--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/harfbuzz/src/hb-ot-shaper-khmer.cc	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,387 @@
+/*
+ * 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-shaper-khmer-machine.hh"
+#include "hb-ot-shaper-indic.hh"
+#include "hb-ot-layout.hh"
+
+
+/*
+ * Khmer shaper.
+ */
+
+
+static const hb_ot_map_feature_t
+khmer_features[] =
+{
+  /*
+   * Basic features.
+   * These features are applied all at once, before reordering, constrained
+   * to the syllable.
+   */
+  {HB_TAG('p','r','e','f'), F_MANUAL_JOINERS | F_PER_SYLLABLE},
+  {HB_TAG('b','l','w','f'), F_MANUAL_JOINERS | F_PER_SYLLABLE},
+  {HB_TAG('a','b','v','f'), F_MANUAL_JOINERS | F_PER_SYLLABLE},
+  {HB_TAG('p','s','t','f'), F_MANUAL_JOINERS | F_PER_SYLLABLE},
+  {HB_TAG('c','f','a','r'), F_MANUAL_JOINERS | F_PER_SYLLABLE},
+  /*
+   * Other features.
+   * These features are applied all at once after clearing syllables.
+   */
+  {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},
+};
+
+/*
+ * Must be in the same order as the khmer_features array.
+ */
+enum {
+  KHMER_PREF,
+  KHMER_BLWF,
+  KHMER_ABVF,
+  KHMER_PSTF,
+  KHMER_CFAR,
+
+  _KHMER_PRES,
+  _KHMER_ABVS,
+  _KHMER_BLWS,
+  _KHMER_PSTS,
+
+  KHMER_NUM_FEATURES,
+  KHMER_BASIC_FEATURES = _KHMER_PRES, /* Don't forget to update this! */
+};
+
+static inline void
+set_khmer_properties (hb_glyph_info_t &info)
+{
+  hb_codepoint_t u = info.codepoint;
+  unsigned int type = hb_indic_get_categories (u);
+
+  info.khmer_category() = (khmer_category_t) (type & 0xFFu);
+}
+
+static bool
+setup_syllables_khmer (const hb_ot_shape_plan_t *plan,
+		       hb_font_t *font,
+		       hb_buffer_t *buffer);
+static bool
+reorder_khmer (const hb_ot_shape_plan_t *plan,
+	       hb_font_t *font,
+	       hb_buffer_t *buffer);
+
+static void
+collect_features_khmer (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_khmer);
+  map->add_gsub_pause (reorder_khmer);
+
+  /* Testing suggests that Uniscribe does NOT pause between basic
+   * features.  Test with KhmerUI.ttf and the following three
+   * sequences:
+   *
+   *   U+1789,U+17BC
+   *   U+1789,U+17D2,U+1789
+   *   U+1789,U+17D2,U+1789,U+17BC
+   *
+   * https://github.com/harfbuzz/harfbuzz/issues/974
+   */
+  map->enable_feature (HB_TAG('l','o','c','l'), F_PER_SYLLABLE);
+  map->enable_feature (HB_TAG('c','c','m','p'), F_PER_SYLLABLE);
+
+  unsigned int i = 0;
+  for (; i < KHMER_BASIC_FEATURES; i++)
+    map->add_feature (khmer_features[i]);
+
+  /* https://github.com/harfbuzz/harfbuzz/issues/3531 */
+  map->add_gsub_pause (hb_syllabic_clear_var); // Don't need syllables anymore, use stop to free buffer var
+
+  for (; i < KHMER_NUM_FEATURES; i++)
+    map->add_feature (khmer_features[i]);
+}
+
+static void
+override_features_khmer (hb_ot_shape_planner_t *plan)
+{
+  hb_ot_map_builder_t *map = &plan->map;
+
+  /* Khmer spec has 'clig' as part of required shaping features:
+   * "Apply feature 'clig' to form ligatures that are desired for
+   * typographical correctness.", hence in overrides... */
+  map->enable_feature (HB_TAG('c','l','i','g'));
+
+  /* Uniscribe does not apply 'kern' in Khmer. */
+  if (hb_options ().uniscribe_bug_compatible)
+  {
+    map->disable_feature (HB_TAG('k','e','r','n'));
+  }
+
+  map->disable_feature (HB_TAG('l','i','g','a'));
+}
+
+
+struct khmer_shape_plan_t
+{
+  hb_mask_t mask_array[KHMER_NUM_FEATURES];
+};
+
+static void *
+data_create_khmer (const hb_ot_shape_plan_t *plan)
+{
+  khmer_shape_plan_t *khmer_plan = (khmer_shape_plan_t *) hb_calloc (1, sizeof (khmer_shape_plan_t));
+  if (unlikely (!khmer_plan))
+    return nullptr;
+
+  for (unsigned int i = 0; i < ARRAY_LENGTH (khmer_plan->mask_array); i++)
+    khmer_plan->mask_array[i] = (khmer_features[i].flags & F_GLOBAL) ?
+				 0 : plan->map.get_1_mask (khmer_features[i].tag);
+
+  return khmer_plan;
+}
+
+static void
+data_destroy_khmer (void *data)
+{
+  hb_free (data);
+}
+
+static void
+setup_masks_khmer (const hb_ot_shape_plan_t *plan HB_UNUSED,
+		   hb_buffer_t              *buffer,
+		   hb_font_t                *font HB_UNUSED)
+{
+  HB_BUFFER_ALLOCATE_VAR (buffer, khmer_category);
+
+  /* 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_khmer_properties (info[i]);
+}
+
+static bool
+setup_syllables_khmer (const hb_ot_shape_plan_t *plan HB_UNUSED,
+		       hb_font_t *font HB_UNUSED,
+		       hb_buffer_t *buffer)
+{
+  HB_BUFFER_ALLOCATE_VAR (buffer, syllable);
+  find_syllables_khmer (buffer);
+  foreach_syllable (buffer, start, end)
+    buffer->unsafe_to_break (start, end);
+  return false;
+}
+
+
+/* Rules from:
+ * https://docs.microsoft.com/en-us/typography/script-development/devanagari */
+
+static void
+reorder_consonant_syllable (const hb_ot_shape_plan_t *plan,
+			    hb_face_t *face HB_UNUSED,
+			    hb_buffer_t *buffer,
+			    unsigned int start, unsigned int end)
+{
+  const khmer_shape_plan_t *khmer_plan = (const khmer_shape_plan_t *) plan->data;
+  hb_glyph_info_t *info = buffer->info;
+
+  /* Setup masks. */
+  {
+    /* Post-base */
+    hb_mask_t mask = khmer_plan->mask_array[KHMER_BLWF] |
+		     khmer_plan->mask_array[KHMER_ABVF] |
+		     khmer_plan->mask_array[KHMER_PSTF];
+    for (unsigned int i = start + 1; i < end; i++)
+      info[i].mask  |= mask;
+  }
+
+  unsigned int num_coengs = 0;
+  for (unsigned int i = start + 1; i < end; i++)
+  {
+    /* """
+     * When a COENG + (Cons | IndV) combination are found (and subscript count
+     * is less than two) the character combination is handled according to the
+     * subscript type of the character following the COENG.
+     *
+     * ...
+     *
+     * Subscript Type 2 - The COENG + RO characters are reordered to immediately
+     * before the base glyph. Then the COENG + RO characters are assigned to have
+     * the 'pref' OpenType feature applied to them.
+     * """
+     */
+    if (info[i].khmer_category() == K_Cat(H) && num_coengs <= 2 && i + 1 < end)
+    {
+      num_coengs++;
+
+      if (info[i + 1].khmer_category() == K_Cat(Ra))
+      {
+	for (unsigned int j = 0; j < 2; j++)
+	  info[i + j].mask |= khmer_plan->mask_array[KHMER_PREF];
+
+	/* Move the Coeng,Ro sequence to the start. */
+	buffer->merge_clusters (start, i + 2);
+	hb_glyph_info_t t0 = info[i];
+	hb_glyph_info_t t1 = info[i + 1];
+	memmove (&info[start + 2], &info[start], (i - start) * sizeof (info[0]));
+	info[start] = t0;
+	info[start + 1] = t1;
+
+	/* Mark the subsequent stuff with 'cfar'.  Used in Khmer.
+	 * Read the feature spec.
+	 * This allows distinguishing the following cases with MS Khmer fonts:
+	 * U+1784,U+17D2,U+179A,U+17D2,U+1782
+	 * U+1784,U+17D2,U+1782,U+17D2,U+179A
+	 */
+	if (khmer_plan->mask_array[KHMER_CFAR])
+	  for (unsigned int j = i + 2; j < end; j++)
+	    info[j].mask |= khmer_plan->mask_array[KHMER_CFAR];
+
+	num_coengs = 2; /* Done. */
+      }
+    }
+
+    /* Reorder left matra piece. */
+    else if (info[i].khmer_category() == K_Cat(VPre))
+    {
+      /* Move to the start. */
+      buffer->merge_clusters (start, i + 1);
+      hb_glyph_info_t t = info[i];
+      memmove (&info[start + 1], &info[start], (i - start) * sizeof (info[0]));
+      info[start] = t;
+    }
+  }
+}
+
+static void
+reorder_syllable_khmer (const hb_ot_shape_plan_t *plan,
+			hb_face_t *face,
+			hb_buffer_t *buffer,
+			unsigned int start, unsigned int end)
+{
+  khmer_syllable_type_t syllable_type = (khmer_syllable_type_t) (buffer->info[start].syllable() & 0x0F);
+  switch (syllable_type)
+  {
+    case khmer_broken_cluster: /* We already inserted dotted-circles, so just call the consonant_syllable. */
+    case khmer_consonant_syllable:
+     reorder_consonant_syllable (plan, face, buffer, start, end);
+     break;
+
+    case khmer_non_khmer_cluster:
+      break;
+  }
+}
+
+static bool
+reorder_khmer (const hb_ot_shape_plan_t *plan,
+	       hb_font_t *font,
+	       hb_buffer_t *buffer)
+{
+  bool ret = false;
+  if (buffer->message (font, "start reordering khmer"))
+  {
+    if (hb_syllabic_insert_dotted_circles (font, buffer,
+					   khmer_broken_cluster,
+					   K_Cat(DOTTEDCIRCLE),
+					   (unsigned) -1))
+      ret = true;
+
+    foreach_syllable (buffer, start, end)
+      reorder_syllable_khmer (plan, font->face, buffer, start, end);
+    (void) buffer->message (font, "end reordering khmer");
+  }
+  HB_BUFFER_DEALLOCATE_VAR (buffer, khmer_category);
+
+  return ret;
+}
+
+
+static bool
+decompose_khmer (const hb_ot_shape_normalize_context_t *c,
+		 hb_codepoint_t  ab,
+		 hb_codepoint_t *a,
+		 hb_codepoint_t *b)
+{
+  switch (ab)
+  {
+    /*
+     * Decompose split matras that don't have Unicode decompositions.
+     */
+
+    /* Khmer */
+    case 0x17BEu  : *a = 0x17C1u; *b= 0x17BEu; return true;
+    case 0x17BFu  : *a = 0x17C1u; *b= 0x17BFu; return true;
+    case 0x17C0u  : *a = 0x17C1u; *b= 0x17C0u; return true;
+    case 0x17C4u  : *a = 0x17C1u; *b= 0x17C4u; return true;
+    case 0x17C5u  : *a = 0x17C1u; *b= 0x17C5u; return true;
+  }
+
+  return (bool) c->unicode->decompose (ab, a, b);
+}
+
+static bool
+compose_khmer (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;
+
+  return (bool) c->unicode->compose (a, b, ab);
+}
+
+
+const hb_ot_shaper_t _hb_ot_shaper_khmer =
+{
+  collect_features_khmer,
+  override_features_khmer,
+  data_create_khmer,
+  data_destroy_khmer,
+  nullptr, /* preprocess_text */
+  nullptr, /* postprocess_glyphs */
+  decompose_khmer,
+  compose_khmer,
+  setup_masks_khmer,
+  nullptr, /* reorder_marks */
+  HB_TAG_NONE, /* gpos_tag */
+  HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,
+  HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,
+  false, /* fallback_position */
+};
+
+
+#endif