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Third Party Harfbuzz
提交 1a96cc82 编写于 作者: B Behdad Esfahbod
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[khmer] Rewrite most of shaper to better follow spec 

Khmer spec has only one reordering phase, and only simple prebase
matra and Coeng-Ro reordering.  Implement that.  Specifically,
this was done to address recognizing different orders of the matra
and Coeng-Ro sequence.  That said, some combinations are now
reordered differently from Uniscribe.  Not clear if that's intended
or a bug in Uniscribe.  The following two sequences render the same
in Uniscribe whereas we reorder them differently:

  U+17A0,U+17D2,U+179A,U+17C2
  U+17A0,U+17C2,U+17D2,U+179A

For that reason, our test suite numbers regressed slightly.  Used
to be at 34 for fails, now at:

KHMER: 299080 out of 299124 tests passed. 44 failed (0.0147096%)

But generally a good change, and removed lots of code.

Fixes https://github.com/harfbuzz/harfbuzz/issues/1026
上级 f5152cea
隐藏空白更改
内联 并排
Showing with 64 addition and 413 deletion
src/hb-ot-shape-complex-indic-private.hh
浏览文件 @ 1a96cc82
......@@ -300,7 +300,9 @@ static const hb_codepoint_t ra_chars[] = {
0x0CB0u, /* Kannada */
0x0D30u, /* Malayalam */ /* No Reph, Logical Repha */
0x0DBBu, /* Sinhala */ /* Reph formed only with ZWJ */
0x0DBBu, /* Sinhala */ /* Reph formed only with ZWJ */
0x179Au, /* Khmer */
};
static inline bool
......
src/hb-ot-shape-complex-khmer.cc
浏览文件 @ 1a96cc82
......@@ -42,7 +42,7 @@ khmer_features[] =
{
/*
* Basic features.
* These features are applied in order, one at a time, after initial_reordering.
* These features are applied in order, one at a time, after reordering.
*/
{HB_TAG('p','r','e','f'), F_NONE},
{HB_TAG('b','l','w','f'), F_NONE},
......@@ -51,9 +51,7 @@ khmer_features[] =
{HB_TAG('c','f','a','r'), F_NONE},
/*
* Other features.
* These features are applied all at once, after final_reordering.
* Default Bengali font in Windows for example has intermixed
* lookups for init,pres,abvs,blws features.
* These features are applied all at once.
*/
{HB_TAG('p','r','e','s'), F_GLOBAL},
{HB_TAG('a','b','v','s'), F_GLOBAL},
......@@ -92,13 +90,9 @@ setup_syllables (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer);
static void
initial_reordering (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer);
static void
final_reordering (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer);
reorder (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer);
static void
clear_syllables (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
......@@ -119,12 +113,11 @@ collect_features_khmer (hb_ot_shape_planner_t *plan)
unsigned int i = 0;
map->add_gsub_pause (initial_reordering);
map->add_gsub_pause (reorder);
for (; i < KHMER_BASIC_FEATURES; i++) {
map->add_feature (khmer_features[i].tag, 1, khmer_features[i].flags | F_MANUAL_ZWJ | F_MANUAL_ZWNJ);
map->add_gsub_pause (nullptr);
}
map->add_gsub_pause (final_reordering);
for (; i < KHMER_NUM_FEATURES; i++) {
map->add_feature (khmer_features[i].tag, 1, khmer_features[i].flags | F_MANUAL_ZWJ | F_MANUAL_ZWNJ);
}
......@@ -264,162 +257,58 @@ setup_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
buffer->unsafe_to_break (start, end);
}
static int
compare_khmer_order (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb)
{
int a = pa->khmer_position();
int b = pb->khmer_position();
return a < b ? -1 : a == b ? 0 : +1;
}
/* Rules from:
* https://docs.microsoft.com/en-us/typography/script-development/devanagari */
static void
initial_reordering_consonant_syllable (const hb_ot_shape_plan_t *plan,
hb_face_t *face,
hb_buffer_t *buffer,
unsigned int start, unsigned int end)
reorder_consonant_syllable (const hb_ot_shape_plan_t *plan,
hb_face_t *face,
hb_buffer_t *buffer,
unsigned int start, unsigned int end)
{
const khmer_shape_plan_t *khmer_plan = (const khmer_shape_plan_t *) plan->data;
hb_glyph_info_t *info = buffer->info;
/* 1. Khmer shaping assumes that a syllable will begin with a Cons, IndV, or Number. */
/* The first consonant is always the base. */
unsigned int base = start;
info[base].khmer_position() = POS_BASE_C;
/* Mark all subsequent consonants as below. */
for (unsigned int i = base + 1; i < end; i++)
if (is_consonant_or_vowel (info[i]))
info[i].khmer_position() = POS_BELOW_C;
/* Mark final consonants. A final consonant is one appearing after a matra,
* like in Khmer. */
for (unsigned int i = base + 1; i < end; i++)
if (info[i].khmer_category() == OT_M) {
for (unsigned int j = i + 1; j < end; j++)
if (is_consonant_or_vowel (info[j])) {
info[j].khmer_position() = POS_FINAL_C;
break;
}
break;
}
/* Attach misc marks to previous char to move with them. */
{
khmer_position_t last_pos = POS_START;
for (unsigned int i = start; i < end; i++)
{
if ((FLAG_UNSAFE (info[i].khmer_category()) & (JOINER_FLAGS | FLAG (OT_N) | FLAG (OT_RS) | MEDIAL_FLAGS | FLAG (OT_Coeng))))
{
info[i].khmer_position() = last_pos;
if (unlikely (info[i].khmer_category() == OT_Coeng &&
info[i].khmer_position() == POS_PRE_M))
{
/*
* Uniscribe doesn't move the Halant with Left Matra.
* TEST: U+092B,U+093F,U+094DE
* We follow. This is important for the Sinhala
* U+0DDA split matra since it decomposes to U+0DD9,U+0DCA
* where U+0DD9 is a left matra and U+0DCA is the virama.
* We don't want to move the virama with the left matra.
* TEST: U+0D9A,U+0DDA
*/
for (unsigned int j = i; j > start; j--)
if (info[j - 1].khmer_position() != POS_PRE_M) {
info[i].khmer_position() = info[j - 1].khmer_position();
break;
}
}
} else if (info[i].khmer_position() != POS_SMVD) {
last_pos = (khmer_position_t) info[i].khmer_position();
}
}
}
/* For post-base consonants let them own anything before them
* since the last consonant or matra. */
{
unsigned int last = base;
for (unsigned int i = base + 1; i < end; i++)
if (is_consonant_or_vowel (info[i]))
{
for (unsigned int j = last + 1; j < i; j++)
if (info[j].khmer_position() < POS_SMVD)
info[j].khmer_position() = info[i].khmer_position();
last = i;
} else if (info[i].khmer_category() == OT_M)
last = i;
}
{
/* Use syllable() for sort accounting temporarily. */
unsigned int syllable = info[start].syllable();
for (unsigned int i = start; i < end; i++)
info[i].syllable() = i - start;
/* Sit tight, rock 'n roll! */
hb_stable_sort (info + start, end - start, compare_khmer_order);
/* Find base again */
base = end;
for (unsigned int i = start; i < end; i++)
if (info[i].khmer_position() == POS_BASE_C)
{
base = i;
break;
}
if (unlikely (end - start >= 127))
buffer->merge_clusters (start, end);
else
/* Note! syllable() is a one-byte field. */
for (unsigned int i = base; i < end; i++)
if (info[i].syllable() != 255)
{
unsigned int max = i;
unsigned int j = start + info[i].syllable();
while (j != i)
{
max = MAX (max, j);
unsigned int next = start + info[j].syllable();
info[j].syllable() = 255; /* So we don't process j later again. */
j = next;
}
if (i != max)
buffer->merge_clusters (i, max + 1);
}
/* Put syllable back in. */
for (unsigned int i = start; i < end; i++)
info[i].syllable() = syllable;
}
/* Setup masks now */
/* Setup masks. */
{
hb_mask_t mask;
/* Post-base */
mask = khmer_plan->mask_array[BLWF] | khmer_plan->mask_array[ABVF] | khmer_plan->mask_array[PSTF];
for (unsigned int i = base + 1; i < end; i++)
hb_mask_t mask = khmer_plan->mask_array[BLWF] | khmer_plan->mask_array[ABVF] | khmer_plan->mask_array[PSTF];
for (unsigned int i = start + 1; i < end; i++)
info[i].mask |= mask;
}
unsigned int pref_len = 2;
if (khmer_plan->mask_array[PREF] && base + pref_len < end)
unsigned int num_coengs = 0;
for (unsigned int i = start + 1; i < end; i++)
{
/* Find a Halant,Ra sequence and mark it for pre-base-reordering processing. */
for (unsigned int i = base + 1; i + pref_len - 1 < end; i++) {
hb_codepoint_t glyphs[2];
for (unsigned int j = 0; j < pref_len; j++)
glyphs[j] = info[i + j].codepoint;
if (khmer_plan->pref.would_substitute (glyphs, pref_len, face))
/* """
* When a COENG + (Cons | IndV) combination are found (and subscript count
* is less than two) the character combination is handled according to the
* subscript type of the character following the COENG.
*
* ...
*
* Subscript Type 2 - The COENG + RO characters are reordered to immediately
* before the base glyph. Then the COENG + RO characters are assigned to have
* the 'pref' OpenType feature applied to them.
* """
*/
if (info[i].khmer_category() == OT_Coeng && num_coengs <= 2 && i + 1 < end)
{
num_coengs++;
if (info[i + 1].khmer_category() == OT_Ra)
{
for (unsigned int j = 0; j < pref_len; j++)
info[i++].mask |= khmer_plan->mask_array[PREF];
for (unsigned int j = 0; j < 2; j++)
info[i + j].mask |= khmer_plan->mask_array[PREF];
/* Move the Coeng,Ro sequence to the start. */
buffer->merge_clusters (start, i + 2);
hb_glyph_info_t t0 = info[i];
hb_glyph_info_t t1 = info[i + 1];
memmove (&info[start + 2], &info[start], (i - start) * sizeof (info[0]));
info[start] = t0;
info[start + 1] = t1;
/* Mark the subsequent stuff with 'cfar'. Used in Khmer.
* Read the feature spec.
......@@ -428,12 +317,22 @@ initial_reordering_consonant_syllable (const hb_ot_shape_plan_t *plan,
* U+1784,U+17D2,U+1782,U+17D2,U+179A
*/
if (khmer_plan->mask_array[CFAR])
for (; i < end; i++)
info[i].mask |= khmer_plan->mask_array[CFAR];
for (unsigned int j = i + 2; j < end; j++)
info[j].mask |= khmer_plan->mask_array[CFAR];
break;
num_coengs = 2; /* Done. */
}
}
/* Reorder left matra piece. */
else if (info[i].khmer_position() == POS_PRE_M)
{
/* Move to the start. */
buffer->merge_clusters (start, i + 1);
hb_glyph_info_t t = info[i];
memmove (&info[start + 1], &info[start], (i - start) * sizeof (info[0]));
info[start] = t;
}
}
}
......@@ -448,7 +347,7 @@ initial_reordering_syllable (const hb_ot_shape_plan_t *plan,
{
case broken_cluster: /* We already inserted dotted-circles, so just call the consonant_syllable. */
case consonant_syllable:
initial_reordering_consonant_syllable (plan, face, buffer, start, end);
reorder_consonant_syllable (plan, face, buffer, start, end);
break;
case non_khmer_cluster:
......@@ -518,263 +417,26 @@ insert_dotted_circles (const hb_ot_shape_plan_t *plan HB_UNUSED,
}
static void
initial_reordering (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer)
reorder (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer)
{
insert_dotted_circles (plan, font, buffer);
foreach_syllable (buffer, start, end)
initial_reordering_syllable (plan, font->face, buffer, start, end);
}
static void
final_reordering_syllable (const hb_ot_shape_plan_t *plan,
hb_buffer_t *buffer,
unsigned int start, unsigned int end)
{
const khmer_shape_plan_t *khmer_plan = (const khmer_shape_plan_t *) plan->data;
hb_glyph_info_t *info = buffer->info;
/* This function relies heavily on halant glyphs. Lots of ligation
* and possibly multiple substitutions happened prior to this
* phase, and that might have messed up our properties. Recover
* from a particular case of that where we're fairly sure that a
* class of OT_Coeng is desired but has been lost. */
if (khmer_plan->virama_glyph)
{
unsigned int virama_glyph = khmer_plan->virama_glyph;
for (unsigned int i = start; i < end; i++)
if (info[i].codepoint == virama_glyph &&
_hb_glyph_info_ligated (&info[i]) &&
_hb_glyph_info_multiplied (&info[i]))
{
/* This will make sure that this glyph passes is_coeng() test. */
info[i].khmer_category() = OT_Coeng;
_hb_glyph_info_clear_ligated_and_multiplied (&info[i]);
}
}
/* 4. Final reordering:
*
* After the localized forms and basic shaping forms GSUB features have been
* applied (see below), the shaping engine performs some final glyph
* reordering before applying all the remaining font features to the entire
* syllable.
*/
bool try_pref = !!khmer_plan->mask_array[PREF];
/* Find base again */
unsigned int base;
for (base = start; base < end; base++)
if (info[base].khmer_position() >= POS_BASE_C)
{
if (try_pref && base + 1 < end)
{
for (unsigned int i = base + 1; i < end; i++)
if ((info[i].mask & khmer_plan->mask_array[PREF]) != 0)
{
if (!(_hb_glyph_info_substituted (&info[i]) &&
_hb_glyph_info_ligated_and_didnt_multiply (&info[i])))
{
/* Ok, this was a 'pref' candidate but didn't form any.
* Base is around here... */
base = i;
while (base < end && is_coeng (info[base]))
base++;
info[base].khmer_position() = POS_BASE_C;
try_pref = false;
}
break;
}
}
if (start < base && info[base].khmer_position() > POS_BASE_C)
base--;
break;
}
if (base == end && start < base &&
is_one_of (info[base - 1], FLAG (OT_ZWJ)))
base--;
if (base < end)
while (start < base &&
is_one_of (info[base], (FLAG (OT_N) | FLAG (OT_Coeng))))
base--;
/* o Reorder matras:
*
* If a pre-base matra character had been reordered before applying basic
* features, the glyph can be moved closer to the main consonant based on
* whether half-forms had been formed. Actual position for the matra is
* defined as “after last standalone halant glyph, after initial matra
* position and before the main consonant”. If ZWJ or ZWNJ follow this
* halant, position is moved after it.
*/
if (start + 1 < end && start < base) /* Otherwise there can't be any pre-base matra characters. */
{
/* If we lost track of base, alas, position before last thingy. */
unsigned int new_pos = base == end ? base - 2 : base - 1;
while (new_pos > start &&
!(is_one_of (info[new_pos], (FLAG (OT_M) | FLAG (OT_Coeng)))))
new_pos--;
/* If we found no Halant we are done.
* Otherwise only proceed if the Halant does
* not belong to the Matra itself! */
if (is_coeng (info[new_pos]) &&
info[new_pos].khmer_position() != POS_PRE_M)
{
/* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
if (new_pos + 1 < end && is_joiner (info[new_pos + 1]))
new_pos++;
}
else
new_pos = start; /* No move. */
if (start < new_pos && info[new_pos].khmer_position () != POS_PRE_M)
{
/* Now go see if there's actually any matras... */
for (unsigned int i = new_pos; i > start; i--)
if (info[i - 1].khmer_position () == POS_PRE_M)
{
unsigned int old_pos = i - 1;
if (old_pos < base && base <= new_pos) /* Shouldn't actually happen. */
base--;
hb_glyph_info_t tmp = info[old_pos];
memmove (&info[old_pos], &info[old_pos + 1], (new_pos - old_pos) * sizeof (info[0]));
info[new_pos] = tmp;
/* Note: this merge_clusters() is intentionally *after* the reordering.
* Indic matra reordering is special and tricky... */
buffer->merge_clusters (new_pos, MIN (end, base + 1));
new_pos--;
}
} else {
for (unsigned int i = start; i < base; i++)
if (info[i].khmer_position () == POS_PRE_M) {
buffer->merge_clusters (i, MIN (end, base + 1));
break;
}
}
}
/* o Reorder pre-base-reordering consonants:
*
* If a pre-base-reordering consonant is found, reorder it according to
* the following rules:
*/
if (try_pref && base + 1 < end) /* Otherwise there can't be any pre-base-reordering Ra. */
{
for (unsigned int i = base + 1; i < end; i++)
if ((info[i].mask & khmer_plan->mask_array[PREF]) != 0)
{
/* 1. Only reorder a glyph produced by substitution during application
* of the <pref> feature. (Note that a font may shape a Ra consonant with
* the feature generally but block it in certain contexts.)
*/
/* Note: We just check that something got substituted. We don't check that
* the <pref> feature actually did it...
*
* Reorder pref only if it ligated. */
if (_hb_glyph_info_ligated_and_didnt_multiply (&info[i]))
{
/*
* 2. Try to find a target position the same way as for pre-base matra.
* If it is found, reorder pre-base consonant glyph.
*
* 3. If position is not found, reorder immediately before main
* consonant.
*/
unsigned int new_pos = base;
while (new_pos > start &&
!(is_one_of (info[new_pos - 1], FLAG(OT_M) | FLAG (OT_Coeng))))
new_pos--;
/* In Khmer coeng model, a H,Ra can go *after* matras. If it goes after a
* split matra, it should be reordered to *before* the left part of such matra. */
if (new_pos > start && info[new_pos - 1].khmer_category() == OT_M)
{
unsigned int old_pos = i;
for (unsigned int j = base + 1; j < old_pos; j++)
if (info[j].khmer_category() == OT_M)
{
new_pos--;
break;
}
}
if (new_pos > start && is_coeng (info[new_pos - 1]))
{
/* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
if (new_pos < end && is_joiner (info[new_pos]))
new_pos++;
}
{
unsigned int old_pos = i;
buffer->merge_clusters (new_pos, old_pos + 1);
hb_glyph_info_t tmp = info[old_pos];
memmove (&info[new_pos + 1], &info[new_pos], (old_pos - new_pos) * sizeof (info[0]));
info[new_pos] = tmp;
if (new_pos <= base && base < old_pos)
base++;
}
}
break;
}
}
/*
* Finish off the clusters and go home!
*/
if (hb_options ().uniscribe_bug_compatible)
{
/* Uniscribe merges the entire syllable into a single cluster... Except for Tamil & Sinhala.
* This means, half forms are submerged into the main consonant's cluster.
* This is unnecessary, and makes cursor positioning harder, but that's what
* Uniscribe does. */
buffer->merge_clusters (start, end);
}
}
static void
final_reordering (const hb_ot_shape_plan_t *plan,
hb_font_t *font HB_UNUSED,
hb_buffer_t *buffer)
{
unsigned int count = buffer->len;
if (unlikely (!count)) return;
foreach_syllable (buffer, start, end)
final_reordering_syllable (plan, buffer, start, end);
HB_BUFFER_DEALLOCATE_VAR (buffer, khmer_category);
HB_BUFFER_DEALLOCATE_VAR (buffer, khmer_position);
}
static void
clear_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
hb_font_t *font HB_UNUSED,
hb_buffer_t *buffer)
{
/* TODO: In USE, we clear syllables right after reorder. Figure out
* what Uniscribe does. */
hb_glyph_info_t *info = buffer->info;
unsigned int count = buffer->len;
for (unsigned int i = 0; i < count; i++)
......
src/hb-ot-shape-complex-private.hh
浏览文件 @ 1a96cc82
......@@ -279,20 +279,7 @@ hb_ot_shape_complex_categorize (const hb_ot_shape_planner_t *planner)
return &_hb_ot_complex_shaper_indic;
case HB_SCRIPT_KHMER:
/* A number of Khmer fonts in the wild don't have a 'pref' feature,
* and as such won't shape properly via the Indic shaper;
* however, they typically have 'liga' / 'clig' features that implement
* the necessary "reordering" by means of ligature substitutions.
* So we send such pref-less fonts through the generic shaper instead. */
if (planner->map.found_script[0] &&
hb_ot_layout_language_find_feature (planner->face, HB_OT_TAG_GSUB,
planner->map.script_index[0],
planner->map.language_index[0],
HB_TAG ('p','r','e','f'),
nullptr))
return &_hb_ot_complex_shaper_khmer;
else
return &_hb_ot_complex_shaper_default;
case HB_SCRIPT_MYANMAR:
if (planner->map.chosen_script[0] == HB_TAG ('m','y','m','2'))
......
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