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+/* This file is taken from the FreeType (1) tree. It's been reindented
+ * to roughly match Pango guidelines (in anticipation of future changes),
+ * but not otherwise much altered.
+ */
+
+/****************************************************************************/
+/* */
+/* The FreeType project -- a free and portable quality TrueType renderer. */
+/* */
+/* Copyright 1996-2000 by */
+/* D. Turner, R.Wilhelm, and W. Lemberg */
+/* */
+/* arabic -- An implementation of the contextual algorithm given in the */
+/* Unicode 2.0 book to assign the `isolated', `initial', `medial', and */
+/* `final' properties to an input string of character codes for the Arabic */
+/* script. */
+/* */
+/* This file is part of the FreeType project, and may only be used */
+/* modified and distributed under the terms of the FreeType project */
+/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
+/* this file you indicate that you have read the license and */
+/* understand and accept it fully. */
+/* */
+/* The code, like the FreeType code it is derived from is dual-licensed */
+/* under the GNU General Public License and the FreeType license. See */
+/* pango/opentype/COPYING for full details of this licensing scheme. */
+/****************************************************************************/
+
+#include <config.h>
+
+#include "arabic-ot.h"
+
+
+/*
+ *
+ * Here a table of the joining classes for characters in the range
+ * U+0620 - U+06FF and U+0750 - U+077F.
+ *
+ * The following character also has a joining class:
+ *
+ * U+200D ZERO WIDTH JOINER -> causing
+ *
+ * All other characters are given the joining class `none'.
+ *
+ */
+
+static const joining_class arabic[] =
+{
+ /* U+0620 */
+ none, none, right, right,
+ right, right, dual, right,
+ dual, right, dual, dual,
+ dual, dual, dual, right,
+
+ /* U+0630 */
+ right, right, right, dual,
+ dual, dual, dual, dual,
+ dual, dual, dual, none,
+ none, none, none, none,
+
+ /* U+0640 */
+ causing, dual, dual, dual,
+ dual, dual, dual, dual,
+ right, dual, dual, transparent,
+ transparent, transparent, transparent, transparent,
+
+ /* U+0650 */
+ transparent, transparent, transparent, transparent,
+ transparent, transparent, transparent, transparent,
+ transparent, transparent, transparent, transparent,
+ transparent, transparent, transparent, none,
+
+ /* U+0660 */
+ none, none, none, none,
+ none, none, none, none,
+ none, none, none, none,
+ none, none, dual, dual,
+
+ /* U+0670 */
+ transparent, right, right, right,
+ none, right, right, right,
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+
+ /* U+0680 */
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+ right, right, right, right,
+ right, right, right, right,
+
+ /* U+0690 */
+ right, right, right, right,
+ right, right, right, right,
+ right, right, dual, dual,
+ dual, dual, dual, dual,
+
+ /* U+06A0 */
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+
+ /* U+06B0 */
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+
+ /* U+06C0 */
+ right, dual, right, right,
+ right, right, right, right,
+ right, right, right, right,
+ dual, right, dual, right,
+
+ /* U+06D0 */
+ dual, dual, right, right,
+ none, right, none, transparent,
+ transparent, transparent, transparent, transparent,
+ transparent, transparent, transparent, transparent,
+
+ /* U+06E0 */
+ transparent, transparent, transparent, transparent,
+ transparent, none, none, transparent,
+ transparent, none, transparent, transparent,
+ transparent, transparent, right, right,
+
+ /* U+06F0 */
+ none, none, none, none,
+ none, none, none, none,
+ none, none, dual, dual,
+ dual, none, none, dual
+};
+
+static const joining_class arabic_supplement[] =
+{
+ /* U+0750 */
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+ dual, right, right, right,
+ dual, dual, dual, dual,
+
+ /* U+0760 */
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+ dual, dual, dual, right,
+ right, dual, none, none,
+
+ /* U+0770 */
+ none, none, none, none,
+ none, none, none, none,
+ none, none, none, none,
+ none, none, none, none
+};
+
+/* Here a table of the joining classes for characters in the range
+ * U+07C0 - U+07FF.
+ *
+ * The following character also has a joining class:
+ *
+ * U+200C ZERO WIDTH NON-JOINER -> causing
+ *
+ * All other characters are given the joining class `none'.
+ */
+static const joining_class nko[] =
+{
+ /* U+07C0 */
+ none, none, none, none,
+ none, none, none, none,
+ none, none, dual, dual,
+ dual, dual, dual, dual,
+
+ /* U+07D0 */
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+
+ /* U+07E0 */
+ dual, dual, dual, dual,
+ dual, dual, dual, dual,
+ dual, dual, dual, transparent,
+ transparent, transparent, transparent, transparent,
+
+ /* U+07F0 */
+ transparent, transparent, transparent, transparent,
+ none, none, none, none,
+ none, none, causing, none,
+ none, none, none, none,
+};
+
+#if 0
+struct cgc_
+{
+ FT_UShort char_code;
+ FT_UShort glyph_index;
+ FT_UShort class;
+};
+
+typedef struct cgc_ cgc;
+
+int compare_cgc (const void* a,
+ const void* b)
+{
+ return (((cgc*)a)->glyph_index > ((cgc*)b)->glyph_index) ?
+ 1 : ((((cgc*)a)->glyph_index == ((cgc*)b)->glyph_index) ?
+ 0 : -1);
+}
+
+
+TT_Error Build_Arabic_Glyph_Properties (TT_CharMap char_map,
+ TT_UShort max_glyphs,
+ TTO_GDEFHeader** gdef)
+{
+ TT_UShort i, j, num_glyphs;
+
+ cgc Arabic[0x0700 - 0x0620];
+
+ TT_UShort glyph_indices[0x700 - 0x0620];
+ TT_UShort classes[0x700 - 0x0620];
+
+ if (!gdef)
+ return TT_Err_Invalid_Argument;
+
+ j = 0;
+
+ for (i = 0x0620; i < 0x0700; i++)
+ {
+ Arabic[j].char_code = i;
+ Arabic[j].class = (arabic[i - 0x0620] == transparent) ?
+ MARK_GLYPH : SIMPLE_GLYPH;
+ Arabic[j].glyph_index = TT_Char_Index (char_map, i);
+ if (Arabic[j].glyph_index)
+ j++;
+ }
+ num_glyphs = j;
+
+ if (!num_glyphs)
+ {
+ /* no Arabic font */
+ *gdef = NULL;
+ return TT_Err_Ok;
+ }
+
+ /* sort it */
+
+ qsort (Arabic, num_glyphs, sizeof (cgc), compare_cgc);
+
+ /* write it to the arrays, removing duplicates */
+
+ glyph_indices[0] = Arabic[0].glyph_index;
+ classes[0] = Arabic[0].class;
+
+ j = 1;
+
+ for (i = 1; i < num_glyphs; i++)
+ {
+ glyph_indices[j] = Arabic[i].glyph_index;
+ classes[j] = Arabic[i].class;
+
+ if (glyph_indices[j - 1] != glyph_indices[j])
+ j++;
+ }
+ num_glyphs = j;
+
+ TT_GDEF_Build_ClassDefinition (*gdef, max_glyphs, num_glyphs,
+ glyph_indices, classes);
+
+ return TT_Err_Ok;
+}
+#endif
+
+/* The joining rules as given in the Unicode 2.0 book (characters are
+ * here specified as appearing in the byte stream, i.e. *not* in
+ * visual order). Joining classes are given in angle brackets, glyph
+ * forms in square brackets. Glyphs affected by a specific rule are
+ * enclosed with vertical bars.
+ *
+ * Note: The description of the joining algorithm in the book is
+ * severely broken. You can get a corrected version from
+ * www.unicode.org (as of 29-Jun-1999, this hasn't appeared).
+ *
+ * R1: <anything1> <transparent> <anything2>
+ *
+ * apply joining rules for
+ * <anything1> <anything2> -> [shape1] [shape2]
+ *
+ * -> [shape1] [isolated] [shape2]
+ *
+ * R2: <causing|left|dual> |<right>|
+ *
+ * -> [final]
+ *
+ * R3: |<left>| <causing|right|dual>
+ *
+ * -> [initial]
+ *
+ * R4: <causing|left|dual> |<dual>| <causing|right|dual>
+ *
+ * -> [medial]
+ *
+ * R5: <causing|left|dual> |<dual>| <!(causing|right|dual)>
+ *
+ * -> [final]
+ *
+ * R6: <!(causing|left|dual)> |<dual>| <causing|right|dual>
+ *
+ * -> [initial]
+ *
+ * R7: If R1-R6 fail:
+ *
+ * <anything> -> [isolated]
+ */
+
+/* `direction' can be -1, 0, or 1 to indicate the last non-transparent
+ * glyph, the current glyph, and the next non-transparent glyph,
+ * respectively.
+ */
+
+static joining_class Get_Joining_Class (gunichar* string,
+ int pos,
+ int length,
+ int direction,
+ gboolean reverse)
+{
+ joining_class j;
+
+
+ while (1)
+ {
+ if (pos == 0 && direction < 0)
+ return none;
+
+ pos += direction;
+
+ if (pos >= length)
+ return none;
+
+ if (string[pos] >= 0x0620 &&
+ string[pos] < 0x0700)
+ j = arabic[string[pos] - 0x0620];
+ else if (string[pos] >= 0x0750 &&
+ string[pos] < 0x0780)
+ j = arabic_supplement[string[pos] - 0x0750];
+ else if (string[pos] >= 0x07C0 &&
+ string[pos] < 0x0800)
+ j = nko[string[pos] - 0x07C0];
+ else if (string[pos] == 0x200D)
+ return causing;
+ else
+ return none;
+
+ if (!direction || j != transparent)
+ {
+ if (G_UNLIKELY (reverse))
+ return j == right ? left : j == left ? right : j;
+ else
+ return j;
+ }
+ }
+}
+
+
+FT_Error Arabic_Assign_Properties (gunichar *string,
+ gulong *properties,
+ int length,
+ gboolean reverse)
+{
+ joining_class previous, current, next;
+ int i;
+
+ if (!string || !properties || length == 0)
+ return FT_Err_Invalid_Argument;
+
+ for (i = 0; i < length; i++)
+ {
+ previous = Get_Joining_Class (string, i, length, -1, reverse);
+ current = Get_Joining_Class (string, i, length, 0, reverse);
+ next = Get_Joining_Class (string, i, length, 1, reverse);
+
+ /* R1 */
+
+ if (current == transparent)
+ {
+ properties[i] |= isolated_p;
+ continue;
+ }
+
+ /* R2 */
+
+ if (previous == causing ||
+ previous == left ||
+ previous == dual )
+ if (current == right)
+ {
+ properties[i] |= reverse ? initial_p : final_p;
+ continue;
+ }
+
+ /* R3 */
+
+ if (current == left)
+ if (next == causing ||
+ next == right ||
+ next == dual )
+ {
+ properties[i] |= reverse ? final_p : initial_p;
+ continue;
+ }
+
+ /* R4 */
+
+ if (previous == causing ||
+ previous == left ||
+ previous == dual )
+ if (current == dual)
+ if (next == causing ||
+ next == right ||
+ next == dual )
+ {
+ properties[i] |= medial_p;
+ continue;
+ }
+
+ /* R5 */
+
+ if (previous == causing ||
+ previous == left ||
+ previous == dual )
+ if (current == dual)
+ if (!(next == causing ||
+ next == right ||
+ next == dual ))
+ {
+ properties[i] |= reverse ? initial_p : final_p;
+ continue;
+ }
+
+ /* R6 */
+
+ if (!(previous == causing ||
+ previous == left ||
+ previous == dual ))
+ if (current == dual)
+ if (next == causing ||
+ next == right ||
+ next == dual )
+ {
+ properties[i] |= reverse ? final_p : initial_p;
+ continue;
+ }
+
+ /* R7 */
+
+ properties[i] |= isolated_p;
+ }
+
+ return FT_Err_Ok;
+}
+
+
+/* End */
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