470 lines
15 KiB
C++
470 lines
15 KiB
C++
/*
|
|
* 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.hh"
|
|
#include "hb-ot-shape-complex.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 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.
|
|
*/
|
|
|
|
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)
|
|
{
|
|
buffer->cur().glyph_index() = glyph;
|
|
buffer->output_glyph (unichar); /* This is very confusing indeed. */
|
|
_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;
|
|
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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
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))
|
|
{
|
|
next_char (buffer, glyph);
|
|
return;
|
|
}
|
|
|
|
if (decompose (c, shortest, u))
|
|
{
|
|
skip_char (buffer);
|
|
return;
|
|
}
|
|
|
|
if (!shortest && c->font->get_nominal_glyph (u, &glyph))
|
|
{
|
|
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 (0x0020u, &space_glyph))
|
|
{
|
|
_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)
|
|
{
|
|
/* 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 && buffer->successful;) {
|
|
if (unlikely (buffer->unicode->is_variation_selector (buffer->cur(+1).codepoint))) {
|
|
/* The next two lines are some ugly lines... But work. */
|
|
if (font->get_variation_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 && 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,
|
|
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 (unlikely (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&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]));
|
|
buffer->next_glyphs (done);
|
|
}
|
|
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_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&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->swap_buffers ();
|
|
}
|
|
|
|
|
|
/* Second round, reorder (inplace) */
|
|
|
|
if (!all_simple)
|
|
{
|
|
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_COMPLEX_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;
|
|
}
|
|
}
|
|
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]) <= info_cc(buffer->info[i+1]))
|
|
{
|
|
_hb_glyph_info_unhide (&buffer->info[i]);
|
|
}
|
|
}
|
|
|
|
|
|
/* Third round, recompose */
|
|
|
|
if (!all_simple &&
|
|
(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;
|
|
buffer->next_glyph ();
|
|
while (buffer->idx < count && 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_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&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. */
|
|
buffer->next_glyph (); /* Copy to out-buffer. */
|
|
if (unlikely (!buffer->successful))
|
|
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);
|
|
|
|
continue;
|
|
}
|
|
}
|
|
|
|
/* Blocked, or doesn't compose. */
|
|
buffer->next_glyph ();
|
|
|
|
if (info_cc (buffer->prev()) == 0)
|
|
starter = buffer->out_len - 1;
|
|
}
|
|
buffer->swap_buffers ();
|
|
}
|
|
}
|