href="ch03s02.html#sec3.name-of-ttf-files" title="Name of TTF font files">Name of TTF font files</a>. Another problem can be if
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the PHP installation is running in "safe mode" (See <code class="uri"><a class="uri" href="http://se.php.net/manual/en/ini.sect.safe-mode.php" target="_top">PHP
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Manual: Security and safe mode</a></code>) and has enabled strict
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directory policy via an "<code class="code">open_basedir</code>" restriction. This
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will prevent the PHP process from reading any files outside the
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specified base directory. If this is enabled there is no way around for
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PHP to read any files outside this restriction and any TTF files
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necessary must be moved so that they can be accessed within the realms
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of the specified basedirectory.</p>
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<p>If you are running IIS and Win2k and get the error "Can't find font"
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when trying to use TTF fonts then try to change the paths to UNIX style,
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i.e. "<code class="filename">/usr/local/fonts/ttf/</code>". Remember that the
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path is absolute and not relative to the <code class="filename">htdocs</code>
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catalogue.</p>
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<p>If you are running on Unix server please keep in mind that file names
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are case sensitive.</p>
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</li><li class="listitem">
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<p><span class="bold"><strong>An error message saying "Headers have already been
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sent"</strong></span></p>
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<p>A common mistake is to have a space in the beginning of the image
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script which the HTTP server will send back to the browser. The browser
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now assumes that the data coming back from this script is text since it
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hasn't received an explicit header. When then the image headers get sent
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back to the browser to forewarn the browser of the forthcoming image
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data the browser will not like that as it has already assumed the data
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stream was a text stream. The browser will then give the infamous
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"Headers already sent error".</p>
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<p>Make sure that your script has no white space before the opening
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"<code class="code"><?php</code>" statement or a number of blank lines after
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the concluding "<code class="code">?></code>"</p>
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</li><li class="listitem">
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<p><span class="bold"><strong>Issues specific to Windows and IIS</strong></span></p>
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<p>Some windows installations seems to have a problem with a PHP script
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ending in more than one newline (This newline seems to be sent to the
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browser and will cause a <span class="italic">Header already sent error</span>). To correct this
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problem check all your scripts for more than one empty newline after the
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ending "<code class="code">?></code>" statement. All files provided with the library
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end in exactly one final newline and should not be a problem.</p>
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</li><li class="listitem">
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<p><span class="bold"><strong>TTF fonts are not displayed correctly</strong></span></p>
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<p>If the TTF fonts only shows up as yellow then the installation is used
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a buggy (too old) installation of the FreeType font library and the only
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thing to do is to re-install and setup PHP+GD again with a newer version
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of the FreeType library. Another symptom of a an (old) buggy FreeType
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library is that the fonts are not correctly rotated (the text string is
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rotated but not the individual characters).</p>
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</li></ol></div><p>As a final advise you should read the FAQ (available in this manual
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see <a class="xref" href="apc.html" title="Appendix C. FAQ">Appendix C. <i>FAQ</i></a>) or on the JpGraph website at <code class="uri"><a class="uri" href="http://jpgraph.net/doc/faq.php" target="_top">http://jpgraph.net/doc/faq.php</a></code></p>
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<p>Depending on your sever it might also help to recompile PHP yourself instead of
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the version included with the system. You can find typical configuration scripts to
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compile PHP4 and PHP5 in the appendices, see <a class="xref" href="api.html" title="Appendix I. Compiling PHP">Appendix I. <i>Compiling PHP</i></a>
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</p>
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</div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"> </td><td width="20%" align="center"><a accesskey="u" href="ch03.html">Up</a></td><td width="40%" align="right"> </td></tr><tr><td width="40%" align="left" valign="top"> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> </td></tr></table></div></body></html>
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