The Free Implementation of the Unicode Bidirectional Algorithm.
One of the missing links stopping the penetration of free software in Middle East is the lack of support for the Arabic and Hebrew alphabets. In order to have proper Arabic and Hebrew support, the bidi algorithm needs to be implemented. It is our hope that this library will stimulate more free software in the Middle Eastern countries.
See HISTORY
on how the project started and evolved.
It is our hope that this library will stimulate the implementation of Hebrew and Arabic support in lots of Free Software.
GNU FriBidi is already being used in projects like Pango (resulting in GTK and GNOME using GNU FriBidi), AbiWord, MLTerm, MPlayer, BiCon, and vlc.
See USERS
for a list of projects using GNU FriBidi.
GNU FriBidi does not depend on any other library. It uses either the GNU Build System or meson for build and installation.
The latest version of GNU FriBidi may be found at: https://github.com/fribidi/fribidi
Start with running the autogen.sh
script and follow the
instructions. Alternatively use meson
.
GNU FriBidi is Free Software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software
Foundation; either version 2.1 of the License, or (at your option) any later version.
GNU FriBidi is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License along with GNU FriBidi, in a file named COPYING; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
For commercial licensing options, contact [email protected].
The library implements the algorithm described in the "Unicode Standard Annex #9, The Bidirectional Algorithm", available at http://www.unicode.org/unicode/reports/tr9/.
The library uses Unicode (UTF-32) entirely. The character properties are automatically extracted from the Unicode data files, available from http://www.unicode.org/Public/UNIDATA/. This means that every Unicode character is treated in strict accordance with the Unicode specification.
There is a limited support for character set conversion from/to the UTF-32 encoding. Data in these character sets must be converted into UTF-32 before the library may be used. iconv(3) can always do a better job on that, so you may find that the character sets conversion code is typically turned off on POSIX machines.
GNU FriBidi has been tested exhaustively against the Unicode Reference Code, and to the best of our knowledge, it completely conforms to the specification, always producing the same result as the Reference Code.
The simplest way of accessing the API is through the convenience function fribidi_log2vis
which has the following signature:
fribidi_boolean fribidi_log2vis(
/* input */
FriBidiChar *str,
FriBidiStrIndex len,
FriBidiCharType *pbase_dir,
/* output */
FriBidiChar *visual_str,
FriBidiStrIndex *position_L_to_V_list,
FriBidiStrIndex *position_V_to_L_list,
FriBidiLevel *embedding_level_list
)
Where...
str
is the Unicode input string.len
is the length of the Unicode string (str
).pbase_dir
is the input and output base direction. Ifpbase_dir == FRIBIDI_TYPE_ON
thenfribidi_log2vis()
calculates the base direction on its own, according to the bidi algorithm.visual_str
is the reordered output unicode string.position_L_to_V_list
maps the positions in the logical string to positions in the visual string.position_V_to_L_list
maps the positions in the visual string to the positions in the logical string.embedding_level_list
returns the classification of each character. Here, even numerical levels indicate LTR characters, and odd levels indicate RTL characters. The main use of this list is in interactive applications where, for example, the embedding level determines cursor display.
If any of the output pointers is equal to NULL
, then that information is not
calculated.
Note that a call to fribidi_log2vis()
is a convenience function to calling the following three functions in order:
fribidi_get_bidi_types()
fribidi_get_par_embedding_levels_ex()
fribidi_reorder_line()
Have a look at test/
directory, to see some input and outputs.
The CapRTL
charset means that CAPITAL letters are right to left, and digits
6, 7, 8, 9 are Arabic digits, try 'fribidi --charsetdesc CapRTL' for the full
description.
There is also a command-line utilitity called fribidi
that loops over the text
of a file and performs the bidi algorithm on each line, also used for testing
the algorithm.
Run fribidi --help
to learn about usage.
The command-line utility is known to have problems with line-breaking and logical-to-vertical/vertical-to-logical lists.
Report bugs and general feedback at: https://github.com/fribidi/fribidi/issues
The mailing list is the place for additional technical discussions and user questions: https://lists.freedesktop.org/mailman/listinfo/fribidi
- Dov Grobgeld [email protected] - Original author and current maintainer
- Behdad Esfahbod [email protected] - Author of most of the code
See also AUTHORS
and THANKS
for the complete list
of contributors.