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