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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>GetDeviceXY</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="GetCallback.html" title="GetCallback" /><link rel="next" href="GetLegendSize.html" title="GetLegendSize" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">GetDeviceXY</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="GetCallback.html">Prev</a> </td><th width="60%" align="center">PHPlot Function Reference</th><td width="20%" align="right"> <a accesskey="n" href="GetLegendSize.html">Next</a></td></tr></table><hr /></div><div class="refentry"><a id="GetDeviceXY"></a><div class="titlepage"></div><div class="refnamediv"><h2><span class="refentrytitle">GetDeviceXY</span></h2><p>GetDeviceXY &#8212; Translate world coordinates into device coordinates</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">list($x, $y) = $plot-&gt;GetDeviceXY(<em class="parameter"><code>$x_world</code></em>, <em class="parameter"><code>$y_world</code></em>)</pre></div><div class="refsect1"><a id="idp1377719388"></a><h2>Description</h2><p>
<code class="function">GetDeviceXY</code> translates values in
<a class="link" href="concepts.html#def-worldcoor">world coordinates</a> into
values in <a class="link" href="concepts.html#def-devcoor">device coordinates</a>.
This is useful if you want to annotate a plot with text or graphics
positioned relative to specific data values. Given the coordinates of a
point in the coordinate space of your data values, this function returns
the pixel coordinates of that point in the image.
    </p></div><div class="refsect1"><a id="idp1377721508"></a><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>$x_world</code></em></span></dt><dd><p>
The X coordinate to translate from world coordinates.
          </p></dd><dt><span class="term"><em class="replaceable"><code>$y_world</code></em></span></dt><dd><p>
The Y coordinate to translate from world coordinates.
          </p></dd></dl></div></div><div class="refsect1"><a id="idp1377723924"></a><h2>Return Value</h2><p>
Returns an array of two values ($x, $y) in device coordinates which
correspond to the world coordinate parameters.
    </p></div><div class="refsect1"><a id="idp1377724652"></a><h2>Notes</h2><p>
This function only works after scaling factors have been established, which
happens in <a class="xref" href="DrawGraph.html" title="DrawGraph"><span class="refentrytitle">DrawGraph</span></a>. So it can only be used in two cases:
      </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
From a drawing callback (see <a class="xref" href="callbacks.html" title="4.4. Callbacks">Section 4.4, &#8220;Callbacks&#8221;</a>) - that is, a
callback whose name starts with 'draw'.
          </p></li><li class="listitem"><p>
If <a class="xref" href="SetPrintImage.html" title="SetPrintImage"><span class="refentrytitle">SetPrintImage</span></a>(False) is used to disable automatic
output of the image file, then <code class="function">GetDeviceXY()</code> can be
used after <a class="xref" href="DrawGraph.html" title="DrawGraph"><span class="refentrytitle">DrawGraph</span></a> returns.
          </p></li></ul></div><p>
    </p><p>
<code class="function">GetDeviceXY()</code> will fail with an error message if it
is called before scaling is set up.
    </p><p>
If the world coordinates represent a point that is not visible on the plot,
the returned device coordinates will be outside the plot area, or even
outside the image area.
    </p><p>
To see how this can be used in callbacks,
see <a class="xref" href="callbacks.html#callbacks-drawing" title="4.4.5. Using Callbacks to Annotate Plots">Section 4.4.5, &#8220;Using Callbacks to Annotate Plots&#8221;</a>.
    </p><p>
Because there are no valid world coordinates for pie charts,
<code class="function">GetDeviceXY()</code> does not work with pie charts.
    </p></div><div class="refsect1"><a id="idp1377730540"></a><h2>History</h2><p>
Starting with PHPlot-5.6.0, this function will fail with pie charts, because
they do not have valid world coordinates. Through PHPlot-5.5.0, this
function returned somewhat meaningless values when used with pie charts.
    </p><p>
This function was added in PHPlot-5.1.0.
    </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="GetCallback.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="GetLegendSize.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">GetCallback </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> GetLegendSize</td></tr></table></div></body></html>