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<!DOCTYPE chapter SYSTEM "chapter.dtd">

<chapter>
  <header>
    <copyright>
      <year>2000</year><year>2009</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      The contents of this file are subject to the Erlang Public License,
      Version 1.1, (the "License"); you may not use this file except in
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    <title>Fonts</title>
    <prepared></prepared>
    <docno></docno>
    <date></date>
    <rev></rev>
    <file>gs_chapter5.xml</file>
  </header>

  <section>
    <title>The Font Model</title>
    <p>Text related objects can be handled with the font option <c><![CDATA[{font,Font}]]></c>. A <c><![CDATA[Font]]></c> is represented as a two or three tuple:</p>
    <list type="bulleted">
      <item><c><![CDATA[{Family,Size}]]></c></item>
      <item><c><![CDATA[{Family,Style,Size}]]></c></item>
    </list>
    <p>Examples of fonts are: <c><![CDATA[{times,12}]]></c>, <c><![CDATA[{symbol,bold,18}]]></c>, <c><![CDATA[{courier,[bold,italic],6}]]></c>, <c><![CDATA[{screen,12}]]></c>.</p>
    <p>The most important requirement with the font model is to ensure that there is always a "best possible" font present. For example, if an application tries to use the font <c><![CDATA[{times,17}]]></c> on a computer system which does not have this font available, the <c><![CDATA[gs]]></c> font model automatically substitutes <c><![CDATA[{times,16}]]></c>.</p>
    <p>Note that GS requires that the following fonts are available if using an X-server display:</p>
    <list type="bulleted">
      <item>fixed</item>
      <item>-*-courier-*</item>
      <item>-*-times-*</item>
      <item>-*-helvetica-*</item>
      <item>-*-symbol-*</item>
      <item>"-*-new century schoolbook-"</item>
      <item>-*-screen-*</item>
    </list>
    <p>To find out which font is actually chosen by the <c><![CDATA[gs]]></c>, use the option <c><![CDATA[{choose_font,Font}]]></c>. For example, the following situation might occur:</p>
    <pre><![CDATA[
1> <input>G=gs:start().</input>
{1,<0.20.0>}
2><input>gs:read(G,{choose_font,{times,38}}).</input>
{times,[],38}
3> <input>gs:read(G,{choose_font,{screen,italic,6}}).</input> 
{courier,italic,6}
4> 
    ]]></pre>
    <p>When programming with fonts, it is often necessary to find the size of a string which uses a specific font. <c><![CDATA[{font_wh,Font}]]></c> returns the width and height of any string and any font. The following example illustrates its usage:</p>
    <marker id="gs_fig6"></marker>
    <image file="images/ex15.gif">
      <icaption>Font Examples</icaption>
    </image>
    <codeinclude file="examples/ex15.erl" tag="" type="erl"></codeinclude>
  </section>
</chapter>

