harfbuzz/src/hb-ot-shape.cc

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/*
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* Copyright (C) 2009,2010 Red Hat, Inc.
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* Copyright (C) 2010 Google, Inc.
*
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* 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
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* Google Author(s): Behdad Esfahbod
*/
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#include "hb-ot-shape-private.hh"
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#include "hb-ot-map-private.hh"
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HB_BEGIN_DECLS
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/* XXX vertical */
hb_tag_t default_features[] = {
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HB_TAG('c','a','l','t'),
HB_TAG('c','c','m','p'),
HB_TAG('c','l','i','g'),
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HB_TAG('c','s','w','h'),
HB_TAG('c','u','r','s'),
HB_TAG('k','e','r','n'),
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HB_TAG('l','i','g','a'),
HB_TAG('l','o','c','l'),
HB_TAG('m','a','r','k'),
HB_TAG('m','k','m','k'),
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HB_TAG('r','l','i','g')
};
static void
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hb_ot_shape_collect_features (hb_ot_map_t *map,
hb_segment_properties_t *props,
const hb_feature_t *user_features,
unsigned int num_user_features)
{
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switch (props->direction) {
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case HB_DIRECTION_LTR:
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map->add_bool_feature (HB_TAG ('l','t','r','a'));
map->add_bool_feature (HB_TAG ('l','t','r','m'));
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break;
case HB_DIRECTION_RTL:
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map->add_bool_feature (HB_TAG ('r','t','l','a'));
map->add_bool_feature (HB_TAG ('r','t','l','m'), false);
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break;
case HB_DIRECTION_TTB:
case HB_DIRECTION_BTT:
default:
break;
}
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for (unsigned int i = 0; i < ARRAY_LENGTH (default_features); i++)
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map->add_bool_feature (default_features[i]);
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/* complex */
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for (unsigned int i = 0; i < num_user_features; i++) {
const hb_feature_t *feature = &user_features[i];
map->add_feature (feature->tag, feature->value, (feature->start == 0 && feature->end == (unsigned int) -1));
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}
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}
static void
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hb_ot_shape_setup_masks (hb_ot_shape_context_t *c)
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{
hb_mask_t global_mask = c->map->get_global_mask ();
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if (global_mask)
c->buffer->set_masks (global_mask, global_mask, 0, (unsigned int) -1);
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for (unsigned int i = 0; i < c->num_user_features; i++)
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{
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const hb_feature_t *feature = &c->user_features[i];
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if (!(feature->start == 0 && feature->end == (unsigned int)-1)) {
unsigned int shift;
hb_mask_t mask = c->map->get_mask (feature->tag, &shift);
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c->buffer->set_masks (feature->value << shift, mask, feature->start, feature->end);
}
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}
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/* complex */
}
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static void
hb_ot_substitute_complex (hb_ot_shape_context_t *c)
{
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if (!hb_ot_layout_has_substitution (c->face))
return;
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c->map->substitute (c->face, c->buffer);
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c->applied_substitute_complex = TRUE;
return;
}
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static void
hb_ot_position_complex (hb_ot_shape_context_t *c)
{
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if (!hb_ot_layout_has_positioning (c->face))
return;
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c->map->position (c->font, c->face, c->buffer);
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hb_ot_layout_position_finish (c->font, c->face, c->buffer);
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c->applied_position_complex = TRUE;
return;
}
/* Main shaper */
/* Prepare */
static inline hb_bool_t
is_variation_selector (hb_codepoint_t unicode)
{
return unlikely ((unicode >= 0x180B && unicode <= 0x180D) || /* MONGOLIAN FREE VARIATION SELECTOR ONE..THREE */
(unicode >= 0xFE00 && unicode <= 0xFE0F) || /* VARIATION SELECTOR-1..16 */
(unicode >= 0xE0100 && unicode <= 0xE01EF)); /* VARIATION SELECTOR-17..256 */
}
static void
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hb_form_clusters (hb_ot_shape_context_t *c)
{
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unsigned int count = c->buffer->len;
for (unsigned int i = 1; i < count; i++)
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if (c->buffer->unicode->v.get_general_category (c->buffer->info[i].codepoint) == HB_CATEGORY_NON_SPACING_MARK)
c->buffer->info[i].cluster = c->buffer->info[i - 1].cluster;
}
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static void
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hb_ensure_native_direction (hb_ot_shape_context_t *c)
{
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hb_direction_t direction = c->buffer->props.direction;
/* TODO vertical */
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if (HB_DIRECTION_IS_HORIZONTAL (direction) &&
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direction != _hb_script_get_horizontal_direction (c->buffer->props.script))
{
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hb_buffer_reverse_clusters (c->buffer);
c->buffer->props.direction = HB_DIRECTION_REVERSE (c->buffer->props.direction);
}
}
/* Substitute */
static void
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hb_mirror_chars (hb_ot_shape_context_t *c)
{
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hb_unicode_get_mirroring_func_t get_mirroring = c->buffer->unicode->v.get_mirroring;
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if (HB_DIRECTION_IS_FORWARD (c->buffer->props.direction))
return;
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hb_mask_t rtlm_mask = c->map->get_mask (HB_TAG ('r','t','l','m'));
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unsigned int count = c->buffer->len;
for (unsigned int i = 0; i < count; i++) {
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hb_codepoint_t codepoint = get_mirroring (c->buffer->info[i].codepoint);
if (likely (codepoint == c->buffer->info[i].codepoint))
c->buffer->info[i].mask |= rtlm_mask;
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else
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c->buffer->info[i].codepoint = codepoint;
}
}
static void
hb_map_glyphs (hb_font_t *font,
hb_face_t *face,
hb_buffer_t *buffer)
{
if (unlikely (!buffer->len))
return;
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buffer->clear_output ();
unsigned int count = buffer->len - 1;
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for (buffer->i = 0; buffer->i < count;) {
if (unlikely (is_variation_selector (buffer->info[buffer->i + 1].codepoint))) {
buffer->add_output_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, buffer->info[buffer->i + 1].codepoint));
buffer->i++;
} else {
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buffer->add_output_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, 0));
}
}
if (likely (buffer->i < buffer->len))
buffer->add_output_glyph (hb_font_get_glyph (font, face, buffer->info[buffer->i].codepoint, 0));
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buffer->swap ();
}
static void
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hb_substitute_default (hb_ot_shape_context_t *c)
{
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hb_map_glyphs (c->font, c->face, c->buffer);
}
static void
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hb_substitute_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
{
/* TODO Arabic */
}
/* Position */
static void
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hb_position_default (hb_ot_shape_context_t *c)
{
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hb_buffer_clear_positions (c->buffer);
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unsigned int count = c->buffer->len;
for (unsigned int i = 0; i < count; i++) {
hb_glyph_metrics_t metrics;
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hb_font_get_glyph_metrics (c->font, c->face, c->buffer->info[i].codepoint, &metrics);
c->buffer->pos[i].x_advance = metrics.x_advance;
c->buffer->pos[i].y_advance = metrics.y_advance;
}
}
static void
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hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
{
/* TODO Mark pos */
}
static void
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hb_truetype_kern (hb_ot_shape_context_t *c)
{
/* TODO Check for kern=0 */
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unsigned int count = c->buffer->len;
for (unsigned int i = 1; i < count; i++) {
hb_position_t kern, kern1, kern2;
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kern = hb_font_get_kerning (c->font, c->face, c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint);
kern1 = kern >> 1;
kern2 = kern - kern1;
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c->buffer->pos[i - 1].x_advance += kern1;
c->buffer->pos[i].x_advance += kern2;
c->buffer->pos[i].x_offset += kern2;
}
}
static void
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hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
{
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hb_truetype_kern (c);
}
/* Do it! */
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static void
hb_ot_shape_internal (hb_ot_shape_context_t *c)
{
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/* Save the original direction, we use it later. */
c->original_direction = c->buffer->props.direction;
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hb_ot_shape_setup_masks (c);
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hb_form_clusters (c);
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/* SUBSTITUTE */
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{
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c->buffer->clear_masks ();
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/* Mirroring needs to see the original direction */
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hb_mirror_chars (c);
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hb_ensure_native_direction (c);
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hb_substitute_default (c);
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hb_ot_substitute_complex (c);
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if (!c->applied_substitute_complex)
hb_substitute_complex_fallback (c);
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}
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/* POSITION */
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{
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c->buffer->clear_masks ();
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hb_position_default (c);
hb_ot_position_complex (c);
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hb_bool_t position_fallback = !c->applied_position_complex;
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if (position_fallback)
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hb_position_complex_fallback (c);
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if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
hb_buffer_reverse (c->buffer);
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if (position_fallback)
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hb_position_complex_fallback_visual (c);
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}
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c->buffer->props.direction = c->original_direction;
}
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void
hb_ot_shape_plan_internal (hb_ot_map_t *map,
hb_face_t *face,
hb_segment_properties_t *props,
const hb_feature_t *user_features,
unsigned int num_user_features)
{
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hb_ot_shape_collect_features (map, props, user_features, num_user_features);
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map->compile (face, props);
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}
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void
hb_ot_shape (hb_font_t *font,
hb_face_t *face,
hb_buffer_t *buffer,
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const hb_feature_t *user_features,
unsigned int num_user_features)
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{
hb_ot_map_t map;
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hb_ot_shape_plan_internal (&map, face, &buffer->props, user_features, num_user_features);
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hb_ot_shape_context_t c = {font, face, buffer, user_features, num_user_features};
c.map = &map;
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hb_ot_shape_internal (&c);
}
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HB_END_DECLS