[arabic] Implement Unicode Arabic Mark Ordering Algorithm UTR#53
Fixes https://github.com/behdad/harfbuzz/issues/509
diff --git a/src/hb-ot-shape-complex-arabic.cc b/src/hb-ot-shape-complex-arabic.cc
index ed7b3f2..28dd4e1 100644
--- a/src/hb-ot-shape-complex-arabic.cc
+++ b/src/hb-ot-shape-complex-arabic.cc
@@ -613,6 +613,80 @@
HB_BUFFER_DEALLOCATE_VAR (buffer, arabic_shaping_action);
}
+/* http://www.unicode.org/reports/tr53/tr53-1.pdf */
+
+static hb_codepoint_t
+modifier_combining_marks[] =
+{
+ 0x0654u, /* ARABIC HAMZA ABOVE */
+ 0x0655u, /* ARABIC HAMZA BELOW */
+ 0x0658u, /* ARABIC MARK NOON GHUNNA */
+ 0x06DCu, /* ARABIC SMALL HIGH SEEN */
+ 0x06E3u, /* ARABIC SMALL LOW SEEN */
+ 0x06E7u, /* ARABIC SMALL HIGH YEH */
+ 0x06E8u, /* ARABIC SMALL HIGH NOON */
+ 0x08F3u, /* ARABIC SMALL HIGH WAW */
+};
+
+static inline bool
+info_is_mcm (const hb_glyph_info_t &info)
+{
+ hb_codepoint_t u = info.codepoint;
+ for (unsigned int i = 0; i < ARRAY_LENGTH (modifier_combining_marks); i++)
+ if (u == modifier_combining_marks[i])
+ return true;
+ return false;
+}
+
+static void
+reorder_marks_arabic (const hb_ot_shape_plan_t *plan,
+ hb_buffer_t *buffer,
+ unsigned int start,
+ unsigned int end)
+{
+ hb_glyph_info_t *info = buffer->info;
+
+ unsigned int i = start;
+ for (unsigned int cc = 220; cc <= 230; cc += 10)
+ {
+ DEBUG_MSG (ARABIC, buffer, "Looking for %d's starting at %d\n", cc, i);
+ while (i < end && info_cc(info[i]) < cc)
+ i++;
+ DEBUG_MSG (ARABIC, buffer, "Looking for %d's stopped at %d\n", cc, i);
+
+ if (i == end)
+ break;
+
+ if (info_cc(info[i]) > cc)
+ continue;
+
+ /* Technically we should also check "info_cc(info[j]) == cc"
+ * in the following loop. But not doing it is safe; we might
+ * end up moving all the 220 MCMs and 230 MCMs together in one
+ * move and be done. */
+ unsigned int j = i;
+ while (j < end && info_is_mcm (info[j]))
+ j++;
+ DEBUG_MSG (ARABIC, buffer, "Found %d's from %d to %d\n", cc, i, j);
+
+ if (i == j)
+ continue;
+
+ /* Shift it! */
+ DEBUG_MSG (ARABIC, buffer, "Shifting %d's: %d %d\n", cc, i, j);
+ hb_glyph_info_t temp[HB_OT_SHAPE_COMPLEX_MAX_COMBINING_MARKS];
+ assert (j - i <= ARRAY_LENGTH (temp));
+ buffer->merge_out_clusters (start, j);
+ memmove (temp, &info[i], (j - i) * sizeof (hb_glyph_info_t));
+ memmove (&info[start + j - i], &info[start], (i - start) * sizeof (hb_glyph_info_t));
+ memmove (&info[start], temp, (j - i) * sizeof (hb_glyph_info_t));
+
+ start += j - i;
+
+ i = j;
+ }
+}
+
const hb_ot_complex_shaper_t _hb_ot_complex_shaper_arabic =
{
"arabic",
@@ -627,6 +701,7 @@
NULL, /* compose */
setup_masks_arabic,
NULL, /* disable_otl */
+ reorder_marks_arabic,
HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE,
true, /* fallback_position */
};
