| /* |
| * 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 (unlikely (_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 |