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Diffstat (limited to 'pango2/break-arabic.c')
| -rw-r--r-- | pango2/break-arabic.c | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/pango2/break-arabic.c b/pango2/break-arabic.c new file mode 100644 index 00000000..2368586b --- /dev/null +++ b/pango2/break-arabic.c @@ -0,0 +1,91 @@ +/* Pango2 + * break-arabic.c: + * + * Copyright (C) 2006 Red Hat Software + * Copyright (C) 2006 Sharif FarsiWeb, Inc. + * Authors: Behdad Esfahbod <besfahbo@redhat.com> + * Roozbeh Pournader <roozbeh@farsiweb.info> + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Library General Public + * License as published by the Free Software Foundation; either + * version 2 of the License, or (at your option) any later version. + * + * This library 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 + * Library General Public License for more details. + * + * You should have received a copy of the GNU Library General Public + * License along with this library; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 02111-1307, USA. + */ + +#include "config.h" + +#include "pango-break.h" + +#define ALEF_WITH_MADDA_ABOVE 0x0622 +#define YEH_WITH_HAMZA_ABOVE 0x0626 +#define ALEF 0x0627 +#define WAW 0x0648 +#define YEH 0x064A + +#define MADDAH_ABOVE 0x0653 +#define HAMZA_ABOVE 0x0654 +#define HAMZA_BELOW 0x0655 + +/* + * Arabic characters with canonical decompositions that are not just + * ligatures. The characters U+06C0, U+06C2, and U+06D3 are intentionally + * excluded as they are marked as "not an independent letter" in Unicode + * Character Database's NamesList.txt + */ +#define IS_COMPOSITE(c) (ALEF_WITH_MADDA_ABOVE <= (c) && (c) <= YEH_WITH_HAMZA_ABOVE) + +/* If a character is the second part of a composite Arabic character with an Alef */ +#define IS_COMPOSITE_WITH_ALEF(c) (MADDAH_ABOVE <= (c) && (c) <= HAMZA_BELOW) + +static void +break_arabic (const char *text, + int length, + const Pango2Analysis *analysis G_GNUC_UNUSED, + Pango2LogAttr *attrs, + int attrs_len G_GNUC_UNUSED) +{ + int i; + const char *p; + gunichar prev_wc, this_wc; + + /* See http://bugzilla.gnome.org/show_bug.cgi?id=350132 for issues this + * module tries to solve. + */ + + for (p = text, i = 0, prev_wc = 0; + p < text + length; + p = g_utf8_next_char (p), i++, prev_wc = this_wc) + { + this_wc = g_utf8_get_char (p); + + /* + * Unset backspace_deletes_character for various combinations. + * + * A few more combinations may need to be handled here, but are not + * handled yet, as expectations of users is not known or may differ + * among different languages or users: + * some letters combined with U+0658 ARABIC MARK NOON GHUNNA; + * combinations considered one letter in Azerbaijani (WAW+SUKUN and + * FARSI_YEH+HAMZA_ABOVE); combinations of YEH and ALEF_MAKSURA with + * HAMZA_BELOW (Qur'anic); TATWEEL+HAMZA_ABOVE (Qur'anic). + * + * FIXME: Ordering these in some other way may lower the time spent here, or not. + */ + if (G_UNLIKELY ( + IS_COMPOSITE (this_wc) || + (prev_wc == ALEF && IS_COMPOSITE_WITH_ALEF (this_wc)) || + (this_wc == HAMZA_ABOVE && (prev_wc == WAW || prev_wc == YEH)) + )) + attrs[i+1].backspace_deletes_character = FALSE; + } +} |