diff options
Diffstat (limited to 'thirdparty/harfbuzz/src/hb-ot-shaper-thai.cc')
| -rw-r--r-- | thirdparty/harfbuzz/src/hb-ot-shaper-thai.cc | 393 |
1 files changed, 393 insertions, 0 deletions
diff --git a/thirdparty/harfbuzz/src/hb-ot-shaper-thai.cc b/thirdparty/harfbuzz/src/hb-ot-shaper-thai.cc new file mode 100644 index 0000000000..15349b1e64 --- /dev/null +++ b/thirdparty/harfbuzz/src/hb-ot-shaper-thai.cc @@ -0,0 +1,393 @@ +/* + * 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.hh" + + +/* Thai / Lao shaper */ + + +/* PUA shaping */ + + +enum thai_consonant_type_t +{ + NC, + AC, + RC, + DC, + NOT_CONSONANT, + NUM_CONSONANT_TYPES = NOT_CONSONANT +}; + +static thai_consonant_type_t +get_consonant_type (hb_codepoint_t u) +{ + if (u == 0x0E1Bu || u == 0x0E1Du || u == 0x0E1Fu/* || u == 0x0E2Cu*/) + return AC; + if (u == 0x0E0Du || u == 0x0E10u) + return RC; + if (u == 0x0E0Eu || u == 0x0E0Fu) + return DC; + if (hb_in_range<hb_codepoint_t> (u, 0x0E01u, 0x0E2Eu)) + return NC; + return NOT_CONSONANT; +} + + +enum thai_mark_type_t +{ + AV, + BV, + T, + NOT_MARK, + NUM_MARK_TYPES = NOT_MARK +}; + +static thai_mark_type_t +get_mark_type (hb_codepoint_t u) +{ + if (u == 0x0E31u || hb_in_range<hb_codepoint_t> (u, 0x0E34u, 0x0E37u) || + u == 0x0E47u || hb_in_range<hb_codepoint_t> (u, 0x0E4Du, 0x0E4Eu)) + return AV; + if (hb_in_range<hb_codepoint_t> (u, 0x0E38u, 0x0E3Au)) + return BV; + if (hb_in_range<hb_codepoint_t> (u, 0x0E48u, 0x0E4Cu)) + return T; + return NOT_MARK; +} + + +enum thai_action_t +{ + NOP, + SD, /* Shift combining-mark down */ + SL, /* Shift combining-mark left */ + SDL, /* Shift combining-mark down-left */ + RD /* Remove descender from base */ +}; + +static hb_codepoint_t +thai_pua_shape (hb_codepoint_t u, thai_action_t action, hb_font_t *font) +{ + struct thai_pua_mapping_t { + hb_codepoint_t u; + hb_codepoint_t win_pua; + hb_codepoint_t mac_pua; + } const *pua_mappings = nullptr; + static const thai_pua_mapping_t SD_mappings[] = { + {0x0E48u, 0xF70Au, 0xF88Bu}, /* MAI EK */ + {0x0E49u, 0xF70Bu, 0xF88Eu}, /* MAI THO */ + {0x0E4Au, 0xF70Cu, 0xF891u}, /* MAI TRI */ + {0x0E4Bu, 0xF70Du, 0xF894u}, /* MAI CHATTAWA */ + {0x0E4Cu, 0xF70Eu, 0xF897u}, /* THANTHAKHAT */ + {0x0E38u, 0xF718u, 0xF89Bu}, /* SARA U */ + {0x0E39u, 0xF719u, 0xF89Cu}, /* SARA UU */ + {0x0E3Au, 0xF71Au, 0xF89Du}, /* PHINTHU */ + {0x0000u, 0x0000u, 0x0000u} + }; + static const thai_pua_mapping_t SDL_mappings[] = { + {0x0E48u, 0xF705u, 0xF88Cu}, /* MAI EK */ + {0x0E49u, 0xF706u, 0xF88Fu}, /* MAI THO */ + {0x0E4Au, 0xF707u, 0xF892u}, /* MAI TRI */ + {0x0E4Bu, 0xF708u, 0xF895u}, /* MAI CHATTAWA */ + {0x0E4Cu, 0xF709u, 0xF898u}, /* THANTHAKHAT */ + {0x0000u, 0x0000u, 0x0000u} + }; + static const thai_pua_mapping_t SL_mappings[] = { + {0x0E48u, 0xF713u, 0xF88Au}, /* MAI EK */ + {0x0E49u, 0xF714u, 0xF88Du}, /* MAI THO */ + {0x0E4Au, 0xF715u, 0xF890u}, /* MAI TRI */ + {0x0E4Bu, 0xF716u, 0xF893u}, /* MAI CHATTAWA */ + {0x0E4Cu, 0xF717u, 0xF896u}, /* THANTHAKHAT */ + {0x0E31u, 0xF710u, 0xF884u}, /* MAI HAN-AKAT */ + {0x0E34u, 0xF701u, 0xF885u}, /* SARA I */ + {0x0E35u, 0xF702u, 0xF886u}, /* SARA II */ + {0x0E36u, 0xF703u, 0xF887u}, /* SARA UE */ + {0x0E37u, 0xF704u, 0xF888u}, /* SARA UEE */ + {0x0E47u, 0xF712u, 0xF889u}, /* MAITAIKHU */ + {0x0E4Du, 0xF711u, 0xF899u}, /* NIKHAHIT */ + {0x0000u, 0x0000u, 0x0000u} + }; + static const thai_pua_mapping_t RD_mappings[] = { + {0x0E0Du, 0xF70Fu, 0xF89Au}, /* YO YING */ + {0x0E10u, 0xF700u, 0xF89Eu}, /* THO THAN */ + {0x0000u, 0x0000u, 0x0000u} + }; + + switch (action) { + case NOP: return u; + case SD: pua_mappings = SD_mappings; break; + case SDL: pua_mappings = SDL_mappings; break; + case SL: pua_mappings = SL_mappings; break; + case RD: pua_mappings = RD_mappings; break; + } + for (; pua_mappings->u; pua_mappings++) + if (pua_mappings->u == u) + { + hb_codepoint_t glyph; + if (hb_font_get_glyph (font, pua_mappings->win_pua, 0, &glyph)) + return pua_mappings->win_pua; + if (hb_font_get_glyph (font, pua_mappings->mac_pua, 0, &glyph)) + return pua_mappings->mac_pua; + break; + } + return u; +} + + +static enum thai_above_state_t +{ /* Cluster above looks like: */ + T0, /* ⣤ */ + T1, /* ⣼ */ + T2, /* ⣾ */ + T3, /* ⣿ */ + NUM_ABOVE_STATES +} thai_above_start_state[NUM_CONSONANT_TYPES + 1/* For NOT_CONSONANT */] = +{ + T0, /* NC */ + T1, /* AC */ + T0, /* RC */ + T0, /* DC */ + T3, /* NOT_CONSONANT */ +}; + +static const struct thai_above_state_machine_edge_t { + thai_action_t action; + thai_above_state_t next_state; +} thai_above_state_machine[NUM_ABOVE_STATES][NUM_MARK_TYPES] = +{ /*AV*/ /*BV*/ /*T*/ +/*T0*/ {{NOP,T3}, {NOP,T0}, {SD, T3}}, +/*T1*/ {{SL, T2}, {NOP,T1}, {SDL,T2}}, +/*T2*/ {{NOP,T3}, {NOP,T2}, {SL, T3}}, +/*T3*/ {{NOP,T3}, {NOP,T3}, {NOP,T3}}, +}; + + +static enum thai_below_state_t +{ + B0, /* No descender */ + B1, /* Removable descender */ + B2, /* Strict descender */ + NUM_BELOW_STATES +} thai_below_start_state[NUM_CONSONANT_TYPES + 1/* For NOT_CONSONANT */] = +{ + B0, /* NC */ + B0, /* AC */ + B1, /* RC */ + B2, /* DC */ + B2, /* NOT_CONSONANT */ +}; + +static const struct thai_below_state_machine_edge_t { + thai_action_t action; + thai_below_state_t next_state; +} thai_below_state_machine[NUM_BELOW_STATES][NUM_MARK_TYPES] = +{ /*AV*/ /*BV*/ /*T*/ +/*B0*/ {{NOP,B0}, {NOP,B2}, {NOP, B0}}, +/*B1*/ {{NOP,B1}, {RD, B2}, {NOP, B1}}, +/*B2*/ {{NOP,B2}, {SD, B2}, {NOP, B2}}, +}; + + +static void +do_thai_pua_shaping (const hb_ot_shape_plan_t *plan HB_UNUSED, + hb_buffer_t *buffer, + hb_font_t *font) +{ +#ifdef HB_NO_OT_SHAPER_THAI_FALLBACK + return; +#endif + + thai_above_state_t above_state = thai_above_start_state[NOT_CONSONANT]; + thai_below_state_t below_state = thai_below_start_state[NOT_CONSONANT]; + unsigned int base = 0; + + hb_glyph_info_t *info = buffer->info; + unsigned int count = buffer->len; + for (unsigned int i = 0; i < count; i++) + { + thai_mark_type_t mt = get_mark_type (info[i].codepoint); + + if (mt == NOT_MARK) { + thai_consonant_type_t ct = get_consonant_type (info[i].codepoint); + above_state = thai_above_start_state[ct]; + below_state = thai_below_start_state[ct]; + base = i; + continue; + } + + const thai_above_state_machine_edge_t &above_edge = thai_above_state_machine[above_state][mt]; + const thai_below_state_machine_edge_t &below_edge = thai_below_state_machine[below_state][mt]; + above_state = above_edge.next_state; + below_state = below_edge.next_state; + + /* At least one of the above/below actions is NOP. */ + thai_action_t action = above_edge.action != NOP ? above_edge.action : below_edge.action; + + buffer->unsafe_to_break (base, i); + if (action == RD) + info[base].codepoint = thai_pua_shape (info[base].codepoint, action, font); + else + info[i].codepoint = thai_pua_shape (info[i].codepoint, action, font); + } +} + + +static void +preprocess_text_thai (const hb_ot_shape_plan_t *plan, + hb_buffer_t *buffer, + hb_font_t *font) +{ + /* This function implements the shaping logic documented here: + * + * https://linux.thai.net/~thep/th-otf/shaping.html + * + * The first shaping rule listed there is needed even if the font has Thai + * OpenType tables. The rest do fallback positioning based on PUA codepoints. + * We implement that only if there exist no Thai GSUB in the font. + */ + + /* The following is NOT specified in the MS OT Thai spec, however, it seems + * to be what Uniscribe and other engines implement. According to Eric Muller: + * + * When you have a SARA AM, decompose it in NIKHAHIT + SARA AA, *and* move the + * NIKHAHIT backwards over any above-base marks. + * + * <0E14, 0E4B, 0E33> -> <0E14, 0E4D, 0E4B, 0E32> + * + * This reordering is legit only when the NIKHAHIT comes from a SARA AM, not + * when it's there to start with. The string <0E14, 0E4B, 0E4D> is probably + * not what a user wanted, but the rendering is nevertheless nikhahit above + * chattawa. + * + * Same for Lao. + * + * Note: + * + * Uniscribe also does some below-marks reordering. Namely, it positions U+0E3A + * after U+0E38 and U+0E39. We do that by modifying the ccc for U+0E3A. + * See unicode->modified_combining_class (). Lao does NOT have a U+0E3A + * equivalent. + */ + + + /* + * Here are the characters of significance: + * + * Thai Lao + * SARA AM: U+0E33 U+0EB3 + * SARA AA: U+0E32 U+0EB2 + * Nikhahit: U+0E4D U+0ECD + * + * Testing shows that Uniscribe reorder the following marks: + * Thai: <0E31,0E34..0E37, 0E47..0E4E> + * Lao: <0EB1,0EB4..0EB7,0EBB,0EC8..0ECD> + * + * Note how the Lao versions are the same as Thai + 0x80. + */ + + /* We only get one script at a time, so a script-agnostic implementation + * is adequate here. */ +#define IS_SARA_AM(x) (((x) & ~0x0080u) == 0x0E33u) +#define NIKHAHIT_FROM_SARA_AM(x) ((x) - 0x0E33u + 0x0E4Du) +#define SARA_AA_FROM_SARA_AM(x) ((x) - 1) +#define IS_ABOVE_BASE_MARK(x) (hb_in_ranges<hb_codepoint_t> ((x) & ~0x0080u, 0x0E34u, 0x0E37u, 0x0E47u, 0x0E4Eu, 0x0E31u, 0x0E31u, 0x0E3Bu, 0x0E3Bu)) + + buffer->clear_output (); + unsigned int count = buffer->len; + for (buffer->idx = 0; buffer->idx < count /* No need for: && buffer->successful */;) + { + hb_codepoint_t u = buffer->cur().codepoint; + if (likely (!IS_SARA_AM (u))) + { + if (unlikely (!buffer->next_glyph ())) break; + continue; + } + + /* Is SARA AM. Decompose and reorder. */ + (void) buffer->output_glyph (NIKHAHIT_FROM_SARA_AM (u)); + _hb_glyph_info_set_continuation (&buffer->prev()); + if (unlikely (!buffer->replace_glyph (SARA_AA_FROM_SARA_AM (u)))) break; + + /* Make Nikhahit be recognized as a ccc=0 mark when zeroing widths. */ + unsigned int end = buffer->out_len; + _hb_glyph_info_set_general_category (&buffer->out_info[end - 2], HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK); + + /* Ok, let's see... */ + unsigned int start = end - 2; + while (start > 0 && IS_ABOVE_BASE_MARK (buffer->out_info[start - 1].codepoint)) + start--; + + if (start + 2 < end) + { + /* Move Nikhahit (end-2) to the beginning */ + buffer->merge_out_clusters (start, end); + hb_glyph_info_t t = buffer->out_info[end - 2]; + memmove (buffer->out_info + start + 1, + buffer->out_info + start, + sizeof (buffer->out_info[0]) * (end - start - 2)); + buffer->out_info[start] = t; + } + else + { + /* Since we decomposed, and NIKHAHIT is combining, merge clusters with the + * previous cluster. */ + if (start && buffer->cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES) + buffer->merge_out_clusters (start - 1, end); + } + } + buffer->sync (); + + /* If font has Thai GSUB, we are done. */ + if (plan->props.script == HB_SCRIPT_THAI && !plan->map.found_script[0]) + do_thai_pua_shaping (plan, buffer, font); +} + +const hb_ot_shaper_t _hb_ot_shaper_thai = +{ + nullptr, /* collect_features */ + nullptr, /* override_features */ + nullptr, /* data_create */ + nullptr, /* data_destroy */ + preprocess_text_thai, + nullptr, /* postprocess_glyphs */ + nullptr, /* decompose */ + nullptr, /* compose */ + nullptr, /* setup_masks */ + nullptr, /* reorder_marks */ + HB_TAG_NONE, /* gpos_tag */ + HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT, + HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE, + false,/* fallback_position */ +}; + + +#endif |