Revised.
This commit is contained in:
Werner Lemberg
parent
6f36900589
commit
15d3dcd900
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@ -199,12 +199,15 @@
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b. Outline descriptor
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</h4>
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<p>A FreeType outline is described through a simple structure, called
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<tt>FT_Outline</tt>, which fields are:</p>
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<p>A FreeType outline is described through a simple structure:</p>
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<center>
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<table cellspacing=3
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cellpadding=3>
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<caption>
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<b><tt>FT_Outline</tt></b>
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</caption>
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<tr>
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<td>
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<tt>n_points</tt>
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@ -267,7 +270,7 @@
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<a name="section-2">
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<hr3>
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<h3>
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2. Bounding and control box computations
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</h3>
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@ -1,12 +1,13 @@
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<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
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<!doctype html public "-//w3c//dtd html 4.0 transitional//en"
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"http://www.w3.org/TR/REC-html40/loose.dtd">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<meta name="Author" content="blob">
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<meta name="GENERATOR" content="Mozilla/4.5 [fr] (Win98; I) [Netscape]">
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<title>FreeType Glyph Conventions</title>
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<meta http-equiv="Content-Type"
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content="text/html; charset=iso-8859-1">
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<meta name="Author"
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content="David Turner">
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<title>FreeType Glyph Conventions</title>
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</head>
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<body>
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<body text="#000000"
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bgcolor="#FFFFFF"
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@ -14,278 +15,342 @@
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vlink="#51188E"
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alink="#FF0000">
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<center>
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<h1>
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FreeType Glyph Conventions</h1></center>
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<h1 align=center>
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FreeType Glyph Conventions
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</h1>
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<h2 align=center>
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Version 2.1
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</h2>
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<h3 align=center>
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Copyright 1998-2000 David Turner (<a
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href="mailto:david@freetype.org">david@freetype.org</a>)<br>
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Copyright 2000 The FreeType Development Team (<a
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href="mailto:devel@freetype.org">devel@freetype.org</a>)
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</h3>
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<center>
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<h2>
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version 2.1</h2></center>
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<table width="65%">
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<tr><td>
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<center>
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<h3>
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Copyright 1998-2000 David Turner (<a href="mailto:david@freetype.org">david@freetype.org</a>)<br>
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Copyright 2000 The FreeType Development Team (<a href="devel@freetype.org">devel@freetype.org</a>)</h3></center>
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<center>
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<table width="100%"
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border=0
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cellpadding=5>
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<tr bgcolor="#CCFFCC"
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valign=center>
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<td align=center
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width="30%">
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<a href="glyphs-6.html">Previous</a>
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</td>
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||||
<td align=center
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width="30%">
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<a href="index.html">Contents</a>
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||||
</td>
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||||
<td align=center
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width="30%">
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|
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</td>
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</tr>
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</table>
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</center>
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<center><table width=650><tr><td>
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<p><hr></p>
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<center><table width="100%" border=0 cellpadding=5><tr bgcolor="#CCFFCC" valign=center>
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<td align=center width="30%">
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<a href="glyphs-6.html">Previous</a>
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||||
</td>
|
||||
<td align=center width="30%">
|
||||
<a href="index.html">Contents</a>
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||||
</td>
|
||||
<td align=center width="30%">
|
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|
||||
</td>
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</tr></table></center>
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<table width="100%">
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<tr bgcolor="#CCCCFF"
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valign=center><td>
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<h2>
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VII. FreeType bitmaps
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</h2>
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</td></tr>
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</table>
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<p>The purpose of this section is to present the way FreeType manages
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bitmaps and pixmaps, and how they relate to the concepts previously
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defined. The relationships between vectorial and pixel coordinates is
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explained.</p>
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<table width="100%"><tr valign=center bgcolor="#CCCCFF"><td><h2>
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VII. FreeType Bitmaps
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</h2></td></tr></table>
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<a name="section-1">
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<h3>
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1. Vectorial versus pixel coordinates
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</h3>
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<p>This sub-section explains the differences between vectorial and pixel
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coordinates. To make things clear, brackets will be used to describe
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pixel coordinates, e.g. [3,5], while parentheses will be used for
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vectorial ones, e.g. (-2,3.5).</p>
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<p>In the pixel case, as we use the <em>Y upwards</em> convention;
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the coordinate [0,0] always refers to the <em>lower left pixel</em> of a
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bitmap, while coordinate [width-1, rows-1] to its <em>upper right
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pixel</em>.</p>
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<p>In the vectorial case, point coordinates are expressed in floating
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units, like (1.25, -2.3). Such a position doesn't refer to a given
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pixel, but simply to an immaterial point in the 2D plane.</p>
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<p>The pixels themselves are indeed <em>square boxes</em> of the 2D
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plane, whose centers lie in half pixel coordinates. For example, the
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lower left pixel of a bitmap is delimited by the square (0,0)-(1,1), its
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center being at location (0.5,0.5).</p>
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<p>This introduces some differences when computing distances. For
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example, the <em>length</em> in pixels of the line [0,0]-[10,0] is 11.
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However, the vectorial distance between (0,0)-(10,0) covers exactly
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10 pixel centers, hence its length is 10.</p>
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<center>
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<img src="grid_1.png"
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height=390 width=402
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alt="bitmap and vector grid">
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</center>
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<p>The purpose of this section is to present the way FreeType
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manages bitmaps and pixmaps, and how they relate to the concepts previously
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defined. The relationships between vectorial and pixel coordinates is
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explained.
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</p>
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<a name="section-2">
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<h3>
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2. FreeType bitmap and pixmap descriptor
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</h3>
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<h3><a name="section-1">
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1. Vectorial versus pixel coordinates :
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</h3><blockquote>
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<p>A bitmap or pixmap is described through a single structure, called
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<tt>FT_Bitmap</tt>, defined in the file
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<tt><freetype/ftimage.h></tt>. It is a simple descriptor whose
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fields are:</p>
|
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|
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<p>This sub-section explains the differences between vectorial
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and pixel coordinates. To make things clear, brackets will be used to describe
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pixel coordinates, e.g. [3,5], while parentheses will be used for vectorial
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ones, e.g. (-2,3.5).
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<p>In the pixel case, as we use the <i>Y upwards</i> convention, the coordinate
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[0,0] always refers to the <i>lower left pixel</i> of a bitmap, while coordinate
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[width-1, rows-1] to its <i>upper right pixel</i>.
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<p>In the vectorial case, point coordinates are expressed in floating units,
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like (1.25, -2.3). Such a position doesn't refer to a given pixel, but
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simply to an immaterial point in the 2D plane
|
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<p>The pixels themselves are indeed <i>square boxes</i> of the 2D plane,
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which centers lie in half pixel coordinates. For example, the <i>lower
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left pixel</i> of a bitmap is delimited by the <i>square</i> (0,0)-(1,1),
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its center being at location (0.5,0.5).
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<p>This introduces some differences when computing distances. For example,
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the "<i>length</i>" in pixels of the line [0,0]-[10,0] is 11. However,
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the vectorial distance between (0,0)-(10,0) covers exactly 10 pixel centers,
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hence its length if 10.
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<center><img SRC="grid_1.png" height=390 width=402></center>
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<center>
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<table cellspacing=3
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cellpadding=5
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width="80%">
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<caption>
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<b><tt>FT_Bitmap</tt></b>
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</caption>
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<tr>
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<td valign=top>
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<tt>rows</tt>
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</td>
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<td valign=top>
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the number of rows, i.e. lines, in the bitmap
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</td>
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</tr>
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<tr>
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<td valign=top>
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<tt>width</tt>
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</td>
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<td valign=top>
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the number of horizontal pixels in the bitmap
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</td>
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</tr>
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<tr>
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<td valign=top>
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<tt>pitch</tt>
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</td>
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<td valign=top>
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its absolute value is the number of bytes per bitmap line; it can
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be either positive or negative depending on the bitmap's vertical
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orientation
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</td>
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</tr>
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<tr>
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<td valign=top>
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<tt>buffer</tt>
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</td>
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<td valign=top>
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a typeless pointer to the bitmap pixel bufer
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</td>
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</tr>
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<tr>
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<td valign=top>
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<tt>pixel_mode</tt>
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</td>
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<td valign=top>
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an enumeration used to describe the pixel format of the bitmap;
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examples are <tt>ft_pixel_mode_mono</tt> for 1-bit monochrome
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bitmaps and <tt>ft_pixel_mode_grays</tt> for 8-bit anti-aliased
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"gray" values
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</td>
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</tr>
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<tr>
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<td valign=top>
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<tt>num_grays</tt>
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</td>
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<td valign=top>
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this is only used for "gray" pixel modes, it gives the number of
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gray levels used to describe the anti-aliased gray levels --
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256 by default with FreeType 2
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</td>
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</tr>
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</table>
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</center>
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||||
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</blockquote><h3><a name="section-2">
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2. FreeType bitmap and pixmap descriptor :
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</h3><blockquote>
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<p>Note that the sign of the <tt>pitch</tt> fields determines whether
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the rows in the pixel buffer are stored in ascending or descending
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order.</p>
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|
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<p>A bitmap or pixmap is described through a single structure,
|
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called <tt>FT_Bitmap</tt>, defined in the file
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||||
<tt><freetype/ftimage.h></tt>. It is a simple descriptor whose fields are:</p>
|
||||
<p>Remember that FreeType uses the <em>Y upwards</em> convention in
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the 2D plane, which means that a coordinate of (0,0) always refer to the
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||||
<em>lower-left corner</em> of a bitmap.</p>
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<center><table CELLSPACING=3 CELLPADDING=5 BGCOLOR="#CCCCCC" width="80%" >
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||||
<caption><tt>FT_Bitmap</tt></caption>
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<p>If the pitch is positive, the rows are stored in decreasing vertical
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position; the first bytes of the pixel buffer are part of the
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<em>upper</em> bitmap row.</p>
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<tr>
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<td><b>rows</b></td>
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<p>On the opposite, if the pitch is negative, the first bytes of the
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pixel buffer are part of the <em>lower</em> bitmap row.</p>
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<td>the number of rows, i.e. lines, in the bitmap</td>
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</tr>
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<p>In all cases, one can see the pitch as the byte increment needed to
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skip to the <em>next lower scanline</em> in a given bitmap buffer.</p>
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<tr>
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<td><b>width</b></td>
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<center>
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<table>
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<tr>
|
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<td>
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<img src="up_flow.png"
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height=261 width=275
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alt="negative 'pitch'">
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</td>
|
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<td>
|
||||
<img src="down_flow.png"
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||||
height=263 width=273
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alt="positive 'pitch'">
|
||||
</td>
|
||||
</tr>
|
||||
</table>
|
||||
</center>
|
||||
|
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<td>the number of horizontal pixels in the bitmap</td>
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</tr>
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<tr>
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<td><b>pitch</b></td>
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|
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<td>its absolute value is the number of bytes per bitmap line.
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it can be either positive or negative depending on the bitmap's
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vertical orientation</td>
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</tr>
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||||
|
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<tr>
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<td><b>buffer</b></td>
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<td>a typeless pointer to the bitmap pixel bufer</td>
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</tr>
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|
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<tr>
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<td><b>pixel_mode</b></td>
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<td>an enumeration used to describe the pixel format of the bitmap.
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Examples are: <tt>ft_pixel_mode_mono</tt> for 1-bit monochrome bitmaps
|
||||
and <tt>ft_pixel_mode_grays</tt> for 8-bit anti-aliased "gray" values
|
||||
</td>
|
||||
|
||||
<tr>
|
||||
<td><b>num_grays</b></td>
|
||||
|
||||
<td>this is only used for "gray" pixel modes, it gives the
|
||||
number of gray levels used to describe the anti-aliased gray levels.
|
||||
256 by default with FreeType 2.
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table></center>
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||||
<p>The "positive pitch" convention is very often used, though
|
||||
some systems might need the other.</p>
|
||||
|
||||
|
||||
<p>Note that the sign of the <b><tt>pitch</tt></b> fields determines wether
|
||||
the rows in the pixel buffer are stored in ascending or descending order.
|
||||
</p>
|
||||
<a name="section-3">
|
||||
<h3>
|
||||
3. Converting outlines into bitmaps and pixmaps
|
||||
</h3>
|
||||
|
||||
<p>Remember that FreeType uses the <i>Y upwards</i> convention in the 2D
|
||||
plane. Which means that a coordinate of (0,0) always refer to the
|
||||
<i>lower-left corner</i> of a bitmap.
|
||||
</p>
|
||||
<p>Generating a bitmap or pixmap image from a vectorial image is easy
|
||||
with FreeType. However, one must understand a few points regarding the
|
||||
positioning of the outline in the 2D plane before converting it to a
|
||||
bitmap:</p>
|
||||
|
||||
<p>When the pitch is positive, the rows are stored in decreasing vertical
|
||||
position, which means that the first bytes of the pixel buffer are part
|
||||
of the <i>upper</i> bitmap row.
|
||||
</p>
|
||||
<ul>
|
||||
<li>
|
||||
<p>The glyph loader and hinter always places the outline in the 2D
|
||||
plane so that (0,0) matches its character origin. This means that
|
||||
the glyph's outline, and corresponding bounding box, can be placed
|
||||
anywhere in the 2D plane (see the graphics in section III).</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>The target bitmap's area is mapped to the 2D plane, with its
|
||||
lower left corner at (0,0). This means that a bitmap or pixmap of
|
||||
dimensions [<tt>w,h</tt>] will be mapped to a 2D rectangle window
|
||||
delimited by (0,0)-(<tt>w,h</tt>).</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>When scan-converting the outline, everything that falls within
|
||||
the bitmap window is rendered, the rest is ignored.</p>
|
||||
</li>
|
||||
|
||||
<p>On the opposite, when the pitch is negative, the first bytes of the
|
||||
pixel buffer are part of the <i>lower</i> bitmap row.</p>
|
||||
<p>A common mistake made by many developers when they begin using
|
||||
FreeType is believing that a loaded outline can be directly rendered
|
||||
in a bitmap of adequate dimensions. The following images illustrate
|
||||
why this is a problem.</p>
|
||||
|
||||
<p>In all cases, one can see the pitch as the byte increment needed
|
||||
to skip to the <em>next lower scanline</em> in a given bitmap buffer.</p>
|
||||
<ul>
|
||||
<li>
|
||||
The first image shows a loaded outline in the 2D plane.
|
||||
</li>
|
||||
<li>
|
||||
The second one shows the target window for a bitmap of arbitrary
|
||||
dimensions [w,h].
|
||||
</li>
|
||||
<li>
|
||||
The third one shows the juxtaposition of the outline and window in
|
||||
the 2D plane.
|
||||
</li>
|
||||
<li>
|
||||
The last image shows what will really be rendered in the bitmap.
|
||||
</li>
|
||||
</ul>
|
||||
|
||||
<p>The two conventions are detailed by this graphics:</p>
|
||||
<center>
|
||||
<img src="clipping.png"
|
||||
height=151 width=539
|
||||
alt="clipping algorithm">
|
||||
</center>
|
||||
</ul>
|
||||
|
||||
<center><table>
|
||||
<tr>
|
||||
<td><img SRC="up_flow.png" height=261 width=275></td>
|
||||
<p>Indeed, in nearly all cases, the loaded or transformed outline must
|
||||
be translated before it is rendered into a target bitmap, in order to
|
||||
adjust its position relative to the target window.</p>
|
||||
|
||||
<td><img SRC="down_flow.png" height=263 width=273></td>
|
||||
</tr>
|
||||
</table></center>
|
||||
<p>For example, the correct way of creating a <em>standalone</em> glyph
|
||||
bitmap is as follows</p>
|
||||
|
||||
<p>The <em>positive pitch</em> convention is very often used, though
|
||||
some systems might need otherwise.</p>
|
||||
<ul>
|
||||
<li>
|
||||
<p>Compute the size of the glyph bitmap. It can be computed
|
||||
directly from the glyph metrics, or by computing its bounding box
|
||||
(this is useful when a transformation has been applied to the
|
||||
outline after the load, as the glyph metrics are not valid
|
||||
anymore).</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Create the bitmap with the computed dimensions. Don't forget to
|
||||
fill the pixel buffer with the background color.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Translate the outline so that its lower left corner matches
|
||||
(0,0). Don't forget that in order to preserve hinting, one should
|
||||
use integer, i.e. rounded distances (of course, this isn't required
|
||||
if preserving hinting information doesn't matter, like with rotated
|
||||
text). Usually, this means translating with a vector
|
||||
<tt>(-ROUND(xMin), -ROUND(yMin))</tt>.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Call the rendering function (it can be
|
||||
<tt>FT_Outline_Render()</tt> for example).</p>
|
||||
</li>
|
||||
</ul>
|
||||
|
||||
<p>In the case where one wants to write glyph images directly into a
|
||||
large bitmap, the outlines must be translated so that their vectorial
|
||||
position correspond to the current text cursor/character origin.</p>
|
||||
|
||||
</blockquote><h3><a name="section-3">
|
||||
3. Converting outlines into bitmaps and pixmaps :
|
||||
</h3><blockquote>
|
||||
<p><hr></p>
|
||||
|
||||
<p>Generating a bitmap or pixmap image from a vectorial image
|
||||
is easy with FreeType. However, one must understand a few points regarding
|
||||
the positioning of the outline in the 2D plane before converting it to
|
||||
a bitmap. These are :</p>
|
||||
<center>
|
||||
<table width="100%"
|
||||
border=0
|
||||
cellpadding=5>
|
||||
<tr bgcolor="#CCFFCC"
|
||||
valign=center>
|
||||
<td align=center
|
||||
width="30%">
|
||||
<a href="glyphs-6.html">Previous</a>
|
||||
</td>
|
||||
<td align=center
|
||||
width="30%">
|
||||
<a href="index.html">Contents</a>
|
||||
</td>
|
||||
<td align=center
|
||||
width="30%">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
</table>
|
||||
</center>
|
||||
|
||||
<ul>
|
||||
|
||||
<li><p>
|
||||
The glyph loader and hinter always places the outline in the 2D plane so
|
||||
that (0,0) matches its character origin. This means that the glyph’s outline,
|
||||
and corresponding bounding box, can be placed anywhere in the 2D plane
|
||||
(see the graphics in section III).
|
||||
</p></li>
|
||||
|
||||
<li><p>
|
||||
The target bitmap’s area is mapped to the 2D plane, with its lower left
|
||||
corner at (0,0). This means that a bitmap or pixmap of dimensions
|
||||
[<tt>w,h</tt>] will be mapped to a 2D rectangle window delimited by
|
||||
(0,0)-(<tt>w,h</tt>).
|
||||
</p></li>
|
||||
|
||||
<li><p>
|
||||
When scan-converting the outline, everything that falls
|
||||
within the bitmap window is rendered, the rest is ignored.
|
||||
</p></li>
|
||||
|
||||
<p>A common mistake made by many developers when they begin using FreeType
|
||||
is believing that a loaded outline can be directly rendered in a bitmap
|
||||
of adequate dimensions. The following images illustrate why this is a problem:
|
||||
</p>
|
||||
|
||||
<p>
|
||||
<ul>
|
||||
|
||||
<li>
|
||||
the first image shows a loaded outline in the 2D plane.
|
||||
</li>
|
||||
|
||||
<li>
|
||||
the second one shows the target window for a bitmap of arbitrary dimensions
|
||||
[w,h]
|
||||
</li>
|
||||
|
||||
<li>
|
||||
the third one shows the juxtaposition of the outline and window in the
|
||||
2D plane
|
||||
</li>
|
||||
|
||||
<li>
|
||||
the last image shows what will really be rendered in the bitmap.
|
||||
</li>
|
||||
</ul>
|
||||
</p>
|
||||
|
||||
</ul>
|
||||
<center><img SRC="clipping.png" height=151 width=539></center>
|
||||
|
||||
<p><br>
|
||||
<br>
|
||||
<br>
|
||||
<p>Indeed, in nearly all cases, the loaded or transformed outline must
|
||||
be translated before it is rendered into a target bitmap, in order to adjust
|
||||
its position relative to the target window.
|
||||
</p>
|
||||
|
||||
<p>For example, the correct way of creating a <i>standalone</i> glyph bitmap
|
||||
is thus to :
|
||||
</p>
|
||||
|
||||
<ul>
|
||||
<li><p>
|
||||
Compute the size of the glyph bitmap. It can be computed directly from
|
||||
the glyph metrics, or by computing its bounding box (this is useful when
|
||||
a transform has been applied to the outline after the load, as the glyph
|
||||
metrics are not valid anymore).
|
||||
</p></li>
|
||||
|
||||
<li><p>
|
||||
Create the bitmap with the computed dimensions. Don't forget to fill the
|
||||
pixel buffer with the background color.
|
||||
</p></li>
|
||||
|
||||
<li><p>
|
||||
Translate the outline so that its lower left corner matches (0,0). Don’t
|
||||
forget that in order to preserve hinting, one should use integer, i.e.
|
||||
rounded distances (of course, this isn’t required if preserving hinting
|
||||
information doesn’t matter, like with rotated text). Usually, this means
|
||||
translating with a vector <tt>( -ROUND(xMin), -ROUND(yMin) )</tt>.
|
||||
</p></li>
|
||||
|
||||
<li><p>
|
||||
Call the rendering function (it can be <tt>FT_Outline_Render</tt> for
|
||||
example).
|
||||
</p></li>
|
||||
|
||||
<p><br>In the case where one wants to write glyph images directly into
|
||||
a large bitmap, the outlines must be translated so that their vectorial
|
||||
position correspond to the current text cursor/character origin.</blockquote>
|
||||
</blockquote>
|
||||
|
||||
<center><table width="100%" border=0 cellpadding=5><tr bgcolor="#CCFFCC" valign=center>
|
||||
<td align=center width="30%">
|
||||
<a href="glyphs-6.html">Previous</a>
|
||||
</td>
|
||||
<td align=center width="30%">
|
||||
<a href="index.html">Contents</a>
|
||||
</td>
|
||||
<td align=center width="30%">
|
||||
|
||||
</td>
|
||||
</tr></table></center>
|
||||
|
||||
</td></tr></table></center>
|
||||
</td></tr>
|
||||
</table>
|
||||
</center>
|
||||
|
||||
</body>
|
||||
</html>
|
||||
|
|
|
|||
|
|
@ -1,12 +1,13 @@
|
|||
<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
|
||||
<!doctype html public "-//w3c//dtd html 4.0 transitional//en"
|
||||
"http://www.w3.org/TR/REC-html40/loose.dtd">
|
||||
<html>
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
|
||||
<meta name="Author" content="blob">
|
||||
<meta name="GENERATOR" content="Mozilla/4.5 [fr] (Win98; I) [Netscape]">
|
||||
<title>FreeType Glyph Conventions</title>
|
||||
<meta http-equiv="Content-Type"
|
||||
content="text/html; charset=iso-8859-1">
|
||||
<meta name="Author"
|
||||
content="David Turner">
|
||||
<title>FreeType Glyph Conventions</title>
|
||||
</head>
|
||||
<body>
|
||||
|
||||
<body text="#000000"
|
||||
bgcolor="#FFFFFF"
|
||||
|
|
@ -14,218 +15,186 @@
|
|||
vlink="#51188E"
|
||||
alink="#FF0000">
|
||||
|
||||
<center>
|
||||
<h1>
|
||||
FreeType Glyph Conventions</h1></center>
|
||||
<h1 align=center>
|
||||
FreeType Glyph Conventions
|
||||
</h1>
|
||||
|
||||
<h2 align=center>
|
||||
Version 2.1
|
||||
</h2>
|
||||
|
||||
<h3 align=center>
|
||||
Copyright 1998-2000 David Turner (<a
|
||||
href="mailto:david@freetype.org">david@freetype.org</a>)<br>
|
||||
Copyright 2000 The FreeType Development Team (<a
|
||||
href="mailto:devel@freetype.org">devel@freetype.org</a>)
|
||||
</h3>
|
||||
|
||||
|
||||
<center>
|
||||
<h2>
|
||||
version 2.1</h2></center>
|
||||
<table width="70%">
|
||||
<tr><td>
|
||||
|
||||
<center>
|
||||
<h3>
|
||||
Copyright 1998-2000 David Turner (<a href="mailto:david@freetype.org">david@freetype.org</a>)<br>
|
||||
Copyright 2000 The FreeType Development Team (<a href="devel@freetype.org">devel@freetype.org</a>)</h3></center>
|
||||
<p>This document presents the core conventions used within the FreeType
|
||||
library to manage font and glyph data. It is a <em>must-read</em> for all
|
||||
developers who need to understand digital typography, especially if you
|
||||
want to use the FreeType 2 library in your projects.</p>
|
||||
|
||||
<center><table width=650><tr><td>
|
||||
<table width="100%">
|
||||
<tr valign=center
|
||||
bgcolor="#CCCCFF">
|
||||
<td align=center>
|
||||
<h2>
|
||||
Table of Contents
|
||||
</h2>
|
||||
</td>
|
||||
</tr>
|
||||
</table>
|
||||
|
||||
<center>
|
||||
<table width="80%">
|
||||
<tr><td>
|
||||
|
||||
<table width="100%"><tr valign=center bgcolor="#CCCCFF"><td align=center><h2>
|
||||
Introduction
|
||||
</h2></td></tr></table>
|
||||
|
||||
<p>This document presents the core conventions used within the FreeType
|
||||
library to manage font and glyph data. It is a <em>must-read</em> for
|
||||
any people that needs to understand digital typography, especially
|
||||
if you want to use the FreeType 2 library in your projects.</p>
|
||||
|
||||
<table width="100%"><tr valign=center bgcolor="#CCCCFF"><td align=center><h2>
|
||||
Table of Contents
|
||||
</h2></td></tr></table>
|
||||
|
||||
<center><table width="80%"><tr><td>
|
||||
|
||||
|
||||
<a href="glyphs-1.html">
|
||||
<h2>I. Basic Typographic Concepts:</h2>
|
||||
</a>
|
||||
<ul>
|
||||
<h2>
|
||||
<a href="glyphs-1.html">I. Basic Typographic Concepts</a>
|
||||
</h2>
|
||||
<blockquote>
|
||||
<h3>
|
||||
<a href="glyphs-1.html#section-1">
|
||||
1. Font files, format and information
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-1.html#section-1">1. Font files, format and
|
||||
information</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-1.html#section-2">
|
||||
2. Character images and mappings
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-1.html#section-2">2. Character images and mappings</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-1.html#section-3">
|
||||
3. Character and font metrics
|
||||
</a>
|
||||
<br>
|
||||
</ul>
|
||||
<a href="glyphs-1.html#section-3">3. Character and font metrics</a>
|
||||
<br>
|
||||
</h3>
|
||||
</blockquote>
|
||||
|
||||
|
||||
|
||||
<a href="glyphs-2.html">
|
||||
<h2>II. Glyph Outlines:</h2>
|
||||
</a>
|
||||
<ul>
|
||||
<h2>
|
||||
<a href="glyphs-2.html">II. Glyph outlines</a>
|
||||
</h2>
|
||||
<blockquote>
|
||||
<h3>
|
||||
<a href="glyphs-2.html#section-1">
|
||||
1. Pixels, Points and Device Resolutions
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-2.html#section-1">1. Pixels, points and device
|
||||
resolutions</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-2.html#section-2">
|
||||
2. Vectorial representation
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-2.html#section-2">2. Vectorial representation</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-2.html#section-3">
|
||||
3. Hinting and bitmap rendering
|
||||
</a>
|
||||
<br>
|
||||
</ul>
|
||||
<a href="glyphs-2.html#section-3">3. Hinting and bitmap rendering</a>
|
||||
<br>
|
||||
</h3>
|
||||
</blockquote>
|
||||
|
||||
|
||||
|
||||
<a href="glyphs-3.html">
|
||||
<h2>III. Glyph Metrics:</h2>
|
||||
</a>
|
||||
<ul>
|
||||
<h2>
|
||||
<a href="glyphs-3.html">III. Glyph metrics</a>
|
||||
</h2>
|
||||
<blockquote>
|
||||
<h3>
|
||||
<a href="glyphs-3.html#section-1">
|
||||
1. Baseline, Pens and Layouts
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-3.html#section-1">1. Baseline, pens and layouts</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-3.html#section-2">
|
||||
2. Typographic metrics
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-3.html#section-2">2. Typographic metrics and
|
||||
bounding boxes</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-3.html#section-3">
|
||||
3. Bearings and Advances
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-3.html#section-3">3. Bearings and advances</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-3.html#section-4">
|
||||
4. The effects of grid-fitting
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-3.html#section-4">4. The effects of grid-fitting</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-3.html#section-5">
|
||||
5. Text widths and bounding box
|
||||
</a>
|
||||
<br>
|
||||
</ul>
|
||||
<a href="glyphs-3.html#section-5">5. Text widths and bounding box</a>
|
||||
<br>
|
||||
</h3>
|
||||
</blockquote>
|
||||
|
||||
|
||||
<a href="glyphs-4.html">
|
||||
<h2>IV. Kerning:</h2>
|
||||
</a>
|
||||
<ul>
|
||||
<h2>
|
||||
<a href="glyphs-4.html">IV. Kerning</a>
|
||||
</h2>
|
||||
<blockquote>
|
||||
<h3>
|
||||
<a href="glyphs-4.html#section-1">
|
||||
1. Kerning pairs
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-4.html#section-1">1. Kerning pairs</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-4.html#section-2">
|
||||
2. Applying kerning
|
||||
</a>
|
||||
<br>
|
||||
</ul>
|
||||
<a href="glyphs-4.html#section-2">2. Applying kerning</a>
|
||||
<br>
|
||||
</h3>
|
||||
</blockquote>
|
||||
|
||||
|
||||
<a href="glyphs-5.html">
|
||||
<h2>V. Text Processing:</h2>
|
||||
</a>
|
||||
<ul>
|
||||
<h2>
|
||||
<a href="glyphs-5.html">V. Text processing</a>
|
||||
</h2>
|
||||
<blockquote>
|
||||
<h3>
|
||||
<a href="glyphs-5.html#section-1">
|
||||
1. Writing simple text strings
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-5.html#section-1">1. Writing simple text strings</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-5.html#section-2">
|
||||
2. Sub-pixel positioning
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-5.html#section-2">2. Sub-pixel positioning</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-5.html#section-3">
|
||||
3. Simple kerning
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-5.html#section-3">3. Simple kerning</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-5.html#section-4">
|
||||
4. Right-to-left layouts
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-5.html#section-4">4. Right-to-left layouts</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-5.html#section-5">
|
||||
5. Vertical layouts
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-5.html#section-5">5. Vertical layouts</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-5.html#section-6">
|
||||
6. WYSIWYG text layouts
|
||||
</a>
|
||||
<br>
|
||||
</ul>
|
||||
<a href="glyphs-5.html#section-6">6. WYSIWYG text layouts</a>
|
||||
<br>
|
||||
</h3>
|
||||
</blockquote>
|
||||
|
||||
|
||||
<a href="glyphs-6.html">
|
||||
<h2>VI. FreeType Outlins:</h2>
|
||||
</a>
|
||||
<ul>
|
||||
<h2>
|
||||
<a href="glyphs-6.html">VI. FreeType Outlines</a>
|
||||
</h2>
|
||||
<blockquote>
|
||||
<h3>
|
||||
<a href="glyphs-6.html#section-1">
|
||||
1. FreeType outline description and structure
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-6.html#section-1">1. FreeType outline description
|
||||
and structure</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-6.html#section-2">
|
||||
2. Bounding and control box computations
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-6.html#section-2">2. Bounding and control box
|
||||
computations</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-6.html#section-3">
|
||||
3. Coordinates, scaling and grid-fitting
|
||||
</a>
|
||||
<br>
|
||||
</ul>
|
||||
<a href="glyphs-6.html#section-3">3. Coordinates, scaling, and
|
||||
grid-fitting</a>
|
||||
<br>
|
||||
</h3>
|
||||
</blockquote>
|
||||
|
||||
|
||||
<a href="glyphs-7.html">
|
||||
<h2>VII. FreeType Bitmaps:</h2>
|
||||
</a>
|
||||
<ul>
|
||||
<h2>
|
||||
<a href="glyphs-7.html">VII. FreeType bitmaps</a>
|
||||
</h2>
|
||||
<blockquote>
|
||||
<h3>
|
||||
<a href="glyphs-7.html#section-1">
|
||||
1. Vectorial versus pixel coordinates
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-7.html#section-1">1. Vectorial versus pixel
|
||||
coordinates</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-7.html#section-2">
|
||||
2. FreeType bitmap descriptor
|
||||
</a>
|
||||
<br>
|
||||
<a href="glyphs-7.html#section-2">2. FreeType bitmap and pixmap
|
||||
descriptor</a>
|
||||
<br>
|
||||
|
||||
<a href="glyphs-7.html#section-3">
|
||||
3. Converting outlines into bitmaps
|
||||
</a>
|
||||
<br>
|
||||
</ul>
|
||||
<a href="glyphs-7.html#section-3">3. Converting outlines into
|
||||
bitmaps and pixmaps</a>
|
||||
<br>
|
||||
</h3>
|
||||
</blockquote>
|
||||
|
||||
</p>
|
||||
</td></tr>
|
||||
</table>
|
||||
</center>
|
||||
|
||||
</td></tr></table></center>
|
||||
|
||||
</td></tr></table></center>
|
||||
</td></tr>
|
||||
</table>
|
||||
</center>
|
||||
|
||||
</body>
|
||||
</html>
|
||||
|
|
|
|||
Loading…
Reference in New Issue