Roll harfbuzz-ng 3b8fd9c48f4bde368bf2d465c148b9743a9216ee

third_party/harfbuzz-ng/src/hb-ot-shape-normalize.cc

 /*
- * Copyright © 2011  Google, Inc.
+ * 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-ot-shape-normalize-private.hh"
 #include "hb-ot-shape-private.hh"
-#include "hb-ot-shape-complex-private.hh"
 
 
 /*
  * HIGHLEVEL DESIGN:
  *
  * This file exports one main function: _hb_ot_shape_normalize().
  *
  * This function closely reflects the Unicode Normalization Algorithm,
- * yet it's different.  The shaper an either prefer decomposed (NFD) or
- * composed (NFC).
+ * yet it's different.
+ *
+ * Each shaper specifies whether it prefers decomposed (NFD) or composed (NFC).
+ * The logic however tries to use whatever the font can support.
  *
  * In general what happens is that: each grapheme is decomposed in a chain
  * of 1:2 decompositions, marks reordered, and then recomposed if desired,
  * so far it's like Unicode Normalization.  However, the decomposition and
  * recomposition only happens if the font supports the resulting characters.
  *
  * The goals are:
  *
  *   - Try to render all canonically equivalent strings similarly.  To really
  *     achieve this we have to always do the full decomposition and then
  *     selectively recompose from there.  It's kinda too expensive though, so
  *     we skip some cases.  For example, if composed is desired, we simply
  *     don't touch 1-character clusters that are supported by the font, even
  *     though their NFC may be different.
  *
  *   - When a font has a precomposed character for a sequence but the 'ccmp'
  *     feature in the font is not adequate, use the precomposed character
  *     which typically has better mark positioning.
  *
  *   - When a font does not support a combining mark, but supports it precomposed
- *     with previous base.  This needs the itemizer to have this knowledge too.
- *     We need ot provide assistance to the itemizer.
+ *     with previous base, use that.  This needs the itemizer to have this
+ *     knowledge too.  We need to provide assistance to the itemizer.
  *
  *   - When a font does not support a character but supports its decomposition,
  *     well, use the decomposition.
  *
  *   - The Indic shaper requests decomposed output.  This will handle splitting
  *     matra for the Indic shaper.
  */
 
 static void
-output_glyph (hb_ot_shape_context_t *c,
-              hb_codepoint_t glyph)
+output_glyph (hb_buffer_t *buffer, hb_codepoint_t glyph)
 {
-  hb_buffer_t *buffer = c->buffer;
-
   buffer->output_glyph (glyph);
-  hb_glyph_info_set_unicode_props (&buffer->out_info[buffer->out_len - 1], buffer->unicode);
+  _hb_glyph_info_set_unicode_props (&buffer->prev(), buffer->unicode);
 }
 
 static bool
-decompose (hb_ot_shape_context_t *c,
+decompose (hb_font_t *font, hb_buffer_t *buffer,
            bool shortest,
            hb_codepoint_t ab)
 {
   hb_codepoint_t a, b, glyph;
 
-  if (!hb_unicode_decompose (c->buffer->unicode, ab, &a, &b) ||
-      (b && !hb_font_get_glyph (c->font, b, 0, &glyph)))
+  if (!hb_unicode_decompose (buffer->unicode, ab, &a, &b) ||
+      (b && !hb_font_get_glyph (font, b, 0, &glyph)))
     return FALSE;
 
-  bool has_a = hb_font_get_glyph (c->font, a, 0, &glyph);
+  bool has_a = hb_font_get_glyph (font, a, 0, &glyph);
   if (shortest && has_a) {
     /* Output a and b */
-    output_glyph (c, a);
+    output_glyph (buffer, a);
     if (b)
-      output_glyph (c, b);
+      output_glyph (buffer, b);
     return TRUE;
   }
 
-  if (decompose (c, shortest, a)) {
+  if (decompose (font, buffer, shortest, a)) {
     if (b)
-      output_glyph (c, b);
+      output_glyph (buffer, b);
     return TRUE;
   }
 
   if (has_a) {
-    output_glyph (c, a);
+    output_glyph (buffer, a);
     if (b)
-      output_glyph (c, b);
+      output_glyph (buffer, b);
     return TRUE;
   }
 
   return FALSE;
 }
 
 static void
-decompose_current_glyph (hb_ot_shape_context_t *c,
+decompose_current_glyph (hb_font_t *font, hb_buffer_t *buffer,
                          bool shortest)
 {
-  if (decompose (c, shortest, c->buffer->info[c->buffer->idx].codepoint))
-    c->buffer->skip_glyph ();
+  if (decompose (font, buffer, shortest, buffer->cur().codepoint))
+    buffer->skip_glyph ();
   else
-    c->buffer->next_glyph ();
+    buffer->next_glyph ();
 }
 
 static void
-decompose_single_char_cluster (hb_ot_shape_context_t *c,
+decompose_single_char_cluster (hb_font_t *font, hb_buffer_t *buffer,
                                bool will_recompose)
 {
   hb_codepoint_t glyph;
 
   /* If recomposing and font supports this, we're good to go */
-  if (will_recompose && hb_font_get_glyph (c->font, c->buffer->info[c->buffer->idx].codepoint, 0, &glyph)) {
-    c->buffer->next_glyph ();
+  if (will_recompose && hb_font_get_glyph (font, buffer->cur().codepoint, 0, &glyph)) {
+    buffer->next_glyph ();
     return;
   }
 
-  decompose_current_glyph (c, will_recompose);
+  decompose_current_glyph (font, buffer, will_recompose);
 }
 
 static void
-decompose_multi_char_cluster (hb_ot_shape_context_t *c,
+decompose_multi_char_cluster (hb_font_t *font, hb_buffer_t *buffer,
                               unsigned int end)
 {
   /* TODO Currently if there's a variation-selector we give-up, it's just too hard. */
-  for (unsigned int i = c->buffer->idx; i < end; i++)
-    if (unlikely (is_variation_selector (c->buffer->info[i].codepoint))) {
-      while (c->buffer->idx < end)
-        c->buffer->next_glyph ();
+  for (unsigned int i = buffer->idx; i < end; i++)
+    if (unlikely (_hb_unicode_is_variation_selector (buffer->info[i].codepoint))) {
+      while (buffer->idx < end)
+        buffer->next_glyph ();
       return;
     }
 
-  while (c->buffer->idx < end)
-    decompose_current_glyph (c, FALSE);
+  while (buffer->idx < end)
+    decompose_current_glyph (font, buffer, FALSE);
 }
 
 static int
 compare_combining_class (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb)
 {
-  unsigned int a = pa->combining_class();
-  unsigned int b = pb->combining_class();
+  unsigned int a = _hb_glyph_info_get_modified_combining_class (pa);
+  unsigned int b = _hb_glyph_info_get_modified_combining_class (pb);
 
   return a < b ? -1 : a == b ? 0 : +1;
 }
 
 void
-_hb_ot_shape_normalize (hb_ot_shape_context_t *c)
+_hb_ot_shape_normalize (hb_font_t *font, hb_buffer_t *buffer,
+                        hb_ot_shape_normalization_mode_t mode)
 {
-  hb_buffer_t *buffer = c->buffer;
-  bool recompose = !hb_ot_shape_complex_prefer_decomposed (c->plan->shaper);
+  bool recompose = mode != HB_OT_SHAPE_NORMALIZATION_MODE_DECOMPOSED;
   bool has_multichar_clusters = FALSE;
   unsigned int count;
 
   /* We do a fairly straightforward yet custom normalization process in three
    * separate rounds: decompose, reorder, recompose (if desired).  Currently
    * this makes two buffer swaps.  We can make it faster by moving the last
    * two rounds into the inner loop for the first round, but it's more readable
    * this way. */
 
 
   /* First round, decompose */
 
   buffer->clear_output ();
   count = buffer->len;
   for (buffer->idx = 0; buffer->idx < count;)
   {
     unsigned int end;
     for (end = buffer->idx + 1; end < count; end++)
-      if (buffer->info[buffer->idx].cluster != buffer->info[end].cluster)
+      if (buffer->cur().cluster != buffer->info[end].cluster)
         break;
 
     if (buffer->idx + 1 == end)
-      decompose_single_char_cluster (c, recompose);
+      decompose_single_char_cluster (font, buffer, recompose);
     else {
-      decompose_multi_char_cluster (c, end);
+      decompose_multi_char_cluster (font, buffer, end);
       has_multichar_clusters = TRUE;
     }
   }
   buffer->swap_buffers ();
 
 
-  /* Technically speaking, two characters with ccc=0 may combine.  But all
-   * those cases are in languages that the indic module handles (which expects
-   * decomposed), or in Hangul jamo, which again, we want decomposed anyway.
-   * So we don't bother combining across cluster boundaries.  This is a huge
-   * performance saver if the compose() callback is slow.
-   *
-   * TODO: Am I right about Hangul?  If I am, we should add a Hangul module
-   * that requests decomposed.  If for Hangul we end up wanting composed, we
-   * can do that in the Hangul module.
-   */
-
-  if (!has_multichar_clusters)
+  if (mode != HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_FULL && !has_multichar_clusters)
     return; /* Done! */
 
 
   /* Second round, reorder (inplace) */
 
   count = buffer->len;
   for (unsigned int i = 0; i < count; i++)
   {
-    if (buffer->info[i].combining_class() == 0)
+    if (_hb_glyph_info_get_modified_combining_class (&buffer->info[i]) == 0)
       continue;
 
     unsigned int end;
     for (end = i + 1; end < count; end++)
-      if (buffer->info[end].combining_class() == 0)
+      if (_hb_glyph_info_get_modified_combining_class (&buffer->info[end]) == 0)
         break;
 
     /* We are going to do a bubble-sort.  Only do this if the
      * sequence is short.  Doing it on long sequences can result
      * in an O(n^2) DoS. */
     if (end - i > 10) {
       i = end;
       continue;
     }
 
@@ skipping 10 matching lines @@
 
   /* As noted in the comment earlier, we don't try to combine
    * ccc=0 chars with their previous Starter. */
 
   buffer->clear_output ();
   count = buffer->len;
   unsigned int starter = 0;
   buffer->next_glyph ();
   while (buffer->idx < count)
   {
-    if (buffer->info[buffer->idx].combining_class() == 0) {
-      starter = buffer->out_len;
-      buffer->next_glyph ();
+    hb_codepoint_t composed, glyph;
+    if (/* If mode is NOT COMPOSED_FULL (ie. it's COMPOSED_DIACRITICS), we don't try to
+         * compose a CCC=0 character with it's preceding starter. */
+        (mode == HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_FULL ||
+         _hb_glyph_info_get_modified_combining_class (&buffer->cur()) != 0) &&
+        /* If there's anything between the starter and this char, they should have CCC
+         * smaller than this character's. */
+        (starter == buffer->out_len - 1 ||
+         _hb_glyph_info_get_modified_combining_class (&buffer->prev()) < _hb_glyph_info_get_modified_combining_class (&buffer->cur())) &&
+        /* And compose. */
+        hb_unicode_compose (buffer->unicode,
+                            buffer->out_info[starter].codepoint,
+                            buffer->cur().codepoint,
+                            &composed) &&
+        /* And the font has glyph for the composite. */
+        hb_font_get_glyph (font, composed, 0, &glyph))
+    {
+      /* Composes. Modify starter and carry on. */
+      buffer->out_info[starter].codepoint = composed;
+      /* XXX update cluster */
+      _hb_glyph_info_set_unicode_props (&buffer->out_info[starter], buffer->unicode);
+
+      buffer->skip_glyph ();
       continue;
     }
 
-    hb_codepoint_t composed, glyph;
-    if ((buffer->out_info[buffer->out_len - 1].combining_class() >=
-         buffer->info[buffer->idx].combining_class()) ||
-        !hb_unicode_compose (c->buffer->unicode,
-                             buffer->out_info[starter].codepoint,
-                             buffer->info[buffer->idx].codepoint,
-                             &composed) ||
-        !hb_font_get_glyph (c->font, composed, 0, &glyph))
-    {
-      /* Blocked, or doesn't compose. */
-      buffer->next_glyph ();
-      continue;
-    }
+    /* Blocked, or doesn't compose. */
+    buffer->next_glyph ();
 
-    /* Composes. Modify starter and carry on. */
-    buffer->out_info[starter].codepoint = composed;
-    hb_glyph_info_set_unicode_props (&buffer->out_info[starter], buffer->unicode);
-
-    buffer->skip_glyph ();
+    if (_hb_glyph_info_get_modified_combining_class (&buffer->prev()) == 0)
+      starter = buffer->out_len - 1;
   }
   buffer->swap_buffers ();
 
 }
-