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Diffstat (limited to 'thirdparty/harfbuzz/src/hb-ot-shape-complex-indic.cc')
| -rw-r--r-- | thirdparty/harfbuzz/src/hb-ot-shape-complex-indic.cc | 1573 |
1 files changed, 1573 insertions, 0 deletions
diff --git a/thirdparty/harfbuzz/src/hb-ot-shape-complex-indic.cc b/thirdparty/harfbuzz/src/hb-ot-shape-complex-indic.cc new file mode 100644 index 0000000000..a4f2d9a847 --- /dev/null +++ b/thirdparty/harfbuzz/src/hb-ot-shape-complex-indic.cc @@ -0,0 +1,1573 @@ +/* + * Copyright © 2011,2012 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-shape-complex-indic.hh" +#include "hb-ot-shape-complex-indic-machine.hh" +#include "hb-ot-shape-complex-vowel-constraints.hh" +#include "hb-ot-layout.hh" + + +/* + * Indic shaper. + */ + + +/* + * Indic configurations. Note that we do not want to keep every single script-specific + * behavior in these tables necessarily. This should mainly be used for per-script + * properties that are cheaper keeping here, than in the code. Ie. if, say, one and + * only one script has an exception, that one script can be if'ed directly in the code, + * instead of adding a new flag in these structs. + */ + +enum base_position_t { + BASE_POS_LAST_SINHALA, + BASE_POS_LAST +}; +enum reph_position_t { + REPH_POS_AFTER_MAIN = POS_AFTER_MAIN, + REPH_POS_BEFORE_SUB = POS_BEFORE_SUB, + REPH_POS_AFTER_SUB = POS_AFTER_SUB, + REPH_POS_BEFORE_POST = POS_BEFORE_POST, + REPH_POS_AFTER_POST = POS_AFTER_POST +}; +enum reph_mode_t { + REPH_MODE_IMPLICIT, /* Reph formed out of initial Ra,H sequence. */ + REPH_MODE_EXPLICIT, /* Reph formed out of initial Ra,H,ZWJ sequence. */ + REPH_MODE_LOG_REPHA /* Encoded Repha character, needs reordering. */ +}; +enum blwf_mode_t { + BLWF_MODE_PRE_AND_POST, /* Below-forms feature applied to pre-base and post-base. */ + BLWF_MODE_POST_ONLY /* Below-forms feature applied to post-base only. */ +}; +struct indic_config_t +{ + hb_script_t script; + bool has_old_spec; + hb_codepoint_t virama; + base_position_t base_pos; + reph_position_t reph_pos; + reph_mode_t reph_mode; + blwf_mode_t blwf_mode; +}; + +static const indic_config_t indic_configs[] = +{ + /* Default. Should be first. */ + {HB_SCRIPT_INVALID, false, 0,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, + {HB_SCRIPT_DEVANAGARI,true, 0x094Du,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, + {HB_SCRIPT_BENGALI, true, 0x09CDu,BASE_POS_LAST, REPH_POS_AFTER_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, + {HB_SCRIPT_GURMUKHI, true, 0x0A4Du,BASE_POS_LAST, REPH_POS_BEFORE_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, + {HB_SCRIPT_GUJARATI, true, 0x0ACDu,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, + {HB_SCRIPT_ORIYA, true, 0x0B4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, + {HB_SCRIPT_TAMIL, true, 0x0BCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, + {HB_SCRIPT_TELUGU, true, 0x0C4Du,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_EXPLICIT, BLWF_MODE_POST_ONLY}, + {HB_SCRIPT_KANNADA, true, 0x0CCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_POST_ONLY}, + {HB_SCRIPT_MALAYALAM, true, 0x0D4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_LOG_REPHA,BLWF_MODE_PRE_AND_POST}, + {HB_SCRIPT_SINHALA, false,0x0DCAu,BASE_POS_LAST_SINHALA, + REPH_POS_AFTER_POST, REPH_MODE_EXPLICIT, BLWF_MODE_PRE_AND_POST}, +}; + + + +/* + * Indic shaper. + */ + +static const hb_ot_map_feature_t +indic_features[] = +{ + /* + * Basic features. + * These features are applied in order, one at a time, after initial_reordering. + */ + {HB_TAG('n','u','k','t'), F_GLOBAL_MANUAL_JOINERS}, + {HB_TAG('a','k','h','n'), F_GLOBAL_MANUAL_JOINERS}, + {HB_TAG('r','p','h','f'), F_MANUAL_JOINERS}, + {HB_TAG('r','k','r','f'), F_GLOBAL_MANUAL_JOINERS}, + {HB_TAG('p','r','e','f'), F_MANUAL_JOINERS}, + {HB_TAG('b','l','w','f'), F_MANUAL_JOINERS}, + {HB_TAG('a','b','v','f'), F_MANUAL_JOINERS}, + {HB_TAG('h','a','l','f'), F_MANUAL_JOINERS}, + {HB_TAG('p','s','t','f'), F_MANUAL_JOINERS}, + {HB_TAG('v','a','t','u'), F_GLOBAL_MANUAL_JOINERS}, + {HB_TAG('c','j','c','t'), F_GLOBAL_MANUAL_JOINERS}, + /* + * Other features. + * These features are applied all at once, after final_reordering + * but before clearing syllables. + * Default Bengali font in Windows for example has intermixed + * lookups for init,pres,abvs,blws features. + */ + {HB_TAG('i','n','i','t'), F_MANUAL_JOINERS}, + {HB_TAG('p','r','e','s'), F_GLOBAL_MANUAL_JOINERS}, + {HB_TAG('a','b','v','s'), F_GLOBAL_MANUAL_JOINERS}, + {HB_TAG('b','l','w','s'), F_GLOBAL_MANUAL_JOINERS}, + {HB_TAG('p','s','t','s'), F_GLOBAL_MANUAL_JOINERS}, + {HB_TAG('h','a','l','n'), F_GLOBAL_MANUAL_JOINERS}, +}; + +/* + * Must be in the same order as the indic_features array. + */ +enum { + _INDIC_NUKT, + _INDIC_AKHN, + INDIC_RPHF, + _INDIC_RKRF, + INDIC_PREF, + INDIC_BLWF, + INDIC_ABVF, + INDIC_HALF, + INDIC_PSTF, + _INDIC_VATU, + _INDIC_CJCT, + + INDIC_INIT, + _INDIC_PRES, + _INDIC_ABVS, + _INDIC_BLWS, + _INDIC_PSTS, + _INDIC_HALN, + + INDIC_NUM_FEATURES, + INDIC_BASIC_FEATURES = INDIC_INIT, /* Don't forget to update this! */ +}; + +static void +setup_syllables_indic (const hb_ot_shape_plan_t *plan, + hb_font_t *font, + hb_buffer_t *buffer); +static void +initial_reordering_indic (const hb_ot_shape_plan_t *plan, + hb_font_t *font, + hb_buffer_t *buffer); +static void +final_reordering_indic (const hb_ot_shape_plan_t *plan, + hb_font_t *font, + hb_buffer_t *buffer); + +static void +collect_features_indic (hb_ot_shape_planner_t *plan) +{ + hb_ot_map_builder_t *map = &plan->map; + + /* Do this before any lookups have been applied. */ + map->add_gsub_pause (setup_syllables_indic); + + map->enable_feature (HB_TAG('l','o','c','l')); + /* The Indic specs do not require ccmp, but we apply it here since if + * there is a use of it, it's typically at the beginning. */ + map->enable_feature (HB_TAG('c','c','m','p')); + + + unsigned int i = 0; + map->add_gsub_pause (initial_reordering_indic); + + for (; i < INDIC_BASIC_FEATURES; i++) { + map->add_feature (indic_features[i]); + map->add_gsub_pause (nullptr); + } + + map->add_gsub_pause (final_reordering_indic); + + for (; i < INDIC_NUM_FEATURES; i++) + map->add_feature (indic_features[i]); + + map->enable_feature (HB_TAG('c','a','l','t')); + map->enable_feature (HB_TAG('c','l','i','g')); + + map->add_gsub_pause (_hb_clear_syllables); +} + +static void +override_features_indic (hb_ot_shape_planner_t *plan) +{ + plan->map.disable_feature (HB_TAG('l','i','g','a')); +} + + +struct indic_shape_plan_t +{ + bool load_virama_glyph (hb_font_t *font, hb_codepoint_t *pglyph) const + { + hb_codepoint_t glyph = virama_glyph.get_relaxed (); + if (unlikely (glyph == (hb_codepoint_t) -1)) + { + if (!config->virama || !font->get_nominal_glyph (config->virama, &glyph)) + glyph = 0; + /* Technically speaking, the spec says we should apply 'locl' to virama too. + * Maybe one day... */ + + /* Our get_nominal_glyph() function needs a font, so we can't get the virama glyph + * during shape planning... Instead, overwrite it here. */ + virama_glyph.set_relaxed ((int) glyph); + } + + *pglyph = glyph; + return glyph != 0; + } + + const indic_config_t *config; + + bool is_old_spec; +#ifndef HB_NO_UNISCRIBE_BUG_COMPATIBLE + bool uniscribe_bug_compatible; +#else + static constexpr bool uniscribe_bug_compatible = false; +#endif + mutable hb_atomic_int_t virama_glyph; + + hb_indic_would_substitute_feature_t rphf; + hb_indic_would_substitute_feature_t pref; + hb_indic_would_substitute_feature_t blwf; + hb_indic_would_substitute_feature_t pstf; + hb_indic_would_substitute_feature_t vatu; + + hb_mask_t mask_array[INDIC_NUM_FEATURES]; +}; + +static void * +data_create_indic (const hb_ot_shape_plan_t *plan) +{ + indic_shape_plan_t *indic_plan = (indic_shape_plan_t *) calloc (1, sizeof (indic_shape_plan_t)); + if (unlikely (!indic_plan)) + return nullptr; + + indic_plan->config = &indic_configs[0]; + for (unsigned int i = 1; i < ARRAY_LENGTH (indic_configs); i++) + if (plan->props.script == indic_configs[i].script) { + indic_plan->config = &indic_configs[i]; + break; + } + + indic_plan->is_old_spec = indic_plan->config->has_old_spec && ((plan->map.chosen_script[0] & 0x000000FFu) != '2'); +#ifndef HB_NO_UNISCRIBE_BUG_COMPATIBLE + indic_plan->uniscribe_bug_compatible = hb_options ().uniscribe_bug_compatible; +#endif + indic_plan->virama_glyph.set_relaxed (-1); + + /* Use zero-context would_substitute() matching for new-spec of the main + * Indic scripts, and scripts with one spec only, but not for old-specs. + * The new-spec for all dual-spec scripts says zero-context matching happens. + * + * However, testing with Malayalam shows that old and new spec both allow + * context. Testing with Bengali new-spec however shows that it doesn't. + * So, the heuristic here is the way it is. It should *only* be changed, + * as we discover more cases of what Windows does. DON'T TOUCH OTHERWISE. + */ + bool zero_context = !indic_plan->is_old_spec && plan->props.script != HB_SCRIPT_MALAYALAM; + indic_plan->rphf.init (&plan->map, HB_TAG('r','p','h','f'), zero_context); + indic_plan->pref.init (&plan->map, HB_TAG('p','r','e','f'), zero_context); + indic_plan->blwf.init (&plan->map, HB_TAG('b','l','w','f'), zero_context); + indic_plan->pstf.init (&plan->map, HB_TAG('p','s','t','f'), zero_context); + indic_plan->vatu.init (&plan->map, HB_TAG('v','a','t','u'), zero_context); + + for (unsigned int i = 0; i < ARRAY_LENGTH (indic_plan->mask_array); i++) + indic_plan->mask_array[i] = (indic_features[i].flags & F_GLOBAL) ? + 0 : plan->map.get_1_mask (indic_features[i].tag); + + return indic_plan; +} + +static void +data_destroy_indic (void *data) +{ + free (data); +} + +static indic_position_t +consonant_position_from_face (const indic_shape_plan_t *indic_plan, + const hb_codepoint_t consonant, + const hb_codepoint_t virama, + hb_face_t *face) +{ + /* For old-spec, the order of glyphs is Consonant,Virama, + * whereas for new-spec, it's Virama,Consonant. However, + * some broken fonts (like Free Sans) simply copied lookups + * from old-spec to new-spec without modification. + * And oddly enough, Uniscribe seems to respect those lookups. + * Eg. in the sequence U+0924,U+094D,U+0930, Uniscribe finds + * base at 0. The font however, only has lookups matching + * 930,94D in 'blwf', not the expected 94D,930 (with new-spec + * table). As such, we simply match both sequences. Seems + * to work. + * + * Vatu is done as well, for: + * https://github.com/harfbuzz/harfbuzz/issues/1587 + */ + hb_codepoint_t glyphs[3] = {virama, consonant, virama}; + if (indic_plan->blwf.would_substitute (glyphs , 2, face) || + indic_plan->blwf.would_substitute (glyphs+1, 2, face) || + indic_plan->vatu.would_substitute (glyphs , 2, face) || + indic_plan->vatu.would_substitute (glyphs+1, 2, face)) + return POS_BELOW_C; + if (indic_plan->pstf.would_substitute (glyphs , 2, face) || + indic_plan->pstf.would_substitute (glyphs+1, 2, face)) + return POS_POST_C; + if (indic_plan->pref.would_substitute (glyphs , 2, face) || + indic_plan->pref.would_substitute (glyphs+1, 2, face)) + return POS_POST_C; + return POS_BASE_C; +} + +static void +setup_masks_indic (const hb_ot_shape_plan_t *plan HB_UNUSED, + hb_buffer_t *buffer, + hb_font_t *font HB_UNUSED) +{ + HB_BUFFER_ALLOCATE_VAR (buffer, indic_category); + HB_BUFFER_ALLOCATE_VAR (buffer, indic_position); + + /* We cannot setup masks here. We save information about characters + * and setup masks later on in a pause-callback. */ + + unsigned int count = buffer->len; + hb_glyph_info_t *info = buffer->info; + for (unsigned int i = 0; i < count; i++) + set_indic_properties (info[i]); +} + +static void +setup_syllables_indic (const hb_ot_shape_plan_t *plan HB_UNUSED, + hb_font_t *font HB_UNUSED, + hb_buffer_t *buffer) +{ + find_syllables_indic (buffer); + foreach_syllable (buffer, start, end) + buffer->unsafe_to_break (start, end); +} + +static int +compare_indic_order (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb) +{ + int a = pa->indic_position(); + int b = pb->indic_position(); + + return a < b ? -1 : a == b ? 0 : +1; +} + + + +static void +update_consonant_positions_indic (const hb_ot_shape_plan_t *plan, + hb_font_t *font, + hb_buffer_t *buffer) +{ + const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data; + + if (indic_plan->config->base_pos != BASE_POS_LAST) + return; + + hb_codepoint_t virama; + if (indic_plan->load_virama_glyph (font, &virama)) + { + hb_face_t *face = font->face; + unsigned int count = buffer->len; + hb_glyph_info_t *info = buffer->info; + for (unsigned int i = 0; i < count; i++) + if (info[i].indic_position() == POS_BASE_C) + { + hb_codepoint_t consonant = info[i].codepoint; + info[i].indic_position() = consonant_position_from_face (indic_plan, consonant, virama, face); + } + } +} + + +/* Rules from: + * https://docs.microsqoft.com/en-us/typography/script-development/devanagari */ + +static void +initial_reordering_consonant_syllable (const hb_ot_shape_plan_t *plan, + hb_face_t *face, + hb_buffer_t *buffer, + unsigned int start, unsigned int end) +{ + const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data; + hb_glyph_info_t *info = buffer->info; + + /* https://github.com/harfbuzz/harfbuzz/issues/435#issuecomment-335560167 + * // For compatibility with legacy usage in Kannada, + * // Ra+h+ZWJ must behave like Ra+ZWJ+h... + */ + if (buffer->props.script == HB_SCRIPT_KANNADA && + start + 3 <= end && + is_one_of (info[start ], FLAG (OT_Ra)) && + is_one_of (info[start+1], FLAG (OT_H)) && + is_one_of (info[start+2], FLAG (OT_ZWJ))) + { + buffer->merge_clusters (start+1, start+3); + hb_glyph_info_t tmp = info[start+1]; + info[start+1] = info[start+2]; + info[start+2] = tmp; + } + + /* 1. Find base consonant: + * + * The shaping engine finds the base consonant of the syllable, using the + * following algorithm: starting from the end of the syllable, move backwards + * until a consonant is found that does not have a below-base or post-base + * form (post-base forms have to follow below-base forms), or that is not a + * pre-base-reordering Ra, or arrive at the first consonant. The consonant + * stopped at will be the base. + * + * o If the syllable starts with Ra + Halant (in a script that has Reph) + * and has more than one consonant, Ra is excluded from candidates for + * base consonants. + */ + + unsigned int base = end; + bool has_reph = false; + + { + /* -> If the syllable starts with Ra + Halant (in a script that has Reph) + * and has more than one consonant, Ra is excluded from candidates for + * base consonants. */ + unsigned int limit = start; + if (indic_plan->mask_array[INDIC_RPHF] && + start + 3 <= end && + ( + (indic_plan->config->reph_mode == REPH_MODE_IMPLICIT && !is_joiner (info[start + 2])) || + (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT && info[start + 2].indic_category() == OT_ZWJ) + )) + { + /* See if it matches the 'rphf' feature. */ + hb_codepoint_t glyphs[3] = {info[start].codepoint, + info[start + 1].codepoint, + indic_plan->config->reph_mode == REPH_MODE_EXPLICIT ? + info[start + 2].codepoint : 0}; + if (indic_plan->rphf.would_substitute (glyphs, 2, face) || + (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT && + indic_plan->rphf.would_substitute (glyphs, 3, face))) + { + limit += 2; + while (limit < end && is_joiner (info[limit])) + limit++; + base = start; + has_reph = true; + } + } else if (indic_plan->config->reph_mode == REPH_MODE_LOG_REPHA && info[start].indic_category() == OT_Repha) + { + limit += 1; + while (limit < end && is_joiner (info[limit])) + limit++; + base = start; + has_reph = true; + } + + switch (indic_plan->config->base_pos) + { + case BASE_POS_LAST: + { + /* -> starting from the end of the syllable, move backwards */ + unsigned int i = end; + bool seen_below = false; + do { + i--; + /* -> until a consonant is found */ + if (is_consonant (info[i])) + { + /* -> that does not have a below-base or post-base form + * (post-base forms have to follow below-base forms), */ + if (info[i].indic_position() != POS_BELOW_C && + (info[i].indic_position() != POS_POST_C || seen_below)) + { + base = i; + break; + } + if (info[i].indic_position() == POS_BELOW_C) + seen_below = true; + + /* -> or that is not a pre-base-reordering Ra, + * + * IMPLEMENTATION NOTES: + * + * Our pre-base-reordering Ra's are marked POS_POST_C, so will be skipped + * by the logic above already. + */ + + /* -> or arrive at the first consonant. The consonant stopped at will + * be the base. */ + base = i; + } + else + { + /* A ZWJ after a Halant stops the base search, and requests an explicit + * half form. + * A ZWJ before a Halant, requests a subjoined form instead, and hence + * search continues. This is particularly important for Bengali + * sequence Ra,H,Ya that should form Ya-Phalaa by subjoining Ya. */ + if (start < i && + info[i].indic_category() == OT_ZWJ && + info[i - 1].indic_category() == OT_H) + break; + } + } while (i > limit); + } + break; + + case BASE_POS_LAST_SINHALA: + { + /* Sinhala base positioning is slightly different from main Indic, in that: + * 1. Its ZWJ behavior is different, + * 2. We don't need to look into the font for consonant positions. + */ + + if (!has_reph) + base = limit; + + /* Find the last base consonant that is not blocked by ZWJ. If there is + * a ZWJ right before a base consonant, that would request a subjoined form. */ + for (unsigned int i = limit; i < end; i++) + if (is_consonant (info[i])) + { + if (limit < i && info[i - 1].indic_category() == OT_ZWJ) + break; + else + base = i; + } + + /* Mark all subsequent consonants as below. */ + for (unsigned int i = base + 1; i < end; i++) + if (is_consonant (info[i])) + info[i].indic_position() = POS_BELOW_C; + } + break; + } + + /* -> If the syllable starts with Ra + Halant (in a script that has Reph) + * and has more than one consonant, Ra is excluded from candidates for + * base consonants. + * + * Only do this for unforced Reph. (ie. not for Ra,H,ZWJ. */ + if (has_reph && base == start && limit - base <= 2) { + /* Have no other consonant, so Reph is not formed and Ra becomes base. */ + has_reph = false; + } + } + + + /* 2. Decompose and reorder Matras: + * + * Each matra and any syllable modifier sign in the syllable are moved to the + * appropriate position relative to the consonant(s) in the syllable. The + * shaping engine decomposes two- or three-part matras into their constituent + * parts before any repositioning. Matra characters are classified by which + * consonant in a conjunct they have affinity for and are reordered to the + * following positions: + * + * o Before first half form in the syllable + * o After subjoined consonants + * o After post-form consonant + * o After main consonant (for above marks) + * + * IMPLEMENTATION NOTES: + * + * The normalize() routine has already decomposed matras for us, so we don't + * need to worry about that. + */ + + + /* 3. Reorder marks to canonical order: + * + * Adjacent nukta and halant or nukta and vedic sign are always repositioned + * if necessary, so that the nukta is first. + * + * IMPLEMENTATION NOTES: + * + * We don't need to do this: the normalize() routine already did this for us. + */ + + + /* Reorder characters */ + + for (unsigned int i = start; i < base; i++) + info[i].indic_position() = hb_min (POS_PRE_C, (indic_position_t) info[i].indic_position()); + + if (base < end) + info[base].indic_position() = POS_BASE_C; + + /* Mark final consonants. A final consonant is one appearing after a matra. + * Happens in Sinhala. */ + for (unsigned int i = base + 1; i < end; i++) + if (info[i].indic_category() == OT_M) { + for (unsigned int j = i + 1; j < end; j++) + if (is_consonant (info[j])) { + info[j].indic_position() = POS_FINAL_C; + break; + } + break; + } + + /* Handle beginning Ra */ + if (has_reph) + info[start].indic_position() = POS_RA_TO_BECOME_REPH; + + /* For old-style Indic script tags, move the first post-base Halant after + * last consonant. + * + * Reports suggest that in some scripts Uniscribe does this only if there + * is *not* a Halant after last consonant already. We know that is the + * case for Kannada, while it reorders unconditionally in other scripts, + * eg. Malayalam, Bengali, and Devanagari. We don't currently know about + * other scripts, so we block Kannada. + * + * Kannada test case: + * U+0C9A,U+0CCD,U+0C9A,U+0CCD + * With some versions of Lohit Kannada. + * https://bugs.freedesktop.org/show_bug.cgi?id=59118 + * + * Malayalam test case: + * U+0D38,U+0D4D,U+0D31,U+0D4D,U+0D31,U+0D4D + * With lohit-ttf-20121122/Lohit-Malayalam.ttf + * + * Bengali test case: + * U+0998,U+09CD,U+09AF,U+09CD + * With Windows XP vrinda.ttf + * https://github.com/harfbuzz/harfbuzz/issues/1073 + * + * Devanagari test case: + * U+091F,U+094D,U+0930,U+094D + * With chandas.ttf + * https://github.com/harfbuzz/harfbuzz/issues/1071 + */ + if (indic_plan->is_old_spec) + { + bool disallow_double_halants = buffer->props.script == HB_SCRIPT_KANNADA; + for (unsigned int i = base + 1; i < end; i++) + if (info[i].indic_category() == OT_H) + { + unsigned int j; + for (j = end - 1; j > i; j--) + if (is_consonant (info[j]) || + (disallow_double_halants && info[j].indic_category() == OT_H)) + break; + if (info[j].indic_category() != OT_H && j > i) { + /* Move Halant to after last consonant. */ + hb_glyph_info_t t = info[i]; + memmove (&info[i], &info[i + 1], (j - i) * sizeof (info[0])); + info[j] = t; + } + break; + } + } + + /* Attach misc marks to previous char to move with them. */ + { + indic_position_t last_pos = POS_START; + for (unsigned int i = start; i < end; i++) + { + if ((FLAG_UNSAFE (info[i].indic_category()) & (JOINER_FLAGS | FLAG (OT_N) | FLAG (OT_RS) | MEDIAL_FLAGS | FLAG (OT_H)))) + { + info[i].indic_position() = last_pos; + if (unlikely (info[i].indic_category() == OT_H && + info[i].indic_position() == POS_PRE_M)) + { + /* + * Uniscribe doesn't move the Halant with Left Matra. + * TEST: U+092B,U+093F,U+094DE + * We follow. This is important for the Sinhala + * U+0DDA split matra since it decomposes to U+0DD9,U+0DCA + * where U+0DD9 is a left matra and U+0DCA is the virama. + * We don't want to move the virama with the left matra. + * TEST: U+0D9A,U+0DDA + */ + for (unsigned int j = i; j > start; j--) + if (info[j - 1].indic_position() != POS_PRE_M) { + info[i].indic_position() = info[j - 1].indic_position(); + break; + } + } + } else if (info[i].indic_position() != POS_SMVD) { + last_pos = (indic_position_t) info[i].indic_position(); + } + } + } + /* For post-base consonants let them own anything before them + * since the last consonant or matra. */ + { + unsigned int last = base; + for (unsigned int i = base + 1; i < end; i++) + if (is_consonant (info[i])) + { + for (unsigned int j = last + 1; j < i; j++) + if (info[j].indic_position() < POS_SMVD) + info[j].indic_position() = info[i].indic_position(); + last = i; + } else if (info[i].indic_category() == OT_M) + last = i; + } + + + { + /* Use syllable() for sort accounting temporarily. */ + unsigned int syllable = info[start].syllable(); + for (unsigned int i = start; i < end; i++) + info[i].syllable() = i - start; + + /* Sit tight, rock 'n roll! */ + hb_stable_sort (info + start, end - start, compare_indic_order); + /* Find base again */ + base = end; + for (unsigned int i = start; i < end; i++) + if (info[i].indic_position() == POS_BASE_C) + { + base = i; + break; + } + /* Things are out-of-control for post base positions, they may shuffle + * around like crazy. In old-spec mode, we move halants around, so in + * that case merge all clusters after base. Otherwise, check the sort + * order and merge as needed. + * For pre-base stuff, we handle cluster issues in final reordering. + * + * We could use buffer->sort() for this, if there was no special + * reordering of pre-base stuff happening later... + * We don't want to merge_clusters all of that, which buffer->sort() + * would. Here's a concrete example: + * + * Assume there's a pre-base consonant and explicit Halant before base, + * followed by a prebase-reordering (left) Matra: + * + * C,H,ZWNJ,B,M + * + * At this point in reordering we would have: + * + * M,C,H,ZWNJ,B + * + * whereas in final reordering we will bring the Matra closer to Base: + * + * C,H,ZWNJ,M,B + * + * That's why we don't want to merge-clusters anything before the Base + * at this point. But if something moved from after Base to before it, + * we should merge clusters from base to them. In final-reordering, we + * only move things around before base, and merge-clusters up to base. + * These two merge-clusters from the two sides of base will interlock + * to merge things correctly. See: + * https://github.com/harfbuzz/harfbuzz/issues/2272 + */ + if (indic_plan->is_old_spec || end - start > 127) + buffer->merge_clusters (base, end); + else + { + /* Note! syllable() is a one-byte field. */ + for (unsigned int i = base; i < end; i++) + if (info[i].syllable() != 255) + { + unsigned int min = i; + unsigned int max = i; + unsigned int j = start + info[i].syllable(); + while (j != i) + { + min = hb_min (min, j); + max = hb_max (max, j); + unsigned int next = start + info[j].syllable(); + info[j].syllable() = 255; /* So we don't process j later again. */ + j = next; + } + buffer->merge_clusters (hb_max (base, min), max + 1); + } + } + + /* Put syllable back in. */ + for (unsigned int i = start; i < end; i++) + info[i].syllable() = syllable; + } + + /* Setup masks now */ + + { + hb_mask_t mask; + + /* Reph */ + for (unsigned int i = start; i < end && info[i].indic_position() == POS_RA_TO_BECOME_REPH; i++) + info[i].mask |= indic_plan->mask_array[INDIC_RPHF]; + + /* Pre-base */ + mask = indic_plan->mask_array[INDIC_HALF]; + if (!indic_plan->is_old_spec && + indic_plan->config->blwf_mode == BLWF_MODE_PRE_AND_POST) + mask |= indic_plan->mask_array[INDIC_BLWF]; + for (unsigned int i = start; i < base; i++) + info[i].mask |= mask; + /* Base */ + mask = 0; + if (base < end) + info[base].mask |= mask; + /* Post-base */ + mask = indic_plan->mask_array[INDIC_BLWF] | + indic_plan->mask_array[INDIC_ABVF] | + indic_plan->mask_array[INDIC_PSTF]; + for (unsigned int i = base + 1; i < end; i++) + info[i].mask |= mask; + } + + if (indic_plan->is_old_spec && + buffer->props.script == HB_SCRIPT_DEVANAGARI) + { + /* Old-spec eye-lash Ra needs special handling. From the + * spec: + * + * "The feature 'below-base form' is applied to consonants + * having below-base forms and following the base consonant. + * The exception is vattu, which may appear below half forms + * as well as below the base glyph. The feature 'below-base + * form' will be applied to all such occurrences of Ra as well." + * + * Test case: U+0924,U+094D,U+0930,U+094d,U+0915 + * with Sanskrit 2003 font. + * + * However, note that Ra,Halant,ZWJ is the correct way to + * request eyelash form of Ra, so we wouldbn't inhibit it + * in that sequence. + * + * Test case: U+0924,U+094D,U+0930,U+094d,U+200D,U+0915 + */ + for (unsigned int i = start; i + 1 < base; i++) + if (info[i ].indic_category() == OT_Ra && + info[i+1].indic_category() == OT_H && + (i + 2 == base || + info[i+2].indic_category() != OT_ZWJ)) + { + info[i ].mask |= indic_plan->mask_array[INDIC_BLWF]; + info[i+1].mask |= indic_plan->mask_array[INDIC_BLWF]; + } + } + + unsigned int pref_len = 2; + if (indic_plan->mask_array[INDIC_PREF] && base + pref_len < end) + { + /* Find a Halant,Ra sequence and mark it for pre-base-reordering processing. */ + for (unsigned int i = base + 1; i + pref_len - 1 < end; i++) { + hb_codepoint_t glyphs[2]; + for (unsigned int j = 0; j < pref_len; j++) + glyphs[j] = info[i + j].codepoint; + if (indic_plan->pref.would_substitute (glyphs, pref_len, face)) + { + for (unsigned int j = 0; j < pref_len; j++) + info[i++].mask |= indic_plan->mask_array[INDIC_PREF]; + break; + } + } + } + + /* Apply ZWJ/ZWNJ effects */ + for (unsigned int i = start + 1; i < end; i++) + if (is_joiner (info[i])) { + bool non_joiner = info[i].indic_category() == OT_ZWNJ; + unsigned int j = i; + + do { + j--; + + /* ZWJ/ZWNJ should disable CJCT. They do that by simply + * being there, since we don't skip them for the CJCT + * feature (ie. F_MANUAL_ZWJ) */ + + /* A ZWNJ disables HALF. */ + if (non_joiner) + info[j].mask &= ~indic_plan->mask_array[INDIC_HALF]; + + } while (j > start && !is_consonant (info[j])); + } +} + +static void +initial_reordering_standalone_cluster (const hb_ot_shape_plan_t *plan, + hb_face_t *face, + hb_buffer_t *buffer, + unsigned int start, unsigned int end) +{ + /* We treat placeholder/dotted-circle as if they are consonants, so we + * should just chain. Only if not in compatibility mode that is... */ + + const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data; + if (indic_plan->uniscribe_bug_compatible) + { + /* For dotted-circle, this is what Uniscribe does: + * If dotted-circle is the last glyph, it just does nothing. + * Ie. It doesn't form Reph. */ + if (buffer->info[end - 1].indic_category() == OT_DOTTEDCIRCLE) + return; + } + + initial_reordering_consonant_syllable (plan, face, buffer, start, end); +} + +static void +initial_reordering_syllable_indic (const hb_ot_shape_plan_t *plan, + hb_face_t *face, + hb_buffer_t *buffer, + unsigned int start, unsigned int end) +{ + indic_syllable_type_t syllable_type = (indic_syllable_type_t) (buffer->info[start].syllable() & 0x0F); + switch (syllable_type) + { + case indic_vowel_syllable: /* We made the vowels look like consonants. So let's call the consonant logic! */ + case indic_consonant_syllable: + initial_reordering_consonant_syllable (plan, face, buffer, start, end); + break; + + case indic_broken_cluster: /* We already inserted dotted-circles, so just call the standalone_cluster. */ + case indic_standalone_cluster: + initial_reordering_standalone_cluster (plan, face, buffer, start, end); + break; + + case indic_symbol_cluster: + case indic_non_indic_cluster: + break; + } +} + +static void +initial_reordering_indic (const hb_ot_shape_plan_t *plan, + hb_font_t *font, + hb_buffer_t *buffer) +{ + if (!buffer->message (font, "start reordering indic initial")) + return; + + update_consonant_positions_indic (plan, font, buffer); + hb_syllabic_insert_dotted_circles (font, buffer, + indic_broken_cluster, + OT_DOTTEDCIRCLE, + OT_Repha); + + foreach_syllable (buffer, start, end) + initial_reordering_syllable_indic (plan, font->face, buffer, start, end); + + (void) buffer->message (font, "end reordering indic initial"); +} + +static void +final_reordering_syllable_indic (const hb_ot_shape_plan_t *plan, + hb_buffer_t *buffer, + unsigned int start, unsigned int end) +{ + const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data; + hb_glyph_info_t *info = buffer->info; + + + /* This function relies heavily on halant glyphs. Lots of ligation + * and possibly multiple substitutions happened prior to this + * phase, and that might have messed up our properties. Recover + * from a particular case of that where we're fairly sure that a + * class of OT_H is desired but has been lost. */ + /* We don't call load_virama_glyph(), since we know it's already + * loaded. */ + hb_codepoint_t virama_glyph = indic_plan->virama_glyph.get_relaxed (); + if (virama_glyph) + { + for (unsigned int i = start; i < end; i++) + if (info[i].codepoint == virama_glyph && + _hb_glyph_info_ligated (&info[i]) && + _hb_glyph_info_multiplied (&info[i])) + { + /* This will make sure that this glyph passes is_halant() test. */ + info[i].indic_category() = OT_H; + _hb_glyph_info_clear_ligated_and_multiplied (&info[i]); + } + } + + + /* 4. Final reordering: + * + * After the localized forms and basic shaping forms GSUB features have been + * applied (see below), the shaping engine performs some final glyph + * reordering before applying all the remaining font features to the entire + * syllable. + */ + + bool try_pref = !!indic_plan->mask_array[INDIC_PREF]; + + /* Find base again */ + unsigned int base; + for (base = start; base < end; base++) + if (info[base].indic_position() >= POS_BASE_C) + { + if (try_pref && base + 1 < end) + { + for (unsigned int i = base + 1; i < end; i++) + if ((info[i].mask & indic_plan->mask_array[INDIC_PREF]) != 0) + { + if (!(_hb_glyph_info_substituted (&info[i]) && + _hb_glyph_info_ligated_and_didnt_multiply (&info[i]))) + { + /* Ok, this was a 'pref' candidate but didn't form any. + * Base is around here... */ + base = i; + while (base < end && is_halant (info[base])) + base++; + info[base].indic_position() = POS_BASE_C; + + try_pref = false; + } + break; + } + } + /* For Malayalam, skip over unformed below- (but NOT post-) forms. */ + if (buffer->props.script == HB_SCRIPT_MALAYALAM) + { + for (unsigned int i = base + 1; i < end; i++) + { + while (i < end && is_joiner (info[i])) + i++; + if (i == end || !is_halant (info[i])) + break; + i++; /* Skip halant. */ + while (i < end && is_joiner (info[i])) + i++; + if (i < end && is_consonant (info[i]) && info[i].indic_position() == POS_BELOW_C) + { + base = i; + info[base].indic_position() = POS_BASE_C; + } + } + } + + if (start < base && info[base].indic_position() > POS_BASE_C) + base--; + break; + } + if (base == end && start < base && + is_one_of (info[base - 1], FLAG (OT_ZWJ))) + base--; + if (base < end) + while (start < base && + is_one_of (info[base], (FLAG (OT_N) | FLAG (OT_H)))) + base--; + + + /* o Reorder matras: + * + * If a pre-base matra character had been reordered before applying basic + * features, the glyph can be moved closer to the main consonant based on + * whether half-forms had been formed. Actual position for the matra is + * defined as “after last standalone halant glyph, after initial matra + * position and before the main consonant”. If ZWJ or ZWNJ follow this + * halant, position is moved after it. + * + * IMPLEMENTATION NOTES: + * + * It looks like the last sentence is wrong. Testing, with Windows 7 Uniscribe + * and Devanagari shows that the behavior is best described as: + * + * "If ZWJ follows this halant, matra is NOT repositioned after this halant. + * If ZWNJ follows this halant, position is moved after it." + * + * Test case, with Adobe Devanagari or Nirmala UI: + * + * U+091F,U+094D,U+200C,U+092F,U+093F + * (Matra moves to the middle, after ZWNJ.) + * + * U+091F,U+094D,U+200D,U+092F,U+093F + * (Matra does NOT move, stays to the left.) + * + * https://github.com/harfbuzz/harfbuzz/issues/1070 + */ + + if (start + 1 < end && start < base) /* Otherwise there can't be any pre-base matra characters. */ + { + /* If we lost track of base, alas, position before last thingy. */ + unsigned int new_pos = base == end ? base - 2 : base - 1; + + /* Malayalam / Tamil do not have "half" forms or explicit virama forms. + * The glyphs formed by 'half' are Chillus or ligated explicit viramas. + * We want to position matra after them. + */ + if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL) + { + search: + while (new_pos > start && + !(is_one_of (info[new_pos], (FLAG (OT_M) | FLAG (OT_H))))) + new_pos--; + + /* If we found no Halant we are done. + * Otherwise only proceed if the Halant does + * not belong to the Matra itself! */ + if (is_halant (info[new_pos]) && + info[new_pos].indic_position() != POS_PRE_M) + { +#if 0 // See comment above + /* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */ + if (new_pos + 1 < end && is_joiner (info[new_pos + 1])) + new_pos++; +#endif + if (new_pos + 1 < end) + { + /* -> If ZWJ follows this halant, matra is NOT repositioned after this halant. */ + if (info[new_pos + 1].indic_category() == OT_ZWJ) + { + /* Keep searching. */ + if (new_pos > start) + { + new_pos--; + goto search; + } + } + /* -> If ZWNJ follows this halant, position is moved after it. + * + * IMPLEMENTATION NOTES: + * + * This is taken care of by the state-machine. A Halant,ZWNJ is a terminating + * sequence for a consonant syllable; any pre-base matras occurring after it + * will belong to the subsequent syllable. + */ + } + } + else + new_pos = start; /* No move. */ + } + + if (start < new_pos && info[new_pos].indic_position () != POS_PRE_M) + { + /* Now go see if there's actually any matras... */ + for (unsigned int i = new_pos; i > start; i--) + if (info[i - 1].indic_position () == POS_PRE_M) + { + unsigned int old_pos = i - 1; + if (old_pos < base && base <= new_pos) /* Shouldn't actually happen. */ + base--; + + hb_glyph_info_t tmp = info[old_pos]; + memmove (&info[old_pos], &info[old_pos + 1], (new_pos - old_pos) * sizeof (info[0])); + info[new_pos] = tmp; + + /* Note: this merge_clusters() is intentionally *after* the reordering. + * Indic matra reordering is special and tricky... */ + buffer->merge_clusters (new_pos, hb_min (end, base + 1)); + + new_pos--; + } + } else { + for (unsigned int i = start; i < base; i++) + if (info[i].indic_position () == POS_PRE_M) { + buffer->merge_clusters (i, hb_min (end, base + 1)); + break; + } + } + } + + + /* o Reorder reph: + * + * Reph’s original position is always at the beginning of the syllable, + * (i.e. it is not reordered at the character reordering stage). However, + * it will be reordered according to the basic-forms shaping results. + * Possible positions for reph, depending on the script, are; after main, + * before post-base consonant forms, and after post-base consonant forms. + */ + + /* Two cases: + * + * - If repha is encoded as a sequence of characters (Ra,H or Ra,H,ZWJ), then + * we should only move it if the sequence ligated to the repha form. + * + * - If repha is encoded separately and in the logical position, we should only + * move it if it did NOT ligate. If it ligated, it's probably the font trying + * to make it work without the reordering. + */ + if (start + 1 < end && + info[start].indic_position() == POS_RA_TO_BECOME_REPH && + ((info[start].indic_category() == OT_Repha) ^ + _hb_glyph_info_ligated_and_didnt_multiply (&info[start]))) + { + unsigned int new_reph_pos; + reph_position_t reph_pos = indic_plan->config->reph_pos; + + /* 1. If reph should be positioned after post-base consonant forms, + * proceed to step 5. + */ + if (reph_pos == REPH_POS_AFTER_POST) + { + goto reph_step_5; + } + + /* 2. If the reph repositioning class is not after post-base: target + * position is after the first explicit halant glyph between the + * first post-reph consonant and last main consonant. If ZWJ or ZWNJ + * are following this halant, position is moved after it. If such + * position is found, this is the target position. Otherwise, + * proceed to the next step. + * + * Note: in old-implementation fonts, where classifications were + * fixed in shaping engine, there was no case where reph position + * will be found on this step. + */ + { + new_reph_pos = start + 1; + while (new_reph_pos < base && !is_halant (info[new_reph_pos])) + new_reph_pos++; + + if (new_reph_pos < base && is_halant (info[new_reph_pos])) + { + /* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */ + if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1])) + new_reph_pos++; + goto reph_move; + } + } + + /* 3. If reph should be repositioned after the main consonant: find the + * first consonant not ligated with main, or find the first + * consonant that is not a potential pre-base-reordering Ra. + */ + if (reph_pos == REPH_POS_AFTER_MAIN) + { + new_reph_pos = base; + while (new_reph_pos + 1 < end && info[new_reph_pos + 1].indic_position() <= POS_AFTER_MAIN) + new_reph_pos++; + if (new_reph_pos < end) + goto reph_move; + } + + /* 4. If reph should be positioned before post-base consonant, find + * first post-base classified consonant not ligated with main. If no + * consonant is found, the target position should be before the + * first matra, syllable modifier sign or vedic sign. + */ + /* This is our take on what step 4 is trying to say (and failing, BADLY). */ + if (reph_pos == REPH_POS_AFTER_SUB) + { + new_reph_pos = base; + while (new_reph_pos + 1 < end && + !( FLAG_UNSAFE (info[new_reph_pos + 1].indic_position()) & (FLAG (POS_POST_C) | FLAG (POS_AFTER_POST) | FLAG (POS_SMVD)))) + new_reph_pos++; + if (new_reph_pos < end) + goto reph_move; + } + + /* 5. If no consonant is found in steps 3 or 4, move reph to a position + * immediately before the first post-base matra, syllable modifier + * sign or vedic sign that has a reordering class after the intended + * reph position. For example, if the reordering position for reph + * is post-main, it will skip above-base matras that also have a + * post-main position. + */ + reph_step_5: + { + /* Copied from step 2. */ + new_reph_pos = start + 1; + while (new_reph_pos < base && !is_halant (info[new_reph_pos])) + new_reph_pos++; + + if (new_reph_pos < base && is_halant (info[new_reph_pos])) + { + /* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */ + if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1])) + new_reph_pos++; + goto reph_move; + } + } + /* See https://github.com/harfbuzz/harfbuzz/issues/2298#issuecomment-615318654 */ + + /* 6. Otherwise, reorder reph to the end of the syllable. + */ + { + new_reph_pos = end - 1; + while (new_reph_pos > start && info[new_reph_pos].indic_position() == POS_SMVD) + new_reph_pos--; + + /* + * If the Reph is to be ending up after a Matra,Halant sequence, + * position it before that Halant so it can interact with the Matra. + * However, if it's a plain Consonant,Halant we shouldn't do that. + * Uniscribe doesn't do this. + * TEST: U+0930,U+094D,U+0915,U+094B,U+094D + */ + if (!indic_plan->uniscribe_bug_compatible && + unlikely (is_halant (info[new_reph_pos]))) + { + for (unsigned int i = base + 1; i < new_reph_pos; i++) + if (info[i].indic_category() == OT_M) { + /* Ok, got it. */ + new_reph_pos--; + } + } + + goto reph_move; + } + + reph_move: + { + /* Move */ + buffer->merge_clusters (start, new_reph_pos + 1); + hb_glyph_info_t reph = info[start]; + memmove (&info[start], &info[start + 1], (new_reph_pos - start) * sizeof (info[0])); + info[new_reph_pos] = reph; + + if (start < base && base <= new_reph_pos) + base--; + } + } + + + /* o Reorder pre-base-reordering consonants: + * + * If a pre-base-reordering consonant is found, reorder it according to + * the following rules: + */ + + if (try_pref && base + 1 < end) /* Otherwise there can't be any pre-base-reordering Ra. */ + { + for (unsigned int i = base + 1; i < end; i++) + if ((info[i].mask & indic_plan->mask_array[INDIC_PREF]) != 0) + { + /* 1. Only reorder a glyph produced by substitution during application + * of the <pref> feature. (Note that a font may shape a Ra consonant with + * the feature generally but block it in certain contexts.) + */ + /* Note: We just check that something got substituted. We don't check that + * the <pref> feature actually did it... + * + * Reorder pref only if it ligated. */ + if (_hb_glyph_info_ligated_and_didnt_multiply (&info[i])) + { + /* + * 2. Try to find a target position the same way as for pre-base matra. + * If it is found, reorder pre-base consonant glyph. + * + * 3. If position is not found, reorder immediately before main + * consonant. + */ + + unsigned int new_pos = base; + /* Malayalam / Tamil do not have "half" forms or explicit virama forms. + * The glyphs formed by 'half' are Chillus or ligated explicit viramas. + * We want to position matra after them. + */ + if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL) + { + while (new_pos > start && + !(is_one_of (info[new_pos - 1], FLAG(OT_M) | FLAG (OT_H)))) + new_pos--; + } + + if (new_pos > start && is_halant (info[new_pos - 1])) + { + /* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */ + if (new_pos < end && is_joiner (info[new_pos])) + new_pos++; + } + + { + unsigned int old_pos = i; + + buffer->merge_clusters (new_pos, old_pos + 1); + hb_glyph_info_t tmp = info[old_pos]; + memmove (&info[new_pos + 1], &info[new_pos], (old_pos - new_pos) * sizeof (info[0])); + info[new_pos] = tmp; + + if (new_pos <= base && base < old_pos) + base++; + } + } + + break; + } + } + + + /* Apply 'init' to the Left Matra if it's a word start. */ + if (info[start].indic_position () == POS_PRE_M) + { + if (!start || + !(FLAG_UNSAFE (_hb_glyph_info_get_general_category (&info[start - 1])) & + FLAG_RANGE (HB_UNICODE_GENERAL_CATEGORY_FORMAT, HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK))) + info[start].mask |= indic_plan->mask_array[INDIC_INIT]; + else + buffer->unsafe_to_break (start - 1, start + 1); + } + + + /* + * Finish off the clusters and go home! + */ + if (indic_plan->uniscribe_bug_compatible) + { + switch ((hb_tag_t) plan->props.script) + { + case HB_SCRIPT_TAMIL: + case HB_SCRIPT_SINHALA: + break; + + default: + /* Uniscribe merges the entire syllable into a single cluster... Except for Tamil & Sinhala. + * This means, half forms are submerged into the main consonant's cluster. + * This is unnecessary, and makes cursor positioning harder, but that's what + * Uniscribe does. */ + buffer->merge_clusters (start, end); + break; + } + } +} + + +static void +final_reordering_indic (const hb_ot_shape_plan_t *plan, + hb_font_t *font HB_UNUSED, + hb_buffer_t *buffer) +{ + unsigned int count = buffer->len; + if (unlikely (!count)) return; + + if (buffer->message (font, "start reordering indic final")) { + foreach_syllable (buffer, start, end) + final_reordering_syllable_indic (plan, buffer, start, end); + (void) buffer->message (font, "end reordering indic final"); + } + + HB_BUFFER_DEALLOCATE_VAR (buffer, indic_category); + HB_BUFFER_DEALLOCATE_VAR (buffer, indic_position); +} + + +static void +preprocess_text_indic (const hb_ot_shape_plan_t *plan, + hb_buffer_t *buffer, + hb_font_t *font) +{ + _hb_preprocess_text_vowel_constraints (plan, buffer, font); +} + +static bool +decompose_indic (const hb_ot_shape_normalize_context_t *c, + hb_codepoint_t ab, + hb_codepoint_t *a, + hb_codepoint_t *b) +{ + switch (ab) + { + /* Don't decompose these. */ + case 0x0931u : return false; /* DEVANAGARI LETTER RRA */ + // https://github.com/harfbuzz/harfbuzz/issues/779 + case 0x09DCu : return false; /* BENGALI LETTER RRA */ + case 0x09DDu : return false; /* BENGALI LETTER RHA */ + case 0x0B94u : return false; /* TAMIL LETTER AU */ + + + /* + * Decompose split matras that don't have Unicode decompositions. + */ + +#if 0 + /* Gujarati */ + /* This one has no decomposition in Unicode, but needs no decomposition either. */ + /* case 0x0AC9u : return false; */ + + /* Oriya */ + case 0x0B57u : *a = no decomp, -> RIGHT; return true; +#endif + } + + if ((ab == 0x0DDAu || hb_in_range<hb_codepoint_t> (ab, 0x0DDCu, 0x0DDEu))) + { + /* + * Sinhala split matras... Let the fun begin. + * + * These four characters have Unicode decompositions. However, Uniscribe + * decomposes them "Khmer-style", that is, it uses the character itself to + * get the second half. The first half of all four decompositions is always + * U+0DD9. + * + * Now, there are buggy fonts, namely, the widely used lklug.ttf, that are + * broken with Uniscribe. But we need to support them. As such, we only + * do the Uniscribe-style decomposition if the character is transformed into + * its "sec.half" form by the 'pstf' feature. Otherwise, we fall back to + * Unicode decomposition. + * + * Note that we can't unconditionally use Unicode decomposition. That would + * break some other fonts, that are designed to work with Uniscribe, and + * don't have positioning features for the Unicode-style decomposition. + * + * Argh... + * + * The Uniscribe behavior is now documented in the newly published Sinhala + * spec in 2012: + * + * https://docs.microsoft.com/en-us/typography/script-development/sinhala#shaping + */ + + + const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) c->plan->data; + hb_codepoint_t glyph; + if (indic_plan->uniscribe_bug_compatible || + (c->font->get_nominal_glyph (ab, &glyph) && + indic_plan->pstf.would_substitute (&glyph, 1, c->font->face))) + { + /* Ok, safe to use Uniscribe-style decomposition. */ + *a = 0x0DD9u; + *b = ab; + return true; + } + } + + return (bool) c->unicode->decompose (ab, a, b); +} + +static bool +compose_indic (const hb_ot_shape_normalize_context_t *c, + hb_codepoint_t a, + hb_codepoint_t b, + hb_codepoint_t *ab) +{ + /* Avoid recomposing split matras. */ + if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a))) + return false; + + /* Composition-exclusion exceptions that we want to recompose. */ + if (a == 0x09AFu && b == 0x09BCu) { *ab = 0x09DFu; return true; } + + return (bool) c->unicode->compose (a, b, ab); +} + + +const hb_ot_complex_shaper_t _hb_ot_complex_shaper_indic = +{ + collect_features_indic, + override_features_indic, + data_create_indic, + data_destroy_indic, + preprocess_text_indic, + nullptr, /* postprocess_glyphs */ + HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT, + decompose_indic, + compose_indic, + setup_masks_indic, + HB_TAG_NONE, /* gpos_tag */ + nullptr, /* reorder_marks */ + HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE, + false, /* fallback_position */ +}; + + +#endif |