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harfbuzz/src/hb-ot-shaper-arabic.cc

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/*
* Copyright © 2010,2012 Google, Inc.
*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Google Author(s): Behdad Esfahbod
*/
#include "hb.hh"
#ifndef HB_NO_OT_SHAPE
#include "hb-ot-shaper-arabic.hh"
#include "hb-ot-shape.hh"
/* buffer var allocations */
#define arabic_shaping_action() ot_shaper_var_u8_auxiliary() /* arabic shaping action */
#define HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH HB_BUFFER_SCRATCH_FLAG_SHAPER0
/* See:
* https://github.com/harfbuzz/harfbuzz/commit/6e6f82b6f3dde0fc6c3c7d991d9ec6cfff57823d#commitcomment-14248516 */
#define HB_ARABIC_GENERAL_CATEGORY_IS_WORD(gen_cat) \
(FLAG_UNSAFE (gen_cat) & \
(FLAG (HB_UNICODE_GENERAL_CATEGORY_UNASSIGNED) | \
FLAG (HB_UNICODE_GENERAL_CATEGORY_PRIVATE_USE) | \
/*FLAG (HB_UNICODE_GENERAL_CATEGORY_LOWERCASE_LETTER) |*/ \
FLAG (HB_UNICODE_GENERAL_CATEGORY_MODIFIER_LETTER) | \
FLAG (HB_UNICODE_GENERAL_CATEGORY_OTHER_LETTER) | \
/*FLAG (HB_UNICODE_GENERAL_CATEGORY_TITLECASE_LETTER) |*/ \
/*FLAG (HB_UNICODE_GENERAL_CATEGORY_UPPERCASE_LETTER) |*/ \
FLAG (HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK) | \
FLAG (HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) | \
FLAG (HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) | \
FLAG (HB_UNICODE_GENERAL_CATEGORY_DECIMAL_NUMBER) | \
FLAG (HB_UNICODE_GENERAL_CATEGORY_LETTER_NUMBER) | \
FLAG (HB_UNICODE_GENERAL_CATEGORY_OTHER_NUMBER) | \
FLAG (HB_UNICODE_GENERAL_CATEGORY_CURRENCY_SYMBOL) | \
FLAG (HB_UNICODE_GENERAL_CATEGORY_MODIFIER_SYMBOL) | \
FLAG (HB_UNICODE_GENERAL_CATEGORY_MATH_SYMBOL) | \
FLAG (HB_UNICODE_GENERAL_CATEGORY_OTHER_SYMBOL)))
/*
* Joining types:
*/
/*
* Bits used in the joining tables
*/
enum hb_arabic_joining_type_t {
JOINING_TYPE_U = 0,
JOINING_TYPE_L = 1,
JOINING_TYPE_R = 2,
JOINING_TYPE_D = 3,
JOINING_TYPE_C = JOINING_TYPE_D,
JOINING_GROUP_ALAPH = 4,
JOINING_GROUP_DALATH_RISH = 5,
NUM_STATE_MACHINE_COLS = 6,
JOINING_TYPE_T = 7,
JOINING_TYPE_X = 8 /* means: use general-category to choose between U or T. */
};
#include "hb-ot-shaper-arabic-table.hh"
static unsigned int get_joining_type (hb_codepoint_t u, hb_unicode_general_category_t gen_cat)
{
unsigned int j_type = joining_type(u);
if (likely (j_type != JOINING_TYPE_X))
return j_type;
return (FLAG_UNSAFE(gen_cat) &
(FLAG(HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) |
FLAG(HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) |
FLAG(HB_UNICODE_GENERAL_CATEGORY_FORMAT))
) ? JOINING_TYPE_T : JOINING_TYPE_U;
}
#define FEATURE_IS_SYRIAC(tag) hb_in_range<unsigned char> ((unsigned char) (tag), '2', '3')
static const hb_tag_t arabic_features[] =
{
HB_TAG('i','s','o','l'),
HB_TAG('f','i','n','a'),
HB_TAG('f','i','n','2'),
HB_TAG('f','i','n','3'),
HB_TAG('m','e','d','i'),
HB_TAG('m','e','d','2'),
HB_TAG('i','n','i','t'),
HB_TAG_NONE
};
/* Same order as the feature array */
enum arabic_action_t {
ISOL,
FINA,
FIN2,
FIN3,
MEDI,
MED2,
INIT,
NONE,
ARABIC_NUM_FEATURES = NONE,
/* We abuse the same byte for other things... */
STCH_FIXED,
STCH_REPEATING,
};
static const struct arabic_state_table_entry {
uint8_t prev_action;
uint8_t curr_action;
uint16_t next_state;
} arabic_state_table[][NUM_STATE_MACHINE_COLS] =
{
/* jt_U, jt_L, jt_R, jt_D, jg_ALAPH, jg_DALATH_RISH */
/* State 0: prev was U, not willing to join. */
{ {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,6}, },
/* State 1: prev was R or ISOL/ALAPH, not willing to join. */
{ {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN2,5}, {NONE,ISOL,6}, },
/* State 2: prev was D/L in ISOL form, willing to join. */
{ {NONE,NONE,0}, {NONE,ISOL,2}, {INIT,FINA,1}, {INIT,FINA,3}, {INIT,FINA,4}, {INIT,FINA,6}, },
/* State 3: prev was D in FINA form, willing to join. */
{ {NONE,NONE,0}, {NONE,ISOL,2}, {MEDI,FINA,1}, {MEDI,FINA,3}, {MEDI,FINA,4}, {MEDI,FINA,6}, },
/* State 4: prev was FINA ALAPH, not willing to join. */
{ {NONE,NONE,0}, {NONE,ISOL,2}, {MED2,ISOL,1}, {MED2,ISOL,2}, {MED2,FIN2,5}, {MED2,ISOL,6}, },
/* State 5: prev was FIN2/FIN3 ALAPH, not willing to join. */
{ {NONE,NONE,0}, {NONE,ISOL,2}, {ISOL,ISOL,1}, {ISOL,ISOL,2}, {ISOL,FIN2,5}, {ISOL,ISOL,6}, },
/* State 6: prev was DALATH/RISH, not willing to join. */
{ {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN3,5}, {NONE,ISOL,6}, }
};
static void
arabic_fallback_shape (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer);
static void
record_stch (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer);
static void
deallocate_buffer_var (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer)
{
HB_BUFFER_DEALLOCATE_VAR (buffer, arabic_shaping_action);
}
static void
collect_features_arabic (hb_ot_shape_planner_t *plan)
{
hb_ot_map_builder_t *map = &plan->map;
/* We apply features according to the Arabic spec, with pauses
* in between most.
*
* The pause between init/medi/... and rlig is required. See eg:
* https://bugzilla.mozilla.org/show_bug.cgi?id=644184
*
* The pauses between init/medi/... themselves are not necessarily
* needed as only one of those features is applied to any character.
* The only difference it makes is when fonts have contextual
* substitutions. We now follow the order of the spec, which makes
* for better experience if that's what Uniscribe is doing.
*
* At least for Arabic, looks like Uniscribe has a pause between
* rlig and calt. Otherwise the IranNastaliq's ALLAH ligature won't
* work. However, testing shows that rlig and calt are applied
* together for Mongolian in Uniscribe. As such, we only add a
* pause for Arabic, not other scripts.
*/
map->enable_feature (HB_TAG('s','t','c','h'));
map->add_gsub_pause (record_stch);
map->enable_feature (HB_TAG('c','c','m','p'), F_MANUAL_ZWJ);
map->enable_feature (HB_TAG('l','o','c','l'), F_MANUAL_ZWJ);
map->add_gsub_pause (nullptr);
for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++)
{
bool has_fallback = plan->props.script == HB_SCRIPT_ARABIC && !FEATURE_IS_SYRIAC (arabic_features[i]);
map->add_feature (arabic_features[i], F_MANUAL_ZWJ | (has_fallback ? F_HAS_FALLBACK : F_NONE));
map->add_gsub_pause (nullptr);
}
map->add_gsub_pause (deallocate_buffer_var);
/* Normally, Unicode says a ZWNJ means "don't ligate". In Arabic script
* however, it says a ZWJ should also mean "don't ligate". So we run
* the main ligating features as MANUAL_ZWJ. */
map->enable_feature (HB_TAG('r','l','i','g'), F_MANUAL_ZWJ | F_HAS_FALLBACK);
if (plan->props.script == HB_SCRIPT_ARABIC)
map->add_gsub_pause (arabic_fallback_shape);
map->enable_feature (HB_TAG('c','a','l','t'), F_MANUAL_ZWJ);
/* https://github.com/harfbuzz/harfbuzz/issues/1573 */
if (!map->has_feature (HB_TAG('r','c','l','t')))
{
map->add_gsub_pause (nullptr);
map->enable_feature (HB_TAG('r','c','l','t'), F_MANUAL_ZWJ);
}
map->enable_feature (HB_TAG('l','i','g','a'), F_MANUAL_ZWJ);
map->enable_feature (HB_TAG('c','l','i','g'), F_MANUAL_ZWJ);
/* The spec includes 'cswh'. Earlier versions of Windows
* used to enable this by default, but testing suggests
* that Windows 8 and later do not enable it by default,
* and spec now says 'Off by default'.
* We disabled this in ae23c24c32.
* Note that IranNastaliq uses this feature extensively
* to fixup broken glyph sequences. Oh well...
* Test case: U+0643,U+0640,U+0631. */
//map->enable_feature (HB_TAG('c','s','w','h'), F_MANUAL_ZWJ);
map->enable_feature (HB_TAG('m','s','e','t'), F_MANUAL_ZWJ);
}
#include "hb-ot-shaper-arabic-fallback.hh"
struct arabic_shape_plan_t
{
/* The "+ 1" in the next array is to accommodate for the "NONE" command,
* which is not an OpenType feature, but this simplifies the code by not
* having to do a "if (... < NONE) ..." and just rely on the fact that
* mask_array[NONE] == 0. */
hb_mask_t mask_array[ARABIC_NUM_FEATURES + 1];
hb_atomic_ptr_t<arabic_fallback_plan_t> fallback_plan;
unsigned int do_fallback : 1;
unsigned int has_stch : 1;
};
void *
data_create_arabic (const hb_ot_shape_plan_t *plan)
{
arabic_shape_plan_t *arabic_plan = (arabic_shape_plan_t *) hb_calloc (1, sizeof (arabic_shape_plan_t));
if (unlikely (!arabic_plan))
return nullptr;
arabic_plan->do_fallback = plan->props.script == HB_SCRIPT_ARABIC;
arabic_plan->has_stch = !!plan->map.get_1_mask (HB_TAG ('s','t','c','h'));
for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++) {
arabic_plan->mask_array[i] = plan->map.get_1_mask (arabic_features[i]);
arabic_plan->do_fallback = arabic_plan->do_fallback &&
(FEATURE_IS_SYRIAC (arabic_features[i]) ||
plan->map.needs_fallback (arabic_features[i]));
}
return arabic_plan;
}
void
data_destroy_arabic (void *data)
{
arabic_shape_plan_t *arabic_plan = (arabic_shape_plan_t *) data;
arabic_fallback_plan_destroy (arabic_plan->fallback_plan);
hb_free (data);
}
static void
arabic_joining (hb_buffer_t *buffer)
{
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
unsigned int prev = UINT_MAX, state = 0;
/* Check pre-context */
for (unsigned int i = 0; i < buffer->context_len[0]; i++)
{
unsigned int this_type = get_joining_type (buffer->context[0][i], buffer->unicode->general_category (buffer->context[0][i]));
if (unlikely (this_type == JOINING_TYPE_T))
continue;
const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
state = entry->next_state;
break;
}
for (unsigned int i = 0; i < count; i++)
{
unsigned int this_type = get_joining_type (info[i].codepoint, _hb_glyph_info_get_general_category (&info[i]));
if (unlikely (this_type == JOINING_TYPE_T)) {
info[i].arabic_shaping_action() = NONE;
continue;
}
const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
if (entry->prev_action != NONE && prev != UINT_MAX)
{
info[prev].arabic_shaping_action() = entry->prev_action;
buffer->safe_to_insert_tatweel (prev, i + 1);
}
else
{
if (prev == UINT_MAX)
{
if (this_type >= JOINING_TYPE_R)
buffer->unsafe_to_concat_from_outbuffer (0, i + 1);
}
else
{
if (this_type >= JOINING_TYPE_R ||
(2 <= state && state <= 5) /* States that have a possible prev_action. */)
buffer->unsafe_to_concat (prev, i + 1);
}
}
info[i].arabic_shaping_action() = entry->curr_action;
prev = i;
state = entry->next_state;
}
for (unsigned int i = 0; i < buffer->context_len[1]; i++)
{
unsigned int this_type = get_joining_type (buffer->context[1][i], buffer->unicode->general_category (buffer->context[1][i]));
if (unlikely (this_type == JOINING_TYPE_T))
continue;
const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];
if (entry->prev_action != NONE && prev != UINT_MAX)
{
info[prev].arabic_shaping_action() = entry->prev_action;
buffer->safe_to_insert_tatweel (prev, buffer->len);
}
else if (2 <= state && state <= 5) /* States that have a possible prev_action. */
{
buffer->unsafe_to_concat (prev, buffer->len);
}
break;
}
}
static void
mongolian_variation_selectors (hb_buffer_t *buffer)
{
/* Copy arabic_shaping_action() from base to Mongolian variation selectors. */
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = 1; i < count; i++)
if (unlikely (hb_in_ranges<hb_codepoint_t> (info[i].codepoint, 0x180Bu, 0x180Du, 0x180Fu, 0x180Fu)))
info[i].arabic_shaping_action() = info[i - 1].arabic_shaping_action();
}
void
setup_masks_arabic_plan (const arabic_shape_plan_t *arabic_plan,
hb_buffer_t *buffer,
hb_script_t script)
{
HB_BUFFER_ALLOCATE_VAR (buffer, arabic_shaping_action);
arabic_joining (buffer);
if (script == HB_SCRIPT_MONGOLIAN)
mongolian_variation_selectors (buffer);
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = 0; i < count; i++)
info[i].mask |= arabic_plan->mask_array[info[i].arabic_shaping_action()];
}
static void
setup_masks_arabic (const hb_ot_shape_plan_t *plan,
hb_buffer_t *buffer,
hb_font_t *font HB_UNUSED)
{
const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
setup_masks_arabic_plan (arabic_plan, buffer, plan->props.script);
}
static void
arabic_fallback_shape (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer)
{
#ifdef HB_NO_OT_SHAPER_ARABIC_FALLBACK
return;
#endif
const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
if (!arabic_plan->do_fallback)
return;
retry:
arabic_fallback_plan_t *fallback_plan = arabic_plan->fallback_plan;
if (unlikely (!fallback_plan))
{
/* This sucks. We need a font to build the fallback plan... */
fallback_plan = arabic_fallback_plan_create (plan, font);
if (unlikely (!arabic_plan->fallback_plan.cmpexch (nullptr, fallback_plan)))
{
arabic_fallback_plan_destroy (fallback_plan);
goto retry;
}
}
arabic_fallback_plan_shape (fallback_plan, font, buffer);
}
/*
* Stretch feature: "stch".
* See example here:
* https://docs.microsoft.com/en-us/typography/script-development/syriac
* We implement this in a generic way, such that the Arabic subtending
* marks can use it as well.
*/
static void
record_stch (const hb_ot_shape_plan_t *plan,
hb_font_t *font HB_UNUSED,
hb_buffer_t *buffer)
{
const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;
if (!arabic_plan->has_stch)
return;
/* 'stch' feature was just applied. Look for anything that multiplied,
* and record it for stch treatment later. Note that rtlm, frac, etc
* are applied before stch, but we assume that they didn't result in
* anything multiplying into 5 pieces, so it's safe-ish... */
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = 0; i < count; i++)
if (unlikely (_hb_glyph_info_multiplied (&info[i])))
{
unsigned int comp = _hb_glyph_info_get_lig_comp (&info[i]);
info[i].arabic_shaping_action() = comp % 2 ? STCH_REPEATING : STCH_FIXED;
buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH;
}
}
static void
apply_stch (const hb_ot_shape_plan_t *plan HB_UNUSED,
hb_buffer_t *buffer,
hb_font_t *font)
{
if (likely (!(buffer->scratch_flags & HB_BUFFER_SCRATCH_FLAG_ARABIC_HAS_STCH)))
return;
/* The Arabic shaper currently always processes in RTL mode, so we should
* stretch / position the stretched pieces to the left / preceding glyphs. */
/* We do a two pass implementation:
* First pass calculates the exact number of extra glyphs we need,
* We then enlarge buffer to have that much room,
* Second pass applies the stretch, copying things to the end of buffer.
*/
int sign = font->x_scale < 0 ? -1 : +1;
unsigned int extra_glyphs_needed = 0; // Set during MEASURE, used during CUT
enum { MEASURE, CUT } /* step_t */;
for (unsigned int step = MEASURE; step <= CUT; step = step + 1)
{
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
hb_glyph_position_t *pos = buffer->pos;
unsigned int new_len = count + extra_glyphs_needed; // write head during CUT
unsigned int j = new_len;
for (unsigned int i = count; i; i--)
{
if (!hb_in_range<uint8_t> (info[i - 1].arabic_shaping_action(), STCH_FIXED, STCH_REPEATING))
{
if (step == CUT)
{
--j;
info[j] = info[i - 1];
pos[j] = pos[i - 1];
}
continue;
}
/* Yay, justification! */
hb_position_t w_total = 0; // Total to be filled
hb_position_t w_fixed = 0; // Sum of fixed tiles
hb_position_t w_repeating = 0; // Sum of repeating tiles
int n_fixed = 0;
int n_repeating = 0;
unsigned int end = i;
while (i &&
hb_in_range<uint8_t> (info[i - 1].arabic_shaping_action(), STCH_FIXED, STCH_REPEATING))
{
i--;
hb_position_t width = font->get_glyph_h_advance (info[i].codepoint);
if (info[i].arabic_shaping_action() == STCH_FIXED)
{
w_fixed += width;
n_fixed++;
}
else
{
w_repeating += width;
n_repeating++;
}
}
unsigned int start = i;
unsigned int context = i;
while (context &&
!hb_in_range<uint8_t> (info[context - 1].arabic_shaping_action(), STCH_FIXED, STCH_REPEATING) &&
(_hb_glyph_info_is_default_ignorable (&info[context - 1]) ||
HB_ARABIC_GENERAL_CATEGORY_IS_WORD (_hb_glyph_info_get_general_category (&info[context - 1]))))
{
context--;
w_total += pos[context].x_advance;
}
i++; // Don't touch i again.
DEBUG_MSG (ARABIC, nullptr, "%s stretch at (%d,%d,%d)",
step == MEASURE ? "measuring" : "cutting", context, start, end);
DEBUG_MSG (ARABIC, nullptr, "rest of word: count=%d width %d", start - context, w_total);
DEBUG_MSG (ARABIC, nullptr, "fixed tiles: count=%d width=%d", n_fixed, w_fixed);
DEBUG_MSG (ARABIC, nullptr, "repeating tiles: count=%d width=%d", n_repeating, w_repeating);
/* Number of additional times to repeat each repeating tile. */
int n_copies = 0;
hb_position_t w_remaining = w_total - w_fixed;
if (sign * w_remaining > sign * w_repeating && sign * w_repeating > 0)
n_copies = (sign * w_remaining) / (sign * w_repeating) - 1;
/* See if we can improve the fit by adding an extra repeat and squeezing them together a bit. */
hb_position_t extra_repeat_overlap = 0;
hb_position_t shortfall = sign * w_remaining - sign * w_repeating * (n_copies + 1);
if (shortfall > 0 && n_repeating > 0)
{
++n_copies;
hb_position_t excess = (n_copies + 1) * sign * w_repeating - sign * w_remaining;
if (excess > 0)
extra_repeat_overlap = excess / (n_copies * n_repeating);
}
if (step == MEASURE)
{
extra_glyphs_needed += n_copies * n_repeating;
DEBUG_MSG (ARABIC, nullptr, "will add extra %d copies of repeating tiles", n_copies);
}
else
{
buffer->unsafe_to_break (context, end);
hb_position_t x_offset = 0;
for (unsigned int k = end; k > start; k--)
{
hb_position_t width = font->get_glyph_h_advance (info[k - 1].codepoint);
unsigned int repeat = 1;
if (info[k - 1].arabic_shaping_action() == STCH_REPEATING)
repeat += n_copies;
DEBUG_MSG (ARABIC, nullptr, "appending %d copies of glyph %d; j=%d",
repeat, info[k - 1].codepoint, j);
for (unsigned int n = 0; n < repeat; n++)
{
x_offset -= width;
if (n > 0)
x_offset += extra_repeat_overlap;
pos[k - 1].x_offset = x_offset;
/* Append copy. */
--j;
info[j] = info[k - 1];
pos[j] = pos[k - 1];
}
}
}
}
if (step == MEASURE)
{
if (unlikely (!buffer->ensure (count + extra_glyphs_needed)))
break;
}
else
{
assert (j == 0);
buffer->len = new_len;
}
}
}
static void
postprocess_glyphs_arabic (const hb_ot_shape_plan_t *plan,
hb_buffer_t *buffer,
hb_font_t *font)
{
apply_stch (plan, buffer, font);
}
/* https://www.unicode.org/reports/tr53/ */
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 */
0x08CAu, /* ARABIC SMALL HIGH FARSI YEH */
0x08CBu, /* ARABIC SMALL HIGH YEH BARREE WITH TWO DOTS BELOW */
0x08CDu, /* ARABIC SMALL HIGH ZAH */
0x08CEu, /* ARABIC LARGE ROUND DOT ABOVE */
0x08CFu, /* ARABIC LARGE ROUND DOT BELOW */
0x08D3u, /* ARABIC SMALL LOW WAW */
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_UNUSED,
hb_buffer_t *buffer,
unsigned int start,
unsigned int end)
{
hb_glyph_info_t *info = buffer->info;
DEBUG_MSG (ARABIC, buffer, "Reordering marks from %d to %d", start, end);
unsigned int i = start;
for (unsigned int cc = 220; cc <= 230; cc += 10)
{
DEBUG_MSG (ARABIC, buffer, "Looking for %d's starting at %d", cc, i);
while (i < end && info_cc(info[i]) < cc)
i++;
DEBUG_MSG (ARABIC, buffer, "Looking for %d's stopped at %d", cc, i);
if (i == end)
break;
if (info_cc(info[i]) > cc)
continue;
unsigned int j = i;
while (j < end && info_cc(info[j]) == cc && info_is_mcm (info[j]))
j++;
if (i == j)
continue;
DEBUG_MSG (ARABIC, buffer, "Found %d's from %d to %d", cc, i, j);
/* Shift it! */
DEBUG_MSG (ARABIC, buffer, "Shifting %d's: %d %d", cc, i, j);
hb_glyph_info_t temp[HB_OT_SHAPE_MAX_COMBINING_MARKS];
assert (j - i <= ARRAY_LENGTH (temp));
buffer->merge_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));
/* Renumber CC such that the reordered sequence is still sorted.
* 22 and 26 are chosen because they are smaller than all Arabic categories,
* and are folded back to 220/230 respectively during fallback mark positioning.
*
* We do this because the CGJ-handling logic in the normalizer relies on
* mark sequences having an increasing order even after this reordering.
* https://github.com/harfbuzz/harfbuzz/issues/554
* This, however, does break some obscure sequences, where the normalizer
* might compose a sequence that it should not. For example, in the seequence
* ALEF, HAMZAH, MADDAH, we should NOT try to compose ALEF+MADDAH, but with this
* renumbering, we will.
*/
unsigned int new_start = start + j - i;
unsigned int new_cc = cc == 220 ? HB_MODIFIED_COMBINING_CLASS_CCC22 : HB_MODIFIED_COMBINING_CLASS_CCC26;
while (start < new_start)
{
_hb_glyph_info_set_modified_combining_class (&info[start], new_cc);
start++;
}
i = j;
}
}
const hb_ot_shaper_t _hb_ot_shaper_arabic =
{
collect_features_arabic,
nullptr, /* override_features */
data_create_arabic,
data_destroy_arabic,
nullptr, /* preprocess_text */
postprocess_glyphs_arabic,
nullptr, /* decompose */
nullptr, /* compose */
setup_masks_arabic,
reorder_marks_arabic,
HB_TAG_NONE, /* gpos_tag */
HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT,
HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE,
true, /* fallback_position */
};
#endif
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