harfbuzz-ng roll

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

 /*
- * Copyright © 2010  Google, Inc.
+ * 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"
 
 
 /* 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 HB_UNUSED,
-                                               const hb_segment_properties_t *props HB_UNUSED)
-{
-}
-
-hb_ot_shape_normalization_mode_t
-_hb_ot_shape_complex_normalization_preference_default (void)
-{
-  return HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS;
-}
-
-void
-_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 */
+/* The default shaper *only* adds additional per-script features.*/
 
 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'),
+  HB_TAG_NONE
 };
 
-void
-_hb_ot_shape_complex_collect_features_hangul (hb_ot_map_builder_t *map,
-                                              const hb_segment_properties_t *props HB_UNUSED)
+static const hb_tag_t tibetan_features[] =
 {
-  for (unsigned int i = 0; i < ARRAY_LENGTH (hangul_features); i++)
-    map->add_bool_feature (hangul_features[i]);
+  HB_TAG('a','b','v','s'),
+  HB_TAG('b','l','w','s'),
+  HB_TAG('a','b','v','m'),
+  HB_TAG('b','l','w','m'),
+  HB_TAG_NONE
+};
+
+static void
+collect_features_default (hb_ot_shape_planner_t *plan)
+{
+  const hb_tag_t *script_features = NULL;
+
+  switch ((hb_tag_t) plan->props.script)
+  {
+    /* Unicode-1.1 additions */
+    case HB_SCRIPT_HANGUL:
+      script_features = hangul_features;
+      break;
+
+    /* Unicode-2.0 additions */
+    case HB_SCRIPT_TIBETAN:
+      script_features = tibetan_features;
+      break;
+  }
+
+  for (; script_features && *script_features; script_features++)
+    plan->map.add_bool_feature (*script_features);
 }
 
-hb_ot_shape_normalization_mode_t
-_hb_ot_shape_complex_normalization_preference_hangul (void)
+static hb_ot_shape_normalization_mode_t
+normalization_preference_default (const hb_ot_shape_plan_t *plan)
 {
-  return HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_FULL;
+  switch ((hb_tag_t) plan->props.script)
+  {
+    /* Unicode-1.1 additions */
+    case HB_SCRIPT_HANGUL:
+      return HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_FULL;
+  }
+  return HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS;
 }
 
-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)
+const hb_ot_complex_shaper_t _hb_ot_complex_shaper_default =
 {
-}
-
+  "default",
+  collect_features_default,
+  NULL, /* override_features */
+  NULL, /* data_create */
+  NULL, /* data_destroy */
+  NULL, /* preprocess_text */
+  normalization_preference_default,
+  NULL, /* setup_masks */
+  true, /* zero_width_attached_marks */
+};
 
 
 /* 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)
+static void
+preprocess_text_thai (const hb_ot_shape_plan_t *plan 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).
+   * 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
+   * 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
+   * not what a user wanted, but the rendering is nevertheless nikhahit above
    * chattawa.
    *
    * Same for Lao.
+   *
+   * Note:
+   *
+   * Uniscribe also does so 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
    *
-   * Tone marks:
-   * Thai:      <0E48..0E4B> CCC=107
-   * Lao:       <0EC8..0ECB> CCC=122
+   * 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) & ~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)
+#define IS_TONE_MARK(x) (hb_in_ranges<hb_codepoint_t> ((x) & ~0x0080, 0x0E34, 0x0E37, 0x0E47, 0x0E4E, 0x0E31, 0x0E31))
 
   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);
+    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->merge_out_clusters (start - 1, end);
+    }
   }
   buffer->swap_buffers ();
 }
+
+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, /* normalization_preference */
+  NULL, /* setup_masks */
+  true, /* zero_width_attached_marks */
+};