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+/*
+ * Copyright © 2010,2012 Google, Inc.
+ *
+ * This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Behdad Esfahbod
+ */
+
+#include "hb-ot-shape-complex-private.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 (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 (u, 0x0E34u, 0x0E37u) ||
+ u == 0x0E47u || hb_in_range (u, 0x0E4Du, 0x0E4Eu))
+ return AV;
+ if (hb_in_range (u, 0x0E38u, 0x0E3Au))
+ return BV;
+ if (hb_in_range (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 = NULL;
+ 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)
+{
+ 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;
+
+ 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:
+ *
+ * http://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 tone mark (0E48-0E4B).
+ *
+ * <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..0EB7,0EC7..0ECE>
+ *
+ * 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_TONE_MARK(x) (hb_in_ranges ((x) & ~0x0080u, 0x0E34u, 0x0E37u, 0x0E47u, 0x0E4Eu, 0x0E31u, 0x0E31u))
+
+ buffer->clear_output ();
+ unsigned int count = buffer->len;
+ for (buffer->idx = 0; buffer->idx < count && !buffer->in_error;)
+ {
+ hb_codepoint_t u = buffer->cur().codepoint;
+ if (likely (!IS_SARA_AM (u))) {
+ buffer->next_glyph ();
+ continue;
+ }
+
+ /* Is SARA AM. Decompose and reorder. */
+ hb_codepoint_t decomposed[2] = {hb_codepoint_t (NIKHAHIT_FROM_SARA_AM (u)),
+ hb_codepoint_t (SARA_AA_FROM_SARA_AM (u))};
+ buffer->replace_glyphs (1, 2, decomposed);
+ if (unlikely (buffer->in_error))
+ return;
+
+ /* 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_TONE_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->swap_buffers ();
+
+ /* 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_complex_shaper_t _hb_ot_complex_shaper_thai =
+{
+ "thai",
+ NULL, /* collect_features */
+ NULL, /* override_features */
+ NULL, /* data_create */
+ NULL, /* data_destroy */
+ preprocess_text_thai,
+ NULL, /* postprocess_glyphs */
+ HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT,
+ NULL, /* decompose */
+ NULL, /* compose */
+ NULL, /* setup_masks */
+ NULL, /* disable_otl */
+ HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE,
+ false,/* fallback_position */
+};