0,0 → 1,148 |
FreeType font driver for BDF fonts |
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Francesco Zappa Nardelli |
<francesco.zappa.nardelli@ens.fr> |
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Introduction |
************ |
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BDF (Bitmap Distribution Format) is a bitmap font format defined by Adobe, |
which is intended to be easily understood by both humans and computers. |
This code implements a BDF driver for the FreeType library, following the |
Adobe Specification V 2.2. The specification of the BDF font format is |
available from Adobe's web site: |
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http://partners.adobe.com/public/developer/en/font/5005.BDF_Spec.pdf |
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Many good bitmap fonts in bdf format come with XFree86 (www.XFree86.org). |
They do not define vertical metrics, because the X Consortium BDF |
specification has removed them. |
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Encodings |
********* |
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The variety of encodings that accompanies bdf fonts appears to encompass the |
small set defined in freetype.h. On the other hand, two properties that |
specify encoding and registry are usually defined in bdf fonts. |
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I decided to make these two properties directly accessible, leaving to the |
client application the work of interpreting them. For instance: |
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#include FT_INTERNAL_BDF_TYPES_H |
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FT_Face face; |
BDF_Public_Face bdfface; |
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FT_New_Face( library, ..., &face ); |
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bdfface = (BDF_Public_Face)face; |
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if ( ( bdfface->charset_registry == "ISO10646" ) && |
( bdfface->charset_encoding == "1" ) ) |
[..] |
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Thus the driver always exports `ft_encoding_none' as face->charmap.encoding. |
FT_Get_Char_Index's behavior is unmodified, that is, it converts the ULong |
value given as argument into the corresponding glyph number. |
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If the two properties are not available, Adobe Standard Encoding should be |
assumed. |
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Anti-Aliased Bitmaps |
******************** |
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The driver supports an extension to the BDF format as used in Mark Leisher's |
xmbdfed bitmap font editor. Microsoft's SBIT tool expects bitmap fonts in |
that format for adding anti-aliased them to TrueType fonts. It introduces a |
fourth field to the `SIZE' keyword which gives the bpp value (bits per |
pixel) of the glyph data in the font. Possible values are 1 (the default), |
2 (four gray levels), 4 (16 gray levels), and 8 (256 gray levels). The |
driver returns either a bitmap with 1 bit per pixel or a pixmap with 8bits |
per pixel (using 4, 16, and 256 gray levels, respectively). |
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Known problems |
************** |
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- A font is entirely loaded into memory. Obviously, this is not the Right |
Thing(TM). If you have big fonts I suggest you convert them into PCF |
format (using the bdftopcf utility): the PCF font drive of FreeType can |
perform incremental glyph loading. |
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When I have some time, I will implement on-demand glyph parsing. |
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- Except for encodings properties, client applications have no visibility of |
the PCF_Face object. This means that applications cannot directly access |
font tables and must trust FreeType. |
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- Currently, glyph names are ignored. |
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I plan to give full visibility of the BDF_Face object in an upcoming |
revision of the driver, thus implementing also glyph names. |
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- As I have never seen a BDF font that defines vertical metrics, vertical |
metrics are (parsed and) discarded. If you own a BDF font that defines |
vertical metrics, please let me know (I will implement them in 5-10 |
minutes). |
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License |
******* |
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Copyright (C) 2001-2002 by Francesco Zappa Nardelli |
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Permission is hereby granted, free of charge, to any person obtaining |
a copy of this software and associated documentation files (the |
"Software"), to deal in the Software without restriction, including |
without limitation the rights to use, copy, modify, merge, publish, |
distribute, sublicense, and/or sell copies of the Software, and to |
permit persons to whom the Software is furnished to do so, subject to |
the following conditions: |
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The above copyright notice and this permission notice shall be |
included in all copies or substantial portions of the Software. |
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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*** Portions of the driver (that is, bdflib.c and bdf.h): |
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Copyright 2000 Computing Research Labs, New Mexico State University |
Copyright 2001-2002, 2011 Francesco Zappa Nardelli |
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Permission is hereby granted, free of charge, to any person obtaining a |
copy of this software and associated documentation files (the "Software"), |
to deal in the Software without restriction, including without limitation |
the rights to use, copy, modify, merge, publish, distribute, sublicense, |
and/or sell copies of the Software, and to permit persons to whom the |
Software is furnished to do so, subject to the following conditions: |
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The above copyright notice and this permission notice shall be included in |
all copies or substantial portions of the Software. |
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
THE COMPUTING RESEARCH LAB OR NEW MEXICO STATE UNIVERSITY BE LIABLE FOR ANY |
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT |
OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR |
THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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Credits |
******* |
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This driver is based on excellent Mark Leisher's bdf library. If you |
find something good in this driver you should probably thank him, not |
me. |