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<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /><title>EncodeImage</title><link rel="stylesheet" type="text/css" href="phplotdoc.css" /><meta name="generator" content="DocBook XSL Stylesheets V1.78.1" /><link rel="home" href="index.html" title="PHPlot Reference Manual" /><link rel="up" href="reference.html" title="PHPlot Function Reference" /><link rel="prev" href="DrawMessage.html" title="DrawMessage" /><link rel="next" href="EndStream.html" title="EndStream" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">EncodeImage</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="DrawMessage.html">Prev</a> </td><th width="60%" align="center">PHPlot Function Reference</th><td width="20%" align="right"> <a accesskey="n" href="EndStream.html">Next</a></td></tr></table><hr /></div><div class="refentry"><a id="EncodeImage"></a><div class="titlepage"></div><div class="refnamediv"><h2><span class="refentrytitle">EncodeImage</span></h2><p>EncodeImage — Returns the plot image data</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">$plot->EncodeImage([<span class="optional"><em class="parameter"><code>$encoding</code></em></span>])</pre></div><div class="refsect1"><a id="idp1377679748"></a><h2>Description</h2><p>
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<code class="function">EncodeImage</code> returns the plot image as a string, using
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one of three encodings. This function can be used when special processing
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of the plot image data is necessary, rather than the default behavior of
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sending the image via standard output (usually to a browser), or writing it
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to a file. In particular, <code class="function">EncodeImage</code> can be used to
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embed a PHPlot image inside an HTML file without requiring a separate script.
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</p></div><div class="refsect1"><a id="idp1377681436"></a><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>$encoding</code></em></span></dt><dd><p>
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Optional string indicating the encoding to use for the return value. If
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supplied, it must be one of the following values:
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</p><div class="informaltable"><table summary="Available encoding types" border="1"><colgroup><col class="c1" /><col class="c2" /></colgroup><thead><tr><th>Encoding</th><th>Description</th></tr></thead><tbody><tr><td>raw</td><td>
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No encoding - the raw data representing the image
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is returned.
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</td></tr><tr><td>base64</td><td>
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Encodes the image data using base64 (RFC2045).
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</td></tr><tr><td>dataurl</td><td>
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Encodes the image data for a 'data:' URL scheme.
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This is the default. See notes below.
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</td></tr></tbody></table></div><p>
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</p></dd></dl></div></div><div class="refsect1"><a id="idp1377687612"></a><h2>Return Value</h2><p>
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Returns the image data, using the indicated encoding.
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</p></div><div class="refsect1"><a id="idp1377688276"></a><h2>Notes</h2><p>
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The default value for <em class="parameter"><code>$encoding</code></em> is
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<code class="literal">dataurl</code>.
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</p><p>
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<code class="literal">raw</code> encoding returns the image data. If the image file
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format was set to the default PNG, the return result would be a valid PNG
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file if it was written to a file.
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</p><p>
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<code class="literal">base64</code> encoding starts with the same data as
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<code class="literal">raw</code>, and encodes it as ASCII characters using the PHP
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function <code class="function">base64_encode</code> and returns the result.
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Note that the result is not broken into lines, as required by some applications.
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Use the PHP function <code class="function">chunk_split</code> if this is needed.
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</p><p>
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<code class="literal">dataurl</code> encoding returns the image data suitable for use as
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the value of the 'src' attribute in an HTML 'img' tag using the data URL
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scheme. This embeds the image into the HTML, and so it does not require
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an external image file. The data URL scheme is defined by
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<a class="ulink" href="http://www.faqs.org/rfcs/rfc2397.html" target="_top">RFC 2397</a>.
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</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>
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RFC 2397 makes it clear that the scheme is intended for embedding small images,
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and that there may be length limitations on the encoded data. However, there
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are other applications (for example LibreOffice) that use the data URL scheme
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for large images. While it has been found to work with large images in the
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major web browsers, testing in your own environment is recommended.
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</p></div><p>
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</p><p>
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When using <code class="function">EncodeImage</code> to get the plot image, rather
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than letting PHPlot output the image to standard output or a file, you must
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call <a class="xref" href="SetPrintImage.html" title="SetPrintImage"><span class="refentrytitle">SetPrintImage</span></a><code class="literal">(False)</code> to prevent
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<a class="xref" href="DrawGraph.html" title="DrawGraph"><span class="refentrytitle">DrawGraph</span></a> from sending the image data to standard output.
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You should also call <a class="xref" href="SetFailureImage.html" title="SetFailureImage"><span class="refentrytitle">SetFailureImage</span></a><code class="literal">(False)</code>
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to prevent PHPlot from producing an unexpected image on standard output in
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case of a fatal error.
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</p><p>
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An example of using the <code class="literal">dataurl</code> encoding is:
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</p><pre class="programlisting">$plot = new PHPlot(800, 600);
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$plot->SetPrintImage(False); // Do not output the image
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... // Plot settings, data, etc.
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$plot->DrawGraph(); // Make the plot but do not output it
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echo "<img src=\"" . $plot->EncodeImage() . "\">\n";
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</pre><p>
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</p><p>
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A more complete example can be found in <a class="xref" href="ex-encodeimage.html" title="5.39. Example - Embedding Image with EncodeImage">Section 5.39, “Example - Embedding Image with EncodeImage”</a>.
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</p></div><div class="refsect1"><a id="idp1377698364"></a><h2>History</h2><p>
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This function was added in PHPlot-5.5.0.
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</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="DrawMessage.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="reference.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="EndStream.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">DrawMessage </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> EndStream</td></tr></table></div></body></html>
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