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<title>Fonts (The Chickadee Game Toolkit)</title>
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Next: <a href="Blending-and-Depth-Testing.html#Blending-and-Depth-Testing" accesskey="n" rel="next">Blending and Depth Testing</a>, Previous: <a href="Lines-and-Shapes.html#Lines-and-Shapes" accesskey="p" rel="prev">Lines and Shapes</a>, Up: <a href="Graphics.html#Graphics" accesskey="u" rel="up">Graphics</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html#Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<a name="Fonts-1"></a>
<h4 class="subsection">2.3.6 Fonts</h4>
<p>Unlike the traditional TrueType font format that many are accustomed
to, Chickadee loads and renders bitmap fonts in the
<a href="http://www.angelcode.com/products/bmfont/doc/file_format.html">Angel Code format</a>. But why use this seemingly obscure format? It’s
easy to find TTFs but not easy to find FNTs (the canonical file
extension used for Angel Code fonts) and bitmap fonts don’t scale
well. The reason is efficiency.
</p>
<p>If all of the glyphs of a font are pre-rendered and packed into an
image file then it becomes possible to use a texture atlas
(see <a href="Textures.html#Textures">Textures</a>) and a sprite batch (see <a href="Sprites.html#Sprites">Sprites</a>) when
rendering, which is a more efficient way to render fonts than using,
say, <a href="https://www.libsdl.org/projects/SDL_ttf/">SDL_ttf</a> or other
solutions that involve using the FreeType library directly.
</p>
<p>Now what about scaling? In libraries that use TTF fonts, one must
choose the size that the glyphs will be rasterized at up front. To
use <code>n</code> sizes of the same font, one must load <code>n</code> variants
of that font. If the size of the text is dynamic, some kind of
texture scaling algorithm must be used and the text will inevitably
look blurry. At first glance, using bitmap fonts seem to have an even
worse issue. Instead of just loading the same font <code>n</code> times at
different sizes, one would need to generate <code>n</code> image files for
each font size needed. This is where the “signed distance field”
rendering technique comes in. Introduced by
<a href="http://www.valvesoftware.com/.../2007/SIGGRAPH2007_AlphaTestedMagnification.pdf">Valve</a> in 2007, signed distance field fonts can be efficiently stored
in a bitmap and be rendered at arbitrary scale factors with good
results.
</p>
<p>While Chickadee does not yet offer a tool for converting TTF fonts
into FNT fonts, tools such as
<a href="https://github.com/libgdx/libgdx/wiki/Hiero">Hiero</a> may be used
in the meantime.
</p>
<p>The following procedures can be found in the <code>(chickadee render
font)</code> module.
</p>
<dl>
<dt><a name="index-load_002dfont"></a>Procedure: <strong>load-font</strong> <em><var>file</var></em></dt>
<dd><p>Load the Angel Code formatted XML document in <var>file</var> and return a
new font object.
</p></dd></dl>
<dl>
<dt><a name="index-font_003f"></a>Procedure: <strong>font?</strong> <em><var>obj</var></em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is a font object.
</p></dd></dl>
<dl>
<dt><a name="index-font_002dface"></a>Procedure: <strong>font-face</strong> <em><var>font</var></em></dt>
<dd><p>Return the name of <var>font</var>.
</p></dd></dl>
<dl>
<dt><a name="index-font_002dline_002dheight"></a>Procedure: <strong>font-line-height</strong> <em><var>font</var></em></dt>
<dd><p>Return the line height of <var>font</var>.
</p></dd></dl>
<dl>
<dt><a name="index-font_002dline_002dheight-1"></a>Procedure: <strong>font-line-height</strong> <em><var>font</var></em></dt>
<dd><p>Return the line height of <var>font</var>.
</p></dd></dl>
<dl>
<dt><a name="index-font_002dbold_003f"></a>Procedure: <strong>font-bold?</strong> <em><var>font</var></em></dt>
<dd><p>Return <code>#t</code> if <var>font</var> is a bold font.
</p></dd></dl>
<dl>
<dt><a name="index-font_002ditalic_003f"></a>Procedure: <strong>font-italic?</strong> <em><var>font</var></em></dt>
<dd><p>Return <code>#t</code> if <var>font</var> is an italicized font.
</p></dd></dl>
<dl>
<dt><a name="index-draw_002dtext"></a>Procedure: <strong>draw-text</strong> <em><var>font</var> <var>text</var> <var>position</var></em></dt>
<dd><p>[#:origin] [#:scale] [#:rotation] [#:blend-mode]
[#:start 0] [#:end <code>(string-length text)</code>]
</p>
<p>Draw the string <var>text</var> with the first character starting at
<var>position</var> using <var>font</var>.
</p>
<div class="example">
<pre class="example">(draw-text font "Hello, world!" (vec2 128.0 128.0))
</pre></div>
<p>To render a substring of <var>text</var>, use the <var>start</var> and <var>end</var>
arguments.
</p>
<p>Refer to <code>draw-sprite</code> (see <a href="Sprites.html#Sprites">Sprites</a>) for information about
the other arguments.
</p></dd></dl>
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Next: <a href="Blending-and-Depth-Testing.html#Blending-and-Depth-Testing" accesskey="n" rel="next">Blending and Depth Testing</a>, Previous: <a href="Lines-and-Shapes.html#Lines-and-Shapes" accesskey="p" rel="prev">Lines and Shapes</a>, Up: <a href="Graphics.html#Graphics" accesskey="u" rel="up">Graphics</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html#Index" title="Index" rel="index">Index</a>]</p>
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