harfbuzz/src/hb-ot-shape.cc

449 lines
12 KiB
C++

/*
* Copyright © 2009,2010 Red Hat, Inc.
* Copyright © 2010,2011 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.
*
* Red Hat Author(s): Behdad Esfahbod
* Google Author(s): Behdad Esfahbod
*/
#include "hb-ot-shape-private.hh"
#include "hb-ot-shape-complex-private.hh"
#include "hb-font-private.hh"
hb_tag_t common_features[] = {
HB_TAG('c','c','m','p'),
HB_TAG('l','o','c','l'),
HB_TAG('m','a','r','k'),
HB_TAG('m','k','m','k'),
HB_TAG('r','l','i','g'),
};
hb_tag_t horizontal_features[] = {
HB_TAG('c','a','l','t'),
HB_TAG('c','l','i','g'),
HB_TAG('c','u','r','s'),
HB_TAG('k','e','r','n'),
HB_TAG('l','i','g','a'),
};
/* Note:
* Technically speaking, vrt2 and vert are mutually exclusive.
* According to the spec, valt and vpal are also mutually exclusive.
* But we apply them all for now.
*/
hb_tag_t vertical_features[] = {
HB_TAG('v','a','l','t'),
HB_TAG('v','e','r','t'),
HB_TAG('v','k','r','n'),
HB_TAG('v','p','a','l'),
HB_TAG('v','r','t','2'),
};
static void
hb_ot_shape_collect_features (hb_ot_shape_planner_t *planner,
const hb_segment_properties_t *props,
const hb_feature_t *user_features,
unsigned int num_user_features)
{
switch (props->direction) {
case HB_DIRECTION_LTR:
planner->map.add_bool_feature (HB_TAG ('l','t','r','a'));
planner->map.add_bool_feature (HB_TAG ('l','t','r','m'));
break;
case HB_DIRECTION_RTL:
planner->map.add_bool_feature (HB_TAG ('r','t','l','a'));
planner->map.add_bool_feature (HB_TAG ('r','t','l','m'), false);
break;
case HB_DIRECTION_TTB:
case HB_DIRECTION_BTT:
case HB_DIRECTION_INVALID:
default:
break;
}
#define ADD_FEATURES(array) \
HB_STMT_START { \
for (unsigned int i = 0; i < ARRAY_LENGTH (array); i++) \
planner->map.add_bool_feature (array[i]); \
} HB_STMT_END
hb_ot_shape_complex_collect_features (planner->shaper, &planner->map, props);
ADD_FEATURES (common_features);
if (HB_DIRECTION_IS_HORIZONTAL (props->direction))
ADD_FEATURES (horizontal_features);
else
ADD_FEATURES (vertical_features);
#undef ADD_FEATURES
for (unsigned int i = 0; i < num_user_features; i++) {
const hb_feature_t *feature = &user_features[i];
planner->map.add_feature (feature->tag, feature->value, (feature->start == 0 && feature->end == (unsigned int) -1));
}
}
static void
hb_ot_shape_setup_masks (hb_ot_shape_context_t *c)
{
hb_mask_t global_mask = c->plan->map.get_global_mask ();
c->buffer->reset_masks (global_mask);
hb_ot_shape_complex_setup_masks (c->plan->shaper, &c->plan->map, c->buffer);
for (unsigned int i = 0; i < c->num_user_features; i++)
{
const hb_feature_t *feature = &c->user_features[i];
if (!(feature->start == 0 && feature->end == (unsigned int)-1)) {
unsigned int shift;
hb_mask_t mask = c->plan->map.get_mask (feature->tag, &shift);
c->buffer->set_masks (feature->value << shift, mask, feature->start, feature->end);
}
}
}
/* Main shaper */
/* Prepare */
void
_hb_set_unicode_props (hb_buffer_t *buffer)
{
unsigned int count = buffer->len;
for (unsigned int i = 1; i < count; i++)
hb_glyph_info_set_unicode_props (&buffer->info[i], buffer->unicode);
}
static void
hb_form_clusters (hb_buffer_t *buffer)
{
unsigned int count = buffer->len;
for (unsigned int i = 1; i < count; i++)
if (FLAG (buffer->info[i].general_category()) &
(FLAG (HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK) |
FLAG (HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) |
FLAG (HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)))
buffer->info[i].cluster = buffer->info[i - 1].cluster;
}
static void
hb_ensure_native_direction (hb_buffer_t *buffer)
{
hb_direction_t direction = buffer->props.direction;
/* TODO vertical:
* The only BTT vertical script is Ogham, but it's not clear to me whether OpenType
* Ogham fonts are supposed to be implemented BTT or not. Need to research that
* first. */
if ((HB_DIRECTION_IS_HORIZONTAL (direction) && direction != hb_script_get_horizontal_direction (buffer->props.script)) ||
(HB_DIRECTION_IS_VERTICAL (direction) && direction != HB_DIRECTION_TTB))
{
hb_buffer_reverse_clusters (buffer);
buffer->props.direction = HB_DIRECTION_REVERSE (buffer->props.direction);
}
}
/* Substitute */
static void
hb_mirror_chars (hb_ot_shape_context_t *c)
{
hb_unicode_funcs_t *unicode = c->buffer->unicode;
if (HB_DIRECTION_IS_FORWARD (c->target_direction))
return;
hb_mask_t rtlm_mask = c->plan->map.get_1_mask (HB_TAG ('r','t','l','m'));
unsigned int count = c->buffer->len;
for (unsigned int i = 0; i < count; i++) {
hb_codepoint_t codepoint = hb_unicode_mirroring (unicode, c->buffer->info[i].codepoint);
if (likely (codepoint == c->buffer->info[i].codepoint))
c->buffer->info[i].mask |= rtlm_mask; /* XXX this should be moved to before setting user-feature masks */
else
c->buffer->info[i].codepoint = codepoint;
}
}
static void
hb_map_glyphs (hb_font_t *font,
hb_buffer_t *buffer)
{
hb_codepoint_t glyph;
if (unlikely (!buffer->len))
return;
buffer->clear_output ();
unsigned int count = buffer->len - 1;
for (buffer->idx = 0; buffer->idx < count;) {
if (unlikely (is_variation_selector (buffer->info[buffer->idx + 1].codepoint))) {
hb_font_get_glyph (font, buffer->info[buffer->idx].codepoint, buffer->info[buffer->idx + 1].codepoint, &glyph);
buffer->replace_glyph (glyph);
buffer->skip_glyph ();
} else {
hb_font_get_glyph (font, buffer->info[buffer->idx].codepoint, 0, &glyph);
buffer->replace_glyph (glyph);
}
}
if (likely (buffer->idx < buffer->len)) {
hb_font_get_glyph (font, buffer->info[buffer->idx].codepoint, 0, &glyph);
buffer->replace_glyph (glyph);
}
buffer->swap_buffers ();
}
static void
hb_substitute_default (hb_ot_shape_context_t *c)
{
hb_ot_layout_substitute_start (c->buffer);
hb_mirror_chars (c);
hb_map_glyphs (c->font, c->buffer);
}
static void
hb_ot_substitute_complex (hb_ot_shape_context_t *c)
{
if (hb_ot_layout_has_substitution (c->face)) {
c->plan->map.substitute (c->face, c->buffer);
c->applied_substitute_complex = TRUE;
}
hb_ot_layout_substitute_finish (c->buffer);
return;
}
static void
hb_substitute_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
{
/* TODO Arabic */
}
/* Position */
static void
hb_position_default (hb_ot_shape_context_t *c)
{
hb_ot_layout_position_start (c->buffer);
unsigned int count = c->buffer->len;
for (unsigned int i = 0; i < count; i++) {
hb_font_get_glyph_advance_for_direction (c->font, c->buffer->info[i].codepoint,
c->buffer->props.direction,
&c->buffer->pos[i].x_advance,
&c->buffer->pos[i].y_advance);
hb_font_subtract_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
c->buffer->props.direction,
&c->buffer->pos[i].x_offset,
&c->buffer->pos[i].y_offset);
}
}
static void
hb_ot_position_complex (hb_ot_shape_context_t *c)
{
if (hb_ot_layout_has_positioning (c->face))
{
/* Change glyph origin to what GPOS expects, apply GPOS, change it back. */
unsigned int count = c->buffer->len;
for (unsigned int i = 0; i < count; i++) {
hb_font_add_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
HB_DIRECTION_LTR,
&c->buffer->pos[i].x_offset,
&c->buffer->pos[i].y_offset);
}
c->plan->map.position (c->font, c->buffer);
for (unsigned int i = 0; i < count; i++) {
hb_font_subtract_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
HB_DIRECTION_LTR,
&c->buffer->pos[i].x_offset,
&c->buffer->pos[i].y_offset);
}
c->applied_position_complex = TRUE;
}
hb_ot_layout_position_finish (c->buffer);
return;
}
static void
hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
{
/* TODO Mark pos */
}
static void
hb_truetype_kern (hb_ot_shape_context_t *c)
{
/* TODO Check for kern=0 */
unsigned int count = c->buffer->len;
for (unsigned int i = 1; i < count; i++) {
hb_position_t x_kern, y_kern, kern1, kern2;
hb_font_get_glyph_kerning_for_direction (c->font,
c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint,
c->buffer->props.direction,
&x_kern, &y_kern);
kern1 = x_kern >> 1;
kern2 = x_kern - kern1;
c->buffer->pos[i - 1].x_advance += kern1;
c->buffer->pos[i].x_advance += kern2;
c->buffer->pos[i].x_offset += kern2;
kern1 = y_kern >> 1;
kern2 = y_kern - kern1;
c->buffer->pos[i - 1].y_advance += kern1;
c->buffer->pos[i].y_advance += kern2;
c->buffer->pos[i].y_offset += kern2;
}
}
static void
hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
{
hb_truetype_kern (c);
}
/* Do it! */
static void
hb_ot_shape_execute_internal (hb_ot_shape_context_t *c)
{
c->buffer->deallocate_var_all ();
/* Save the original direction, we use it later. */
c->target_direction = c->buffer->props.direction;
HB_BUFFER_ALLOCATE_VAR (c->buffer, general_category);
HB_BUFFER_ALLOCATE_VAR (c->buffer, combining_class);
_hb_set_unicode_props (c->buffer); /* BUFFER: Set general_category and combining_class */
hb_form_clusters (c->buffer);
hb_ensure_native_direction (c->buffer);
_hb_ot_shape_normalize (c);
hb_ot_shape_setup_masks (c);
/* SUBSTITUTE */
{
hb_substitute_default (c);
hb_ot_substitute_complex (c);
if (!c->applied_substitute_complex)
hb_substitute_complex_fallback (c);
}
/* POSITION */
{
hb_position_default (c);
hb_ot_position_complex (c);
hb_bool_t position_fallback = !c->applied_position_complex;
if (position_fallback)
hb_position_complex_fallback (c);
if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
hb_buffer_reverse (c->buffer);
if (position_fallback)
hb_position_complex_fallback_visual (c);
}
HB_BUFFER_DEALLOCATE_VAR (c->buffer, combining_class);
HB_BUFFER_DEALLOCATE_VAR (c->buffer, general_category);
c->buffer->props.direction = c->target_direction;
c->buffer->deallocate_var_all ();
}
static void
hb_ot_shape_plan_internal (hb_ot_shape_plan_t *plan,
hb_face_t *face,
const hb_segment_properties_t *props,
const hb_feature_t *user_features,
unsigned int num_user_features)
{
hb_ot_shape_planner_t planner;
planner.shaper = hb_ot_shape_complex_categorize (props);
hb_ot_shape_collect_features (&planner, props, user_features, num_user_features);
planner.compile (face, props, *plan);
}
static void
hb_ot_shape_execute (hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer,
const hb_feature_t *user_features,
unsigned int num_user_features)
{
hb_ot_shape_context_t c = {plan, font, font->face, buffer, user_features, num_user_features};
hb_ot_shape_execute_internal (&c);
}
hb_bool_t
hb_ot_shape (hb_font_t *font,
hb_buffer_t *buffer,
const hb_feature_t *features,
unsigned int num_features,
const char * const *shaper_options)
{
hb_ot_shape_plan_t plan;
buffer->guess_properties ();
hb_ot_shape_plan_internal (&plan, font->face, &buffer->props, features, num_features);
hb_ot_shape_execute (&plan, font, buffer, features, num_features);
return TRUE;
}