diff options
Diffstat (limited to 'gfx/harfbuzz/src/hb-ot-shaper-arabic.cc')
| -rw-r--r-- | gfx/harfbuzz/src/hb-ot-shaper-arabic.cc | 755 |
1 files changed, 755 insertions, 0 deletions
diff --git a/gfx/harfbuzz/src/hb-ot-shaper-arabic.cc b/gfx/harfbuzz/src/hb-ot-shaper-arabic.cc new file mode 100644 index 0000000000..256f8f1d14 --- /dev/null +++ b/gfx/harfbuzz/src/hb-ot-shaper-arabic.cc @@ -0,0 +1,755 @@ +/* + * 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 bool +arabic_fallback_shape (const hb_ot_shape_plan_t *plan, + hb_font_t *font, + hb_buffer_t *buffer); + +static bool +record_stch (const hb_ot_shape_plan_t *plan, + hb_font_t *font, + hb_buffer_t *buffer); + +static bool +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); + return false; +} + +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 bool +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 false; +#endif + + const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data; + + if (!arabic_plan->do_fallback) + return false; + +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); + return true; +} + +/* + * 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 bool +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 false; + + /* '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; + } + return false; +} + +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 (%u,%u,%u)", + step == MEASURE ? "measuring" : "cutting", context, start, end); + DEBUG_MSG (ARABIC, nullptr, "rest of word: count=%u 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 %u copies of glyph %u; j=%u", + 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 %u to %u", start, end); + + unsigned int i = start; + for (unsigned int cc = 220; cc <= 230; cc += 10) + { + DEBUG_MSG (ARABIC, buffer, "Looking for %u's starting at %u", cc, i); + while (i < end && info_cc(info[i]) < cc) + i++; + DEBUG_MSG (ARABIC, buffer, "Looking for %u's stopped at %u", 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 %u's from %u to %u", cc, i, j); + + /* Shift it! */ + DEBUG_MSG (ARABIC, buffer, "Shifting %u's: %u %u", 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 |