1 /* FriBidi
2 * fribidi-bidi.h - bidirectional algorithm
3 *
4 * Authors:
5 * Behdad Esfahbod, 2001, 2002, 2004
6 * Dov Grobgeld, 1999, 2000
7 *
8 * Copyright (C) 2004 Sharif FarsiWeb, Inc
9 * Copyright (C) 2001,2002 Behdad Esfahbod
10 * Copyright (C) 1999,2000 Dov Grobgeld
11 *
12 * This library is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU Lesser General Public
14 * License as published by the Free Software Foundation; either
15 * version 2.1 of the License, or (at your option) any later version.
16 *
17 * This library is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 * Lesser General Public License for more details.
21 *
22 * You should have received a copy of the GNU Lesser General Public License
23 * along with this library, in a file named COPYING; if not, write to the
24 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
25 * Boston, MA 02110-1301, USA
26 *
27 * For licensing issues, contact <fribidi.license@gmail.com>.
28 */
29 #ifndef _FRIBIDI_BIDI_H
30 #define _FRIBIDI_BIDI_H
31
32 #include "fribidi-common.h"
33
34 #include "fribidi-types.h"
35 #include "fribidi-flags.h"
36 #include "fribidi-bidi-types.h"
37
38 #include "fribidi-begindecls.h"
39
40 /* fribidi_get_par_direction - get base paragraph direction
41 *
42 * This function finds the base direction of a single paragraph,
43 * as defined by rule P2 of the Unicode Bidirectional Algorithm available at
44 * http://www.unicode.org/reports/tr9/#P2.
45 *
46 * You typically do not need this function as
47 * fribidi_get_par_embedding_levels() knows how to compute base direction
48 * itself, but you may need this to implement a more sophisticated paragraph
49 * direction handling. Note that you can pass more than a paragraph to this
50 * function and the direction of the first non-neutral paragraph is returned,
51 * which is a very good heuristic to set direction of the neutral paragraphs
52 * at the beginning of text. For other neutral paragraphs, you better use the
53 * direction of the previous paragraph.
54 *
55 * Returns: Base pargraph direction. No weak paragraph direction is returned,
56 * only LTR, RTL, or ON.
57 */
58 FRIBIDI_ENTRY FriBidiParType fribidi_get_par_direction (
59 const FriBidiCharType *bidi_types, /* input list of bidi types as returned by
60 fribidi_get_bidi_types() */
61 const FriBidiStrIndex len /* input string length */
62 );
63
64 /* fribidi_get_par_embedding_levels_ex - get bidi embedding levels of a paragraph
65 *
66 * This function finds the bidi embedding levels of a single paragraph,
67 * as defined by the Unicode Bidirectional Algorithm available at
68 * http://www.unicode.org/reports/tr9/. This function implements rules P2 to
69 * I1 inclusive, and parts 1 to 3 of L1, except for rule X9 which is
70 * implemented in fribidi_remove_bidi_marks(). Part 4 of L1 is implemented
71 * in fribidi_reorder_line().
72 *
73 * There are a few macros defined in fribidi-bidi-types.h to work with this
74 * embedding levels.
75 *
76 * Returns: Maximum level found plus one, or zero if any error occurred
77 * (memory allocation failure most probably).
78 */
79 FRIBIDI_ENTRY FriBidiLevel
80 fribidi_get_par_embedding_levels_ex (
81 const FriBidiCharType *bidi_types, /* input list of bidi types as returned by
82 fribidi_get_bidi_types() */
83 const FriBidiBracketType *bracket_types, /* input list of bracket types as returned by
84 fribidi_get_bracket_types() */
85 const FriBidiStrIndex len, /* input string length of the paragraph */
86 FriBidiParType *pbase_dir, /* requested and resolved paragraph
87 * base direction */
88 FriBidiLevel *embedding_levels /* output list of embedding levels */
89 ) FRIBIDI_GNUC_WARN_UNUSED;
90
91 /* fribidi_reorder_line - reorder a line of logical string to visual
92 *
93 * This function reorders the characters in a line of text from logical to
94 * final visual order. This function implements part 4 of rule L1, and rules
95 * L2 and L3 of the Unicode Bidirectional Algorithm available at
96 * http://www.unicode.org/reports/tr9/#Reordering_Resolved_Levels.
97 *
98 * As a side effect it also sets position maps if not NULL.
99 *
100 * You should provide the resolved paragraph direction and embedding levels as
101 * set by fribidi_get_par_embedding_levels(). Also note that the embedding
102 * levels may change a bit. To be exact, the embedding level of any sequence
103 * of white space at the end of line is reset to the paragraph embedding level
104 * (That is part 4 of rule L1).
105 *
106 * Note that the bidi types and embedding levels are not reordered. You can
107 * reorder these (or any other) arrays using the map later. The user is
108 * responsible to initialize map to something sensible, like an identity
109 * mapping, or pass NULL if no map is needed.
110 *
111 * There is an optional part to this function, which is whether non-spacing
112 * marks for right-to-left parts of the text should be reordered to come after
113 * their base characters in the visual string or not. Most rendering engines
114 * expect this behavior, but console-based systems for example do not like it.
115 * This is controlled by the FRIBIDI_FLAG_REORDER_NSM flag. The flag is on
116 * in FRIBIDI_FLAGS_DEFAULT.
117 *
118 * Returns: Maximum level found in this line plus one, or zero if any error
119 * occurred (memory allocation failure most probably).
120 */
121 FRIBIDI_ENTRY FriBidiLevel fribidi_reorder_line (
122 FriBidiFlags flags, /* reorder flags */
123 const FriBidiCharType *bidi_types, /* input list of bidi types as returned by
124 fribidi_get_bidi_types() */
125 const FriBidiStrIndex len, /* input length of the line */
126 const FriBidiStrIndex off, /* input offset of the beginning of the line
127 in the paragraph */
128 const FriBidiParType base_dir, /* resolved paragraph base direction */
129 FriBidiLevel *embedding_levels, /* input list of embedding levels,
130 as returned by
131 fribidi_get_par_embedding_levels */
132 FriBidiChar *visual_str, /* visual string to reorder */
133 FriBidiStrIndex *map /* a map of string indices which is reordered
134 * to reflect where each glyph ends up. */
135 ) FRIBIDI_GNUC_WARN_UNUSED;
136
137 #include "fribidi-enddecls.h"
138
139 #endif /* !_FRIBIDI_BIDI_H */
140 /* Editor directions:
141 * vim:textwidth=78:tabstop=8:shiftwidth=2:autoindent:cindent
142 */