394 lines
12 KiB
C++
394 lines
12 KiB
C++
/*
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* Copyright © 2010,2012 Google, Inc.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* Google Author(s): Behdad Esfahbod
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*/
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#include "hb.hh"
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#ifndef HB_NO_OT_SHAPE
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#include "hb-ot-shape-complex.hh"
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/* Thai / Lao shaper */
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/* PUA shaping */
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enum thai_consonant_type_t
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{
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NC,
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AC,
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RC,
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DC,
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NOT_CONSONANT,
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NUM_CONSONANT_TYPES = NOT_CONSONANT
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};
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static thai_consonant_type_t
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get_consonant_type (hb_codepoint_t u)
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{
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if (u == 0x0E1Bu || u == 0x0E1Du || u == 0x0E1Fu/* || u == 0x0E2Cu*/)
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return AC;
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if (u == 0x0E0Du || u == 0x0E10u)
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return RC;
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if (u == 0x0E0Eu || u == 0x0E0Fu)
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return DC;
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if (hb_in_range<hb_codepoint_t> (u, 0x0E01u, 0x0E2Eu))
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return NC;
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return NOT_CONSONANT;
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}
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enum thai_mark_type_t
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{
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AV,
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BV,
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T,
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NOT_MARK,
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NUM_MARK_TYPES = NOT_MARK
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};
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static thai_mark_type_t
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get_mark_type (hb_codepoint_t u)
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{
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if (u == 0x0E31u || hb_in_range<hb_codepoint_t> (u, 0x0E34u, 0x0E37u) ||
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u == 0x0E47u || hb_in_range<hb_codepoint_t> (u, 0x0E4Du, 0x0E4Eu))
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return AV;
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if (hb_in_range<hb_codepoint_t> (u, 0x0E38u, 0x0E3Au))
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return BV;
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if (hb_in_range<hb_codepoint_t> (u, 0x0E48u, 0x0E4Cu))
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return T;
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return NOT_MARK;
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}
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enum thai_action_t
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{
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NOP,
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SD, /* Shift combining-mark down */
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SL, /* Shift combining-mark left */
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SDL, /* Shift combining-mark down-left */
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RD /* Remove descender from base */
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};
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static hb_codepoint_t
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thai_pua_shape (hb_codepoint_t u, thai_action_t action, hb_font_t *font)
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{
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struct thai_pua_mapping_t {
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hb_codepoint_t u;
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hb_codepoint_t win_pua;
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hb_codepoint_t mac_pua;
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} const *pua_mappings = nullptr;
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static const thai_pua_mapping_t SD_mappings[] = {
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{0x0E48u, 0xF70Au, 0xF88Bu}, /* MAI EK */
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{0x0E49u, 0xF70Bu, 0xF88Eu}, /* MAI THO */
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{0x0E4Au, 0xF70Cu, 0xF891u}, /* MAI TRI */
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{0x0E4Bu, 0xF70Du, 0xF894u}, /* MAI CHATTAWA */
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{0x0E4Cu, 0xF70Eu, 0xF897u}, /* THANTHAKHAT */
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{0x0E38u, 0xF718u, 0xF89Bu}, /* SARA U */
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{0x0E39u, 0xF719u, 0xF89Cu}, /* SARA UU */
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{0x0E3Au, 0xF71Au, 0xF89Du}, /* PHINTHU */
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{0x0000u, 0x0000u, 0x0000u}
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};
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static const thai_pua_mapping_t SDL_mappings[] = {
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{0x0E48u, 0xF705u, 0xF88Cu}, /* MAI EK */
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{0x0E49u, 0xF706u, 0xF88Fu}, /* MAI THO */
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{0x0E4Au, 0xF707u, 0xF892u}, /* MAI TRI */
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{0x0E4Bu, 0xF708u, 0xF895u}, /* MAI CHATTAWA */
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{0x0E4Cu, 0xF709u, 0xF898u}, /* THANTHAKHAT */
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{0x0000u, 0x0000u, 0x0000u}
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};
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static const thai_pua_mapping_t SL_mappings[] = {
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{0x0E48u, 0xF713u, 0xF88Au}, /* MAI EK */
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{0x0E49u, 0xF714u, 0xF88Du}, /* MAI THO */
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{0x0E4Au, 0xF715u, 0xF890u}, /* MAI TRI */
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{0x0E4Bu, 0xF716u, 0xF893u}, /* MAI CHATTAWA */
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{0x0E4Cu, 0xF717u, 0xF896u}, /* THANTHAKHAT */
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{0x0E31u, 0xF710u, 0xF884u}, /* MAI HAN-AKAT */
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{0x0E34u, 0xF701u, 0xF885u}, /* SARA I */
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{0x0E35u, 0xF702u, 0xF886u}, /* SARA II */
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{0x0E36u, 0xF703u, 0xF887u}, /* SARA UE */
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{0x0E37u, 0xF704u, 0xF888u}, /* SARA UEE */
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{0x0E47u, 0xF712u, 0xF889u}, /* MAITAIKHU */
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{0x0E4Du, 0xF711u, 0xF899u}, /* NIKHAHIT */
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{0x0000u, 0x0000u, 0x0000u}
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};
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static const thai_pua_mapping_t RD_mappings[] = {
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{0x0E0Du, 0xF70Fu, 0xF89Au}, /* YO YING */
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{0x0E10u, 0xF700u, 0xF89Eu}, /* THO THAN */
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{0x0000u, 0x0000u, 0x0000u}
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};
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switch (action) {
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case NOP: return u;
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case SD: pua_mappings = SD_mappings; break;
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case SDL: pua_mappings = SDL_mappings; break;
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case SL: pua_mappings = SL_mappings; break;
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case RD: pua_mappings = RD_mappings; break;
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}
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for (; pua_mappings->u; pua_mappings++)
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if (pua_mappings->u == u)
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{
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hb_codepoint_t glyph;
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if (hb_font_get_glyph (font, pua_mappings->win_pua, 0, &glyph))
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return pua_mappings->win_pua;
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if (hb_font_get_glyph (font, pua_mappings->mac_pua, 0, &glyph))
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return pua_mappings->mac_pua;
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break;
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}
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return u;
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}
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static enum thai_above_state_t
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{ /* Cluster above looks like: */
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T0, /* ⣤ */
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T1, /* ⣼ */
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T2, /* ⣾ */
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T3, /* ⣿ */
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NUM_ABOVE_STATES
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} thai_above_start_state[NUM_CONSONANT_TYPES + 1/* For NOT_CONSONANT */] =
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{
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T0, /* NC */
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T1, /* AC */
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T0, /* RC */
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T0, /* DC */
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T3, /* NOT_CONSONANT */
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};
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static const struct thai_above_state_machine_edge_t {
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thai_action_t action;
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thai_above_state_t next_state;
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} thai_above_state_machine[NUM_ABOVE_STATES][NUM_MARK_TYPES] =
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{ /*AV*/ /*BV*/ /*T*/
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/*T0*/ {{NOP,T3}, {NOP,T0}, {SD, T3}},
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/*T1*/ {{SL, T2}, {NOP,T1}, {SDL,T2}},
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/*T2*/ {{NOP,T3}, {NOP,T2}, {SL, T3}},
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/*T3*/ {{NOP,T3}, {NOP,T3}, {NOP,T3}},
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};
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static enum thai_below_state_t
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{
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B0, /* No descender */
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B1, /* Removable descender */
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B2, /* Strict descender */
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NUM_BELOW_STATES
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} thai_below_start_state[NUM_CONSONANT_TYPES + 1/* For NOT_CONSONANT */] =
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{
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B0, /* NC */
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B0, /* AC */
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B1, /* RC */
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B2, /* DC */
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B2, /* NOT_CONSONANT */
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};
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static const struct thai_below_state_machine_edge_t {
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thai_action_t action;
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thai_below_state_t next_state;
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} thai_below_state_machine[NUM_BELOW_STATES][NUM_MARK_TYPES] =
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{ /*AV*/ /*BV*/ /*T*/
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/*B0*/ {{NOP,B0}, {NOP,B2}, {NOP, B0}},
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/*B1*/ {{NOP,B1}, {RD, B2}, {NOP, B1}},
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/*B2*/ {{NOP,B2}, {SD, B2}, {NOP, B2}},
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};
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static void
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do_thai_pua_shaping (const hb_ot_shape_plan_t *plan HB_UNUSED,
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hb_buffer_t *buffer,
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hb_font_t *font)
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{
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#ifdef HB_NO_OT_SHAPE_COMPLEX_THAI_FALLBACK
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return;
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#endif
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thai_above_state_t above_state = thai_above_start_state[NOT_CONSONANT];
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thai_below_state_t below_state = thai_below_start_state[NOT_CONSONANT];
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unsigned int base = 0;
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hb_glyph_info_t *info = buffer->info;
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unsigned int count = buffer->len;
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for (unsigned int i = 0; i < count; i++)
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{
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thai_mark_type_t mt = get_mark_type (info[i].codepoint);
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if (mt == NOT_MARK) {
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thai_consonant_type_t ct = get_consonant_type (info[i].codepoint);
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above_state = thai_above_start_state[ct];
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below_state = thai_below_start_state[ct];
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base = i;
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continue;
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}
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const thai_above_state_machine_edge_t &above_edge = thai_above_state_machine[above_state][mt];
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const thai_below_state_machine_edge_t &below_edge = thai_below_state_machine[below_state][mt];
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above_state = above_edge.next_state;
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below_state = below_edge.next_state;
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/* At least one of the above/below actions is NOP. */
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thai_action_t action = above_edge.action != NOP ? above_edge.action : below_edge.action;
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buffer->unsafe_to_break (base, i);
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if (action == RD)
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info[base].codepoint = thai_pua_shape (info[base].codepoint, action, font);
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else
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info[i].codepoint = thai_pua_shape (info[i].codepoint, action, font);
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}
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}
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static void
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preprocess_text_thai (const hb_ot_shape_plan_t *plan,
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hb_buffer_t *buffer,
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hb_font_t *font)
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{
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/* This function implements the shaping logic documented here:
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*
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* https://linux.thai.net/~thep/th-otf/shaping.html
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*
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* The first shaping rule listed there is needed even if the font has Thai
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* OpenType tables. The rest do fallback positioning based on PUA codepoints.
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* We implement that only if there exist no Thai GSUB in the font.
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*/
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/* The following is NOT specified in the MS OT Thai spec, however, it seems
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* to be what Uniscribe and other engines implement. According to Eric Muller:
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*
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* When you have a SARA AM, decompose it in NIKHAHIT + SARA AA, *and* move the
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* NIKHAHIT backwards over any tone mark (0E48-0E4B).
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*
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* <0E14, 0E4B, 0E33> -> <0E14, 0E4D, 0E4B, 0E32>
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*
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* This reordering is legit only when the NIKHAHIT comes from a SARA AM, not
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* when it's there to start with. The string <0E14, 0E4B, 0E4D> is probably
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* not what a user wanted, but the rendering is nevertheless nikhahit above
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* chattawa.
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*
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* Same for Lao.
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*
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* Note:
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*
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* Uniscribe also does some below-marks reordering. Namely, it positions U+0E3A
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* after U+0E38 and U+0E39. We do that by modifying the ccc for U+0E3A.
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* See unicode->modified_combining_class (). Lao does NOT have a U+0E3A
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* equivalent.
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*/
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/*
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* Here are the characters of significance:
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*
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* Thai Lao
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* SARA AM: U+0E33 U+0EB3
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* SARA AA: U+0E32 U+0EB2
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* Nikhahit: U+0E4D U+0ECD
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*
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* Testing shows that Uniscribe reorder the following marks:
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* Thai: <0E31,0E34..0E37,0E47..0E4E>
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* Lao: <0EB1,0EB4..0EB7,0EC7..0ECE>
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*
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* Note how the Lao versions are the same as Thai + 0x80.
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*/
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/* We only get one script at a time, so a script-agnostic implementation
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* is adequate here. */
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#define IS_SARA_AM(x) (((x) & ~0x0080u) == 0x0E33u)
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#define NIKHAHIT_FROM_SARA_AM(x) ((x) - 0x0E33u + 0x0E4Du)
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#define SARA_AA_FROM_SARA_AM(x) ((x) - 1)
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#define IS_TONE_MARK(x) (hb_in_ranges<hb_codepoint_t> ((x) & ~0x0080u, 0x0E34u, 0x0E37u, 0x0E47u, 0x0E4Eu, 0x0E31u, 0x0E31u))
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buffer->clear_output ();
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unsigned int count = buffer->len;
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for (buffer->idx = 0; buffer->idx < count /* No need for: && buffer->successful */;)
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{
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hb_codepoint_t u = buffer->cur().codepoint;
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if (likely (!IS_SARA_AM (u)))
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{
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if (unlikely (!buffer->next_glyph ())) break;
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continue;
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}
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/* Is SARA AM. Decompose and reorder. */
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(void) buffer->output_glyph (NIKHAHIT_FROM_SARA_AM (u));
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_hb_glyph_info_set_continuation (&buffer->prev());
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if (unlikely (!buffer->replace_glyph (SARA_AA_FROM_SARA_AM (u)))) break;
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/* Make Nikhahit be recognized as a ccc=0 mark when zeroing widths. */
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unsigned int end = buffer->out_len;
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_hb_glyph_info_set_general_category (&buffer->out_info[end - 2], HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK);
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/* Ok, let's see... */
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unsigned int start = end - 2;
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while (start > 0 && IS_TONE_MARK (buffer->out_info[start - 1].codepoint))
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start--;
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if (start + 2 < end)
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{
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/* Move Nikhahit (end-2) to the beginning */
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buffer->merge_out_clusters (start, end);
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hb_glyph_info_t t = buffer->out_info[end - 2];
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memmove (buffer->out_info + start + 1,
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buffer->out_info + start,
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sizeof (buffer->out_info[0]) * (end - start - 2));
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buffer->out_info[start] = t;
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}
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else
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{
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/* Since we decomposed, and NIKHAHIT is combining, merge clusters with the
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* previous cluster. */
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if (start && buffer->cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES)
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buffer->merge_out_clusters (start - 1, end);
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}
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}
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buffer->sync ();
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/* If font has Thai GSUB, we are done. */
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if (plan->props.script == HB_SCRIPT_THAI && !plan->map.found_script[0])
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do_thai_pua_shaping (plan, buffer, font);
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}
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const hb_ot_complex_shaper_t _hb_ot_complex_shaper_thai =
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{
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nullptr, /* collect_features */
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nullptr, /* override_features */
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nullptr, /* data_create */
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nullptr, /* data_destroy */
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preprocess_text_thai,
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nullptr, /* postprocess_glyphs */
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HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT,
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nullptr, /* decompose */
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nullptr, /* compose */
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nullptr, /* setup_masks */
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HB_TAG_NONE, /* gpos_tag */
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nullptr, /* reorder_marks */
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HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE,
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false,/* fallback_position */
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};
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#endif
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