116 lines
9.8 KiB
HTML
116 lines
9.8 KiB
HTML
<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Using the cache with Client Side Image Maps (CSIM)</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="ch09.html" title="Chapter 9. Using the JpGraph cache system"></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">Using the cache with Client Side Image Maps (CSIM)</th></tr><tr><td width="20%" align="left"> </td><th width="60%" align="center">Chapter 9. Using the JpGraph cache system</th><td width="20%" align="right"> </td></tr></table><hr></div><div class="sect1" title="Using the cache with Client Side Image Maps (CSIM)"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sect1.cache-csim"></a>Using the cache with Client Side Image Maps (CSIM)</h2></div></div></div>
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<p>(See <a class="xref" href="ch10.html" title="Chapter 10. Using CSIM (Client side image maps)">Chapter 10. <i>Using CSIM (Client side image maps)</i></a> for a full description on the usage of CSIM
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together with the library)</p>
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<p>You can also use the cache system for images that uses image maps (CSIM) as well.
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The cache system interface is slightly different in this case since the cache needs
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to store both the cached image and the cached image-map. It also needs to change due
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to the added complexity with CSIM scripts not sending back an image but rather a
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pre-formatted HTML page. The two major differences from the non-CSIM cache
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is:</p>
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<p>
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</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
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<p>The cached version will <span class="bold"><strong>not</strong></span> be stored in the previous defined cache
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directory. It uses a different cache directory.</p>
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</li><li class="listitem">
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<p>The script that want to make use of the cache system together with
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CSIM must call an extra method, <code class="code">CheckCSIMCache()</code>, to check
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the cache.</p>
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</li></ol></div><p>
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</p>
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<p>
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</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
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<p>Please remember that when using CSIM you must end your script with a call
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to <code class="code">Graph::StrokeCSIM()</code> method instead of the
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<code class="code">Graph::Stroke()</code> used for non-CSIM. </p>
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</div><p>
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</p>
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<p>To use the cache with CSIM you have to call the
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<code class="code">Graph::CheckCSIMCache()</code>. As with the caching for non-CSIM you have
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to supply a name to be used for the cached version (it can be manually or automatic)
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as well as an optional timeout value. The default timeout value if nothing else is
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specified is 60 minutes.</p>
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<p>The name argument requires some more explanations. The file name must be specified
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as a relative name. </p>
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<p>For example "<code class="filename">myimage</code>" or perhaps
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"<code class="filename">firstpage/image3</code>". </p>
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<p>The reason for his is that a script that uses CSIM does not send back an image.
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Instad it sends back a HTML page which includes the image map coordinates and has an
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included "<span class="markup"><img href=" ... "></span>" tag which references the image
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script recursively in normal cases but if the image is found in the cache this
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reference will be to a static image instead.</p>
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<p>Depending on the installation of the library this will now end up in the directory
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specified in the <code class="code">CSIMCACHE_DIR</code> define. This must also be a directory
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accessible by the normal HTTP/PHP process. By default, if nothing else is specified,
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a directory called "<code class="filename">csimcache</code>" will be created in the same
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directory as the image script itself.</p>
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<p>The default value has the drawback that the directory from where the script is
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executed must also be writable by the process running PHP. Best practice here is to
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keep the number of writable directory for PHP down to a minimum and re-use the same
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directory as is used for the standard cache. </p>
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<p>This however, requires that the PHP and HTTP setup is such that the cache
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directory is also accessible by the HTTP server from the htdocs root.</p>
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<p>The <code class="code">CheckCSIMCache()</code> method checks the cache for an existing cached
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version and if found it returns it and halts execution of the script. So, this call
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should be the first call after the creation of the core graph instance, i.e.
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<code class="code">$graph = Graph($width,$height)</code> and before any heavy work is done to
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create the image so that no unnecessary work is done in case a cached image + image
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map is found.</p>
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<p>The general structure of a script that uses CSIM and cache should follow the
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template shown in </p>
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<p>
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</p><div class="example"><a name="id2535468"></a><p class="title"><b>Example 9.2. General structure for a CSIM script that uses CSIM</b></p><div class="example-contents">
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</pre></td><td class="hl-main" valign="top"><pre><span class="hl-inlinetags"><?php</span><span class="hl-code">
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</span><span class="hl-reserved">require_once</span><span class="hl-brackets">(</span><span class="hl-code"> </span><span class="hl-quotes">'</span><span class="hl-string">jpgraph.php</span><span class="hl-quotes">'</span><span class="hl-brackets">)</span><span class="hl-code">;
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</span><span class="hl-comment">//</span><span class="hl-comment"> ... any necessary includes</span><span class="hl-comment"></span><span class="hl-code">
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</span><span class="hl-var">$width</span><span class="hl-code"> = ...
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</span><span class="hl-var">$height</span><span class="hl-code"> = ...
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</span><span class="hl-var">$graph</span><span class="hl-code"> = </span><span class="hl-reserved">new</span><span class="hl-code"> </span><span class="hl-identifier">Graph</span><span class="hl-brackets">(</span><span class="hl-var">$width</span><span class="hl-code">,</span><span class="hl-var">$height</span><span class="hl-brackets">)</span><span class="hl-code">;
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</span><span class="hl-comment">//</span><span class="hl-comment"> Check cache and use a 10 min timeout</span><span class="hl-comment"></span><span class="hl-code">
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</span><span class="hl-var">$graph</span><span class="hl-code">-></span><span class="hl-identifier">CheckCSIMCache</span><span class="hl-brackets">(</span><span class="hl-quotes">'</span><span class="hl-string">csim_image1</span><span class="hl-quotes">'</span><span class="hl-code">,</span><span class="hl-number">10</span><span class="hl-brackets">)</span><span class="hl-code">;
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</span><span class="hl-comment">//</span><span class="hl-comment"> If a cached version exists, execution halts here</span><span class="hl-comment"></span><span class="hl-code">
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</span><span class="hl-comment">//</span><span class="hl-comment"> and the cached HTML image map is sent back</span><span class="hl-comment"></span><span class="hl-code">
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</span><span class="hl-comment">//</span><span class="hl-comment"> ... construct and format the graph</span><span class="hl-comment"></span><span class="hl-code">
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</span><span class="hl-comment">//</span><span class="hl-comment"> ... finally send back the image map HTML script</span><span class="hl-comment"></span><span class="hl-code">
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</span><span class="hl-var">$graph</span><span class="hl-code">-></span><span class="hl-identifier">StrokeCSIM</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">;
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</span><span class="hl-inlinetags">?></span></pre></td></tr></table></div>
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</div></div><p><br class="example-break">
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</p>
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<p>Please note that it is not necessary to pass any argument to the final call of
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StrokeCSIM()</p>
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<p>
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</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
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<p>The CSIM caching works by storing two files in the cache directory. One
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file being the image and the other file being the corresponding image map as
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a pure HTML file. The HTML file will reference the static image.</p>
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</div><p>
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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="ch09.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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