The Tor Browser: gfx/harfbuzz/src/hb-ot-shape-complex-hangul.cc@925c144e1f1f (annotated)

gfx/harfbuzz/src/hb-ot-shape-complex-hangul.cc@925c144e1f1f (annotated)

gfx/harfbuzz/src/hb-ot-shape-complex-hangul.cc

Fri, 16 Jan 2015 18:13:44 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Fri, 16 Jan 2015 18:13:44 +0100
branch: TOR_BUG_9701
changeset 14: 925c144e1f1f
permissions: -rw-r--r--

Integrate suggestion from review to improve consistency with existing code.

 /*
  * Copyright © 2013  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"
 /* Hangul shaper */
 /* Same order as the feature array below */
 enum {
   NONE,
   LJMO,
   VJMO,
   TJMO,
   FIRST_HANGUL_FEATURE = LJMO,
   HANGUL_FEATURE_COUNT = TJMO + 1
 };
 static const hb_tag_t hangul_features[HANGUL_FEATURE_COUNT] =
 {
   HB_TAG_NONE,
   HB_TAG('l','j','m','o'),
   HB_TAG('v','j','m','o'),
   HB_TAG('t','j','m','o')
 };
 static void
 collect_features_hangul (hb_ot_shape_planner_t *plan)
 {
   hb_ot_map_builder_t *map = &plan->map;
   for (unsigned int i = FIRST_HANGUL_FEATURE; i < HANGUL_FEATURE_COUNT; i++)
     map->add_feature (hangul_features[i], 1, F_NONE);
 }
 struct hangul_shape_plan_t
 {
   ASSERT_POD ();
   hb_mask_t mask_array[HANGUL_FEATURE_COUNT];
 };
 static void *
 data_create_hangul (const hb_ot_shape_plan_t *plan)
 {
   hangul_shape_plan_t *hangul_plan = (hangul_shape_plan_t *) calloc (1, sizeof (hangul_shape_plan_t));
   if (unlikely (!hangul_plan))
     return NULL;
   for (unsigned int i = 0; i < HANGUL_FEATURE_COUNT; i++)
     hangul_plan->mask_array[i] = plan->map.get_1_mask (hangul_features[i]);
   return hangul_plan;
 }
 static void
 data_destroy_hangul (void *data)
 {
   free (data);
 }
 /* Constants for algorithmic hangul syllable [de]composition. */
 #define LBase 0x1100
 #define VBase 0x1161
 #define TBase 0x11A7
 #define LCount 19
 #define VCount 21
 #define TCount 28
 #define SBase 0xAC00
 #define NCount (VCount * TCount)
 #define SCount (LCount * NCount)
 #define isCombiningL(u) (hb_in_range<hb_codepoint_t> ((u), LBase, LBase+LCount-1))
 #define isCombiningV(u) (hb_in_range<hb_codepoint_t> ((u), VBase, VBase+VCount-1))
 #define isCombiningT(u) (hb_in_range<hb_codepoint_t> ((u), TBase+1, TBase+TCount-1))
 #define isCombinedS(u) (hb_in_range<hb_codepoint_t> ((u), SBase, SBase+SCount-1))
 #define isL(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x1100, 0x115F, 0xA960, 0xA97C))
 #define isV(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x1160, 0x11A7, 0xD7B0, 0xD7C6))
 #define isT(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x11A8, 0x11FF, 0xD7CB, 0xD7FB))
 #define isHangulTone(u) (hb_in_range<hb_codepoint_t> ((u), 0x302e, 0x302f))
 /* buffer var allocations */
 #define hangul_shaping_feature() complex_var_u8_0() /* hangul jamo shaping feature */
 static bool
 is_zero_width_char (hb_font_t *font,
 		    hb_codepoint_t unicode)
 {
   hb_codepoint_t glyph;
   return hb_font_get_glyph (font, unicode, 0, &glyph) && hb_font_get_glyph_h_advance (font, glyph) == 0;
 }
 static void
 preprocess_text_hangul (const hb_ot_shape_plan_t *plan,
 			hb_buffer_t              *buffer,
 			hb_font_t                *font)
 {
   HB_BUFFER_ALLOCATE_VAR (buffer, hangul_shaping_feature);
   /* Hangul syllables come in two shapes: LV, and LVT.  Of those:
    *
    *   - LV can be precomposed, or decomposed.  Lets call those
    *     <LV> and <L,V>,
    *   - LVT can be fully precomposed, partically precomposed, or
    *     fully decomposed.  Ie. <LVT>, <LV,T>, or <L,V,T>.
    *
    * The composition / decomposition is mechanical.  However, not
    * all <L,V> sequences compose, and not all <LV,T> sequences
    * compose.
    *
    * Here are the specifics:
    *
    *   - <L>: U+1100..115F, U+A960..A97F
    *   - <V>: U+1160..11A7, U+D7B0..D7C7
    *   - <T>: U+11A8..11FF, U+D7CB..D7FB
    *
    *   - Only the <L,V> sequences for the 11xx ranges combine.
    *   - Only <LV,T> sequences for T in U+11A8..11C3 combine.
    *
    * Here is what we want to accomplish in this shaper:
    *
    *   - If the whole syllable can be precomposed, do that,
    *   - Otherwise, fully decompose and apply ljmo/vjmo/tjmo features.
    *   - If a valid syllable is followed by a Hangul tone mark, reorder the tone
    *     mark to precede the whole syllable - unless it is a zero-width glyph, in
    *     which case we leave it untouched, assuming it's designed to overstrike.
    *
    * That is, of the different possible syllables:
    *
    *   <L>
    *   <L,V>
    *   <L,V,T>
    *   <LV>
    *   <LVT>
    *   <LV, T>
    *
    * - <L> needs no work.
    *
    * - <LV> and <LVT> can stay the way they are if the font supports them, otherwise we
    *   should fully decompose them if font supports.
    *
    * - <L,V> and <L,V,T> we should compose if the whole thing can be composed.
    *
    * - <LV,T> we should compose if the whole thing can be composed, otherwise we should
    *   decompose.
    */
   buffer->clear_output ();
   unsigned int start = 0, end = 0; /* Extent of most recently seen syllable;
 				    * valid only if start < end
 				    */
   unsigned int count = buffer->len;
   for (buffer->idx = 0; buffer->idx < count;)
   {
     hb_codepoint_t u = buffer->cur().codepoint;
     if (isHangulTone (u))
     {
       /*
        * We could cache the width of the tone marks and the existence of dotted-circle,
        * but the use of the Hangul tone mark characters seems to be rare enough that
        * I didn't bother for now.
        */
       if (start < end && end == buffer->out_len)
       {
 	/* Tone mark follows a valid syllable; move it in front, unless it's zero width. */
 	buffer->next_glyph ();
 	if (!is_zero_width_char (font, u))
 	{
 	  hb_glyph_info_t *info = buffer->out_info;
 	  hb_glyph_info_t tone = info[end];
 	  memmove (&info[start + 1], &info[start], (end - start) * sizeof (hb_glyph_info_t));
 	  info[start] = tone;
 	}
 	/* Merge clusters across the (possibly reordered) syllable+tone.
 	 * We want to merge even in the zero-width tone mark case here,
 	 * so that clustering behavior isn't dependent on how the tone mark
 	 * is handled by the font.
 	 */
 	buffer->merge_out_clusters (start, end + 1);
       }
       else
       {
 	/* No valid syllable as base for tone mark; try to insert dotted circle. */
 	if (font->has_glyph (0x25cc))
 	{
 	  hb_codepoint_t chars[2];
 	  if (!is_zero_width_char (font, u)) {
 	    chars[0] = u;
 	    chars[1] = 0x25cc;
 	  } else {
 	    chars[0] = 0x25cc;
 	    chars[1] = u;
 	  }
 	  buffer->replace_glyphs (1, 2, chars);
 	}
 	else
 	{
 	  /* No dotted circle available in the font; just leave tone mark untouched. */
 	  buffer->next_glyph ();
 	}
       }
       start = end = buffer->out_len;
       continue;
     }
     start = buffer->out_len; /* Remember current position as a potential syllable start;
 			      * will only be used if we set end to a later position.
 			      */
     if (isL (u) && buffer->idx + 1 < count)
     {
       hb_codepoint_t l = u;
       hb_codepoint_t v = buffer->cur(+1).codepoint;
       if (isV (v))
       {
 	/* Have <L,V> or <L,V,T>. */
 	hb_codepoint_t t = 0;
 	unsigned int tindex = 0;
 	if (buffer->idx + 2 < count)
 	{
 	  t = buffer->cur(+2).codepoint;
 	  if (isT (t))
 	    tindex = t - TBase; /* Only used if isCombiningT (t); otherwise invalid. */
 	  else
 	    t = 0; /* The next character was not a trailing jamo. */
 	}
 	/* We've got a syllable <L,V,T?>; see if it can potentially be composed. */
 	if (isCombiningL (l) && isCombiningV (v) && (t == 0 || isCombiningT (t)))
 	{
 	  /* Try to compose; if this succeeds, end is set to start+1. */
 	  hb_codepoint_t s = SBase + (l - LBase) * NCount + (v - VBase) * TCount + tindex;
 	  if (font->has_glyph (s))
 	  {
 	    buffer->replace_glyphs (t ? 3 : 2, 1, &s);
 	    if (unlikely (buffer->in_error))
 	      return;
 	    end = start + 1;
 	    continue;
 	  }
 	}
 	/* We didn't compose, either because it's an Old Hangul syllable without a
 	 * precomposed character in Unicode, or because the font didn't support the
 	 * necessary precomposed glyph.
 	 * Set jamo features on the individual glyphs, and advance past them.
 	 */
 	buffer->cur().hangul_shaping_feature() = LJMO;
 	buffer->next_glyph ();
 	buffer->cur().hangul_shaping_feature() = VJMO;
 	buffer->next_glyph ();
 	if (t)
 	{
 	  buffer->cur().hangul_shaping_feature() = TJMO;
 	  buffer->next_glyph ();
 	  end = start + 3;
 	}
 	else
 	  end = start + 2;
 	buffer->merge_out_clusters (start, end);
 	continue;
       }
     }
     else if (isCombinedS (u))
     {
       /* Have <LV>, <LVT>, or <LV,T> */
       hb_codepoint_t s = u;
       bool has_glyph = font->has_glyph (s);
       unsigned int lindex = (s - SBase) / NCount;
       unsigned int nindex = (s - SBase) % NCount;
       unsigned int vindex = nindex / TCount;
       unsigned int tindex = nindex % TCount;
       if (!tindex &&
 	  buffer->idx + 1 < count &&
 	  isCombiningT (buffer->cur(+1).codepoint))
       {
 	/* <LV,T>, try to combine. */
 	unsigned int new_tindex = buffer->cur(+1).codepoint - TBase;
 	hb_codepoint_t new_s = s + new_tindex;
 	if (font->has_glyph (new_s))
 	{
 	  buffer->replace_glyphs (2, 1, &new_s);
 	  if (unlikely (buffer->in_error))
 	    return;
 	  end = start + 1;
 	  continue;
 	}
       }
       /* Otherwise, decompose if font doesn't support <LV> or <LVT>,
        * or if having non-combining <LV,T>.  Note that we already handled
        * combining <LV,T> above. */
       if (!has_glyph ||
 	  (!tindex &&
 	   buffer->idx + 1 < count &&
 	   isT (buffer->cur(+1).codepoint)))
       {
 	hb_codepoint_t decomposed[3] = {LBase + lindex,
 					VBase + vindex,
 					TBase + tindex};
 	if (font->has_glyph (decomposed[0]) &&
 	    font->has_glyph (decomposed[1]) &&
 	    (!tindex || font->has_glyph (decomposed[2])))
 	{
 	  unsigned int s_len = tindex ? 3 : 2;
 	  buffer->replace_glyphs (1, s_len, decomposed);
 	  if (unlikely (buffer->in_error))
 	    return;
 	  /* We decomposed S: apply jamo features to the individual glyphs
 	   * that are now in buffer->out_info.
 	   */
 	  hb_glyph_info_t *info = buffer->out_info;
 	  /* If we decomposed an LV because of a non-combining T following,
 	   * we want to include this T in the syllable.
 	   */
 	  if (has_glyph && !tindex)
 	  {
             buffer->next_glyph ();
             s_len++;
           }
           end = start + s_len;
 	  unsigned int i = start;
 	  info[i++].hangul_shaping_feature() = LJMO;
 	  info[i++].hangul_shaping_feature() = VJMO;
 	  if (i < end)
 	    info[i++].hangul_shaping_feature() = TJMO;
 	  buffer->merge_out_clusters (start, end);
 	  continue;
 	}
       }
       if (has_glyph)
       {
         /* We didn't decompose the S, so just advance past it. */
 	end = start + 1;
 	buffer->next_glyph ();
 	continue;
       }
     }
     /* Didn't find a recognizable syllable, so we leave end <= start;
      * this will prevent tone-mark reordering happening.
      */
     buffer->next_glyph ();
   }
   buffer->swap_buffers ();
 }
 static void
 setup_masks_hangul (const hb_ot_shape_plan_t *plan,
 		    hb_buffer_t              *buffer,
 		    hb_font_t                *font HB_UNUSED)
 {
   const hangul_shape_plan_t *hangul_plan = (const hangul_shape_plan_t *) plan->data;
   if (likely (hangul_plan))
   {
     unsigned int count = buffer->len;
     hb_glyph_info_t *info = buffer->info;
     for (unsigned int i = 0; i < count; i++, info++)
       info->mask |= hangul_plan->mask_array[info->hangul_shaping_feature()];
   }
   HB_BUFFER_DEALLOCATE_VAR (buffer, hangul_shaping_feature);
 }
 const hb_ot_complex_shaper_t _hb_ot_complex_shaper_hangul =
 {
   "hangul",
   collect_features_hangul,
   NULL, /* override_features */
   data_create_hangul, /* data_create */
   data_destroy_hangul, /* data_destroy */
   preprocess_text_hangul,
   HB_OT_SHAPE_NORMALIZATION_MODE_NONE,
   NULL, /* decompose */
   NULL, /* compose */
   setup_masks_hangul, /* setup_masks */
   HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,
   false, /* fallback_position */
 };

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gfx/harfbuzz/src/hb-ot-shape-complex-hangul.cc@925c144e1f1f (annotated)

gfx/harfbuzz/src/hb-ot-shape-complex-hangul.cc