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harfbuzz/src/hb-ot-shape-fallback.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.hh"
#ifndef HB_NO_OT_SHAPE
#include "hb-ot-shape-fallback.hh"
#include "hb-kern.hh"
static unsigned int
recategorize_combining_class (hb_codepoint_t u,
unsigned int klass)
{
if (klass >= 200)
return klass;
/* Thai / Lao need some per-character work. */
if ((u & ~0xFF) == 0x0E00u)
{
if (unlikely (klass == 0))
{
switch (u)
{
case 0x0E31u:
case 0x0E34u:
case 0x0E35u:
case 0x0E36u:
case 0x0E37u:
case 0x0E47u:
case 0x0E4Cu:
case 0x0E4Du:
case 0x0E4Eu:
klass = HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
break;
case 0x0EB1u:
case 0x0EB4u:
case 0x0EB5u:
case 0x0EB6u:
case 0x0EB7u:
case 0x0EBBu:
case 0x0ECCu:
case 0x0ECDu:
klass = HB_UNICODE_COMBINING_CLASS_ABOVE;
break;
case 0x0EBCu:
klass = HB_UNICODE_COMBINING_CLASS_BELOW;
break;
}
} else {
/* Thai virama is below-right */
if (u == 0x0E3Au)
klass = HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
}
}
switch (klass)
{
/* Hebrew */
case HB_MODIFIED_COMBINING_CLASS_CCC10: /* sheva */
case HB_MODIFIED_COMBINING_CLASS_CCC11: /* hataf segol */
case HB_MODIFIED_COMBINING_CLASS_CCC12: /* hataf patah */
case HB_MODIFIED_COMBINING_CLASS_CCC13: /* hataf qamats */
case HB_MODIFIED_COMBINING_CLASS_CCC14: /* hiriq */
case HB_MODIFIED_COMBINING_CLASS_CCC15: /* tsere */
case HB_MODIFIED_COMBINING_CLASS_CCC16: /* segol */
case HB_MODIFIED_COMBINING_CLASS_CCC17: /* patah */
case HB_MODIFIED_COMBINING_CLASS_CCC18: /* qamats & qamats qatan */
case HB_MODIFIED_COMBINING_CLASS_CCC20: /* qubuts */
case HB_MODIFIED_COMBINING_CLASS_CCC22: /* meteg */
return HB_UNICODE_COMBINING_CLASS_BELOW;
case HB_MODIFIED_COMBINING_CLASS_CCC23: /* rafe */
return HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE;
case HB_MODIFIED_COMBINING_CLASS_CCC24: /* shin dot */
return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
case HB_MODIFIED_COMBINING_CLASS_CCC25: /* sin dot */
case HB_MODIFIED_COMBINING_CLASS_CCC19: /* holam & holam haser for vav */
return HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT;
case HB_MODIFIED_COMBINING_CLASS_CCC26: /* point varika */
return HB_UNICODE_COMBINING_CLASS_ABOVE;
case HB_MODIFIED_COMBINING_CLASS_CCC21: /* dagesh */
break;
/* Arabic and Syriac */
case HB_MODIFIED_COMBINING_CLASS_CCC27: /* fathatan */
case HB_MODIFIED_COMBINING_CLASS_CCC28: /* dammatan */
case HB_MODIFIED_COMBINING_CLASS_CCC30: /* fatha */
case HB_MODIFIED_COMBINING_CLASS_CCC31: /* damma */
case HB_MODIFIED_COMBINING_CLASS_CCC33: /* shadda */
case HB_MODIFIED_COMBINING_CLASS_CCC34: /* sukun */
case HB_MODIFIED_COMBINING_CLASS_CCC35: /* superscript alef */
case HB_MODIFIED_COMBINING_CLASS_CCC36: /* superscript alaph */
return HB_UNICODE_COMBINING_CLASS_ABOVE;
case HB_MODIFIED_COMBINING_CLASS_CCC29: /* kasratan */
case HB_MODIFIED_COMBINING_CLASS_CCC32: /* kasra */
return HB_UNICODE_COMBINING_CLASS_BELOW;
/* Thai */
case HB_MODIFIED_COMBINING_CLASS_CCC103: /* sara u / sara uu */
return HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
case HB_MODIFIED_COMBINING_CLASS_CCC107: /* mai */
return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
/* Lao */
case HB_MODIFIED_COMBINING_CLASS_CCC118: /* sign u / sign uu */
return HB_UNICODE_COMBINING_CLASS_BELOW;
case HB_MODIFIED_COMBINING_CLASS_CCC122: /* mai */
return HB_UNICODE_COMBINING_CLASS_ABOVE;
/* Tibetan */
case HB_MODIFIED_COMBINING_CLASS_CCC129: /* sign aa */
return HB_UNICODE_COMBINING_CLASS_BELOW;
case HB_MODIFIED_COMBINING_CLASS_CCC130: /* sign i*/
return HB_UNICODE_COMBINING_CLASS_ABOVE;
case HB_MODIFIED_COMBINING_CLASS_CCC132: /* sign u */
return HB_UNICODE_COMBINING_CLASS_BELOW;
}
return klass;
}
void
_hb_ot_shape_fallback_mark_position_recategorize_marks (const hb_ot_shape_plan_t *plan HB_UNUSED,
hb_font_t *font HB_UNUSED,
hb_buffer_t *buffer)
{
#ifdef HB_NO_OT_SHAPE_FALLBACK
return;
#endif
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = 0; i < count; i++)
if (_hb_glyph_info_get_general_category (&info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) {
unsigned int combining_class = _hb_glyph_info_get_modified_combining_class (&info[i]);
combining_class = recategorize_combining_class (info[i].codepoint, combining_class);
_hb_glyph_info_set_modified_combining_class (&info[i], combining_class);
}
}
static void
zero_mark_advances (hb_buffer_t *buffer,
unsigned int start,
unsigned int end,
bool adjust_offsets_when_zeroing)
{
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = start; i < end; i++)
if (_hb_glyph_info_get_general_category (&info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
{
if (adjust_offsets_when_zeroing)
{
buffer->pos[i].x_offset -= buffer->pos[i].x_advance;
buffer->pos[i].y_offset -= buffer->pos[i].y_advance;
}
buffer->pos[i].x_advance = 0;
buffer->pos[i].y_advance = 0;
}
}
static inline void
position_mark (const hb_ot_shape_plan_t *plan HB_UNUSED,
hb_font_t *font,
hb_buffer_t *buffer,
hb_glyph_extents_t &base_extents,
unsigned int i,
unsigned int combining_class)
{
hb_glyph_extents_t mark_extents;
if (!font->get_glyph_extents (buffer->info[i].codepoint, &mark_extents))
return;
hb_position_t y_gap = font->y_scale / 16;
hb_glyph_position_t &pos = buffer->pos[i];
pos.x_offset = pos.y_offset = 0;
/* We don't position LEFT and RIGHT marks. */
/* X positioning */
switch (combining_class)
{
case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
if (buffer->props.direction == HB_DIRECTION_LTR) {
pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width / 2 - mark_extents.x_bearing;
break;
} else if (buffer->props.direction == HB_DIRECTION_RTL) {
pos.x_offset += base_extents.x_bearing - mark_extents.width / 2 - mark_extents.x_bearing;
break;
}
HB_FALLTHROUGH;
default:
case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
case HB_UNICODE_COMBINING_CLASS_BELOW:
case HB_UNICODE_COMBINING_CLASS_ABOVE:
/* Center align. */
pos.x_offset += base_extents.x_bearing + (base_extents.width - mark_extents.width) / 2 - mark_extents.x_bearing;
break;
case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
/* Left align. */
pos.x_offset += base_extents.x_bearing - mark_extents.x_bearing;
break;
case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
/* Right align. */
pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width - mark_extents.x_bearing;
break;
}
/* Y positioning */
switch (combining_class)
{
case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
case HB_UNICODE_COMBINING_CLASS_BELOW:
case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
/* Add gap, fall-through. */
base_extents.height -= y_gap;
HB_FALLTHROUGH;
case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
pos.y_offset = base_extents.y_bearing + base_extents.height - mark_extents.y_bearing;
/* Never shift up "below" marks. */
if ((y_gap > 0) == (pos.y_offset > 0))
{
base_extents.height -= pos.y_offset;
pos.y_offset = 0;
}
base_extents.height += mark_extents.height;
break;
case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
case HB_UNICODE_COMBINING_CLASS_ABOVE:
case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
/* Add gap, fall-through. */
base_extents.y_bearing += y_gap;
base_extents.height -= y_gap;
HB_FALLTHROUGH;
case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
pos.y_offset = base_extents.y_bearing - (mark_extents.y_bearing + mark_extents.height);
/* Don't shift down "above" marks too much. */
if ((y_gap > 0) != (pos.y_offset > 0))
{
int correction = -pos.y_offset / 2;
base_extents.y_bearing += correction;
base_extents.height -= correction;
pos.y_offset += correction;
}
base_extents.y_bearing -= mark_extents.height;
base_extents.height += mark_extents.height;
break;
}
}
static inline void
position_around_base (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer,
unsigned int base,
unsigned int end,
bool adjust_offsets_when_zeroing)
{
hb_direction_t horiz_dir = HB_DIRECTION_INVALID;
buffer->unsafe_to_break (base, end);
hb_glyph_extents_t base_extents;
if (!font->get_glyph_extents (buffer->info[base].codepoint,
&base_extents))
{
/* If extents don't work, zero marks and go home. */
zero_mark_advances (buffer, base + 1, end, adjust_offsets_when_zeroing);
return;
}
base_extents.y_bearing += buffer->pos[base].y_offset;
/* Use horizontal advance for horizontal positioning.
* Generally a better idea. Also works for zero-ink glyphs. See:
* https://github.com/harfbuzz/harfbuzz/issues/1532 */
base_extents.x_bearing = 0;
base_extents.width = font->get_glyph_h_advance (buffer->info[base].codepoint);
unsigned int lig_id = _hb_glyph_info_get_lig_id (&buffer->info[base]);
/* Use integer for num_lig_components such that it doesn't convert to unsigned
* when we divide or multiply by it. */
int num_lig_components = _hb_glyph_info_get_lig_num_comps (&buffer->info[base]);
hb_position_t x_offset = 0, y_offset = 0;
if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
x_offset -= buffer->pos[base].x_advance;
y_offset -= buffer->pos[base].y_advance;
}
hb_glyph_extents_t component_extents = base_extents;
int last_lig_component = -1;
unsigned int last_combining_class = 255;
hb_glyph_extents_t cluster_extents = base_extents; /* Initialization is just to shut gcc up. */
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = base + 1; i < end; i++)
if (_hb_glyph_info_get_modified_combining_class (&info[i]))
{
if (num_lig_components > 1) {
unsigned int this_lig_id = _hb_glyph_info_get_lig_id (&info[i]);
int this_lig_component = _hb_glyph_info_get_lig_comp (&info[i]) - 1;
/* Conditions for attaching to the last component. */
if (!lig_id || lig_id != this_lig_id || this_lig_component >= num_lig_components)
this_lig_component = num_lig_components - 1;
if (last_lig_component != this_lig_component)
{
last_lig_component = this_lig_component;
last_combining_class = 255;
component_extents = base_extents;
if (unlikely (horiz_dir == HB_DIRECTION_INVALID)) {
if (HB_DIRECTION_IS_HORIZONTAL (plan->props.direction))
horiz_dir = plan->props.direction;
else
horiz_dir = hb_script_get_horizontal_direction (plan->props.script);
}
if (horiz_dir == HB_DIRECTION_LTR)
component_extents.x_bearing += (this_lig_component * component_extents.width) / num_lig_components;
else
component_extents.x_bearing += ((num_lig_components - 1 - this_lig_component) * component_extents.width) / num_lig_components;
component_extents.width /= num_lig_components;
}
}
unsigned int this_combining_class = _hb_glyph_info_get_modified_combining_class (&info[i]);
if (last_combining_class != this_combining_class)
{
last_combining_class = this_combining_class;
cluster_extents = component_extents;
}
position_mark (plan, font, buffer, cluster_extents, i, this_combining_class);
buffer->pos[i].x_advance = 0;
buffer->pos[i].y_advance = 0;
buffer->pos[i].x_offset += x_offset;
buffer->pos[i].y_offset += y_offset;
} else {
if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
x_offset -= buffer->pos[i].x_advance;
y_offset -= buffer->pos[i].y_advance;
} else {
x_offset += buffer->pos[i].x_advance;
y_offset += buffer->pos[i].y_advance;
}
}
}
static inline void
position_cluster (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer,
unsigned int start,
unsigned int end,
bool adjust_offsets_when_zeroing)
{
if (end - start < 2)
return;
/* Find the base glyph */
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = start; i < end; i++)
if (!_hb_glyph_info_is_unicode_mark (&info[i]))
{
/* Find mark glyphs */
unsigned int j;
for (j = i + 1; j < end; j++)
if (!_hb_glyph_info_is_unicode_mark (&info[j]))
break;
position_around_base (plan, font, buffer, i, j, adjust_offsets_when_zeroing);
i = j - 1;
}
}
void
_hb_ot_shape_fallback_mark_position (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer,
bool adjust_offsets_when_zeroing)
{
#ifdef HB_NO_OT_SHAPE_FALLBACK
return;
#endif
if (!buffer->message (font, "start fallback mark"))
return;
_hb_buffer_assert_gsubgpos_vars (buffer);
unsigned int start = 0;
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = 1; i < count; i++)
if (likely (!_hb_glyph_info_is_unicode_mark (&info[i]))) {
position_cluster (plan, font, buffer, start, i, adjust_offsets_when_zeroing);
start = i;
}
position_cluster (plan, font, buffer, start, count, adjust_offsets_when_zeroing);
(void) buffer->message (font, "end fallback mark");
}
#ifndef HB_DISABLE_DEPRECATED
struct hb_ot_shape_fallback_kern_driver_t
{
hb_ot_shape_fallback_kern_driver_t (hb_font_t *font_,
hb_buffer_t *buffer) :
font (font_), direction (buffer->props.direction) {}
hb_position_t get_kerning (hb_codepoint_t first, hb_codepoint_t second) const
{
hb_position_t kern = 0;
font->get_glyph_kerning_for_direction (first, second,
direction,
&kern, &kern);
return kern;
}
hb_font_t *font;
hb_direction_t direction;
};
#endif
/* Performs font-assisted kerning. */
void
_hb_ot_shape_fallback_kern (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer)
{
#ifdef HB_NO_OT_SHAPE_FALLBACK
return;
#endif
#ifndef HB_DISABLE_DEPRECATED
if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction) ?
!font->has_glyph_h_kerning_func () :
!font->has_glyph_v_kerning_func ())
return;
if (!buffer->message (font, "start fallback kern"))
return;
bool reverse = HB_DIRECTION_IS_BACKWARD (buffer->props.direction);
if (reverse)
buffer->reverse ();
hb_ot_shape_fallback_kern_driver_t driver (font, buffer);
OT::hb_kern_machine_t<hb_ot_shape_fallback_kern_driver_t> machine (driver);
machine.kern (font, buffer, plan->kern_mask, false);
if (reverse)
buffer->reverse ();
(void) buffer->message (font, "end fallback kern");
#endif
}
/* Adjusts width of various spaces. */
void
_hb_ot_shape_fallback_spaces (const hb_ot_shape_plan_t *plan HB_UNUSED,
hb_font_t *font,
hb_buffer_t *buffer)
{
hb_glyph_info_t *info = buffer->info;
hb_glyph_position_t *pos = buffer->pos;
bool horizontal = HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction);
unsigned int count = buffer->len;
for (unsigned int i = 0; i < count; i++)
if (_hb_glyph_info_is_unicode_space (&info[i]) && !_hb_glyph_info_ligated (&info[i]))
{
/* If font had no ASCII space and we used the invisible glyph, give it a 1/4 EM default advance. */
if (buffer->invisible && info[i].codepoint == buffer->invisible)
{
if (horizontal)
pos[i].x_advance = +font->x_scale / 4;
else
pos[i].y_advance = -font->y_scale / 4;
}
hb_unicode_funcs_t::space_t space_type = _hb_glyph_info_get_unicode_space_fallback_type (&info[i]);
hb_codepoint_t glyph;
typedef hb_unicode_funcs_t t;
switch (space_type)
{
case t::NOT_SPACE: /* Shouldn't happen. */
case t::SPACE:
break;
case t::SPACE_EM:
case t::SPACE_EM_2:
case t::SPACE_EM_3:
case t::SPACE_EM_4:
case t::SPACE_EM_5:
case t::SPACE_EM_6:
case t::SPACE_EM_16:
if (horizontal)
pos[i].x_advance = +(font->x_scale + ((int) space_type)/2) / (int) space_type;
else
pos[i].y_advance = -(font->y_scale + ((int) space_type)/2) / (int) space_type;
break;
case t::SPACE_4_EM_18:
if (horizontal)
pos[i].x_advance = (int64_t) +font->x_scale * 4 / 18;
else
pos[i].y_advance = (int64_t) -font->y_scale * 4 / 18;
break;
case t::SPACE_FIGURE:
for (char u = '0'; u <= '9'; u++)
if (font->get_nominal_glyph (u, &glyph))
{
if (horizontal)
pos[i].x_advance = font->get_glyph_h_advance (glyph);
else
pos[i].y_advance = font->get_glyph_v_advance (glyph);
break;
}
break;
case t::SPACE_PUNCTUATION:
if (font->get_nominal_glyph ('.', &glyph) ||
font->get_nominal_glyph (',', &glyph))
{
if (horizontal)
pos[i].x_advance = font->get_glyph_h_advance (glyph);
else
pos[i].y_advance = font->get_glyph_v_advance (glyph);
}
break;
case t::SPACE_NARROW:
/* Half-space?
* Unicode doc https://unicode.org/charts/PDF/U2000.pdf says ~1/4 or 1/5 of EM.
* However, in my testing, many fonts have their regular space being about that
* size. To me, a percentage of the space width makes more sense. Half is as
* good as any. */
if (horizontal)
pos[i].x_advance /= 2;
else
pos[i].y_advance /= 2;
break;
}
}
}
#endif
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