source: trunk/poppler/freetype2/src/pcf/README @ 159

Last change on this file since 159 was 150, checked in by Eugene Romanenko, 15 years ago

update freetype to 2.2.1

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1                  FreeType font driver for PCF fonts
2
3                       Francesco Zappa Nardelli
4                  <francesco.zappa.nardelli@ens.fr>
5
6
7Introduction
8************
9
10PCF (Portable Compiled Format) is a binary bitmap font format, largely used
11in X world. This code implements a PCF driver for the FreeType library.
12Glyph images are loaded into memory only on demand, thus leading to a small
13memory footprint.
14
15Informations on the PCF font format can only be worked out from
16``pcfread.c'', and ``pcfwrite.c'', to be found, for instance, in the XFree86
17(www.xfree86.org) source tree (xc/lib/font/bitmap/).
18
19Many good bitmap fonts in bdf format come with XFree86: they can be
20compiled into the pcf format using the ``bdftopcf'' utility.
21
22
23Supported hardware
24******************
25
26The driver has been tested on linux/x86 and sunos5.5/sparc.  In both
27cases the compiler was gcc.  When back in Paris, I will test it also
28on linux/alpha.
29
30
31Encodings
32*********
33
34The variety of encodings that accompanies pcf fonts appears to encompass the
35small set defined in freetype.h.  On the other hand, each pcf font defines
36two properties that specify encoding and registry.
37
38I decided to make these two properties directly accessible, leaving to the
39client application the work of interpreting them.  For instance:
40
41  #include "pcftypes.h"  /* include/freetype/internal/pcftypes.h */
42
43  FT_Face     face;
44  PCF_Public_Face  pcfface;
45
46  FT_New_Face( library,..., &face );
47
48  pcfface = (PCF_Public_Face)face;
49 
50  if ((pcfface->charset_registry == "ISO10646") &&
51        (pcfface->charset_encoding) == "1")) [..]
52
53Thus the driver always export ``ft_encoding_none'' as
54face->charmap.encoding.  FT_Get_Char_Index() behavior is unmodified, that
55is, it converts the ULong value given as argument into the corresponding
56glyph number.
57
58
59Known problems
60**************
61
62- dealing explicitly with encodings breaks the uniformity of freetype2
63  api.
64
65- except for encodings properties, client applications have no
66  visibility of the PCF_Face object.  This means that applications
67  cannot directly access font tables and are obliged to trust
68  FreeType.
69
70- currently, glyph names and ink_metrics are ignored.
71
72I plan to give full visibility of the PCF_Face object in the next
73release of the driver, thus implementing also glyph names and
74ink_metrics.
75
76- height is defined as (ascent - descent).  Is this correct?
77
78- if unable to read size informations from the font, PCF_Init_Face
79  sets available_size->width and available_size->height to 12.
80
81- too many english grammar errors in the readme file :-(
82
83
84License
85*******
86
87Copyright (C) 2000 by Francesco Zappa Nardelli
88
89Permission is hereby granted, free of charge, to any person obtaining
90a copy of this software and associated documentation files (the
91"Software"), to deal in the Software without restriction, including
92without limitation the rights to use, copy, modify, merge, publish,
93distribute, sublicense, and/or sell copies of the Software, and to
94permit persons to whom the Software is furnished to do so, subject to
95the following conditions:
96
97The above copyright notice and this permission notice shall be
98included in all copies or substantial portions of the Software.
99
100THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
101EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
102MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
103IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
104CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
105TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
106SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
107
108
109Credits
110*******
111
112Keith Packard wrote the pcf driver found in XFree86.  His work is at
113the same time the specification and the sample implementation of the
114PCF format.  Undoubtedly, this driver is inspired from his work.
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