📄 loca.htm

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<TITLE>The 'loca' Table</TITLE>
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<TD><H1>Table Formats</H1></TD>
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<H2>loca - Index to Location
</H2>
<P>
The indexToLoc table stores the offsets to
the locations of the glyphs in the font, relative to the beginning
of the glyphData table. In order to compute the length of the
last glyph element, there is an extra entry after the last valid
index.
<P>
By definition, index zero points to the &quot;missing character,&quot;
which is the character that appears if a character is not found
in the font. The missing character is commonly represented by
a blank box (such as <IMG  WIDTH=9 HEIGHT=13 ALT="DIAGRAM" SRC="/TRUETYPE/OTSPEC/IMG00286.GIF">) or a space. If
the font does not contain an outline for the missing character,
then the first and second offsets should have the same value.
This also applies to any other character without an outline, such
as the space character.
<P>
Most routines will look at the 'maxp' table to determine the number
of glyphs in the font, but the value in the 'loca' table should
agree.
<P>
There are two versions of this table, the short and the long.
The version is specified in the indexToLocFormat entry in the
'head' table.Short version
<P><BR><H4>Short version</H4>

<TABLE WIDTH=480 BGCOLOR="#F0F0F0">
<THEAD>
<TR><TH BGCOLOR="#C0C0C0">TypeM</TH>
<TH BGCOLOR="#C0C0C0">Name</TH><TH BGCOLOR="#C0C0C0">Description</TH></TR></THEAD>
<TBODY>
<TR><TD VALIGN=TOP>USHORT</TD><TD VALIGN=TOP>offsets[<CITE>n</CITE>]</TD>
<TD VALIGN=TOP>The actual local offset divided by 2 is stored. The value of <CITE>n</CITE>  is numGlyphs + 1. The value for numGlyphs is found in the 'maxp' table.</TD></TR>
</TABLE>&nbsp;&nbsp;<P>
<P><BR><H4>Long version</H4>

<TABLE WIDTH=480 BGCOLOR="#F0F0F0">
<THEAD>
<TR><TH BGCOLOR="#C0C0C0">Type</TH>
<TH BGCOLOR="#C0C0C0">Name</TH><TH BGCOLOR="#C0C0C0">Description</TH></TR></THEAD>
<TBODY>
<TR><TD VALIGN=TOP>ULONG</TD><TD VALIGN=TOP>offsets[<CITE>n</CITE>]</TD>
<TD VALIGN=TOP>The actual local offset is stored. The value of <CITE>n</CITE>  is numGlyphs + 1. The value for numGlyphs is found in the 'maxp' table.</TD></TR>
</TABLE>&nbsp;&nbsp;<P>
<P>

<P>
Note that the local offsets should be long-aligned, i.e., multiples
of 4. Offsets which are not long-aligned may seriously degrade
performance of some processors.

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Microsoft Typography Web Site <A HREF="/truetype/otspec/CPYRIGHT.htm">&copy; 1996 Microsoft Corporation</A>
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Comments to the Microsoft Typography group: <A HREF="mailto:ttwsite@microsoft.com">ttwsite@microsoft.com</A>
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<A HREF="/truetype/default.htm">Home</a> | <a href="/truetype/creators.htm">Information for Developers</a>
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Last updated 05 September 1996
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