49 lines
5.6 KiB
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49 lines
5.6 KiB
HTML
<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Understanding text alignment and anchor point</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="ch08.html" title="Chapter 8. Text and font handling"></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">Understanding text alignment and anchor point</th></tr><tr><td width="20%" align="left"> </td><th width="60%" align="center">Chapter 8. Text and font handling</th><td width="20%" align="right"> </td></tr></table><hr></div><div class="sect1" title="Understanding text alignment and anchor point"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2498561"></a>Understanding text alignment and anchor point</h2></div></div></div>
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<p>When a text string position is specified that screen (or scale) position by
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default gets aligned with the top left corner of the strings bounding box. We say
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that the top left corner is the <span class="italic">anchor point</span> of the text string. The alignment of the
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anchor point can be adjusted with a call to <code class="code">Text::SetAlignment($aHorAlign,
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$vertAlign)</code>. The two arguments are given as text strings and the
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admissible values for each argument are: </p>
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<p>
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</p><div class="variablelist"><dl><dt><span class="term">Horizontal alignment</span></dt><dd>
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<p><code class="code">'left'</code>, <code class="code">'center'</code>,
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<code class="code">'right'</code></p>
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</dd><dt><span class="term">Vertical alignment</span></dt><dd>
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<p><code class="code">'bottom'</code>, <code class="code">'center'</code> (or
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<code class="code">'middle'</code>) , <code class="code">'top'</code></p>
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</dd></dl></div><p>
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</p>
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<div class="caution" title="Caution" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Caution</h3>
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<p>Even though from an API perspective both bitmap fonts and TTF fonts share the
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same user API the implementation is vastly different. There are a number of
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subtle differences in the way built-in bit-map fonts and TrueType fonts are
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rendered to the screen. This means for example that the alignment of, say the
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bottom of the text string, is not pixel-perfect between bitmap and TrueType
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fonts However, JpGraph, abstracts away 99.9% of the differences so it will be,
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for all practical uses of the library completely transparent to switch between
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the different font types.</p>
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</div>
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<p>Manually setting the alignment for the anchor point is mostly useful when adding
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Text object to the graph to get the wanted alignment. You can see an example of how
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the anchor point changes depending on how the combination of alignments are used in <a class="xref" href="ch08s03.html#fig.textalignex1" title="Figure 8.2. Illustration of anchor point alignment (textalignex1.php)">Figure 8.2. Illustration of anchor point alignment <code class="uri"><a class="uri" href="example_src/textalignex1.html" target="_top">(<code class="filename">textalignex1.php</code>)</a></code> </a></p>
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<p>
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</p><div class="figure"><a name="fig.textalignex1"></a><p class="title"><b>Figure 8.2. Illustration of anchor point alignment <code class="uri"><a class="uri" href="example_src/textalignex1.html" target="_top">(<code class="filename">textalignex1.php</code>)</a></code> </b></p><div class="figure-contents"> <span class="inlinemediaobject"><img src="images/textalignex1.png" alt="Illustration of anchor point alignment (textalignex1.php)"></span> </div></div><p><br class="figure-break">
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</p>
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<p>
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</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
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<p>It might seem strange to have the method name
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"<code class="code">SetAlignment()</code>" when it really should make more sense to use
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the name "<code class="code">SetAnchor()</code>". We agree. This naming scheme is due to
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historical reasons.</p>
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</div><p>
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</p>
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<p>
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</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
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<p>The graph legend box also have an anchor point that is specified as the
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3:rd and 4:th argument to Legend::SetPos()</p>
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</div><p>
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</p>
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</div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"> </td><td width="20%" align="center"><a accesskey="u" href="ch08.html">Up</a></td><td width="40%" align="right"> </td></tr><tr><td width="40%" align="left" valign="top"> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> </td></tr></table></div></body></html>
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