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++ /*
++ * 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 inline void
++ set_glyph (hb_glyph_info_t &info, hb_font_t *font)
++ {
++ (void) font->get_nominal_glyph (info.codepoint, &info.normalizer_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().normalizer_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().normalizer_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, buffer->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, buffer->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().normalizer_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 ();
++
++ buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_VARIATION_SELECTOR_FALLBACK;
++ _hb_glyph_info_set_variation_selector (&buffer->cur(), true);
++ if (buffer->not_found_variation_selector != HB_CODEPOINT_INVALID)
++ _hb_glyph_info_clear_default_ignorable (&buffer->cur());
++
++ 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)
++ //mode = HB_OT_SHAPE_NORMALIZATION_MODE_DECOMPOSED;
++ mode = HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS;
++ else
++ mode = HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS;
++ }
++
++ hb_ot_shape_normalize_context_t c = {
++ plan,
++ buffer,
++ font,
++ buffer->unicode,
++ plan->shaper->decompose ? plan->shaper->decompose : hb_ot_shape_normalize_context_t::decompose_unicode,
++ plan->shaper->compose ? plan->shaper->compose : hb_ot_shape_normalize_context_t::compose_unicode
++ };
++ c.override_decompose_and_compose (plan->shaper->decompose, plan->shaper->compose);
++
++ 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;
++ if (buffer->message (font, "start decompose"))
++ {
++ buffer->clear_output ();
++ count = buffer->len;
++ buffer->idx = 0;
++ do
++ {
++ unsigned int end;
++ for (end = buffer->idx + 1; end < count; end++)
++ if (_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().normalizer_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 ();
++ (void) buffer->message (font, "end decompose");
++ }
++
++
++ /* Second round, reorder (inplace) */
++
++ if (!all_simple && buffer->message(font, "start reorder"))
++ {
++ count = buffer->len;
++ hb_glyph_info_t *info = buffer->info;
++ for (unsigned int i = 0; i < count; i++)
++ {
++ if (_hb_glyph_info_get_modified_combining_class (&info[i]) == 0)
++ continue;
++
++ unsigned int end;
++ for (end = i + 1; end < count; end++)
++ if (_hb_glyph_info_get_modified_combining_class (&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.
++ */
++ unsigned count = buffer->len;
++ hb_glyph_info_t *info = buffer->info;
++ for (unsigned int i = 1; i + 1 < count; i++)
++ if (info[i].codepoint == 0x034Fu/*CGJ*/ &&
++ (info_cc(info[i+1]) == 0 || info_cc(info[i-1]) <= info_cc(info[i+1])))
++ {
++ _hb_glyph_info_unhide (&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) &&
++ buffer->message (font, "start compose"))
++ {
++ /* 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].normalizer_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 ();
++ (void) buffer->message (font, "end compose");
++ }
++ }
++
++
++ #endif