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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 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 (_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
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