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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>3.2. Programming Overview</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="concepts.html" title="Chapter 3. PHPlot Concepts" /><link rel="prev" href="concepts.html" title="Chapter 3. PHPlot Concepts" /><link rel="next" href="conc-datatypes.html" title="3.3. PHPlot Data Types" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">3.2. Programming Overview</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="concepts.html">Prev</a> </td><th width="60%" align="center">Chapter 3. PHPlot Concepts</th><td width="20%" align="right"> <a accesskey="n" href="conc-datatypes.html">Next</a></td></tr></table><hr /></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="conc-overview"></a>3.2. Programming Overview</h2></div></div></div><div class="abstract"><p class="title"><strong></strong></p><p>
This section contains an overview of how to use PHPlot.
  </p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="conc-overview-howitworks"></a>3.2.1. How It Works</h3></div></div></div><p>
To create a plot with PHPlot, your PHP script will generally do the
following:
</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>
Include the <code class="filename">phplot.php</code> source using
<code class="literal">require_once</code>.
    </p></li><li class="listitem"><p>
Create an object which is an instance of the <code class="literal">PHPlot</code> class.
    </p></li><li class="listitem"><p>
Use PHPlot functions (methods of the class object) to select the plot type,
present the data array, and optionally change settings which control the
appearance of the plot.
    </p></li><li class="listitem"><p>
Output the plot, typically to the user's browser but possibly to a file
instead.
    </p></li></ol></div><p>
The order of operations you use between creating a PHPlot object and output
of the plot does not matter. The PHPlot class sets internal class variables
as you configure the plot, but doesn't do anything with the values until
you are ready. For example, setting a font for the plot title, then setting
the title text, is the same as setting the title text first, then the font.
In both cases, the title will be drawn using the font you selected.
</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
It is important to remember that if you are writing a PHP script that uses
PHPlot to create an image for a web page, that PHP script must output
<span class="emphasis"><em>only</em></span> the image data.
If you want your plot image to appear on a web page with text and other images,
you need at least two scripts.
Your main script returns an HTML page which includes an IMG (Image) tag for
the plot.
The IMG tag has a SRC attribute which references the second script, and it
is this second script which creates the PHPlot image.
An example of this can be found in <a class="xref" href="ex-webform.html" title="5.23. Example - Complete Web Form with Plot">Section 5.23, &#8220;Example - Complete Web Form with Plot&#8221;</a>.
You will most likely need a way to communicate parameters from your main
script to your image script. Two good ways to do this are using URL parameters,
and with PHP session variables.
  </p><p>
An alternative to using two scripts - one generating HTML, and one using PHPlot
to create the plot image - is available starting with PHPlot-5.5.0. You can
write a single script which generates HTML and also embeds the PHPlot-generated
plot image.  See <a class="xref" href="ex-encodeimage.html" title="5.39. Example - Embedding Image with EncodeImage">Section 5.39, &#8220;Example - Embedding Image with EncodeImage&#8221;</a>.
  </p></div></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="conc-overview-annoex"></a>3.2.2. Annotated Example</h3></div></div></div><p>
Here is a simple, annotated example of a script which produces an image.
More examples can be found in <a class="xref" href="examples.html" title="Chapter 5. PHPlot Examples">Chapter 5, <em>PHPlot Examples</em></a>.
</p><p>
</p><pre class="programlisting">require_once 'phplot.php';
</pre><p>
This brings in the PHPlot source into your script. For this to work,
PHP needs to be able to find the PHPlot source file. A good way to arrange
this is to install PHPlot into a directory outside your web server's
document root and on the PHP Include Path. Other ways are to include a full
path to <code class="filename">phplot.php</code> when including it, or to copy
<code class="filename">phplot.php</code> into the same directory as your script.
</p><p>
</p><pre class="programlisting">$plot = new PHPlot();
</pre><p>
Here we create a new PHPlot object and call it <code class="literal">plot</code>.
Everything else we do with the plot will be through the $plot object.
</p><p>
</p><pre class="programlisting">$plot-&gt;SetPlotType('lines');
$plot-&gt;SetDataType('text-data');
</pre><p>
Here we select the plot type 'lines', for a line plot
(see <a class="xref" href="conc-plottypes.html" title="3.4. PHPlot Plot Types">Section 3.4, &#8220;PHPlot Plot Types&#8221;</a>),
and indicate our data will be represented in the 'text-data' format
(see <a class="xref" href="conc-datatypes.html" title="3.3. PHPlot Data Types">Section 3.3, &#8220;PHPlot Data Types&#8221;</a>).
</p><p>
</p><pre class="programlisting">$plot-&gt;SetDataValues($data);
</pre><p>
The data array $data is where we store the values to be plotted.
We haven't shown where the data came from, but in a typical application
it might be from a database query.
How the data array is constructed is described in 
<a class="xref" href="conc-datatypes.html" title="3.3. PHPlot Data Types">Section 3.3, &#8220;PHPlot Data Types&#8221;</a>.
</p><p>
</p><pre class="programlisting">$plot-&gt;SetXDataLabelPos('none');
$plot-&gt;SetLineWidths(3);
$plot-&gt;SetDrawXGrid(True);
</pre><p>
These three functions illustrate how to change the appearance of the plot.
</p><p>
</p><pre class="programlisting">$plot-&gt;DrawGraph();
</pre><p>
This final function call outputs the plot.
More accurately,
this function creates the plot using all the data and settings
which were established by previous functions, and then outputs the plot.
This is a crucial point when using PHPlot: Until you call DrawGraph,
PHPlot is simply recording all the settings resulting from the functions
you call, and saving a copy of your data array. Nothing really happens
until you complete the plot with DrawGraph.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="concepts.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="concepts.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="conc-datatypes.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 3. PHPlot Concepts </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 3.3. PHPlot Data Types</td></tr></table></div></body></html>