| /* |
| * 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 (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (unicode->general_category (a))) |
| 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 (); |
| |
| } |