Roll harfbuzz-ng 3b8fd9c48f4bde368bf2d465c148b9743a9216ee

third_party/harfbuzz-ng/src/hb-ot-shape-complex-misc.cc

 /*
  * Copyright © 2010  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"
 
 
-/* TODO Add kana, hangul, and other small sahpers here */
+/* TODO Add kana, and other small shapers here */
 
 /* When adding trivial shapers, eg. kana, hangul, etc, we can either
  * add a full shaper enum value for them, or switch on the script in
  * the default complex shaper.  The former is faster, so I think that's
  * what we would do, and hence the default complex shaper shall remain
  * empty.
  */
 
 void
-_hb_ot_shape_complex_collect_features_default (hb_ot_map_builder_t *map, const hb_segment_properties_t  *props)
+_hb_ot_shape_complex_collect_features_default (hb_ot_map_builder_t *map HB_UNUSED,
+                                               const hb_segment_properties_t *props HB_UNUSED)
 {
 }
 
-bool
-_hb_ot_shape_complex_prefer_decomposed_default (void)
+hb_ot_shape_normalization_mode_t
+_hb_ot_shape_complex_normalization_preference_default (void)
 {
-  return FALSE;
+  return HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS;
 }
 
 void
-_hb_ot_shape_complex_setup_masks_default (hb_ot_map_t *map, hb_buffer_t *buffer)
+_hb_ot_shape_complex_setup_masks_default (hb_ot_map_t *map HB_UNUSED,
+                                          hb_buffer_t *buffer HB_UNUSED,
+                                          hb_font_t *font HB_UNUSED)
 {
 }
 
 
+
+/* Hangul shaper */
+
+static const hb_tag_t hangul_features[] =
+{
+  HB_TAG('l','j','m','o'),
+  HB_TAG('v','j','m','o'),
+  HB_TAG('t','j','m','o'),
+};
+
+void
+_hb_ot_shape_complex_collect_features_hangul (hb_ot_map_builder_t *map,
+                                              const hb_segment_properties_t *props HB_UNUSED)
+{
+  for (unsigned int i = 0; i < ARRAY_LENGTH (hangul_features); i++)
+    map->add_bool_feature (hangul_features[i]);
+}
+
+hb_ot_shape_normalization_mode_t
+_hb_ot_shape_complex_normalization_preference_hangul (void)
+{
+  return HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_FULL;
+}
+
+void
+_hb_ot_shape_complex_setup_masks_hangul (hb_ot_map_t *map HB_UNUSED,
+                                         hb_buffer_t *buffer HB_UNUSED,
+                                         hb_font_t *font HB_UNUSED)
+{
+}
+
+
+
+/* Thai / Lao shaper */
+
+void
+_hb_ot_shape_complex_collect_features_thai (hb_ot_map_builder_t *map HB_UNUSED,
+                                            const hb_segment_properties_t *props HB_UNUSED)
+{
+}
+
+hb_ot_shape_normalization_mode_t
+_hb_ot_shape_complex_normalization_preference_thai (void)
+{
+  return HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_FULL;
+}
+
+void
+_hb_ot_shape_complex_setup_masks_thai (hb_ot_map_t *map HB_UNUSED,
+                                       hb_buffer_t *buffer,
+                                       hb_font_t *font HB_UNUSED)
+{
+  /* 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 a, *and* mode the
+   * nihka hit 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 u↪ser wanted, but the rendering is nevertheless nikhahit above
+   * chattawa.
+   *
+   * Same for Lao.
+   */
+
+  /*
+   * 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
+   *
+   * Tone marks:
+   * Thai:      <0E48..0E4B> CCC=107
+   * Lao:       <0EC8..0ECB> CCC=122
+   *
+   * 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) & ~0x0080) == 0x0E33)
+#define NIKHAHIT_FROM_SARA_AM(x) ((x) - 0xE33 + 0xE4D)
+#define SARA_AA_FROM_SARA_AM(x) ((x) - 1)
+#define IS_TONE_MARK(x) (((x) & ~0x0083) == 0x0E48)
+
+  buffer->clear_output ();
+  unsigned int count = buffer->len;
+  for (buffer->idx = 0; buffer->idx < count;)
+  {
+    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;
+
+    /* Ok, let's see... */
+    unsigned int end = buffer->out_len;
+    unsigned int start = end - 2;
+    while (start > 0 && IS_TONE_MARK (buffer->out_info[start - 1].codepoint))
+      start--;
+
+    /* Move Nikhahit (end-2) to the beginning */
+    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;
+
+    /* XXX Make this easier! */
+    /* Make cluster */
+    for (; start > 0 && buffer->out_info[start - 1].cluster == buffer->out_info[start].cluster; start--)
+      ;
+    for (; buffer->idx < count;)
+      if (buffer->cur().cluster == buffer->prev().cluster)
+        buffer->next_glyph ();
+      else
+        break;
+    end = buffer->out_len;
+
+    buffer->merge_out_clusters (start, end);
+  }
+  buffer->swap_buffers ();
+}