harfbuzz/src/hb-ot-layout.hh

/*
 * Copyright © 2007,2008,2009  Red Hat, Inc.
 * Copyright © 2012,2013  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
 */

#ifndef HB_OT_LAYOUT_HH
#define HB_OT_LAYOUT_HH

#include "hb.hh"

#include "hb-font.hh"
#include "hb-buffer.hh"
#include "hb-open-type.hh"
#include "hb-ot-shape.hh"
#include "hb-set-digest.hh"

struct hb_ot_shape_plan_t;

/*
 * kern
 */

HB_INTERNAL bool hb_ot_layout_has_kerning(hb_face_t *face);

HB_INTERNAL bool hb_ot_layout_has_machine_kerning(hb_face_t *face);

HB_INTERNAL bool hb_ot_layout_has_cross_kerning(hb_face_t *face);

HB_INTERNAL void hb_ot_layout_kern(const hb_ot_shape_plan_t *plan, hb_font_t *font, hb_buffer_t *buffer);

/* Private API corresponding to hb-ot-layout.h: */

HB_INTERNAL bool
hb_ot_layout_table_find_feature(hb_face_t *face, hb_tag_t table_tag, hb_tag_t feature_tag, unsigned int *feature_index);

/*
 * GDEF
 */

enum hb_ot_layout_glyph_props_flags_t {
    /* The following three match LookupFlags::Ignore* numbers. */
    HB_OT_LAYOUT_GLYPH_PROPS_BASE_GLYPH = 0x02u,
    HB_OT_LAYOUT_GLYPH_PROPS_LIGATURE = 0x04u,
    HB_OT_LAYOUT_GLYPH_PROPS_MARK = 0x08u,

    HB_OT_LAYOUT_GLYPH_PROPS_CLASS_MASK =
        HB_OT_LAYOUT_GLYPH_PROPS_BASE_GLYPH | HB_OT_LAYOUT_GLYPH_PROPS_LIGATURE | HB_OT_LAYOUT_GLYPH_PROPS_MARK,

    /* The following are used internally; not derived from GDEF. */
    HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED = 0x10u,
    HB_OT_LAYOUT_GLYPH_PROPS_LIGATED = 0x20u,
    HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED = 0x40u,
};
HB_MARK_AS_FLAG_T(hb_ot_layout_glyph_props_flags_t);

/*
 * GSUB/GPOS
 */

/* Should be called before all the substitute_lookup's are done. */
HB_INTERNAL void hb_ot_layout_substitute_start(hb_font_t *font, hb_buffer_t *buffer);

HB_INTERNAL void hb_ot_layout_delete_glyphs_inplace(hb_buffer_t *buffer, bool (*filter)(const hb_glyph_info_t *info));

namespace OT {
struct hb_ot_apply_context_t;
struct SubstLookup;
struct hb_ot_layout_lookup_accelerator_t;
} // namespace OT

HB_INTERNAL void hb_ot_layout_substitute_lookup(OT::hb_ot_apply_context_t *c,
                                                const OT::SubstLookup &lookup,
                                                const OT::hb_ot_layout_lookup_accelerator_t &accel);

/* Should be called before all the position_lookup's are done. */
HB_INTERNAL void hb_ot_layout_position_start(hb_font_t *font, hb_buffer_t *buffer);

/* Should be called after all the position_lookup's are done, to fini advances. */
HB_INTERNAL void hb_ot_layout_position_finish_advances(hb_font_t *font, hb_buffer_t *buffer);

/* Should be called after hb_ot_layout_position_finish_advances, to fini offsets. */
HB_INTERNAL void hb_ot_layout_position_finish_offsets(hb_font_t *font, hb_buffer_t *buffer);

/*
 * Buffer var routines.
 */

/* buffer var allocations, used during the entire shaping process */
#define unicode_props() var2.u16[0]

/* buffer var allocations, used during the GSUB/GPOS processing */
#define glyph_props() var1.u16[0] /* GDEF glyph properties */
#define lig_props() var1.u8[2]    /* GSUB/GPOS ligature tracking */
#define syllable() var1.u8[3]     /* GSUB/GPOS shaping boundaries */

/* Loop over syllables. Based on foreach_cluster(). */
#define foreach_syllable(buffer, start, end)                                                                           \
    for (unsigned int _count = buffer->len, start = 0, end = _count ? _hb_next_syllable(buffer, 0) : 0;                \
         start < _count;                                                                                               \
         start = end, end = _hb_next_syllable(buffer, start))

static inline unsigned int _hb_next_syllable(hb_buffer_t *buffer, unsigned int start)
{
    hb_glyph_info_t *info = buffer->info;
    unsigned int count = buffer->len;

    unsigned int syllable = info[start].syllable();
    while (++start < count && syllable == info[start].syllable())
        ;

    return start;
}

static inline void
_hb_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;
}

/* unicode_props */

/* Design:
 * unicode_props() is a two-byte number.  The low byte includes:
 * - General_Category: 5 bits.
 * - A bit each for:
 *   * Is it Default_Ignorable(); we have a modified Default_Ignorable().
 *   * Whether it's one of the three Mongolian Free Variation Selectors,
 *     CGJ, or other characters that are hidden but should not be ignored
 *     like most other Default_Ignorable()s do during matching.
 *   * Whether it's a grapheme continuation.
 *
 * The high-byte has different meanings, switched by the Gen-Cat:
 * - For Mn,Mc,Me: the modified Combining_Class.
 * - For Cf: whether it's ZWJ, ZWNJ, or something else.
 * - For Ws: index of which space character this is, if space fallback
 *   is needed, ie. we don't set this by default, only if asked to.
 */

enum hb_unicode_props_flags_t {
    UPROPS_MASK_GEN_CAT = 0x001Fu,
    UPROPS_MASK_IGNORABLE = 0x0020u,
    UPROPS_MASK_HIDDEN = 0x0040u, /* MONGOLIAN FREE VARIATION SELECTOR 1..3, or TAG characters */
    UPROPS_MASK_CONTINUATION = 0x0080u,

    /* If GEN_CAT=FORMAT, top byte masks: */
    UPROPS_MASK_Cf_ZWJ = 0x0100u,
    UPROPS_MASK_Cf_ZWNJ = 0x0200u
};
HB_MARK_AS_FLAG_T(hb_unicode_props_flags_t);

static inline void _hb_glyph_info_set_unicode_props(hb_glyph_info_t *info, hb_buffer_t *buffer)
{
    hb_unicode_funcs_t *unicode = buffer->unicode;
    unsigned int u = info->codepoint;
    unsigned int gen_cat = (unsigned int)unicode->general_category(u);
    unsigned int props = gen_cat;

    if (u >= 0x80u) {
        buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_NON_ASCII;

        if (unlikely(unicode->is_default_ignorable(u))) {
            buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_DEFAULT_IGNORABLES;
            props |= UPROPS_MASK_IGNORABLE;
            if (u == 0x200Cu)
                props |= UPROPS_MASK_Cf_ZWNJ;
            else if (u == 0x200Du)
                props |= UPROPS_MASK_Cf_ZWJ;
            /* Mongolian Free Variation Selectors need to be remembered
             * because although we need to hide them like default-ignorables,
             * they need to non-ignorable during shaping.  This is similar to
             * what we do for joiners in Indic-like shapers, but since the
             * FVSes are GC=Mn, we have use a separate bit to remember them.
             * Fixes:
             * https://github.com/harfbuzz/harfbuzz/issues/234 */
            else if (unlikely(hb_in_range<hb_codepoint_t>(u, 0x180Bu, 0x180Du)))
                props |= UPROPS_MASK_HIDDEN;
            /* TAG characters need similar treatment. Fixes:
             * https://github.com/harfbuzz/harfbuzz/issues/463 */
            else if (unlikely(hb_in_range<hb_codepoint_t>(u, 0xE0020u, 0xE007Fu)))
                props |= UPROPS_MASK_HIDDEN;
            /* COMBINING GRAPHEME JOINER should not be skipped; at least some times.
             * https://github.com/harfbuzz/harfbuzz/issues/554 */
            else if (unlikely(u == 0x034Fu)) {
                buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_CGJ;
                props |= UPROPS_MASK_HIDDEN;
            }
        }

        if (unlikely(HB_UNICODE_GENERAL_CATEGORY_IS_MARK(gen_cat))) {
            props |= UPROPS_MASK_CONTINUATION;
            props |= unicode->modified_combining_class(u) << 8;
        }
    }

    info->unicode_props() = props;
}

static inline void _hb_glyph_info_set_general_category(hb_glyph_info_t *info, hb_unicode_general_category_t gen_cat)
{
    /* Clears top-byte. */
    info->unicode_props() = (unsigned int)gen_cat | (info->unicode_props() & (0xFF & ~UPROPS_MASK_GEN_CAT));
}

static inline hb_unicode_general_category_t _hb_glyph_info_get_general_category(const hb_glyph_info_t *info)
{
    return (hb_unicode_general_category_t)(info->unicode_props() & UPROPS_MASK_GEN_CAT);
}

static inline bool _hb_glyph_info_is_unicode_mark(const hb_glyph_info_t *info)
{
    return HB_UNICODE_GENERAL_CATEGORY_IS_MARK(info->unicode_props() & UPROPS_MASK_GEN_CAT);
}
static inline void _hb_glyph_info_set_modified_combining_class(hb_glyph_info_t *info, unsigned int modified_class)
{
    if (unlikely(!_hb_glyph_info_is_unicode_mark(info)))
        return;
    info->unicode_props() = (modified_class << 8) | (info->unicode_props() & 0xFF);
}
static inline unsigned int _hb_glyph_info_get_modified_combining_class(const hb_glyph_info_t *info)
{
    return _hb_glyph_info_is_unicode_mark(info) ? info->unicode_props() >> 8 : 0;
}
#define info_cc(info) (_hb_glyph_info_get_modified_combining_class(&(info)))

static inline bool _hb_glyph_info_is_unicode_space(const hb_glyph_info_t *info)
{
    return _hb_glyph_info_get_general_category(info) == HB_UNICODE_GENERAL_CATEGORY_SPACE_SEPARATOR;
}
static inline void _hb_glyph_info_set_unicode_space_fallback_type(hb_glyph_info_t *info, hb_unicode_funcs_t::space_t s)
{
    if (unlikely(!_hb_glyph_info_is_unicode_space(info)))
        return;
    info->unicode_props() = (((unsigned int)s) << 8) | (info->unicode_props() & 0xFF);
}
static inline hb_unicode_funcs_t::space_t _hb_glyph_info_get_unicode_space_fallback_type(const hb_glyph_info_t *info)
{
    return _hb_glyph_info_is_unicode_space(info) ? (hb_unicode_funcs_t::space_t)(info->unicode_props() >> 8)
                                                 : hb_unicode_funcs_t::NOT_SPACE;
}

static inline bool _hb_glyph_info_ligated(const hb_glyph_info_t *info);

static inline bool _hb_glyph_info_is_default_ignorable(const hb_glyph_info_t *info)
{
    return (info->unicode_props() & UPROPS_MASK_IGNORABLE) && !_hb_glyph_info_ligated(info);
}
static inline bool _hb_glyph_info_is_default_ignorable_and_not_hidden(const hb_glyph_info_t *info)
{
    return ((info->unicode_props() & (UPROPS_MASK_IGNORABLE | UPROPS_MASK_HIDDEN)) == UPROPS_MASK_IGNORABLE) &&
           !_hb_glyph_info_ligated(info);
}
static inline void _hb_glyph_info_unhide(hb_glyph_info_t *info)
{
    info->unicode_props() &= ~UPROPS_MASK_HIDDEN;
}

static inline void _hb_glyph_info_set_continuation(hb_glyph_info_t *info)
{
    info->unicode_props() |= UPROPS_MASK_CONTINUATION;
}
static inline void _hb_glyph_info_reset_continuation(hb_glyph_info_t *info)
{
    info->unicode_props() &= ~UPROPS_MASK_CONTINUATION;
}
static inline bool _hb_glyph_info_is_continuation(const hb_glyph_info_t *info)
{
    return info->unicode_props() & UPROPS_MASK_CONTINUATION;
}
/* Loop over grapheme. Based on foreach_cluster(). */
#define foreach_grapheme(buffer, start, end)                                                                           \
    for (unsigned int _count = buffer->len, start = 0, end = _count ? _hb_next_grapheme(buffer, 0) : 0;                \
         start < _count;                                                                                               \
         start = end, end = _hb_next_grapheme(buffer, start))

static inline unsigned int _hb_next_grapheme(hb_buffer_t *buffer, unsigned int start)
{
    hb_glyph_info_t *info = buffer->info;
    unsigned int count = buffer->len;

    while (++start < count && _hb_glyph_info_is_continuation(&info[start]))
        ;

    return start;
}

static inline bool _hb_glyph_info_is_unicode_format(const hb_glyph_info_t *info)
{
    return _hb_glyph_info_get_general_category(info) == HB_UNICODE_GENERAL_CATEGORY_FORMAT;
}
static inline bool _hb_glyph_info_is_zwnj(const hb_glyph_info_t *info)
{
    return _hb_glyph_info_is_unicode_format(info) && (info->unicode_props() & UPROPS_MASK_Cf_ZWNJ);
}
static inline bool _hb_glyph_info_is_zwj(const hb_glyph_info_t *info)
{
    return _hb_glyph_info_is_unicode_format(info) && (info->unicode_props() & UPROPS_MASK_Cf_ZWJ);
}
static inline bool _hb_glyph_info_is_joiner(const hb_glyph_info_t *info)
{
    return _hb_glyph_info_is_unicode_format(info) &&
           (info->unicode_props() & (UPROPS_MASK_Cf_ZWNJ | UPROPS_MASK_Cf_ZWJ));
}
static inline void _hb_glyph_info_flip_joiners(hb_glyph_info_t *info)
{
    if (!_hb_glyph_info_is_unicode_format(info))
        return;
    info->unicode_props() ^= UPROPS_MASK_Cf_ZWNJ | UPROPS_MASK_Cf_ZWJ;
}

/* lig_props: aka lig_id / lig_comp
 *
 * When a ligature is formed:
 *
 *   - The ligature glyph and any marks in between all the same newly allocated
 *     lig_id,
 *   - The ligature glyph will get lig_num_comps set to the number of components
 *   - The marks get lig_comp > 0, reflecting which component of the ligature
 *     they were applied to.
 *   - This is used in GPOS to attach marks to the right component of a ligature
 *     in MarkLigPos,
 *   - Note that when marks are ligated together, much of the above is skipped
 *     and the current lig_id reused.
 *
 * When a multiple-substitution is done:
 *
 *   - All resulting glyphs will have lig_id = 0,
 *   - The resulting glyphs will have lig_comp = 0, 1, 2, ... respectively.
 *   - This is used in GPOS to attach marks to the first component of a
 *     multiple substitution in MarkBasePos.
 *
 * The numbers are also used in GPOS to do mark-to-mark positioning only
 * to marks that belong to the same component of the same ligature.
 */

static inline void _hb_glyph_info_clear_lig_props(hb_glyph_info_t *info)
{
    info->lig_props() = 0;
}

#define IS_LIG_BASE 0x10

static inline void
_hb_glyph_info_set_lig_props_for_ligature(hb_glyph_info_t *info, unsigned int lig_id, unsigned int lig_num_comps)
{
    info->lig_props() = (lig_id << 5) | IS_LIG_BASE | (lig_num_comps & 0x0F);
}

static inline void
_hb_glyph_info_set_lig_props_for_mark(hb_glyph_info_t *info, unsigned int lig_id, unsigned int lig_comp)
{
    info->lig_props() = (lig_id << 5) | (lig_comp & 0x0F);
}

static inline void _hb_glyph_info_set_lig_props_for_component(hb_glyph_info_t *info, unsigned int comp)
{
    _hb_glyph_info_set_lig_props_for_mark(info, 0, comp);
}

static inline unsigned int _hb_glyph_info_get_lig_id(const hb_glyph_info_t *info)
{
    return info->lig_props() >> 5;
}

static inline bool _hb_glyph_info_ligated_internal(const hb_glyph_info_t *info)
{
    return !!(info->lig_props() & IS_LIG_BASE);
}

static inline unsigned int _hb_glyph_info_get_lig_comp(const hb_glyph_info_t *info)
{
    if (_hb_glyph_info_ligated_internal(info))
        return 0;
    else
        return info->lig_props() & 0x0F;
}

static inline unsigned int _hb_glyph_info_get_lig_num_comps(const hb_glyph_info_t *info)
{
    if ((info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_LIGATURE) && _hb_glyph_info_ligated_internal(info))
        return info->lig_props() & 0x0F;
    else
        return 1;
}

static inline uint8_t _hb_allocate_lig_id(hb_buffer_t *buffer)
{
    uint8_t lig_id = buffer->next_serial() & 0x07;
    if (unlikely(!lig_id))
        lig_id = _hb_allocate_lig_id(buffer); /* in case of overflow */
    return lig_id;
}

/* glyph_props: */

static inline void _hb_glyph_info_set_glyph_props(hb_glyph_info_t *info, unsigned int props)
{
    info->glyph_props() = props;
}

static inline unsigned int _hb_glyph_info_get_glyph_props(const hb_glyph_info_t *info)
{
    return info->glyph_props();
}

static inline bool _hb_glyph_info_is_base_glyph(const hb_glyph_info_t *info)
{
    return !!(info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_BASE_GLYPH);
}

static inline bool _hb_glyph_info_is_ligature(const hb_glyph_info_t *info)
{
    return !!(info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_LIGATURE);
}

static inline bool _hb_glyph_info_is_mark(const hb_glyph_info_t *info)
{
    return !!(info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_MARK);
}

static inline bool _hb_glyph_info_substituted(const hb_glyph_info_t *info)
{
    return !!(info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED);
}

static inline bool _hb_glyph_info_ligated(const hb_glyph_info_t *info)
{
    return !!(info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_LIGATED);
}

static inline bool _hb_glyph_info_multiplied(const hb_glyph_info_t *info)
{
    return !!(info->glyph_props() & HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED);
}

static inline bool _hb_glyph_info_ligated_and_didnt_multiply(const hb_glyph_info_t *info)
{
    return _hb_glyph_info_ligated(info) && !_hb_glyph_info_multiplied(info);
}

static inline void _hb_glyph_info_clear_ligated_and_multiplied(hb_glyph_info_t *info)
{
    info->glyph_props() &= ~(HB_OT_LAYOUT_GLYPH_PROPS_LIGATED | HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED);
}

static inline void _hb_glyph_info_clear_substituted(hb_glyph_info_t *info)
{
    info->glyph_props() &= ~(HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED);
}

static inline void
_hb_clear_substitution_flags(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++)
        _hb_glyph_info_clear_substituted(&info[i]);
}

/* Allocation / deallocation. */

static inline void _hb_buffer_allocate_unicode_vars(hb_buffer_t *buffer)
{
    HB_BUFFER_ALLOCATE_VAR(buffer, unicode_props);
}

static inline void _hb_buffer_deallocate_unicode_vars(hb_buffer_t *buffer)
{
    HB_BUFFER_DEALLOCATE_VAR(buffer, unicode_props);
}

static inline void _hb_buffer_assert_unicode_vars(hb_buffer_t *buffer)
{
    HB_BUFFER_ASSERT_VAR(buffer, unicode_props);
}

static inline void _hb_buffer_allocate_gsubgpos_vars(hb_buffer_t *buffer)
{
    HB_BUFFER_ALLOCATE_VAR(buffer, glyph_props);
    HB_BUFFER_ALLOCATE_VAR(buffer, lig_props);
    HB_BUFFER_ALLOCATE_VAR(buffer, syllable);
}

static inline void _hb_buffer_deallocate_gsubgpos_vars(hb_buffer_t *buffer)
{
    HB_BUFFER_DEALLOCATE_VAR(buffer, syllable);
    HB_BUFFER_DEALLOCATE_VAR(buffer, lig_props);
    HB_BUFFER_DEALLOCATE_VAR(buffer, glyph_props);
}

static inline void _hb_buffer_assert_gsubgpos_vars(hb_buffer_t *buffer)
{
    HB_BUFFER_ASSERT_VAR(buffer, glyph_props);
    HB_BUFFER_ASSERT_VAR(buffer, lig_props);
    HB_BUFFER_ASSERT_VAR(buffer, syllable);
}

/* Make sure no one directly touches our props... */
#undef unicode_props0
#undef unicode_props1
#undef lig_props
#undef glyph_props

#endif /* HB_OT_LAYOUT_HH */