--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/java.desktop/share/native/libfontmanager/harfbuzz/hb-ot-shape-normalize.cc Mon Nov 23 09:58:44 2015 -0800
@@ -0,0 +1,416 @@
+/*
+ * 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-ot-shape-normalize-private.hh"
+#include "hb-ot-shape-complex-private.hh"
+#include "hb-ot-shape-private.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 decomposition,
+ * well, use the decomposition (preferring the canonical decomposition, but
+ * falling back to the compatibility decomposition if necessary). The
+ * compatibility decomposition is really nice to have, for characters like
+ * ellipsis, or various-sized space characters.
+ *
+ * - The complex 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.
+ *
+ * - We try compatibility decomposition if decomposing through canonical
+ * decomposition alone failed to find a sequence that the font supports.
+ * We don't try compatibility decomposition recursively during the canonical
+ * decomposition phase. This has minimal impact. There are only a handful
+ * of Greek letter that have canonical decompositions that include characters
+ * with compatibility decomposition. Those can be found using this command:
+ *
+ * egrep "`echo -n ';('; grep ';<' UnicodeData.txt | cut -d';' -f1 | tr '\n' '|'; echo ') '`" UnicodeData.txt
+ */
+
+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 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 c->unicode->compose (a, b, ab);
+}
+
+static inline void
+set_glyph (hb_glyph_info_t &info, hb_font_t *font)
+{
+ font->get_glyph (info.codepoint, 0, &info.glyph_index());
+}
+
+static inline void
+output_char (hb_buffer_t *buffer, hb_codepoint_t unichar, hb_codepoint_t glyph)
+{
+ buffer->cur().glyph_index() = glyph;
+ buffer->output_glyph (unichar);
+ _hb_glyph_info_set_unicode_props (&buffer->prev(), buffer->unicode);
+}
+
+static inline void
+next_char (hb_buffer_t *buffer, hb_codepoint_t glyph)
+{
+ buffer->cur().glyph_index() = glyph;
+ 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, b, a_glyph, b_glyph;
+ hb_buffer_t * const buffer = c->buffer;
+ hb_font_t * const font = c->font;
+
+ if (!c->decompose (c, ab, &a, &b) ||
+ (b && !font->get_glyph (b, 0, &b_glyph)))
+ return 0;
+
+ bool has_a = font->get_glyph (a, 0, &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;
+ }
+
+ unsigned int ret;
+ if ((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;
+}
+
+/* Returns 0 if didn't decompose, number of resulting characters otherwise. */
+static inline unsigned int
+decompose_compatibility (const hb_ot_shape_normalize_context_t *c, hb_codepoint_t u)
+{
+ unsigned int len, i;
+ hb_codepoint_t decomposed[HB_UNICODE_MAX_DECOMPOSITION_LEN];
+ hb_codepoint_t glyphs[HB_UNICODE_MAX_DECOMPOSITION_LEN];
+
+ len = c->buffer->unicode->decompose_compatibility (u, decomposed);
+ if (!len)
+ return 0;
+
+ for (i = 0; i < len; i++)
+ if (!c->font->get_glyph (decomposed[i], 0, &glyphs[i]))
+ return 0;
+
+ for (i = 0; i < len; i++)
+ output_char (c->buffer, decomposed[i], glyphs[i]);
+
+ return len;
+}
+
+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;
+
+ /* Kind of a cute waterfall here... */
+ if (shortest && c->font->get_glyph (u, 0, &glyph))
+ next_char (buffer, glyph);
+ else if (decompose (c, shortest, u))
+ skip_char (buffer);
+ else if (!shortest && c->font->get_glyph (u, 0, &glyph))
+ next_char (buffer, glyph);
+ else if (decompose_compatibility (c, u))
+ skip_char (buffer);
+ else
+ 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)
+{
+ /* TODO Currently if there's a variation-selector we give-up, it's just too hard. */
+ hb_buffer_t * const buffer = c->buffer;
+ hb_font_t * const font = c->font;
+ for (; buffer->idx < end - 1;) {
+ if (unlikely (buffer->unicode->is_variation_selector (buffer->cur(+1).codepoint))) {
+ /* The next two lines are some ugly lines... But work. */
+ if (font->get_glyph (buffer->cur().codepoint, buffer->cur(+1).codepoint, &buffer->cur().glyph_index()))
+ {
+ buffer->replace_glyphs (2, 1, &buffer->cur().codepoint);
+ }
+ else
+ {
+ /* Just pass on the two characters separately, let GSUB do its magic. */
+ set_glyph (buffer->cur(), font);
+ buffer->next_glyph ();
+ set_glyph (buffer->cur(), font);
+ buffer->next_glyph ();
+ }
+ /* Skip any further variation selectors. */
+ while (buffer->idx < end && unlikely (buffer->unicode->is_variation_selector (buffer->cur().codepoint)))
+ {
+ set_glyph (buffer->cur(), font);
+ buffer->next_glyph ();
+ }
+ } else {
+ set_glyph (buffer->cur(), font);
+ buffer->next_glyph ();
+ }
+ }
+ if (likely (buffer->idx < end)) {
+ set_glyph (buffer->cur(), font);
+ 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; 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)
+ decompose_current_character (c, short_circuit);
+}
+
+static inline void
+decompose_cluster (const hb_ot_shape_normalize_context_t *c, unsigned int end, bool might_short_circuit, bool always_short_circuit)
+{
+ if (likely (c->buffer->idx + 1 == end))
+ decompose_current_character (c, might_short_circuit);
+ else
+ decompose_multi_char_cluster (c, end, always_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;
+ const hb_ot_shape_normalize_context_t c = {
+ plan,
+ buffer,
+ font,
+ buffer->unicode,
+ 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 */
+
+ buffer->clear_output ();
+ count = buffer->len;
+ for (buffer->idx = 0; buffer->idx < count;)
+ {
+ unsigned int end;
+ for (end = buffer->idx + 1; end < count; end++)
+ if (likely (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&buffer->info[end]))))
+ break;
+
+ decompose_cluster (&c, end, might_short_circuit, always_short_circuit);
+ }
+ buffer->swap_buffers ();
+
+
+ /* Second round, reorder (inplace) */
+
+ 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 > 10) {
+ i = end;
+ continue;
+ }
+
+ buffer->sort (i, end, compare_combining_class);
+
+ i = end;
+ }
+
+
+ if (mode == HB_OT_SHAPE_NORMALIZATION_MODE_NONE ||
+ mode == HB_OT_SHAPE_NORMALIZATION_MODE_DECOMPOSED)
+ return;
+
+ /* Third round, recompose */
+
+ /* 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;
+ buffer->next_glyph ();
+ while (buffer->idx < count)
+ {
+ 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_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&buffer->cur())) &&
+ /* If there's anything between the starter and this char, they should have CCC
+ * smaller than this character's. */
+ (starter == buffer->out_len - 1 ||
+ _hb_glyph_info_get_modified_combining_class (&buffer->prev()) < _hb_glyph_info_get_modified_combining_class (&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_glyph (composed, 0, &glyph))
+ {
+ /* Composes. */
+ buffer->next_glyph (); /* Copy to out-buffer. */
+ if (unlikely (buffer->in_error))
+ return;
+ 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->unicode);
+
+ continue;
+ }
+
+ /* Blocked, or doesn't compose. */
+ buffer->next_glyph ();
+
+ if (_hb_glyph_info_get_modified_combining_class (&buffer->prev()) == 0)
+ starter = buffer->out_len - 1;
+ }
+ buffer->swap_buffers ();
+
+}