505 lines
14 KiB
C++
505 lines
14 KiB
C++
/*
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* Copyright © 2011,2012 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-ot-shape-complex-khmer.hh"
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#include "hb-ot-layout.hh"
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/*
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* Khmer shaper.
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*/
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static const hb_ot_map_feature_t
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khmer_features[] =
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{
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/*
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* Basic features.
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* These features are applied in order, one at a time, after reordering.
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*/
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{HB_TAG('p','r','e','f'), F_MANUAL_JOINERS},
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{HB_TAG('b','l','w','f'), F_MANUAL_JOINERS},
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{HB_TAG('a','b','v','f'), F_MANUAL_JOINERS},
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{HB_TAG('p','s','t','f'), F_MANUAL_JOINERS},
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{HB_TAG('c','f','a','r'), F_MANUAL_JOINERS},
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/*
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* Other features.
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* These features are applied all at once after clearing syllables.
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*/
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{HB_TAG('p','r','e','s'), F_GLOBAL_MANUAL_JOINERS},
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{HB_TAG('a','b','v','s'), F_GLOBAL_MANUAL_JOINERS},
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{HB_TAG('b','l','w','s'), F_GLOBAL_MANUAL_JOINERS},
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{HB_TAG('p','s','t','s'), F_GLOBAL_MANUAL_JOINERS},
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/*
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* Positioning features.
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* We don't care about the types.
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*/
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{HB_TAG('d','i','s','t'), F_GLOBAL},
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{HB_TAG('a','b','v','m'), F_GLOBAL},
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{HB_TAG('b','l','w','m'), F_GLOBAL},
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};
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/*
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* Must be in the same order as the khmer_features array.
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*/
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enum {
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PREF,
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BLWF,
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ABVF,
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PSTF,
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CFAR,
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_PRES,
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_ABVS,
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_BLWS,
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_PSTS,
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_DIST,
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_ABVM,
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_BLWM,
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KHMER_NUM_FEATURES,
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KHMER_BASIC_FEATURES = _PRES, /* Don't forget to update this! */
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};
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static void
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setup_syllables (const hb_ot_shape_plan_t *plan,
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hb_font_t *font,
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hb_buffer_t *buffer);
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static void
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reorder (const hb_ot_shape_plan_t *plan,
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hb_font_t *font,
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hb_buffer_t *buffer);
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static void
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clear_syllables (const hb_ot_shape_plan_t *plan,
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hb_font_t *font,
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hb_buffer_t *buffer);
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static void
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collect_features_khmer (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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/* Do this before any lookups have been applied. */
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map->add_gsub_pause (setup_syllables);
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map->add_gsub_pause (reorder);
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/* Testing suggests that Uniscribe does NOT pause between basic
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* features. Test with KhmerUI.ttf and the following three
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* sequences:
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*
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* U+1789,U+17BC
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* U+1789,U+17D2,U+1789
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* U+1789,U+17D2,U+1789,U+17BC
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*
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* https://github.com/harfbuzz/harfbuzz/issues/974
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*/
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map->enable_feature (HB_TAG('l','o','c','l'));
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map->enable_feature (HB_TAG('c','c','m','p'));
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unsigned int i = 0;
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for (; i < KHMER_BASIC_FEATURES; i++)
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map->add_feature (khmer_features[i]);
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map->add_gsub_pause (clear_syllables);
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for (; i < KHMER_NUM_FEATURES; i++)
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map->add_feature (khmer_features[i]);
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}
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static void
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override_features_khmer (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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/* Khmer spec has 'clig' as part of required shaping features:
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* "Apply feature 'clig' to form ligatures that are desired for
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* typographical correctness.", hence in overrides... */
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map->enable_feature (HB_TAG('c','l','i','g'));
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/* Uniscribe does not apply 'kern' in Khmer. */
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if (hb_options ().uniscribe_bug_compatible)
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{
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map->disable_feature (HB_TAG('k','e','r','n'));
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}
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map->disable_feature (HB_TAG('l','i','g','a'));
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}
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struct would_substitute_feature_t
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{
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void init (const hb_ot_map_t *map, hb_tag_t feature_tag, bool zero_context_)
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{
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zero_context = zero_context_;
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map->get_stage_lookups (0/*GSUB*/,
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map->get_feature_stage (0/*GSUB*/, feature_tag),
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&lookups, &count);
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}
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bool would_substitute (const hb_codepoint_t *glyphs,
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unsigned int glyphs_count,
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hb_face_t *face) const
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{
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for (unsigned int i = 0; i < count; i++)
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if (hb_ot_layout_lookup_would_substitute_fast (face, lookups[i].index, glyphs, glyphs_count, zero_context))
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return true;
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return false;
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}
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private:
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const hb_ot_map_t::lookup_map_t *lookups;
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unsigned int count;
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bool zero_context;
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};
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struct khmer_shape_plan_t
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{
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bool get_virama_glyph (hb_font_t *font, hb_codepoint_t *pglyph) const
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{
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hb_codepoint_t glyph = virama_glyph;
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if (unlikely (virama_glyph == (hb_codepoint_t) -1))
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{
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if (!font->get_nominal_glyph (0x17D2u, &glyph))
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glyph = 0;
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/* Technically speaking, the spec says we should apply 'locl' to virama too.
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* Maybe one day... */
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/* Our get_nominal_glyph() function needs a font, so we can't get the virama glyph
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* during shape planning... Instead, overwrite it here. It's safe. Don't worry! */
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virama_glyph = glyph;
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}
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*pglyph = glyph;
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return glyph != 0;
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}
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mutable hb_codepoint_t virama_glyph;
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would_substitute_feature_t pref;
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hb_mask_t mask_array[KHMER_NUM_FEATURES];
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};
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static void *
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data_create_khmer (const hb_ot_shape_plan_t *plan)
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{
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khmer_shape_plan_t *khmer_plan = (khmer_shape_plan_t *) calloc (1, sizeof (khmer_shape_plan_t));
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if (unlikely (!khmer_plan))
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return nullptr;
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khmer_plan->virama_glyph = (hb_codepoint_t) -1;
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khmer_plan->pref.init (&plan->map, HB_TAG('p','r','e','f'), true);
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for (unsigned int i = 0; i < ARRAY_LENGTH (khmer_plan->mask_array); i++)
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khmer_plan->mask_array[i] = (khmer_features[i].flags & F_GLOBAL) ?
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0 : plan->map.get_1_mask (khmer_features[i].tag);
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return khmer_plan;
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}
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static void
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data_destroy_khmer (void *data)
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{
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free (data);
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}
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enum syllable_type_t {
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consonant_syllable,
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broken_cluster,
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non_khmer_cluster,
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};
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#include "hb-ot-shape-complex-khmer-machine.hh"
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static void
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setup_masks_khmer (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 HB_UNUSED)
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{
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HB_BUFFER_ALLOCATE_VAR (buffer, khmer_category);
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/* We cannot setup masks here. We save information about characters
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* and setup masks later on in a pause-callback. */
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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++)
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set_khmer_properties (info[i]);
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}
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static void
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setup_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
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hb_font_t *font HB_UNUSED,
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hb_buffer_t *buffer)
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{
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find_syllables (buffer);
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foreach_syllable (buffer, start, end)
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buffer->unsafe_to_break (start, end);
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}
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/* Rules from:
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* https://docs.microsoft.com/en-us/typography/script-development/devanagari */
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static void
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reorder_consonant_syllable (const hb_ot_shape_plan_t *plan,
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hb_face_t *face HB_UNUSED,
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hb_buffer_t *buffer,
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unsigned int start, unsigned int end)
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{
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const khmer_shape_plan_t *khmer_plan = (const khmer_shape_plan_t *) plan->data;
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hb_glyph_info_t *info = buffer->info;
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/* Setup masks. */
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{
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/* Post-base */
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hb_mask_t mask = khmer_plan->mask_array[BLWF] | khmer_plan->mask_array[ABVF] | khmer_plan->mask_array[PSTF];
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for (unsigned int i = start + 1; i < end; i++)
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info[i].mask |= mask;
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}
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unsigned int num_coengs = 0;
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for (unsigned int i = start + 1; i < end; i++)
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{
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/* """
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* When a COENG + (Cons | IndV) combination are found (and subscript count
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* is less than two) the character combination is handled according to the
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* subscript type of the character following the COENG.
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*
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* ...
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*
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* Subscript Type 2 - The COENG + RO characters are reordered to immediately
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* before the base glyph. Then the COENG + RO characters are assigned to have
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* the 'pref' OpenType feature applied to them.
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* """
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*/
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if (info[i].khmer_category() == OT_Coeng && num_coengs <= 2 && i + 1 < end)
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{
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num_coengs++;
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if (info[i + 1].khmer_category() == OT_Ra)
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{
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for (unsigned int j = 0; j < 2; j++)
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info[i + j].mask |= khmer_plan->mask_array[PREF];
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/* Move the Coeng,Ro sequence to the start. */
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buffer->merge_clusters (start, i + 2);
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hb_glyph_info_t t0 = info[i];
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hb_glyph_info_t t1 = info[i + 1];
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memmove (&info[start + 2], &info[start], (i - start) * sizeof (info[0]));
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info[start] = t0;
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info[start + 1] = t1;
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/* Mark the subsequent stuff with 'cfar'. Used in Khmer.
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* Read the feature spec.
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* This allows distinguishing the following cases with MS Khmer fonts:
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* U+1784,U+17D2,U+179A,U+17D2,U+1782
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* U+1784,U+17D2,U+1782,U+17D2,U+179A
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*/
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if (khmer_plan->mask_array[CFAR])
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for (unsigned int j = i + 2; j < end; j++)
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info[j].mask |= khmer_plan->mask_array[CFAR];
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num_coengs = 2; /* Done. */
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}
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}
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/* Reorder left matra piece. */
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else if (info[i].khmer_category() == OT_VPre)
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{
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/* Move to the start. */
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buffer->merge_clusters (start, i + 1);
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hb_glyph_info_t t = info[i];
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memmove (&info[start + 1], &info[start], (i - start) * sizeof (info[0]));
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info[start] = t;
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}
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}
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}
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static void
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initial_reordering_syllable (const hb_ot_shape_plan_t *plan,
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hb_face_t *face,
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hb_buffer_t *buffer,
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unsigned int start, unsigned int end)
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{
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syllable_type_t syllable_type = (syllable_type_t) (buffer->info[start].syllable() & 0x0F);
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switch (syllable_type)
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{
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case broken_cluster: /* We already inserted dotted-circles, so just call the consonant_syllable. */
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case consonant_syllable:
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reorder_consonant_syllable (plan, face, buffer, start, end);
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break;
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case non_khmer_cluster:
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break;
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}
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}
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static inline void
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insert_dotted_circles (const hb_ot_shape_plan_t *plan HB_UNUSED,
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hb_font_t *font,
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hb_buffer_t *buffer)
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{
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if (unlikely (buffer->flags & HB_BUFFER_FLAG_DO_NOT_INSERT_DOTTED_CIRCLE))
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return;
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/* Note: This loop is extra overhead, but should not be measurable. */
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bool has_broken_syllables = false;
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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++)
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if ((info[i].syllable() & 0x0F) == broken_cluster)
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{
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has_broken_syllables = true;
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break;
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}
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if (likely (!has_broken_syllables))
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return;
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hb_codepoint_t dottedcircle_glyph;
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if (!font->get_nominal_glyph (0x25CCu, &dottedcircle_glyph))
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return;
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hb_glyph_info_t dottedcircle = {0};
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dottedcircle.codepoint = 0x25CCu;
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set_khmer_properties (dottedcircle);
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dottedcircle.codepoint = dottedcircle_glyph;
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buffer->clear_output ();
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buffer->idx = 0;
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unsigned int last_syllable = 0;
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while (buffer->idx < buffer->len && buffer->successful)
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{
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unsigned int syllable = buffer->cur().syllable();
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syllable_type_t syllable_type = (syllable_type_t) (syllable & 0x0F);
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if (unlikely (last_syllable != syllable && syllable_type == broken_cluster))
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{
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last_syllable = syllable;
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hb_glyph_info_t ginfo = dottedcircle;
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ginfo.cluster = buffer->cur().cluster;
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ginfo.mask = buffer->cur().mask;
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ginfo.syllable() = buffer->cur().syllable();
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/* TODO Set glyph_props? */
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/* Insert dottedcircle after possible Repha. */
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while (buffer->idx < buffer->len && buffer->successful &&
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last_syllable == buffer->cur().syllable() &&
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buffer->cur().khmer_category() == OT_Repha)
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buffer->next_glyph ();
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buffer->output_info (ginfo);
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}
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else
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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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reorder (const hb_ot_shape_plan_t *plan,
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hb_font_t *font,
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hb_buffer_t *buffer)
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{
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insert_dotted_circles (plan, font, buffer);
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foreach_syllable (buffer, start, end)
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initial_reordering_syllable (plan, font->face, buffer, start, end);
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HB_BUFFER_DEALLOCATE_VAR (buffer, khmer_category);
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}
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static void
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clear_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
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hb_font_t *font HB_UNUSED,
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hb_buffer_t *buffer)
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{
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hb_glyph_info_t *info = buffer->info;
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unsigned int count = buffer->len;
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for (unsigned int i = 0; i < count; i++)
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info[i].syllable() = 0;
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}
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static bool
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decompose_khmer (const hb_ot_shape_normalize_context_t *c,
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hb_codepoint_t ab,
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hb_codepoint_t *a,
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hb_codepoint_t *b)
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{
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switch (ab)
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{
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/*
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* Decompose split matras that don't have Unicode decompositions.
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*/
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/* Khmer */
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case 0x17BEu : *a = 0x17C1u; *b= 0x17BEu; return true;
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case 0x17BFu : *a = 0x17C1u; *b= 0x17BFu; return true;
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case 0x17C0u : *a = 0x17C1u; *b= 0x17C0u; return true;
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case 0x17C4u : *a = 0x17C1u; *b= 0x17C4u; return true;
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case 0x17C5u : *a = 0x17C1u; *b= 0x17C5u; return true;
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}
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return (bool) c->unicode->decompose (ab, a, b);
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}
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static bool
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compose_khmer (const hb_ot_shape_normalize_context_t *c,
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hb_codepoint_t a,
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hb_codepoint_t b,
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hb_codepoint_t *ab)
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{
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/* Avoid recomposing split matras. */
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if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a)))
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return false;
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return (bool) c->unicode->compose (a, b, ab);
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}
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const hb_ot_complex_shaper_t _hb_ot_complex_shaper_khmer =
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{
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collect_features_khmer,
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override_features_khmer,
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data_create_khmer,
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data_destroy_khmer,
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nullptr, /* preprocess_text */
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nullptr, /* postprocess_glyphs */
|
|
HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,
|
|
decompose_khmer,
|
|
compose_khmer,
|
|
setup_masks_khmer,
|
|
HB_TAG_NONE, /* gpos_tag */
|
|
nullptr, /* reorder_marks */
|
|
HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,
|
|
false, /* fallback_position */
|
|
};
|