HarfBuzz text shaping engine
http://harfbuzz.github.io/
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439 lines
13 KiB
439 lines
13 KiB
/* |
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* Copyright © 2013 Google, Inc. |
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* |
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* This is part of HarfBuzz, a text shaping library. |
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* |
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* Permission is hereby granted, without written agreement and without |
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* license or royalty fees, to use, copy, modify, and distribute this |
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* software and its documentation for any purpose, provided that the |
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* above copyright notice and the following two paragraphs appear in |
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* all copies of this software. |
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* |
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR |
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES |
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN |
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH |
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* DAMAGE. |
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* |
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, |
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND |
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS |
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO |
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. |
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* |
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* Google Author(s): Behdad Esfahbod |
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*/ |
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#include "hb.hh" |
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#ifndef HB_NO_OT_SHAPE |
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#include "hb-ot-shape-complex.hh" |
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/* Hangul shaper */ |
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/* Same order as the feature array below */ |
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enum { |
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_JMO, |
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LJMO, |
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VJMO, |
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TJMO, |
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FIRST_HANGUL_FEATURE = LJMO, |
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HANGUL_FEATURE_COUNT = TJMO + 1 |
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}; |
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static const hb_tag_t hangul_features[HANGUL_FEATURE_COUNT] = |
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{ |
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HB_TAG_NONE, |
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HB_TAG('l','j','m','o'), |
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HB_TAG('v','j','m','o'), |
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HB_TAG('t','j','m','o') |
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}; |
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static void |
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collect_features_hangul (hb_ot_shape_planner_t *plan) |
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{ |
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hb_ot_map_builder_t *map = &plan->map; |
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for (unsigned int i = FIRST_HANGUL_FEATURE; i < HANGUL_FEATURE_COUNT; i++) |
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map->add_feature (hangul_features[i]); |
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} |
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static void |
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override_features_hangul (hb_ot_shape_planner_t *plan) |
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{ |
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/* Uniscribe does not apply 'calt' for Hangul, and certain fonts |
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* (Noto Sans CJK, Source Sans Han, etc) apply all of jamo lookups |
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* in calt, which is not desirable. */ |
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plan->map.disable_feature (HB_TAG('c','a','l','t')); |
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} |
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struct hangul_shape_plan_t |
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{ |
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hb_mask_t mask_array[HANGUL_FEATURE_COUNT]; |
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}; |
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static void * |
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data_create_hangul (const hb_ot_shape_plan_t *plan) |
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{ |
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hangul_shape_plan_t *hangul_plan = (hangul_shape_plan_t *) calloc (1, sizeof (hangul_shape_plan_t)); |
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if (unlikely (!hangul_plan)) |
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return nullptr; |
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for (unsigned int i = 0; i < HANGUL_FEATURE_COUNT; i++) |
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hangul_plan->mask_array[i] = plan->map.get_1_mask (hangul_features[i]); |
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return hangul_plan; |
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} |
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static void |
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data_destroy_hangul (void *data) |
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{ |
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free (data); |
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} |
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/* Constants for algorithmic hangul syllable [de]composition. */ |
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#define LBase 0x1100u |
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#define VBase 0x1161u |
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#define TBase 0x11A7u |
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#define LCount 19u |
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#define VCount 21u |
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#define TCount 28u |
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#define SBase 0xAC00u |
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#define NCount (VCount * TCount) |
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#define SCount (LCount * NCount) |
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#define isCombiningL(u) (hb_in_range<hb_codepoint_t> ((u), LBase, LBase+LCount-1)) |
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#define isCombiningV(u) (hb_in_range<hb_codepoint_t> ((u), VBase, VBase+VCount-1)) |
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#define isCombiningT(u) (hb_in_range<hb_codepoint_t> ((u), TBase+1, TBase+TCount-1)) |
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#define isCombinedS(u) (hb_in_range<hb_codepoint_t> ((u), SBase, SBase+SCount-1)) |
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#define isL(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x1100u, 0x115Fu, 0xA960u, 0xA97Cu)) |
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#define isV(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x1160u, 0x11A7u, 0xD7B0u, 0xD7C6u)) |
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#define isT(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x11A8u, 0x11FFu, 0xD7CBu, 0xD7FBu)) |
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#define isHangulTone(u) (hb_in_range<hb_codepoint_t> ((u), 0x302Eu, 0x302Fu)) |
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/* buffer var allocations */ |
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#define hangul_shaping_feature() complex_var_u8_0() /* hangul jamo shaping feature */ |
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static bool |
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is_zero_width_char (hb_font_t *font, |
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hb_codepoint_t unicode) |
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{ |
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hb_codepoint_t glyph; |
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return hb_font_get_glyph (font, unicode, 0, &glyph) && hb_font_get_glyph_h_advance (font, glyph) == 0; |
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} |
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static void |
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preprocess_text_hangul (const hb_ot_shape_plan_t *plan HB_UNUSED, |
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hb_buffer_t *buffer, |
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hb_font_t *font) |
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{ |
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HB_BUFFER_ALLOCATE_VAR (buffer, hangul_shaping_feature); |
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/* Hangul syllables come in two shapes: LV, and LVT. Of those: |
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* |
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* - LV can be precomposed, or decomposed. Lets call those |
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* <LV> and <L,V>, |
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* - LVT can be fully precomposed, partically precomposed, or |
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* fully decomposed. Ie. <LVT>, <LV,T>, or <L,V,T>. |
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* |
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* The composition / decomposition is mechanical. However, not |
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* all <L,V> sequences compose, and not all <LV,T> sequences |
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* compose. |
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* |
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* Here are the specifics: |
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* |
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* - <L>: U+1100..115F, U+A960..A97F |
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* - <V>: U+1160..11A7, U+D7B0..D7C7 |
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* - <T>: U+11A8..11FF, U+D7CB..D7FB |
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* |
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* - Only the <L,V> sequences for some of the U+11xx ranges combine. |
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* - Only <LV,T> sequences for some of the Ts in U+11xx range combine. |
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* |
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* Here is what we want to accomplish in this shaper: |
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* |
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* - If the whole syllable can be precomposed, do that, |
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* - Otherwise, fully decompose and apply ljmo/vjmo/tjmo features. |
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* - If a valid syllable is followed by a Hangul tone mark, reorder the tone |
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* mark to precede the whole syllable - unless it is a zero-width glyph, in |
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* which case we leave it untouched, assuming it's designed to overstrike. |
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* |
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* That is, of the different possible syllables: |
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* |
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* <L> |
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* <L,V> |
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* <L,V,T> |
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* <LV> |
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* <LVT> |
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* <LV, T> |
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* |
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* - <L> needs no work. |
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* |
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* - <LV> and <LVT> can stay the way they are if the font supports them, otherwise we |
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* should fully decompose them if font supports. |
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* |
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* - <L,V> and <L,V,T> we should compose if the whole thing can be composed. |
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* |
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* - <LV,T> we should compose if the whole thing can be composed, otherwise we should |
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* decompose. |
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*/ |
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buffer->clear_output (); |
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unsigned int start = 0, end = 0; /* Extent of most recently seen syllable; |
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* valid only if start < end |
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*/ |
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unsigned int count = buffer->len; |
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for (buffer->idx = 0; buffer->idx < count && buffer->successful;) |
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{ |
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hb_codepoint_t u = buffer->cur().codepoint; |
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if (isHangulTone (u)) |
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{ |
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/* |
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* We could cache the width of the tone marks and the existence of dotted-circle, |
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* but the use of the Hangul tone mark characters seems to be rare enough that |
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* I didn't bother for now. |
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*/ |
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if (start < end && end == buffer->out_len) |
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{ |
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/* Tone mark follows a valid syllable; move it in front, unless it's zero width. */ |
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buffer->unsafe_to_break_from_outbuffer (start, buffer->idx); |
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buffer->next_glyph (); |
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if (!is_zero_width_char (font, u)) |
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{ |
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buffer->merge_out_clusters (start, end + 1); |
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hb_glyph_info_t *info = buffer->out_info; |
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hb_glyph_info_t tone = info[end]; |
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memmove (&info[start + 1], &info[start], (end - start) * sizeof (hb_glyph_info_t)); |
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info[start] = tone; |
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} |
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} |
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else |
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{ |
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/* No valid syllable as base for tone mark; try to insert dotted circle. */ |
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if (!(buffer->flags & HB_BUFFER_FLAG_DO_NOT_INSERT_DOTTED_CIRCLE) && |
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font->has_glyph (0x25CCu)) |
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{ |
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hb_codepoint_t chars[2]; |
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if (!is_zero_width_char (font, u)) { |
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chars[0] = u; |
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chars[1] = 0x25CCu; |
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} else { |
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chars[0] = 0x25CCu; |
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chars[1] = u; |
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} |
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buffer->replace_glyphs (1, 2, chars); |
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} |
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else |
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{ |
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/* No dotted circle available in the font; just leave tone mark untouched. */ |
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buffer->next_glyph (); |
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} |
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} |
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start = end = buffer->out_len; |
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continue; |
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} |
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start = buffer->out_len; /* Remember current position as a potential syllable start; |
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* will only be used if we set end to a later position. |
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*/ |
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if (isL (u) && buffer->idx + 1 < count) |
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{ |
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hb_codepoint_t l = u; |
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hb_codepoint_t v = buffer->cur(+1).codepoint; |
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if (isV (v)) |
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{ |
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/* Have <L,V> or <L,V,T>. */ |
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hb_codepoint_t t = 0; |
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unsigned int tindex = 0; |
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if (buffer->idx + 2 < count) |
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{ |
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t = buffer->cur(+2).codepoint; |
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if (isT (t)) |
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tindex = t - TBase; /* Only used if isCombiningT (t); otherwise invalid. */ |
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else |
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t = 0; /* The next character was not a trailing jamo. */ |
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} |
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buffer->unsafe_to_break (buffer->idx, buffer->idx + (t ? 3 : 2)); |
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/* We've got a syllable <L,V,T?>; see if it can potentially be composed. */ |
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if (isCombiningL (l) && isCombiningV (v) && (t == 0 || isCombiningT (t))) |
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{ |
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/* Try to compose; if this succeeds, end is set to start+1. */ |
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hb_codepoint_t s = SBase + (l - LBase) * NCount + (v - VBase) * TCount + tindex; |
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if (font->has_glyph (s)) |
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{ |
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buffer->replace_glyphs (t ? 3 : 2, 1, &s); |
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if (unlikely (!buffer->successful)) |
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return; |
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end = start + 1; |
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continue; |
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} |
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} |
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/* We didn't compose, either because it's an Old Hangul syllable without a |
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* precomposed character in Unicode, or because the font didn't support the |
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* necessary precomposed glyph. |
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* Set jamo features on the individual glyphs, and advance past them. |
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*/ |
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buffer->cur().hangul_shaping_feature() = LJMO; |
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buffer->next_glyph (); |
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buffer->cur().hangul_shaping_feature() = VJMO; |
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buffer->next_glyph (); |
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if (t) |
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{ |
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buffer->cur().hangul_shaping_feature() = TJMO; |
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buffer->next_glyph (); |
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end = start + 3; |
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} |
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else |
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end = start + 2; |
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if (buffer->cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES) |
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buffer->merge_out_clusters (start, end); |
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continue; |
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} |
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} |
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else if (isCombinedS (u)) |
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{ |
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/* Have <LV>, <LVT>, or <LV,T> */ |
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hb_codepoint_t s = u; |
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bool has_glyph = font->has_glyph (s); |
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unsigned int lindex = (s - SBase) / NCount; |
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unsigned int nindex = (s - SBase) % NCount; |
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unsigned int vindex = nindex / TCount; |
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unsigned int tindex = nindex % TCount; |
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if (!tindex && |
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buffer->idx + 1 < count && |
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isCombiningT (buffer->cur(+1).codepoint)) |
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{ |
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/* <LV,T>, try to combine. */ |
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unsigned int new_tindex = buffer->cur(+1).codepoint - TBase; |
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hb_codepoint_t new_s = s + new_tindex; |
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if (font->has_glyph (new_s)) |
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{ |
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buffer->replace_glyphs (2, 1, &new_s); |
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if (unlikely (!buffer->successful)) |
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return; |
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end = start + 1; |
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continue; |
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} |
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else |
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buffer->unsafe_to_break (buffer->idx, buffer->idx + 2); /* Mark unsafe between LV and T. */ |
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} |
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/* Otherwise, decompose if font doesn't support <LV> or <LVT>, |
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* or if having non-combining <LV,T>. Note that we already handled |
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* combining <LV,T> above. */ |
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if (!has_glyph || |
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(!tindex && |
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buffer->idx + 1 < count && |
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isT (buffer->cur(+1).codepoint))) |
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{ |
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hb_codepoint_t decomposed[3] = {LBase + lindex, |
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VBase + vindex, |
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TBase + tindex}; |
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if (font->has_glyph (decomposed[0]) && |
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font->has_glyph (decomposed[1]) && |
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(!tindex || font->has_glyph (decomposed[2]))) |
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{ |
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unsigned int s_len = tindex ? 3 : 2; |
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buffer->replace_glyphs (1, s_len, decomposed); |
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/* If we decomposed an LV because of a non-combining T following, |
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* we want to include this T in the syllable. |
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*/ |
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if (has_glyph && !tindex) |
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{ |
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buffer->next_glyph (); |
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s_len++; |
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} |
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if (unlikely (!buffer->successful)) |
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return; |
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/* We decomposed S: apply jamo features to the individual glyphs |
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* that are now in buffer->out_info. |
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*/ |
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hb_glyph_info_t *info = buffer->out_info; |
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end = start + s_len; |
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unsigned int i = start; |
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info[i++].hangul_shaping_feature() = LJMO; |
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info[i++].hangul_shaping_feature() = VJMO; |
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if (i < end) |
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info[i++].hangul_shaping_feature() = TJMO; |
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if (buffer->cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES) |
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buffer->merge_out_clusters (start, end); |
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continue; |
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} |
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else if ((!tindex && buffer->idx + 1 < count && isT (buffer->cur(+1).codepoint))) |
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buffer->unsafe_to_break (buffer->idx, buffer->idx + 2); /* Mark unsafe between LV and T. */ |
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} |
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if (has_glyph) |
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{ |
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/* We didn't decompose the S, so just advance past it. */ |
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end = start + 1; |
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buffer->next_glyph (); |
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continue; |
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} |
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} |
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/* Didn't find a recognizable syllable, so we leave end <= start; |
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* this will prevent tone-mark reordering happening. |
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*/ |
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buffer->next_glyph (); |
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} |
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buffer->swap_buffers (); |
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} |
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static void |
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setup_masks_hangul (const hb_ot_shape_plan_t *plan, |
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hb_buffer_t *buffer, |
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hb_font_t *font HB_UNUSED) |
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{ |
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const hangul_shape_plan_t *hangul_plan = (const hangul_shape_plan_t *) plan->data; |
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if (likely (hangul_plan)) |
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{ |
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unsigned int count = buffer->len; |
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hb_glyph_info_t *info = buffer->info; |
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for (unsigned int i = 0; i < count; i++, info++) |
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info->mask |= hangul_plan->mask_array[info->hangul_shaping_feature()]; |
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} |
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HB_BUFFER_DEALLOCATE_VAR (buffer, hangul_shaping_feature); |
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} |
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const hb_ot_complex_shaper_t _hb_ot_complex_shaper_hangul = |
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{ |
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collect_features_hangul, |
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override_features_hangul, |
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data_create_hangul, |
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data_destroy_hangul, |
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preprocess_text_hangul, |
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nullptr, /* postprocess_glyphs */ |
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HB_OT_SHAPE_NORMALIZATION_MODE_NONE, |
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nullptr, /* decompose */ |
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nullptr, /* compose */ |
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setup_masks_hangul, |
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HB_TAG_NONE, /* gpos_tag */ |
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nullptr, /* reorder_marks */ |
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HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE, |
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false, /* fallback_position */ |
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}; |
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#endif
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