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Added information from Yegor on font storage

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git-svn-id: https://svn.apache.org/repos/asf/jakarta/poi/trunk@353786 13f79535-47bb-0310-9956-ffa450edef68
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Nick Burch 2005-09-17 15:40:15 +00:00
parent c508058158
commit a5d4a16967
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src/documentation/content/xdocs/hslf/ppt-file-format.xml
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@ -308,5 +308,43 @@ FF33 00FE 4261426175 Red
1800 24 Font Size = 24
</source>
</section>
<section><title>Fonts in PowerPoint</title>
<p>
PowerPoint stores information about the fonts used in FontEntityAtoms,
which live inside Document.Environment.FontCollection. For every different
font used, a FontEntityAtom must exist for that font. There is always at
least one FontEntityAtom in Document.Environment.FontCollection,
which describes the default font.
</p>
</section>
<section><title>FontEntityAtom</title>
<p>
The instance field of the record header contains the zero based index of the
font. Font index entries in StyleTextPropAtoms will refer to their required
font via this index.
</p>
<p>
The length of FontEntityAtoms is always 68 bytes. The first 64 bytes of
it hold the typeface name of the font to be used. This is stored as
a null-terminated string, and encoded as little endian unicode. (The
length of the string must not exceed 32 characters including the null
termination, so the typeface name cannot exceed 31 characters).
</p>
<p>
After the typeface name there are 4 bytes of bitmask flags. The details of these
can be found in the Windows API, under the LOGFONT structure.
The 65th byte is the output precision, which defines how closely the system chosen
font must match the requested font, in terms of heigh, width, pitch etc.
The 66th byte is the clipping precision, which defines how to clip characters
that occur partly outside the clipping region.
The 67th byte is the output quality, which defines how closely the system
must match the logical font's attributes to those of the physical font used.
The 68th (and final) byte is the pitch and family, which is used by the
system when matching fonts.
</p>
</section>
</body>
</document>