harfbuzz/src/hb-ot-shape-complex-khmer.cc

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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-ot-shape-complex-khmer.hh"
#include "hb-ot-layout.hh"
/*
* Khmer shaper.
*/
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static const hb_ot_map_feature_t
khmer_features[] =
{
/*
* Basic features.
* These features are applied in order, one at a time, after reordering.
*/
{HB_TAG('p','r','e','f'), F_MANUAL_JOINERS},
{HB_TAG('b','l','w','f'), F_MANUAL_JOINERS},
{HB_TAG('a','b','v','f'), F_MANUAL_JOINERS},
{HB_TAG('p','s','t','f'), F_MANUAL_JOINERS},
{HB_TAG('c','f','a','r'), F_MANUAL_JOINERS},
/*
* Other features.
* These features are applied all at once after clearing syllables.
*/
{HB_TAG('p','r','e','s'), F_GLOBAL_MANUAL_JOINERS},
{HB_TAG('a','b','v','s'), F_GLOBAL_MANUAL_JOINERS},
{HB_TAG('b','l','w','s'), F_GLOBAL_MANUAL_JOINERS},
{HB_TAG('p','s','t','s'), F_GLOBAL_MANUAL_JOINERS},
/*
* Positioning features.
* We don't care about the types.
*/
{HB_TAG('d','i','s','t'), F_GLOBAL},
{HB_TAG('a','b','v','m'), F_GLOBAL},
{HB_TAG('b','l','w','m'), F_GLOBAL},
};
/*
* Must be in the same order as the khmer_features array.
*/
enum {
PREF,
BLWF,
ABVF,
PSTF,
CFAR,
_PRES,
_ABVS,
_BLWS,
_PSTS,
_DIST,
_ABVM,
_BLWM,
KHMER_NUM_FEATURES,
KHMER_BASIC_FEATURES = _PRES, /* Don't forget to update this! */
};
static void
setup_syllables (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer);
static void
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,
hb_buffer_t *buffer);
static void
collect_features_khmer (hb_ot_shape_planner_t *plan)
{
hb_ot_map_builder_t *map = &plan->map;
/* Do this before any lookups have been applied. */
map->add_gsub_pause (setup_syllables);
map->add_gsub_pause (reorder);
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/* Testing suggests that Uniscribe does NOT pause between basic
* features. Test with KhmerUI.ttf and the following three
* sequences:
*
* U+1789,U+17BC
* U+1789,U+17D2,U+1789
* U+1789,U+17D2,U+1789,U+17BC
*
* https://github.com/harfbuzz/harfbuzz/issues/974
*/
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map->enable_feature (HB_TAG('l','o','c','l'));
map->enable_feature (HB_TAG('c','c','m','p'));
unsigned int i = 0;
for (; i < KHMER_BASIC_FEATURES; i++)
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map->add_feature (khmer_features[i]);
map->add_gsub_pause (clear_syllables);
for (; i < KHMER_NUM_FEATURES; i++)
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map->add_feature (khmer_features[i]);
}
static void
override_features_khmer (hb_ot_shape_planner_t *plan)
{
hb_ot_map_builder_t *map = &plan->map;
/* Khmer spec has 'clig' as part of required shaping features:
* "Apply feature 'clig' to form ligatures that are desired for
* typographical correctness.", hence in overrides... */
map->enable_feature (HB_TAG('c','l','i','g'));
/* Uniscribe does not apply 'kern' in Khmer. */
if (hb_options ().uniscribe_bug_compatible)
{
map->disable_feature (HB_TAG('k','e','r','n'));
}
map->disable_feature (HB_TAG('l','i','g','a'));
}
struct would_substitute_feature_t
{
void init (const hb_ot_map_t *map, hb_tag_t feature_tag, bool zero_context_)
{
zero_context = zero_context_;
map->get_stage_lookups (0/*GSUB*/,
map->get_feature_stage (0/*GSUB*/, feature_tag),
&lookups, &count);
}
bool would_substitute (const hb_codepoint_t *glyphs,
unsigned int glyphs_count,
hb_face_t *face) const
{
for (unsigned int i = 0; i < count; i++)
if (hb_ot_layout_lookup_would_substitute_fast (face, lookups[i].index, glyphs, glyphs_count, zero_context))
return true;
return false;
}
private:
const hb_ot_map_t::lookup_map_t *lookups;
unsigned int count;
bool zero_context;
};
struct khmer_shape_plan_t
{
bool get_virama_glyph (hb_font_t *font, hb_codepoint_t *pglyph) const
{
hb_codepoint_t glyph = virama_glyph;
if (unlikely (virama_glyph == (hb_codepoint_t) -1))
{
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if (!font->get_nominal_glyph (0x17D2u, &glyph))
glyph = 0;
/* Technically speaking, the spec says we should apply 'locl' to virama too.
* Maybe one day... */
/* Our get_nominal_glyph() function needs a font, so we can't get the virama glyph
* during shape planning... Instead, overwrite it here. It's safe. Don't worry! */
virama_glyph = glyph;
}
*pglyph = glyph;
return glyph != 0;
}
mutable hb_codepoint_t virama_glyph;
would_substitute_feature_t pref;
hb_mask_t mask_array[KHMER_NUM_FEATURES];
};
static void *
data_create_khmer (const hb_ot_shape_plan_t *plan)
{
khmer_shape_plan_t *khmer_plan = (khmer_shape_plan_t *) calloc (1, sizeof (khmer_shape_plan_t));
if (unlikely (!khmer_plan))
return nullptr;
khmer_plan->virama_glyph = (hb_codepoint_t) -1;
khmer_plan->pref.init (&plan->map, HB_TAG('p','r','e','f'), true);
for (unsigned int i = 0; i < ARRAY_LENGTH (khmer_plan->mask_array); i++)
khmer_plan->mask_array[i] = (khmer_features[i].flags & F_GLOBAL) ?
0 : plan->map.get_1_mask (khmer_features[i].tag);
return khmer_plan;
}
static void
data_destroy_khmer (void *data)
{
free (data);
}
enum syllable_type_t {
consonant_syllable,
broken_cluster,
non_khmer_cluster,
};
#include "hb-ot-shape-complex-khmer-machine.hh"
static void
setup_masks_khmer (const hb_ot_shape_plan_t *plan HB_UNUSED,
hb_buffer_t *buffer,
hb_font_t *font HB_UNUSED)
{
HB_BUFFER_ALLOCATE_VAR (buffer, khmer_category);
/* We cannot setup masks here. We save information about characters
* and setup masks later on in a pause-callback. */
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = 0; i < count; i++)
set_khmer_properties (info[i]);
}
static void
setup_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
hb_font_t *font HB_UNUSED,
hb_buffer_t *buffer)
{
find_syllables (buffer);
foreach_syllable (buffer, start, end)
buffer->unsafe_to_break (start, end);
}
/* Rules from:
* https://docs.microsoft.com/en-us/typography/script-development/devanagari */
static void
reorder_consonant_syllable (const hb_ot_shape_plan_t *plan,
hb_face_t *face HB_UNUSED,
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;
/* Setup masks. */
{
/* Post-base */
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 num_coengs = 0;
for (unsigned int i = start + 1; i < end; i++)
{
/* """
* 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 < 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.
* This allows distinguishing the following cases with MS Khmer fonts:
* U+1784,U+17D2,U+179A,U+17D2,U+1782
* U+1784,U+17D2,U+1782,U+17D2,U+179A
*/
if (khmer_plan->mask_array[CFAR])
for (unsigned int j = i + 2; j < end; j++)
info[j].mask |= khmer_plan->mask_array[CFAR];
num_coengs = 2; /* Done. */
}
}
/* Reorder left matra piece. */
else if (info[i].khmer_category() == OT_VPre)
{
/* 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;
}
}
}
static void
initial_reordering_syllable (const hb_ot_shape_plan_t *plan,
hb_face_t *face,
hb_buffer_t *buffer,
unsigned int start, unsigned int end)
{
syllable_type_t syllable_type = (syllable_type_t) (buffer->info[start].syllable() & 0x0F);
switch (syllable_type)
{
case broken_cluster: /* We already inserted dotted-circles, so just call the consonant_syllable. */
case consonant_syllable:
reorder_consonant_syllable (plan, face, buffer, start, end);
break;
case non_khmer_cluster:
break;
}
}
static inline void
insert_dotted_circles (const hb_ot_shape_plan_t *plan HB_UNUSED,
hb_font_t *font,
hb_buffer_t *buffer)
{
/* Note: This loop is extra overhead, but should not be measurable. */
bool has_broken_syllables = false;
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = 0; i < count; i++)
if ((info[i].syllable() & 0x0F) == broken_cluster)
{
has_broken_syllables = true;
break;
}
if (likely (!has_broken_syllables))
return;
hb_codepoint_t dottedcircle_glyph;
if (!font->get_nominal_glyph (0x25CCu, &dottedcircle_glyph))
return;
hb_glyph_info_t dottedcircle = {0};
dottedcircle.codepoint = 0x25CCu;
set_khmer_properties (dottedcircle);
dottedcircle.codepoint = dottedcircle_glyph;
buffer->clear_output ();
buffer->idx = 0;
unsigned int last_syllable = 0;
while (buffer->idx < buffer->len && buffer->successful)
{
unsigned int syllable = buffer->cur().syllable();
syllable_type_t syllable_type = (syllable_type_t) (syllable & 0x0F);
if (unlikely (last_syllable != syllable && syllable_type == broken_cluster))
{
last_syllable = syllable;
hb_glyph_info_t ginfo = dottedcircle;
ginfo.cluster = buffer->cur().cluster;
ginfo.mask = buffer->cur().mask;
ginfo.syllable() = buffer->cur().syllable();
/* TODO Set glyph_props? */
/* Insert dottedcircle after possible Repha. */
while (buffer->idx < buffer->len && buffer->successful &&
last_syllable == buffer->cur().syllable() &&
buffer->cur().khmer_category() == OT_Repha)
buffer->next_glyph ();
buffer->output_info (ginfo);
}
else
buffer->next_glyph ();
}
buffer->swap_buffers ();
}
static void
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);
HB_BUFFER_DEALLOCATE_VAR (buffer, khmer_category);
}
static void
clear_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
hb_font_t *font HB_UNUSED,
hb_buffer_t *buffer)
{
hb_glyph_info_t *info = buffer->info;
unsigned int count = buffer->len;
for (unsigned int i = 0; i < count; i++)
info[i].syllable() = 0;
}
static bool
decompose_khmer (const hb_ot_shape_normalize_context_t *c,
hb_codepoint_t ab,
hb_codepoint_t *a,
hb_codepoint_t *b)
{
switch (ab)
{
/*
* Decompose split matras that don't have Unicode decompositions.
*/
/* Khmer */
case 0x17BEu : *a = 0x17C1u; *b= 0x17BEu; return true;
case 0x17BFu : *a = 0x17C1u; *b= 0x17BFu; return true;
case 0x17C0u : *a = 0x17C1u; *b= 0x17C0u; return true;
case 0x17C4u : *a = 0x17C1u; *b= 0x17C4u; return true;
case 0x17C5u : *a = 0x17C1u; *b= 0x17C5u; return true;
}
return (bool) c->unicode->decompose (ab, a, b);
}
static bool
compose_khmer (const hb_ot_shape_normalize_context_t *c,
hb_codepoint_t a,
hb_codepoint_t b,
hb_codepoint_t *ab)
{
/* Avoid recomposing split matras. */
if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a)))
return false;
return (bool) c->unicode->compose (a, b, ab);
}
const hb_ot_complex_shaper_t _hb_ot_complex_shaper_khmer =
{
collect_features_khmer,
override_features_khmer,
data_create_khmer,
data_destroy_khmer,
nullptr, /* preprocess_text */
nullptr, /* postprocess_glyphs */
HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,
decompose_khmer,
compose_khmer,
setup_masks_khmer,
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HB_TAG_NONE, /* gpos_tag */
nullptr, /* reorder_marks */
HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,
false, /* fallback_position */
};