/* * 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" /* * 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 decomposition, * well, use the decomposition (preferring the canonical decomposition, but * falling back to the compatibility decomposition if necessary). The * compatibility decomposition is really nice to have, for characters like * ellipsis, or various-sized space characters. * * - The complex 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. * * - We try compatibility decomposition if decomposing through canonical * decomposition alone failed to find a sequence that the font supports. * We don't try compatibility decomposition recursively during the canonical * decomposition phase. This has minimal impact. There are only a handful * of Greek letter that have canonical decompositions that include characters * with compatibility decomposition. Those can be found using this command: * * egrep "`echo -n ';('; grep ';<' UnicodeData.txt | cut -d';' -f1 | tr '\n' '|'; echo ') '`" UnicodeData.txt */ static hb_bool_t decompose_func (hb_unicode_funcs_t *unicode, hb_codepoint_t ab, hb_codepoint_t *a, hb_codepoint_t *b) { /* XXX FIXME, move these to complex shapers and propagage to normalizer.*/ switch (ab) { case 0x0AC9 : return false; case 0x0931 : return false; case 0x0B94 : return false; /* These ones have Unicode decompositions, but we do it * this way to be close to what Uniscribe does. */ case 0x0DDA : *a = 0x0DD9; *b= 0x0DDA; return true; case 0x0DDC : *a = 0x0DD9; *b= 0x0DDC; return true; case 0x0DDD : *a = 0x0DD9; *b= 0x0DDD; return true; case 0x0DDE : *a = 0x0DD9; *b= 0x0DDE; return true; case 0x0F77 : *a = 0x0FB2; *b= 0x0F81; return true; case 0x0F79 : *a = 0x0FB3; *b= 0x0F81; return true; case 0x17BE : *a = 0x17C1; *b= 0x17BE; return true; case 0x17BF : *a = 0x17C1; *b= 0x17BF; return true; case 0x17C0 : *a = 0x17C1; *b= 0x17C0; return true; case 0x17C4 : *a = 0x17C1; *b= 0x17C4; return true; case 0x17C5 : *a = 0x17C1; *b= 0x17C5; return true; case 0x1925 : *a = 0x1920; *b= 0x1923; return true; case 0x1926 : *a = 0x1920; *b= 0x1924; return true; case 0x1B3C : *a = 0x1B42; *b= 0x1B3C; return true; case 0x1112E : *a = 0x11127; *b= 0x11131; return true; case 0x1112F : *a = 0x11127; *b= 0x11132; return true; #if 0 case 0x0B57 : *a = 0xno decomp, -> RIGHT; return true; case 0x1C29 : *a = 0xno decomp, -> LEFT; return true; case 0xA9C0 : *a = 0xno decomp, -> RIGHT; return true; case 0x111BF : *a = 0xno decomp, -> ABOVE; return true; #endif } return unicode->decompose (ab, a, b); } static hb_bool_t compose_func (hb_unicode_funcs_t *unicode, hb_codepoint_t a, hb_codepoint_t b, hb_codepoint_t *ab) { /* XXX, this belongs to indic normalizer. */ if ((FLAG (unicode->general_category (a)) & (FLAG (HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK) | FLAG (HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) | FLAG (HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)))) return false; /* XXX, add composition-exclusion exceptions to Indic shaper. */ if (a == 0x09AF && b == 0x09BC) { *ab = 0x09DF; return true; } /* XXX, these belong to the hebew / default shaper. */ /* Hebrew presentation-form shaping. * https://bugzilla.mozilla.org/show_bug.cgi?id=728866 */ // Hebrew presentation forms with dagesh, for characters 0x05D0..0x05EA; // note that some letters do not have a dagesh presForm encoded static const hb_codepoint_t sDageshForms[0x05EA - 0x05D0 + 1] = { 0xFB30, // ALEF 0xFB31, // BET 0xFB32, // GIMEL 0xFB33, // DALET 0xFB34, // HE 0xFB35, // VAV 0xFB36, // ZAYIN 0, // HET 0xFB38, // TET 0xFB39, // YOD 0xFB3A, // FINAL KAF 0xFB3B, // KAF 0xFB3C, // LAMED 0, // FINAL MEM 0xFB3E, // MEM 0, // FINAL NUN 0xFB40, // NUN 0xFB41, // SAMEKH 0, // AYIN 0xFB43, // FINAL PE 0xFB44, // PE 0, // FINAL TSADI 0xFB46, // TSADI 0xFB47, // QOF 0xFB48, // RESH 0xFB49, // SHIN 0xFB4A // TAV }; hb_bool_t found = unicode->compose (a, b, ab); if (!found && (b & ~0x7F) == 0x0580) { // special-case Hebrew presentation forms that are excluded from // standard normalization, but wanted for old fonts switch (b) { case 0x05B4: // HIRIQ if (a == 0x05D9) { // YOD *ab = 0xFB1D; found = true; } break; case 0x05B7: // patah if (a == 0x05F2) { // YIDDISH YOD YOD *ab = 0xFB1F; found = true; } else if (a == 0x05D0) { // ALEF *ab = 0xFB2E; found = true; } break; case 0x05B8: // QAMATS if (a == 0x05D0) { // ALEF *ab = 0xFB2F; found = true; } break; case 0x05B9: // HOLAM if (a == 0x05D5) { // VAV *ab = 0xFB4B; found = true; } break; case 0x05BC: // DAGESH if (a >= 0x05D0 && a <= 0x05EA) { *ab = sDageshForms[a - 0x05D0]; found = (*ab != 0); } else if (a == 0xFB2A) { // SHIN WITH SHIN DOT *ab = 0xFB2C; found = true; } else if (a == 0xFB2B) { // SHIN WITH SIN DOT *ab = 0xFB2D; found = true; } break; case 0x05BF: // RAFE switch (a) { case 0x05D1: // BET *ab = 0xFB4C; found = true; break; case 0x05DB: // KAF *ab = 0xFB4D; found = true; break; case 0x05E4: // PE *ab = 0xFB4E; found = true; break; } break; case 0x05C1: // SHIN DOT if (a == 0x05E9) { // SHIN *ab = 0xFB2A; found = true; } else if (a == 0xFB49) { // SHIN WITH DAGESH *ab = 0xFB2C; found = true; } break; case 0x05C2: // SIN DOT if (a == 0x05E9) { // SHIN *ab = 0xFB2B; found = true; } else if (a == 0xFB49) { // SHIN WITH DAGESH *ab = 0xFB2D; found = true; } break; } } return found; } static inline void set_glyph (hb_glyph_info_t &info, hb_font_t *font) { font->get_glyph (info.codepoint, 0, &info.glyph_index()); } static inline void output_char (hb_buffer_t *buffer, hb_codepoint_t unichar, hb_codepoint_t glyph) { buffer->cur().glyph_index() = glyph; buffer->output_glyph (unichar); _hb_glyph_info_set_unicode_props (&buffer->prev(), buffer->unicode); } static inline void next_char (hb_buffer_t *buffer, hb_codepoint_t glyph) { buffer->cur().glyph_index() = glyph; 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 (hb_font_t *font, hb_buffer_t *buffer, bool shortest, hb_codepoint_t ab) { hb_codepoint_t a, b, a_glyph, b_glyph; if (!decompose_func (buffer->unicode, ab, &a, &b) || (b && !font->get_glyph (b, 0, &b_glyph))) return 0; bool has_a = font->get_glyph (a, 0, &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; } unsigned int ret; if ((ret = decompose (font, buffer, 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; } /* Returns 0 if didn't decompose, number of resulting characters otherwise. */ static inline bool decompose_compatibility (hb_font_t *font, hb_buffer_t *buffer, hb_codepoint_t u) { unsigned int len, i; hb_codepoint_t decomposed[HB_UNICODE_MAX_DECOMPOSITION_LEN]; hb_codepoint_t glyphs[HB_UNICODE_MAX_DECOMPOSITION_LEN]; len = buffer->unicode->decompose_compatibility (u, decomposed); if (!len) return 0; for (i = 0; i < len; i++) if (!font->get_glyph (decomposed[i], 0, &glyphs[i])) return 0; for (i = 0; i < len; i++) output_char (buffer, decomposed[i], glyphs[i]); return len; } /* Returns true if recomposition may be benefitial. */ static inline bool decompose_current_character (hb_font_t *font, hb_buffer_t *buffer, bool shortest) { hb_codepoint_t glyph; unsigned int len = 1; /* Kind of a cute waterfall here... */ if (shortest && font->get_glyph (buffer->cur().codepoint, 0, &glyph)) next_char (buffer, glyph); else if ((len = decompose (font, buffer, shortest, buffer->cur().codepoint))) skip_char (buffer); else if (!shortest && font->get_glyph (buffer->cur().codepoint, 0, &glyph)) next_char (buffer, glyph); else if ((len = decompose_compatibility (font, buffer, buffer->cur().codepoint))) skip_char (buffer); else next_char (buffer, glyph); /* glyph is initialized in earlier branches. */ /* * A recomposition would only be useful if we decomposed into at least three * characters... */ return len > 2; } static inline void handle_variation_selector_cluster (hb_font_t *font, hb_buffer_t *buffer, unsigned int end) { for (; buffer->idx < end - 1;) { if (unlikely (buffer->unicode->is_variation_selector (buffer->cur(+1).codepoint))) { /* The next two lines are some ugly lines... But work. */ font->get_glyph (buffer->cur().codepoint, buffer->cur(+1).codepoint, &buffer->cur().glyph_index()); buffer->replace_glyphs (2, 1, &buffer->cur().codepoint); } else { set_glyph (buffer->cur(), font); buffer->next_glyph (); } } if (likely (buffer->idx < end)) { set_glyph (buffer->cur(), font); buffer->next_glyph (); } } /* Returns true if recomposition may be benefitial. */ static inline bool 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 = buffer->idx; i < end; i++) if (unlikely (buffer->unicode->is_variation_selector (buffer->info[i].codepoint))) { handle_variation_selector_cluster (font, buffer, end); return false; } while (buffer->idx < end) decompose_current_character (font, buffer, false); /* We can be smarter here and only return true if there are at least two ccc!=0 marks. * But does not matter. */ return true; } static inline bool decompose_cluster (hb_font_t *font, hb_buffer_t *buffer, bool short_circuit, unsigned int end) { if (likely (buffer->idx + 1 == end)) return decompose_current_character (font, buffer, short_circuit); else return decompose_multi_char_cluster (font, buffer, end); } 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 (hb_font_t *font, hb_buffer_t *buffer, hb_ot_shape_normalization_mode_t mode) { bool short_circuit = mode != HB_OT_SHAPE_NORMALIZATION_MODE_DECOMPOSED && mode != HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT; bool can_use_recompose = 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->cur().cluster != buffer->info[end].cluster) break; can_use_recompose = decompose_cluster (font, buffer, short_circuit, end) || can_use_recompose; } buffer->swap_buffers (); if (mode != HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_FULL && !can_use_recompose) return; /* Done! */ /* Second round, reorder (inplace) */ 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 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; } hb_bubble_sort (buffer->info + i, end - i, compare_combining_class); i = end; } if (mode == HB_OT_SHAPE_NORMALIZATION_MODE_DECOMPOSED) return; /* Third round, recompose */ /* 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) { 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. */ compose_func (buffer->unicode, buffer->out_info[starter].codepoint, buffer->cur().codepoint, &composed) && /* And the font has glyph for the composite. */ font->get_glyph (composed, 0, &glyph)) { /* Composes. */ buffer->next_glyph (); /* Copy to out-buffer. */ if (unlikely (buffer->in_error)) return; buffer->merge_out_clusters (starter, buffer->out_len); buffer->out_len--; /* Remove the second composable. */ buffer->out_info[starter].codepoint = composed; /* Modify starter and carry on. */ set_glyph (buffer->out_info[starter], font); _hb_glyph_info_set_unicode_props (&buffer->out_info[starter], buffer->unicode); continue; } /* Blocked, or doesn't compose. */ buffer->next_glyph (); if (_hb_glyph_info_get_modified_combining_class (&buffer->prev()) == 0) starter = buffer->out_len - 1; } buffer->swap_buffers (); }