--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/harfbuzz/src/hb-ot-shaper-thai.cc	Mon Sep 15 11:43:07 2025 +0200
@@ -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 {
+    uint16_t u;
+    uint16_t win_pua;
+    uint16_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