Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 485 insertions, 0 deletions

diff --git a/gfx/harfbuzz/src/hb-ot-shape-normalize.cc b/gfx/harfbuzz/src/hb-ot-shape-normalize.cc
new file mode 100644
index 0000000000..897377aa15
--- /dev/null
+++ b/gfx/harfbuzz/src/hb-ot-shape-normalize.cc
@@ -0,0 +1,485 @@
+/*
+ * 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-shape-normalize.hh"
+#include "hb-ot-shaper.hh"
+#include "hb-ot-shape.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.
+ *
+ * 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, 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 canonical
+ *     decomposition, well, use the decomposition.
+ *
+ *   - The shapers can customize the compose and decompose functions to
+ *     offload some of their requirements to the normalizer.  For example, the
+ *     Indic shaper may want to disallow recomposing of two matras.
+ */
+
+static bool
+decompose_unicode (const hb_ot_shape_normalize_context_t *c,
+		   hb_codepoint_t  ab,
+		   hb_codepoint_t *a,
+		   hb_codepoint_t *b)
+{
+  return (bool) c->unicode->decompose (ab, a, b);
+}
+
+static bool
+compose_unicode (const hb_ot_shape_normalize_context_t *c,
+		 hb_codepoint_t  a,
+		 hb_codepoint_t  b,
+		 hb_codepoint_t *ab)
+{
+  return (bool) c->unicode->compose (a, b, ab);
+}
+
+static inline void
+set_glyph (hb_glyph_info_t &info, hb_font_t *font)
+{
+  (void) font->get_nominal_glyph (info.codepoint, &info.glyph_index());
+}
+
+static inline void
+output_char (hb_buffer_t *buffer, hb_codepoint_t unichar, hb_codepoint_t glyph)
+{
+  /* This is very confusing indeed. */
+  buffer->cur().glyph_index() = glyph;
+  (void) buffer->output_glyph (unichar);
+  _hb_glyph_info_set_unicode_props (&buffer->prev(), buffer);
+}
+
+static inline void
+next_char (hb_buffer_t *buffer, hb_codepoint_t glyph)
+{
+  buffer->cur().glyph_index() = glyph;
+  (void) buffer->next_glyph ();
+}
+
+static inline void
+skip_char (hb_buffer_t *buffer)
+{
+  buffer->skip_glyph ();
+}
+
+/* Returns 0 if didn't decompose, number of resulting characters otherwise. */
+static inline unsigned int
+decompose (const hb_ot_shape_normalize_context_t *c, bool shortest, hb_codepoint_t ab)
+{
+  hb_codepoint_t a = 0, b = 0, a_glyph = 0, b_glyph = 0;
+  hb_buffer_t * const buffer = c->buffer;
+  hb_font_t * const font = c->font;
+
+  if (!c->decompose (c, ab, &a, &b) ||
+      (b && !font->get_nominal_glyph (b, &b_glyph)))
+    return 0;
+
+  bool has_a = (bool) font->get_nominal_glyph (a, &a_glyph);
+  if (shortest && has_a) {
+    /* Output a and b */
+    output_char (buffer, a, a_glyph);
+    if (likely (b)) {
+      output_char (buffer, b, b_glyph);
+      return 2;
+    }
+    return 1;
+  }
+
+  if (unsigned ret = decompose (c, shortest, a)) {
+    if (b) {
+      output_char (buffer, b, b_glyph);
+      return ret + 1;
+    }
+    return ret;
+  }
+
+  if (has_a) {
+    output_char (buffer, a, a_glyph);
+    if (likely (b)) {
+      output_char (buffer, b, b_glyph);
+      return 2;
+    }
+    return 1;
+  }
+
+  return 0;
+}
+
+static inline void
+decompose_current_character (const hb_ot_shape_normalize_context_t *c, bool shortest)
+{
+  hb_buffer_t * const buffer = c->buffer;
+  hb_codepoint_t u = buffer->cur().codepoint;
+  hb_codepoint_t glyph = 0;
+
+  if (shortest && c->font->get_nominal_glyph (u, &glyph, c->not_found))
+  {
+    next_char (buffer, glyph);
+    return;
+  }
+
+  if (decompose (c, shortest, u))
+  {
+    skip_char (buffer);
+    return;
+  }
+
+  if (!shortest && c->font->get_nominal_glyph (u, &glyph, c->not_found))
+  {
+    next_char (buffer, glyph);
+    return;
+  }
+
+  if (_hb_glyph_info_is_unicode_space (&buffer->cur()))
+  {
+    hb_codepoint_t space_glyph;
+    hb_unicode_funcs_t::space_t space_type = buffer->unicode->space_fallback_type (u);
+    if (space_type != hb_unicode_funcs_t::NOT_SPACE &&
+	(c->font->get_nominal_glyph (0x0020, &space_glyph) || (space_glyph = buffer->invisible)))
+    {
+      _hb_glyph_info_set_unicode_space_fallback_type (&buffer->cur(), space_type);
+      next_char (buffer, space_glyph);
+      buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_SPACE_FALLBACK;
+      return;
+    }
+  }
+
+  if (u == 0x2011u)
+  {
+    /* U+2011 is the only sensible character that is a no-break version of another character
+     * and not a space.  The space ones are handled already.  Handle this lone one. */
+    hb_codepoint_t other_glyph;
+    if (c->font->get_nominal_glyph (0x2010u, &other_glyph))
+    {
+      next_char (buffer, other_glyph);
+      return;
+    }
+  }
+
+  next_char (buffer, glyph); /* glyph is initialized in earlier branches. */
+}
+
+static inline void
+handle_variation_selector_cluster (const hb_ot_shape_normalize_context_t *c,
+				   unsigned int end,
+				   bool short_circuit HB_UNUSED)
+{
+  /* Currently if there's a variation-selector we give-up on normalization, it's just too hard. */
+  hb_buffer_t * const buffer = c->buffer;
+  hb_font_t * const font = c->font;
+  for (; buffer->idx < end - 1 && buffer->successful;) {
+    if (unlikely (buffer->unicode->is_variation_selector (buffer->cur(+1).codepoint))) {
+      if (font->get_variation_glyph (buffer->cur().codepoint, buffer->cur(+1).codepoint, &buffer->cur().glyph_index()))
+      {
+	hb_codepoint_t unicode = buffer->cur().codepoint;
+	(void) buffer->replace_glyphs (2, 1, &unicode);
+      }
+      else
+      {
+	/* Just pass on the two characters separately, let GSUB do its magic. */
+	set_glyph (buffer->cur(), font);
+	(void) buffer->next_glyph ();
+	set_glyph (buffer->cur(), font);
+	(void) buffer->next_glyph ();
+      }
+      /* Skip any further variation selectors. */
+      while (buffer->idx < end &&
+	     buffer->successful &&
+	     unlikely (buffer->unicode->is_variation_selector (buffer->cur().codepoint)))
+      {
+	set_glyph (buffer->cur(), font);
+	(void) buffer->next_glyph ();
+      }
+    }
+    else
+    {
+      set_glyph (buffer->cur(), font);
+      (void) buffer->next_glyph ();
+    }
+  }
+  if (likely (buffer->idx < end))
+  {
+    set_glyph (buffer->cur(), font);
+    (void) buffer->next_glyph ();
+  }
+}
+
+static inline void
+decompose_multi_char_cluster (const hb_ot_shape_normalize_context_t *c, unsigned int end, bool short_circuit)
+{
+  hb_buffer_t * const buffer = c->buffer;
+  for (unsigned int i = buffer->idx; i < end && buffer->successful; i++)
+    if (unlikely (buffer->unicode->is_variation_selector (buffer->info[i].codepoint))) {
+      handle_variation_selector_cluster (c, end, short_circuit);
+      return;
+    }
+
+  while (buffer->idx < end && buffer->successful)
+    decompose_current_character (c, short_circuit);
+}
+
+
+static int
+compare_combining_class (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb)
+{
+  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 (const hb_ot_shape_plan_t *plan,
+			hb_buffer_t *buffer,
+			hb_font_t *font)
+{
+  if (unlikely (!buffer->len)) return;
+
+  _hb_buffer_assert_unicode_vars (buffer);
+
+  hb_ot_shape_normalization_mode_t mode = plan->shaper->normalization_preference;
+  if (mode == HB_OT_SHAPE_NORMALIZATION_MODE_AUTO)
+  {
+    if (plan->has_gpos_mark)
+      // https://github.com/harfbuzz/harfbuzz/issues/653#issuecomment-423905920
+      //mode = HB_OT_SHAPE_NORMALIZATION_MODE_DECOMPOSED;
+      mode = HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS;
+    else
+      mode = HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS;
+  }
+
+  const hb_ot_shape_normalize_context_t c = {
+    plan,
+    buffer,
+    font,
+    buffer->unicode,
+    buffer->not_found,
+    plan->shaper->decompose ? plan->shaper->decompose : decompose_unicode,
+    plan->shaper->compose   ? plan->shaper->compose   : compose_unicode
+  };
+
+  bool always_short_circuit = mode == HB_OT_SHAPE_NORMALIZATION_MODE_NONE;
+  bool might_short_circuit = always_short_circuit ||
+			     (mode != HB_OT_SHAPE_NORMALIZATION_MODE_DECOMPOSED &&
+			      mode != HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT);
+  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 */
+
+  bool all_simple = true;
+  {
+    buffer->clear_output ();
+    count = buffer->len;
+    buffer->idx = 0;
+    do
+    {
+      unsigned int end;
+      for (end = buffer->idx + 1; end < count; end++)
+	if (_hb_glyph_info_is_unicode_mark (&buffer->info[end]))
+	  break;
+
+      if (end < count)
+	end--; /* Leave one base for the marks to cluster with. */
+
+      /* From idx to end are simple clusters. */
+      if (might_short_circuit)
+      {
+	unsigned int done = font->get_nominal_glyphs (end - buffer->idx,
+						      &buffer->cur().codepoint,
+						      sizeof (buffer->info[0]),
+						      &buffer->cur().glyph_index(),
+						      sizeof (buffer->info[0]));
+	if (unlikely (!buffer->next_glyphs (done))) break;
+      }
+      while (buffer->idx < end && buffer->successful)
+	decompose_current_character (&c, might_short_circuit);
+
+      if (buffer->idx == count || !buffer->successful)
+	break;
+
+      all_simple = false;
+
+      /* Find all the marks now. */
+      for (end = buffer->idx + 1; end < count; end++)
+	if (!_hb_glyph_info_is_unicode_mark(&buffer->info[end]))
+	  break;
+
+      /* idx to end is one non-simple cluster. */
+      decompose_multi_char_cluster (&c, end, always_short_circuit);
+    }
+    while (buffer->idx < count && buffer->successful);
+    buffer->sync ();
+  }
+
+
+  /* Second round, reorder (inplace) */
+
+  if (!all_simple && buffer->message(font, "start reorder"))
+  {
+    count = buffer->len;
+    for (unsigned int i = 0; i < count; i++)
+    {
+      if (_hb_glyph_info_get_modified_combining_class (&buffer->info[i]) == 0)
+	continue;
+
+      unsigned int end;
+      for (end = i + 1; end < count; end++)
+	if (_hb_glyph_info_get_modified_combining_class (&buffer->info[end]) == 0)
+	  break;
+
+      /* We are going to do a O(n^2).  Only do this if the sequence is short. */
+      if (end - i > HB_OT_SHAPE_MAX_COMBINING_MARKS) {
+	i = end;
+	continue;
+      }
+
+      buffer->sort (i, end, compare_combining_class);
+
+      if (plan->shaper->reorder_marks)
+	plan->shaper->reorder_marks (plan, buffer, i, end);
+
+      i = end;
+    }
+    (void) buffer->message(font, "end reorder");
+  }
+  if (buffer->scratch_flags & HB_BUFFER_SCRATCH_FLAG_HAS_CGJ)
+  {
+    /* For all CGJ, check if it prevented any reordering at all.
+     * If it did NOT, then make it skippable.
+     * https://github.com/harfbuzz/harfbuzz/issues/554
+     */
+    for (unsigned int i = 1; i + 1 < buffer->len; i++)
+      if (buffer->info[i].codepoint == 0x034Fu/*CGJ*/ &&
+	  (info_cc(buffer->info[i+1]) == 0 || info_cc(buffer->info[i-1]) <= info_cc(buffer->info[i+1])))
+      {
+	_hb_glyph_info_unhide (&buffer->info[i]);
+      }
+  }
+
+
+  /* Third round, recompose */
+
+  if (!all_simple &&
+      buffer->successful &&
+      (mode == HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS ||
+       mode == HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT))
+  {
+    /* 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;
+    (void) buffer->next_glyph ();
+    while (buffer->idx < count /* No need for: && buffer->successful */)
+    {
+      hb_codepoint_t composed, glyph;
+      if (/* We don't try to compose a non-mark character with it's preceding starter.
+	   * This is both an optimization to avoid trying to compose every two neighboring
+	   * glyphs in most scripts AND a desired feature for Hangul.  Apparently Hangul
+	   * fonts are not designed to mix-and-match pre-composed syllables and Jamo. */
+	  _hb_glyph_info_is_unicode_mark(&buffer->cur()))
+      {
+	if (/* If there's anything between the starter and this char, they should have CCC
+	     * smaller than this character's. */
+	    (starter == buffer->out_len - 1 ||
+	     info_cc (buffer->prev()) < info_cc (buffer->cur())) &&
+	    /* And compose. */
+	    c.compose (&c,
+		       buffer->out_info[starter].codepoint,
+		       buffer->cur().codepoint,
+		       &composed) &&
+	    /* And the font has glyph for the composite. */
+	    font->get_nominal_glyph (composed, &glyph))
+	{
+	  /* Composes. */
+	  if (unlikely (!buffer->next_glyph ())) break; /* Copy to out-buffer. */
+	  buffer->merge_out_clusters (starter, buffer->out_len);
+	  buffer->out_len--; /* Remove the second composable. */
+	  /* Modify starter and carry on. */
+	  buffer->out_info[starter].codepoint = composed;
+	  buffer->out_info[starter].glyph_index() = glyph;
+	  _hb_glyph_info_set_unicode_props (&buffer->out_info[starter], buffer);
+
+	  continue;
+	}
+      }
+
+      /* Blocked, or doesn't compose. */
+      if (unlikely (!buffer->next_glyph ())) break;
+
+      if (info_cc (buffer->prev()) == 0)
+	starter = buffer->out_len - 1;
+    }
+    buffer->sync ();
+  }
+}
+
+
+#endif