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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Creating barcodes</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="ch27.html" title="Chapter 27. QR (2D-Barcode)"></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">Creating barcodes</th></tr><tr><td width="20%" align="left"> </td><th width="60%" align="center">Chapter 27. QR (2D-Barcode)</th><td width="20%" align="right"> </td></tr></table><hr></div><div class="sect1" title="Creating barcodes"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2607930"></a>Creating barcodes</h2></div></div></div>
<p>In order to use QR codes the module "<code class="filename">QR/qrencoder.inc.php</code>" must
first be included.</p>
<p>Usage of QR codes follows a similar schema as for the linear, PDF417 and Datamatrix
barcodes with the concepts of an encoder and backend. The principle of the overall
encodation process is shown in <a class="xref" href="ch26s02.html#fig.datamatrix-encodation-principle" title="Figure 26.4. Datamatrix encodation principle">Figure 26.4. Datamatrix encodation principle</a></p>
<div class="figure"><a name="id2616655"></a><p class="title"><b>Figure 27.5. QR Encodation Process</b></p><div class="figure-contents">
<div class="mediaobject"><img src="images/qr-encodation-principle.png" alt="QR Encodation Process"></div>
</div></div><br class="figure-break">
<div class="sect2" title="Getting started"><div class="titlepage"><div><div><h3 class="title"><a name="id2616673"></a>Getting started</h3></div></div></div>
<p>In order to use the QR barcodes the library module
"<code class="filename">QR/qrencoder.inc.php</code>" must first be included in the
script.</p>
<p>
</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<p>Create an instance of the encoder and optionally specify size and
error correction level. The encoder is created as an instance of
<code class="code">class QREncoder</code></p>
</li><li class="listitem">
<p>Create an instance of a suitable backend for the chosen output format
(image or postscript) by calling the
<code class="code">DatamatrixBackenFactory::Create()</code></p>
</li><li class="listitem">
<p>Encode data and send it back to the browser or to a file with a call
to the backend <code class="code">Backend::Stroke()</code> method.</p>
</li></ol></div><p>
</p>
<p>The following script shows how to create the simplest possible QR code (in PNG
format) representing the data string "<code class="code">The first QR code</code>" encoded using
all default values. The resulting QR Code is shown in <a class="xref" href="ch27s02.html#fig.qrexample00" title="Figure 27.6. The first very basic QR code (qrexample00.php)">Figure 27.6. The first very basic QR code <code class="uri"><a class="uri" href="example_src/qrexample00.html" target="_top">(<code class="filename">qrexample00.php</code>)</a></code> </a></p>
<p>
</p><div class="example"><a name="example.qrexample00"></a><p class="title"><b>Example 27.1. The first very basic QR code (<code class="filename">qrexample00.php</code>) </b></p><div class="example-contents"> <div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
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</pre></td><td class="hl-main" valign="top"><pre><span class="hl-inlinetags">&lt;?php</span><span class="hl-code">
</span><span class="hl-reserved">require_once</span><span class="hl-code"> </span><span class="hl-brackets">(</span><span class="hl-quotes">'</span><span class="hl-string">jpgraph/QR/qrencoder.inc.php</span><span class="hl-quotes">'</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Data to be encoded</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$data</span><span class="hl-code"> = </span><span class="hl-quotes">'</span><span class="hl-string">01234567</span><span class="hl-quotes">'</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Create a new instance of the encoder and let the library</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-comment">//</span><span class="hl-comment"> decide a suitable QR version and error level</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$e</span><span class="hl-code">=</span><span class="hl-reserved">new</span><span class="hl-code"> </span><span class="hl-identifier">QREncoder</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Use the image backend (this is also the default)</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$b</span><span class="hl-code">=</span><span class="hl-identifier">QRCodeBackendFactory</span><span class="hl-code">::</span><span class="hl-identifier">Create</span><span class="hl-brackets">(</span><span class="hl-var">$e</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> .. send the barcode back to the browser for the data</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$b</span><span class="hl-code">-&gt;</span><span class="hl-identifier">Stroke</span><span class="hl-brackets">(</span><span class="hl-var">$data</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-inlinetags">?&gt;</span></pre></td></tr></table></div></div></div><p><br class="example-break"> </p><div class="figure"><a name="fig.qrexample00"></a><p class="title"><b>Figure 27.6. The first very basic QR code <code class="uri"><a class="uri" href="example_src/qrexample00.html" target="_top">(<code class="filename">qrexample00.php</code>)</a></code> </b></p><div class="figure-contents"> <span class="inlinemediaobject"><img src="images/qrexample00.png" alt="The first very basic QR code (qrexample00.php)"></span> </div></div><p><br class="figure-break">
</p>
<p>(As can be seen this follows the same principles as the creation of Datamatrix
symbols)</p>
<p>The principle is the same for all type of data QR code creations. First an
instance of the chosen encoder is instantiated. In this case using all default
parameters by creating an instance of <code class="code">class QREncoder</code>. We then create a
suitable backend that handles the output of the barcode. By default the output will
be an image encoded in the PNG image format.</p>
<p>The final step is to send back the generated image to the browser with a call to
the method <code class="code">Backend::Stroke()</code> with the data to be encoded as its first
argument.</p>
<p>The example above does not have any error handling. If there is some error in the
process an exception will be thrown in the same way as in other places in the
library. The default exception will display a standard library image error box. An
example of this is shown in <a class="xref" href="ch27s02.html#fig.qr-errmsg" title="Figure 27.7. QR Error message">Figure 27.7. QR Error message</a></p>
<div class="figure"><a name="fig.qr-errmsg"></a><p class="title"><b>Figure 27.7. QR Error message</b></p><div class="figure-contents">
<div class="mediaobject"><img src="images/qr_errmsg.png" alt="QR Error message"></div>
</div></div><br class="figure-break">
<p>If some additional processing is necessary and to just display a text based
re-formatted error message we could change the above code to catch this exception as
the following example shows.</p>
<p>
</p><div class="example"><a name="example.qrexample0"></a><p class="title"><b>Example 27.2. Adding basic exception handling (<code class="filename">qrexample0.php</code>) </b></p><div class="example-contents"> <div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
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</pre></td><td class="hl-main" valign="top"><pre><span class="hl-inlinetags">&lt;?php</span><span class="hl-code">
</span><span class="hl-reserved">require_once</span><span class="hl-code"> </span><span class="hl-brackets">(</span><span class="hl-quotes">'</span><span class="hl-string">jpgraph/QR/qrencoder.inc.php</span><span class="hl-quotes">'</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Data to be encoded</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$data</span><span class="hl-code"> = </span><span class="hl-quotes">'</span><span class="hl-string">01234567</span><span class="hl-quotes">'</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Create a new instance of the encoder and let the library</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-comment">//</span><span class="hl-comment"> decide a suitable QR version and error level</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$encoder</span><span class="hl-code"> = </span><span class="hl-reserved">new</span><span class="hl-code"> </span><span class="hl-identifier">QREncoder</span><span class="hl-brackets">(</span><span class="hl-number">1</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Use the image backend (this is also the default)</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$backend</span><span class="hl-code"> = </span><span class="hl-identifier">QRCodeBackendFactory</span><span class="hl-code">::</span><span class="hl-identifier">Create</span><span class="hl-brackets">(</span><span class="hl-var">$encoder</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-reserved">try</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
</span><span class="hl-comment">//</span><span class="hl-comment"> . send the QR Code back to the browser</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">Stroke</span><span class="hl-brackets">(</span><span class="hl-var">$data</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-brackets">}</span><span class="hl-code"> </span><span class="hl-reserved">catch</span><span class="hl-code"> </span><span class="hl-brackets">(</span><span class="hl-identifier">Exception</span><span class="hl-code"> </span><span class="hl-var">$e</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
</span><span class="hl-var">$errstr</span><span class="hl-code"> = </span><span class="hl-var">$e</span><span class="hl-code">-&gt;</span><span class="hl-identifier">GetMessage</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-reserved">echo</span><span class="hl-code"> </span><span class="hl-quotes">'</span><span class="hl-string">QR Code error: </span><span class="hl-quotes">'</span><span class="hl-code">.</span><span class="hl-var">$e</span><span class="hl-code">-&gt;</span><span class="hl-identifier">GetMessage</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">.</span><span class="hl-quotes">&quot;</span><span class="hl-special">\n</span><span class="hl-quotes">&quot;</span><span class="hl-code">;
</span><span class="hl-reserved">exit</span><span class="hl-brackets">(</span><span class="hl-number">1</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-inlinetags">?&gt;</span></pre></td></tr></table></div></div></div><p><br class="example-break"> </p><div class="figure"><a name="fig.qrexample0"></a><p class="title"><b>Figure 27.8. Adding basic exception handling <code class="uri"><a class="uri" href="example_src/qrexample0.html" target="_top">(<code class="filename">qrexample0.php</code>)</a></code> </b></p><div class="figure-contents"> <span class="inlinemediaobject"><img src="images/qrexample0.png" alt="Adding basic exception handling (qrexample0.php)"></span> </div></div><p><br class="figure-break">
</p>
<p>As a final initial example the next script uses the backend method
<code class="code">Backend::SetModuleWidth($aWidth)</code> to increase the size of one
module. Since a module in QR code refers to the smallest square used adjusting the
module width will also adjust the height of the overall QR code</p>
<p>
</p><div class="example"><a name="example.qrexample01"></a><p class="title"><b>Example 27.3. Adjusting the module width for the QR code (<code class="filename">qrexample01.php</code>) </b></p><div class="example-contents"> <div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
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</pre></td><td class="hl-main" valign="top"><pre><span class="hl-inlinetags">&lt;?php</span><span class="hl-code">
</span><span class="hl-reserved">require_once</span><span class="hl-code"> </span><span class="hl-brackets">(</span><span class="hl-quotes">'</span><span class="hl-string">jpgraph/QR/qrencoder.inc.php</span><span class="hl-quotes">'</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Data to be encoded</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$data</span><span class="hl-code"> = </span><span class="hl-quotes">'</span><span class="hl-string">01234567</span><span class="hl-quotes">'</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Create a new instance of the encoder and let the library</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-comment">//</span><span class="hl-comment"> decide a suitable QR version and error level</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$encoder</span><span class="hl-code"> = </span><span class="hl-reserved">new</span><span class="hl-code"> </span><span class="hl-identifier">QREncoder</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Use the image backend</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$backend</span><span class="hl-code"> = </span><span class="hl-identifier">QRCodeBackendFactory</span><span class="hl-code">::</span><span class="hl-identifier">Create</span><span class="hl-brackets">(</span><span class="hl-var">$encoder</span><span class="hl-code">, </span><span class="hl-identifier">BACKEND_IMAGE</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Set the module size (quite big)</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">SetModuleWidth</span><span class="hl-brackets">(</span><span class="hl-number">5</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> .. send the barcode back to the browser for the data</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">Stroke</span><span class="hl-brackets">(</span><span class="hl-var">$data</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-inlinetags">?&gt;</span></pre></td></tr></table></div></div></div><p><br class="example-break"> </p><div class="figure"><a name="fig.qrexample01"></a><p class="title"><b>Figure 27.9. Adjusting the module width for the QR code <code class="uri"><a class="uri" href="example_src/qrexample01.html" target="_top">(<code class="filename">qrexample01.php</code>)</a></code> </b></p><div class="figure-contents"> <span class="inlinemediaobject"><img src="images/qrexample01.png" alt="Adjusting the module width for the QR code (qrexample01.php)"></span> </div></div><p><br class="figure-break">
</p>
</div>
<div class="sect2" title="Error handling"><div class="titlepage"><div><div><h3 class="title"><a name="id2616978"></a>Error handling</h3></div></div></div>
<p>As in other parts of the library the QR module throws an exception when an error
occurs. As shown in the previous section an error image is the default if no
explicit <code class="code">try {} catch {}</code> statement is added to the script.</p>
<p>
</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
<p>The fact that an image is shown as the default exception is caused by the
library module "qrexception.inc.php" installing its own default error
handler which will be called when an exception happens. However, this
handler is intelligent enough to know if the exception is caused by the
library or not. If the exception is not caused by the library the exception
is re-thrown and the original error handler restored. This means that
JpGraph will not interfere with previously installed error handlers for
other parts of an application.</p>
</div><p>
</p>
<p>The script below shows how to catch the error, do some possible clean up and then
explicitly create and send back the error image.</p>
<p>
</p><div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
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</pre></td><td class="hl-main" valign="top"><pre><span class="hl-inlinetags">&lt;?php</span><span class="hl-code">
...
</span><span class="hl-reserved">try</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
</span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">Stroke</span><span class="hl-brackets">(</span><span class="hl-var">$data</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-brackets">}</span><span class="hl-code"> </span><span class="hl-reserved">catch</span><span class="hl-brackets">(</span><span class="hl-code"> </span><span class="hl-identifier">Exception</span><span class="hl-code"> </span><span class="hl-var">$e</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
</span><span class="hl-identifier">doCleanup</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-var">$errobj</span><span class="hl-code"> = </span><span class="hl-reserved">new</span><span class="hl-code"> </span><span class="hl-identifier">QRErrObjectImg</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-var">$errobj</span><span class="hl-code">-&gt;</span><span class="hl-identifier">Raise</span><span class="hl-brackets">(</span><span class="hl-var">$e</span><span class="hl-code">-&gt;</span><span class="hl-identifier">getMessage</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-inlinetags">?&gt;</span></pre></td></tr></table></div><p>
</p>
<p>another variant of this would be to re-throw the exception after the cleanup has
been performed as the following example shows</p>
<p>
</p><div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
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</pre></td><td class="hl-main" valign="top"><pre><span class="hl-inlinetags">&lt;?php</span><span class="hl-code">
...
</span><span class="hl-reserved">try</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
</span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">Stroke</span><span class="hl-brackets">(</span><span class="hl-var">$data</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-brackets">}</span><span class="hl-code"> </span><span class="hl-reserved">catch</span><span class="hl-brackets">(</span><span class="hl-code"> </span><span class="hl-identifier">Exception</span><span class="hl-code"> </span><span class="hl-var">$e</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
</span><span class="hl-identifier">doCleanup</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-reserved">throw</span><span class="hl-code"> </span><span class="hl-var">$e</span><span class="hl-code">;
</span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-inlinetags">?&gt;</span></pre></td></tr></table></div><p>
</p>
<p>It is also possible to get hold of the internal error code that corresponds to
each error message by calling the PHP standard exception method
<code class="code">Exception::getCode()</code> as the following example shows</p>
<p>
</p><div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
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</pre></td><td class="hl-main" valign="top"><pre><span class="hl-inlinetags">&lt;?php</span><span class="hl-code">
...
</span><span class="hl-reserved">try</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
</span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">Stroke</span><span class="hl-brackets">(</span><span class="hl-var">$data</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-brackets">}</span><span class="hl-code"> </span><span class="hl-reserved">catch</span><span class="hl-code"> </span><span class="hl-brackets">(</span><span class="hl-identifier">Exception</span><span class="hl-code"> </span><span class="hl-var">$e</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
</span><span class="hl-var">$errstr</span><span class="hl-code"> = </span><span class="hl-var">$e</span><span class="hl-code">-&gt;</span><span class="hl-identifier">GetMessage</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-var">$errcode</span><span class="hl-code"> = </span><span class="hl-var">$e</span><span class="hl-code">-&gt;</span><span class="hl-identifier">GetCode</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-reserved">echo</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">QR error (</span><span class="hl-var">$errcode</span><span class="hl-string">). Message: </span><span class="hl-var">$errstr</span><span class="hl-special">\n</span><span class="hl-quotes">&quot;</span><span class="hl-code">;
</span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-inlinetags">?&gt;</span></pre></td></tr></table></div><p>
</p>
<p><a class="xref" href="ch27s02.html#table.qr-error-messages" title="Table 27.4. QR Error messages">Table 27.4. QR Error messages</a> lists the public errors that can be
thrown by the QR code module (the table deliberately excludes internal error
messages)</p>
<div class="table"><a name="table.qr-error-messages"></a><p class="title"><b>Table 27.4. QR Error messages</b></p><div class="table-contents">
<table summary="QR Error messages" border="1"><colgroup><col class="c1"><col class="c2"></colgroup><thead><tr><th align="center">Error number</th><th align="center">Error string</th></tr></thead><tbody><tr><td class="error-number" align="center">1000</td><td class="error-text">
<p>Tilde processing is not yet supported for QR Barcodes.</p>
</td></tr><tr><td class="error-number" align="center">1001</td><td class="error-text">
<p>Inverting the bit pattern is not supported for QR
Barcodes.</p>
</td></tr><tr><td class="error-number" align="center">1002</td><td class="error-text">
<p>Cannot read data from file %s</p>
</td></tr><tr><td class="error-number" align="center">1003</td><td class="error-text">
<p>Cannot open file %s</p>
</td></tr><tr><td class="error-number" align="center">1004</td><td class="error-text">
<p>Cannot write QR barcode to file %s</p>
</td></tr><tr><td class="error-number" align="center">1005</td><td class="error-text">
<p>Unsupported image format selected. Check your GD
installation</p>
</td></tr><tr><td class="error-number" align="center">1006</td><td class="error-text">
<p>Cannot set the selected barcode colors. Check your GD
installation and spelling of color name</p>
</td></tr><tr><td class="error-number" align="center">1007</td><td class="error-text">
<p>QR Error: HTTP headers have already been sent.</p>
<p>Caused by output from file %s at line %d</p>
<p>Explanation: HTTP headers have already been sent back to the
browser indicating the data as text before the library got a
chance to send it's image HTTP header to this browser. This
makes it impossible for the QR library to send back image data
to the browser (since that would be interpretated as text by the
browser and show up as junk text).</p>
<p>Most likely you have some text in your script before the call
to QRBackend::Stroke(). </p>
<p>If this texts gets sent back to the browser the browser will
assume that all data is plain text. Look for any text (even
spaces and newlines) that might have been sent back to the
browser.</p>
<p>For example it is a common mistake to leave a blank line
before the opening "&lt;?php"</p>
</td></tr><tr><td class="error-number" align="center">1008</td><td class="error-text">
<p>Could not create the barcode image with image format=%s. Check
your GD/PHP installation.</p>
</td></tr><tr><td class="error-number" align="center">1009</td><td class="error-text">
<p>Cannot open log file %s for writing.</p>
</td></tr><tr><td class="error-number" align="center">1010</td><td class="error-text">
<p>Cannot write log info to log file %s.</p>
</td></tr><tr><td class="error-number" align="center">1011</td><td class="error-text">
<p>Could not write the QR Code to file. Check the file system
permissions.</p>
</td></tr><tr><td class="error-number" align="center">1400</td><td class="error-text">
<p>QR Version must be specified as a value in the range [1,40]
got %d</p>
</td></tr><tr><td class="error-number" align="center">1401</td><td class="error-text">
<p>Input data to barcode can not be empty.</p>
</td></tr><tr><td class="error-number" align="center">1402</td><td class="error-text">
<p>Automatic encodation mode was specified but input data looks
like specification for manual encodation.</p>
</td></tr><tr><td class="error-number" align="center">1403</td><td class="error-text">
<p>Was expecting an array of arrays as input data for manual
encoding.</p>
</td></tr><tr><td class="error-number" align="center">1404</td><td class="error-text">
<p>Each input data array element must consist of two entries.
Element $i has of $nn entries</p>
</td></tr><tr><td class="error-number" align="center">1405</td><td class="error-text">
<p>Each input data array element must consist of two entries with
first entry being the encodation constant and the second element
the data string. Element %d is incorrect in this respect.</p>
</td></tr><tr><td class="error-number" align="center">1406</td><td class="error-text">
<p>Was expecting either a string or an array as input data</p>
</td></tr><tr><td class="error-number" align="center">1407</td><td class="error-text">
<p>Manual encodation mode was specified but input data looks like
specification for automatic encodation.</p>
</td></tr><tr><td class="error-number" align="center">1408</td><td class="error-text">
<p>Input data too large to fit into one QR Symbol</p>
</td></tr><tr><td class="error-number" align="center">1409</td><td class="error-text">
<p>The selected symbol version %d is too small to fit the
specified data and selected error correction level.</p>
</td></tr><tr><td class="error-number" align="center">1410</td><td class="error-text">
<p>Trying to read past the last available codeword in block
split.</p>
</td></tr><tr><td class="error-number" align="center">1415</td><td class="error-text">
<p>Manually specified encodation schema MODE_NUMERIC has no data
that can be encoded using this schema.</p>
</td></tr><tr><td class="error-number" align="center">1416</td><td class="error-text">
<p>Manually specified encodation schema MODE_ALPHANUM has no data
that can be encoded using this schema.</p>
</td></tr><tr><td class="error-number" align="center">1417</td><td class="error-text">
<p>Manually specified encodation schema MODE_BYTE has no data
that can be encoded using this schema.</p>
</td></tr><tr><td class="error-number" align="center">1418</td><td class="error-text">
<p>Unsupported encodation schema specified (%d)</p>
</td></tr><tr><td class="error-number" align="center">1419</td><td class="error-text">
<p>Found character in data stream that cannot be encoded with the
selected manual encodation mode.</p>
</td></tr><tr><td class="error-number" align="center">1420</td><td class="error-text">
<p>Encodation using KANJI mode not yet supported.</p>
</td></tr><tr><td class="error-number" align="center">1422</td><td class="error-text">
<p>Found unknown characters in the data stream that can't be
encoded with any available encodation mode.</p>
</td></tr><tr><td class="error-number" align="center">1423</td><td class="error-text">
<p>Kanji character set not yet supported.</p>
</td></tr><tr><td class="error-number" align="center">1427</td><td class="error-text">
<p>Expected either DIGIT, ALNUM or BYTE but found ASCII
code=%d</p>
</td></tr></tbody></table>
</div></div><br class="table-break">
</div>
<div class="sect2" title="Creating an encoder"><div class="titlepage"><div><div><h3 class="title"><a name="id2617132"></a>Creating an encoder</h3></div></div></div>
<p>A QR encoder is created as an instance of <code class="code">class QREncoder</code>. The
constructor have the following signature</p>
<p>
</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
<p><code class="code">QREncoder::__construct($aVersion = -1, $aErrLevel =
QRCapacity::ErrM)</code></p>
<p><code class="code">$aVersion</code>, Specifies the QR version and is specified as
an integer in the range [1,40], see <a class="xref" href="ch27.html#table.qr-symbol-sizes" title="Table 27.2. Maximum data capacity for the different symbol sizes in the QR-code.">Table 27.2. Maximum data capacity for the
different symbol sizes in the QR-code.</a>
</p>
<p><code class="code">$aErrLevel</code>, Specifies the error correction level to be
used, see <a class="xref" href="ch27.html#table.qr-error-correction-levels" title="Table 27.3. QR Error correction levels">Table 27.3. QR Error correction levels</a></p>
</li></ul></div><p>
</p>
<p>The following examples creates a basic encoder which will automatically select the
smallest possible size to fit the data given</p>
<p>
</p><div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
</pre></td><td class="hl-main" valign="top"><pre><span class="hl-code">$encoder = new QREncoder();</span></pre></td></tr></table></div><p>
</p>
<p>The following example will create an instance of an encoder with size 22 and error
correction level 'Q'</p>
<p>
</p><div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
</pre></td><td class="hl-main" valign="top"><pre><span class="hl-code">$encoder = new QREncoder(22, QRCapacity::ErrQ);</span></pre></td></tr></table></div><p>
</p>
</div>
<div class="sect2" title="Encodation of input data options"><div class="titlepage"><div><div><h3 class="title"><a name="id2617978"></a>Encodation of input data options</h3></div></div></div>
<p>The absolute simplest way of encoding data is simply to create a simple string
representing the data to be encoded and then pass that string as the first argument
to the <code class="code">Stroke()</code> method in the backend. The encoder will then analyze
the input data and choose the most efficient space saving encoding schema for this
data. </p>
<p>
</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
<p>Unless there are some really good reasons to use manual encodation it
should be left to the library to determine this in an optimal way!</p>
</div><p>
</p>
<p>The QR standard allows 3 different compaction schema that can be used to minimize
the number of codewords used for a particular data string. This also means that a
particular data string may have several different valid barcodes that visually looks
different. </p>
<p>The supported compaction modes in the library are:</p>
<p>
</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
<p><span class="bold"><strong>Alpha compaction mode</strong></span> Efficient
encoding of digits 0 - 9; upper case letters A -Z and nine other
characters: space, $ % * + - . / : . </p>
</li><li class="listitem">
<p><span class="bold"><strong>Numeric compaction mode.</strong></span> Efficient
encoding of numeric data. For long consecutive strings of digits this
gives a better compaction than the alpha mode.</p>
</li><li class="listitem">
<p><span class="bold"><strong>Byte compaction mode.</strong></span> Used only when
there is a need to encode byte values as is, i.e. values in the range
0-255. Please note that some barcode readers, especially those with a
keyboard wedge, don't send back the proper encoding for ASCII values
lower than 32 or higher than 126. </p>
</li></ul></div><p>
</p>
<p>When the automatic encoding is chosen this will create an optimum encoding (from a
size perspective) of the supplied data. This includes shifting encoding method in
the middle of the data one or several time depending on the structure of the data. </p>
<p>It is also possible to manually control the exact encodation of the input data.
This is done by supplying one or more data tuples where the first entry in the tuple
is the compaction schema and the second the data. To encode the data manually the
following structure must then be followed:</p>
<p>
</p><div class="figure"><a name="id2618092"></a><p class="title"><b>Figure 27.10. Structure for manually specify QR encodation schema</b></p><div class="figure-contents">
<pre class="screen">$data = array( array( &lt;encoding_mode1&gt; , &lt;data1&gt; ),
array( &lt;encoding_mode2&gt; , &lt;data2&gt; ),
...
array( &lt;encoding_modeN&gt; , &lt;dataN&gt; ));</pre>
</div></div><p><br class="figure-break">
</p>
<p>The encoding mode is specified as one of three symbolic constants</p>
<p>
</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
<p><code class="code">QREncoder::MODE_NUMERIC</code></p>
</li><li class="listitem">
<p><code class="code">QREncoder::MODE_ALPHANUM</code></p>
</li><li class="listitem">
<p><code class="code">QREncoder::MODE_BYTE</code></p>
</li></ul></div><p>
</p>
<p>and the data is specified as a regular text string. Each section of data must
therefore have the compaction mode specified. </p>
<p>In order to use a specific encodation schema one has to create an array as input
instead of the normal string input. For example, to specify an input where the
encodation should be alphanumeric encoding of the digits '0123456789' one would have
to create the array </p>
<p>
</p><div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
2
3
4
5
</pre></td><td class="hl-main" valign="top"><pre><span class="hl-inlinetags">&lt;?php</span><span class="hl-code">
</span><span class="hl-var">$data</span><span class="hl-code"> = </span><span class="hl-reserved">array</span><span class="hl-brackets">(</span><span class="hl-code"> </span><span class="hl-reserved">array</span><span class="hl-brackets">(</span><span class="hl-code"> </span><span class="hl-identifier">QREncoder</span><span class="hl-code">::</span><span class="hl-identifier">MODE_ALPHANUM</span><span class="hl-code">,</span><span class="hl-quotes">'</span><span class="hl-string">0123456789</span><span class="hl-quotes">'</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
...
</span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">Stroke</span><span class="hl-brackets">(</span><span class="hl-var">$data</span><span class="hl-brackets">)</span><span class="hl-code">
</span><span class="hl-inlinetags">?&gt;</span></pre></td></tr></table></div><p>
</p>
<p>It is also possible to use different encodings for different parts of the data in
a similar way as the following example shows</p>
<p>
</p><div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
2
3
4
5
6
7
8
</pre></td><td class="hl-main" valign="top"><pre><span class="hl-inlinetags">&lt;?php</span><span class="hl-code">
</span><span class="hl-var">$data</span><span class="hl-code"> = </span><span class="hl-reserved">array</span><span class="hl-brackets">(</span><span class="hl-code"> </span><span class="hl-reserved">array</span><span class="hl-brackets">(</span><span class="hl-identifier">QREncoder</span><span class="hl-code">::</span><span class="hl-identifier">MODE_ALPHANUM</span><span class="hl-code">,</span><span class="hl-quotes">'</span><span class="hl-string">0123456789</span><span class="hl-quotes">'</span><span class="hl-brackets">)</span><span class="hl-code">,
</span><span class="hl-reserved">array</span><span class="hl-brackets">(</span><span class="hl-identifier">QREncoder</span><span class="hl-code">::</span><span class="hl-identifier">MODE_BYTE</span><span class="hl-code">,</span><span class="hl-quotes">'</span><span class="hl-string">ABCDEFGH</span><span class="hl-quotes">'</span><span class="hl-brackets">)</span><span class="hl-code">
</span><span class="hl-brackets">)</span><span class="hl-code">;
...
...
</span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">Stroke</span><span class="hl-brackets">(</span><span class="hl-var">$data</span><span class="hl-brackets">)</span><span class="hl-code">
</span><span class="hl-inlinetags">?&gt;</span></pre></td></tr></table></div><p>
</p>
</div>
<div class="sect2" title="Reading input data from a file"><div class="titlepage"><div><div><h3 class="title"><a name="id2618170"></a>Reading input data from a file</h3></div></div></div>
<p>Normally the method Backend::Stroke($aData) is sued to create a QR code from the
datastring given. This string can of course come from a database, user input or from
a file. The library provides a utility method </p>
<p>
</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
<p><code class="code">Backend::StrokeFromFile($aFromFile,$aToFile='')</code></p>
<p><code class="code">$aFromFile</code>, The file to read the data from</p>
<p><code class="code">$aToFile</code>, Optional filename to write the generated QR
code to</p>
</li></ul></div><p>
</p>
<p>which makes it easy to get data directly from a file. Otherwise it behaves exactly
the same as the normal <code class="code">Backend::Stroke()</code>.</p>
</div>
<div class="sect2" title="Creating different backends"><div class="titlepage"><div><div><h3 class="title"><a name="id2618220"></a>Creating different backends</h3></div></div></div>
<p>In order to create the actual output one or more backends must be created. The QR
Code supports the following backends:</p>
<p>
</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
<p><code class="code">BACKEND_IMAGE</code>, Create an image backend. This is the
default backend if no explicit backend is specified.</p>
</li><li class="listitem">
<p><code class="code">BACKEND_PS</code>, Create a postscript backend. The text string
that represents the postscript for the barcode is returned directly from
the <code class="code">Backend::Stroke()</code></p>
</li><li class="listitem">
<p><code class="code">BACKEND_EPS</code>, Create an encapsulated postscript
backend</p>
</li><li class="listitem">
<p><code class="code">BACKEND_ASCII</code>, This is a special backend which will
generate an ASCII rendering of the datamatrix barcode. This is mostly
practical for technical investigations regarding the technical structure
of a Datamatrix barcode.</p>
</li></ul></div><p>
</p>
<p>The following code snippet shows two ways of creating a barcode image
backend.</p>
<p>
</p><div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
2
3
4
5
</pre></td><td class="hl-main" valign="top"><pre><span class="hl-inlinetags">&lt;?php</span><span class="hl-code">
</span><span class="hl-var">$encoder</span><span class="hl-code"> = </span><span class="hl-reserved">new</span><span class="hl-code"> </span><span class="hl-identifier">QREncoder</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-var">$backend</span><span class="hl-code"> = </span><span class="hl-identifier">QRCodeBackendFactory</span><span class="hl-code">::</span><span class="hl-identifier">Create</span><span class="hl-brackets">(</span><span class="hl-var">$encoder</span><span class="hl-brackets">)</span><span class="hl-code">;
...
</span><span class="hl-inlinetags">?&gt;</span></pre></td></tr></table></div><p>
</p>
<p>
</p><div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
2
3
4
5
</pre></td><td class="hl-main" valign="top"><pre><span class="hl-inlinetags">&lt;?php</span><span class="hl-code">
</span><span class="hl-var">$encoder</span><span class="hl-code"> = </span><span class="hl-reserved">new</span><span class="hl-code"> </span><span class="hl-identifier">QREncoder</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-var">$backend</span><span class="hl-code"> = </span><span class="hl-identifier">QRCodeBackendFactory</span><span class="hl-code">::</span><span class="hl-identifier">Create</span><span class="hl-brackets">(</span><span class="hl-var">$encoder</span><span class="hl-code">,</span><span class="hl-identifier">BACKEND_IMAGE</span><span class="hl-brackets">)</span><span class="hl-code">;
...
</span><span class="hl-inlinetags">?&gt;</span></pre></td></tr></table></div><p>
</p>
<p>The following code shows a complete script to generate a postscript output</p>
<p>
</p><div class="example"><a name="example.qrexample11"></a><p class="title"><b>Example 27.4. Generating Postscript output (<code class="filename">qrexample11.php</code>) </b></p><div class="example-contents"> <div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
</pre></td><td class="hl-main" valign="top"><pre><span class="hl-inlinetags">&lt;?php</span><span class="hl-code">
</span><span class="hl-comment">//</span><span class="hl-comment"> Include the library</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-reserved">require_once</span><span class="hl-code"> </span><span class="hl-brackets">(</span><span class="hl-quotes">'</span><span class="hl-string">jpgraph/QR/qrencoder.inc.php</span><span class="hl-quotes">'</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Example 11 : Generate postscript output</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$data</span><span class="hl-code"> = </span><span class="hl-quotes">'</span><span class="hl-string">ABCDEFGH01234567</span><span class="hl-quotes">'</span><span class="hl-code">; </span><span class="hl-comment">//</span><span class="hl-comment"> Data to be encoded</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$version</span><span class="hl-code"> = -</span><span class="hl-number">1</span><span class="hl-code">; </span><span class="hl-comment">//</span><span class="hl-comment"> -1 = Let the library decide version (same as default)</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$corrlevel</span><span class="hl-code"> = </span><span class="hl-identifier">QRCapacity</span><span class="hl-code">::</span><span class="hl-identifier">ErrH</span><span class="hl-code">; </span><span class="hl-comment">//</span><span class="hl-comment"> Error correction level H (Highest possible)</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$modulewidth</span><span class="hl-code"> = </span><span class="hl-number">3</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Create a new instance of the encoder using the specified</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-comment">//</span><span class="hl-comment"> QR version and error correction</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$encoder</span><span class="hl-code"> = </span><span class="hl-reserved">new</span><span class="hl-code"> </span><span class="hl-identifier">QREncoder</span><span class="hl-brackets">(</span><span class="hl-var">$version</span><span class="hl-code">,</span><span class="hl-var">$corrlevel</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Use the image backend</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$backend</span><span class="hl-code"> = </span><span class="hl-identifier">QRCodeBackendFactory</span><span class="hl-code">::</span><span class="hl-identifier">Create</span><span class="hl-brackets">(</span><span class="hl-var">$encoder</span><span class="hl-code">, </span><span class="hl-identifier">BACKEND_PS</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Set the module size</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">SetModuleWidth</span><span class="hl-brackets">(</span><span class="hl-var">$modulewidth</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Store the barcode in the specifed file</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$ps_str</span><span class="hl-code"> = </span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">Stroke</span><span class="hl-brackets">(</span><span class="hl-var">$data</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-reserved">echo</span><span class="hl-code"> </span><span class="hl-quotes">'</span><span class="hl-string">&lt;pre&gt;</span><span class="hl-quotes">'</span><span class="hl-code">.</span><span class="hl-var">$ps_str</span><span class="hl-code">.</span><span class="hl-quotes">'</span><span class="hl-string">&lt;/pre&gt;</span><span class="hl-quotes">'</span><span class="hl-code">;
</span><span class="hl-inlinetags">?&gt;</span></pre></td></tr></table></div></div></div><p><br class="example-break">
</p>
<div class="figure"><a name="id2618334"></a><p class="title"><b>Figure 27.11. QR Code - Example Postscript Output</b></p><div class="figure-contents">
<div class="mediaobject"><img src="images/qr-postscript.png" alt="QR Code - Example Postscript Output"></div>
</div></div><br class="figure-break">
</div>
<div class="sect2" title="Generic backend methods"><div class="titlepage"><div><div><h3 class="title"><a name="id2618316"></a>Generic backend methods</h3></div></div></div>
<p>The following methods are available to adjust the final look and feel of the
barcode</p>
<p>
</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<p><code class="code">Backend::SetColor($aOne, $aZero,
$aBackground='white')</code></p>
<p>the color of the 'black' and 'white' modules in the barcode and the
quiet area around the barcode</p>
</li><li class="listitem">
<p><code class="code">Backend::SetQuietZone($aSize)</code></p>
<p>the size of the "quiet zone" in pixels for the image backend and in
points (1 pt = 1/72 inch) for the postscript backend</p>
</li><li class="listitem">
<p><code class="code">Backend::SetModuleWidth($aWidth)</code></p>
<p>the module width specified in pixels for the image backend and in
points (1 pt = 1/72 inch) for the postscript backend</p>
</li><li class="listitem">
<p><code class="code">Backend::Stroke($aData, $aFileName='')</code></p>
<p>create the barcode and send it back the client or store it to a file
if the second parameter is set. For postscript backends the postscript
string is returned directly from the method. (See example above)</p>
</li><li class="listitem">
<p><code class="code">Backend::StrokeFromFile($aFromFileName,$aFileName='')</code></p>
<p>This allows the creation of barcode directly from data in a
file.</p>
</li></ol></div><p>
</p>
</div>
<div class="sect2" title="Image backend methods"><div class="titlepage"><div><div><h3 class="title"><a name="id2618431"></a>Image backend methods</h3></div></div></div>
<p>For the image backend it is possible to adjust the image encoding format with the
following method</p>
<p>
</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<p>
<code class="code">Backend::SetImgFormat($aFormat,$aQuality=75)</code>
</p>
<p>Specify image format. Possible values are </p>
<p>
</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
<p>
<code class="code">'auto'</code>
</p>
</li><li class="listitem">
<p>
<code class="code">'png'</code>
</p>
</li><li class="listitem">
<p>
<code class="code">'jpeg'</code>
</p>
</li><li class="listitem">
<p>
<code class="code">'gif'</code>
</p>
</li></ul></div><p>
</p>
<p>For 'jpeg' format the quality parameter is a number in range [1-100]
and specified how much compression / (Data loss) should be used. 100=no
compression. Normal values are in the range [60-95]</p>
<p>The following example sets the image format to 'JPEG' with quality
80.</p>
<p>
</p><div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
</pre></td><td class="hl-main" valign="top"><pre><span class="hl-code">$backend-&gt;SetImgFormat('jpeg', 80);</span></pre></td></tr></table></div><p>
</p>
</li></ol></div><p>
</p>
</div>
<div class="sect2" title="Postscript backend methods"><div class="titlepage"><div><div><h3 class="title"><a name="id2618458"></a>Postscript backend methods</h3></div></div></div>
<p>For postscript backend it is possible to select whether the postscript should be
generated as encapsulated postscript. This is controlled by the method</p>
<p>
</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
<p><code class="code">Backend::SetEPS($aFlg=true)</code></p>
</li></ul></div><p>
</p>
</div>
<div class="sect2" title="A template to create barcodes"><div class="titlepage"><div><div><h3 class="title"><a name="id2618569"></a>A template to create barcodes</h3></div></div></div>
<p>The following (complete) script can be used as a starting point for creation of
more advanced barcode scripts</p>
<p>
</p><div class="example"><a name="example.qr_template"></a><p class="title"><b>Example 27.5. A QR code template (<code class="filename">qr_template.php</code>) </b></p><div class="example-contents"> <div class="hl-main"><table class="hl-table" width="100%"><tr><td class="hl-gutter" align="right" valign="top"><pre>1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
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32
</pre></td><td class="hl-main" valign="top"><pre><span class="hl-inlinetags">&lt;?php</span><span class="hl-code">
</span><span class="hl-reserved">require_once</span><span class="hl-code"> </span><span class="hl-brackets">(</span><span class="hl-quotes">'</span><span class="hl-string">jpgraph/QR/qrencoder.inc.php</span><span class="hl-quotes">'</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Data to be encoded</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$data</span><span class="hl-code"> = </span><span class="hl-quotes">'</span><span class="hl-string">ABCDEFGH01234567</span><span class="hl-quotes">'</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> QR Code specification</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$version</span><span class="hl-code"> = -</span><span class="hl-number">1</span><span class="hl-code">; </span><span class="hl-comment">//</span><span class="hl-comment"> -1 = Let the library decide version (same as default)</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$corrlevel</span><span class="hl-code"> = </span><span class="hl-identifier">QRCapacity</span><span class="hl-code">::</span><span class="hl-identifier">ErrM</span><span class="hl-code">; </span><span class="hl-comment">//</span><span class="hl-comment"> Medium erro correction</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$modulewidth</span><span class="hl-code"> = </span><span class="hl-number">2</span><span class="hl-code">; </span><span class="hl-comment">//</span><span class="hl-comment"> Module width</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$back</span><span class="hl-code"> = </span><span class="hl-identifier">BACKEND_IMAGE</span><span class="hl-code">; </span><span class="hl-comment">//</span><span class="hl-comment"> Default backend</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$quiet</span><span class="hl-code"> = </span><span class="hl-number">4</span><span class="hl-code">; </span><span class="hl-comment">//</span><span class="hl-comment"> Same as default value</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-comment">//</span><span class="hl-comment"> Create encoder and backend</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$encoder</span><span class="hl-code"> = </span><span class="hl-reserved">new</span><span class="hl-code"> </span><span class="hl-identifier">QREncoder</span><span class="hl-brackets">(</span><span class="hl-var">$version</span><span class="hl-code">, </span><span class="hl-var">$corrlevel</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-var">$backend</span><span class="hl-code"> = </span><span class="hl-identifier">QRCodeBackendFactory</span><span class="hl-code">::</span><span class="hl-identifier">Create</span><span class="hl-brackets">(</span><span class="hl-var">$encoder</span><span class="hl-code">, </span><span class="hl-var">$back</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Set the module size</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">SetModuleWidth</span><span class="hl-brackets">(</span><span class="hl-var">$modulewidth</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-comment">//</span><span class="hl-comment"> Set Quiet zone (this should rarely need changing from the default)</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">SetQuietZone</span><span class="hl-brackets">(</span><span class="hl-var">$quiet</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-reserved">if</span><span class="hl-brackets">(</span><span class="hl-code"> </span><span class="hl-var">$back</span><span class="hl-code"> == </span><span class="hl-identifier">BACKEND_IMAGE</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
</span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">Stroke</span><span class="hl-brackets">(</span><span class="hl-var">$data</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-reserved">else</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
</span><span class="hl-var">$str</span><span class="hl-code"> = </span><span class="hl-var">$backend</span><span class="hl-code">-&gt;</span><span class="hl-identifier">Stroke</span><span class="hl-brackets">(</span><span class="hl-var">$data</span><span class="hl-brackets">)</span><span class="hl-code">;
</span><span class="hl-reserved">echo</span><span class="hl-code"> </span><span class="hl-quotes">'</span><span class="hl-string">&lt;pre&gt;</span><span class="hl-quotes">'</span><span class="hl-code">.</span><span class="hl-var">$str</span><span class="hl-code">.</span><span class="hl-quotes">'</span><span class="hl-string">&lt;/pre&gt;</span><span class="hl-quotes">'</span><span class="hl-code">;
</span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-inlinetags">?&gt;</span></pre></td></tr></table></div></div></div><p><br class="example-break"> </p><div class="figure"><a name="fig.qr_template"></a><p class="title"><b>Figure 27.12. A QR code template <code class="uri"><a class="uri" href="example_src/qr_template.html" target="_top">(<code class="filename">qr_template.php</code>)</a></code> </b></p><div class="figure-contents"> <span class="inlinemediaobject"><img src="images/qr_template.png" alt="A QR code template (qr_template.php)"></span> </div></div><p><br class="figure-break">
</p>
</div>
<div class="sect2" title="Sample application"><div class="titlepage"><div><div><h3 class="title"><a name="id2618643"></a>Sample application</h3></div></div></div>
<p>As an example the library includes a WEB-based demo barcode creation application.
This application can be used to easily create barcode through it's WEB interface. It
is available at '<code class="filename">qr/demoapp/index.html</code>'</p>
<p>This application is primarily included as a demo on the features available in the
library and not as a finalized product.</p>
<p><a class="xref" href="ch27s02.html#fig.qr-demo-app" title="Figure 27.13. QR Code WEB-based demo application">Figure 27.13. QR Code WEB-based demo application</a> shows a screen shot of the application
interface.</p>
<div class="figure"><a name="fig.qr-demo-app"></a><p class="title"><b>Figure 27.13. QR Code WEB-based demo application</b></p><div class="figure-contents">
<div class="mediaobject"><img src="images/qr-demoapp.png" alt="QR Code WEB-based demo application"></div>
</div></div><br class="figure-break">
</div>
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