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/*
* Copyright © 2017 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
*/
#ifndef HB_KERN_HH
#define HB_KERN_HH
#include "hb-open-type.hh"
#include "hb-aat-layout-common.hh"
#include "hb-ot-layout-gpos-table.hh"
namespace OT {
template <typename Driver>
struct hb_kern_machine_t
{
hb_kern_machine_t (const Driver &driver_,
bool crossStream_ = false) :
driver (driver_),
crossStream (crossStream_) {}
HB_NO_SANITIZE_SIGNED_INTEGER_OVERFLOW
void kern (hb_font_t *font,
hb_buffer_t *buffer,
hb_mask_t kern_mask,
bool scale = true) const
{
if (!buffer->message (font, "start kern"))
return;
buffer->unsafe_to_concat ();
OT::hb_ot_apply_context_t c (1, font, buffer, hb_blob_get_empty ());
c.set_lookup_mask (kern_mask);
c.set_lookup_props (OT::LookupFlag::IgnoreMarks);
auto &skippy_iter = c.iter_input;
bool horizontal = HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction);
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
hb_glyph_position_t *pos = buffer->pos;
for (unsigned int idx = 0; idx < count;)
{
if (!(info[idx].mask & kern_mask))
{
idx++;
continue;
}
skippy_iter.reset (idx);
unsigned unsafe_to;
if (!skippy_iter.next (&unsafe_to))
{
idx++;
continue;
}
unsigned int i = idx;
unsigned int j = skippy_iter.idx;
hb_position_t kern = driver.get_kerning (info[i].codepoint,
info[j].codepoint);
if (likely (!kern))
goto skip;
if (horizontal)
{
if (scale)
kern = font->em_scale_x (kern);
if (crossStream)
{
pos[j].y_offset = kern;
buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT;
}
else
{
hb_position_t kern1 = kern >> 1;
hb_position_t kern2 = kern - kern1;
pos[i].x_advance += kern1;
pos[j].x_advance += kern2;
pos[j].x_offset += kern2;
}
}
else
{
if (scale)
kern = font->em_scale_y (kern);
if (crossStream)
{
pos[j].x_offset = kern;
buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT;
}
else
{
hb_position_t kern1 = kern >> 1;
hb_position_t kern2 = kern - kern1;
pos[i].y_advance += kern1;
pos[j].y_advance += kern2;
pos[j].y_offset += kern2;
}
}
buffer->unsafe_to_break (i, j + 1);
skip:
idx = skippy_iter.idx;
}
(void) buffer->message (font, "end kern");
}
const Driver &driver;
bool crossStream;
};
} /* namespace OT */
#endif /* HB_KERN_HH */
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