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/*
* Copyright © 2018 Ebrahim Byagowi
* Copyright © 2018 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_AAT_LAYOUT_TRAK_TABLE_HH
#define HB_AAT_LAYOUT_TRAK_TABLE_HH
#include "hb-aat-layout-common-private.hh"
#include "hb-open-type-private.hh"
#define HB_AAT_TAG_trak HB_TAG('t','r','a','k')
namespace AAT {
struct TrackTableEntry
{
inline bool sanitize (hb_sanitize_context_t *c, const void *base, unsigned int size) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) && (values.sanitize (c, base, size)));
}
inline float get_track_value () const
{
return track.to_float ();
}
inline int get_value (const void *base, unsigned int index) const
{
return (base+values)[index];
}
protected:
Fixed track; /* Track value for this record. */
NameID trackNameID; /* The 'name' table index for this track */
OffsetTo<UnsizedArrayOf<FWORD> >
values; /* Offset from start of tracking table to
* per-size tracking values for this track. */
public:
DEFINE_SIZE_STATIC (8);
};
struct TrackData
{
inline bool sanitize (hb_sanitize_context_t *c, const void *base) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) &&
sizeTable.sanitize (c, base, nSizes) &&
trackTable.sanitize (c, nTracks, base, nSizes));
}
inline float get_tracking (const void *base, float ptem) const
{
/* CoreText points are CSS pixels (96 per inch),
* NOT typographic points (72 per inch).
*
* https://developer.apple.com/library/content/documentation/GraphicsAnimation/Conceptual/HighResolutionOSX/Explained/Explained.html
*/
float csspx = ptem * 96.f / 72.f;
Fixed fixed_size;
fixed_size.set_float (csspx);
/* XXX Clean this up. Make it work with nSizes==1 and 0. */
unsigned int sizes = nSizes;
const TrackTableEntry *trackTableEntry = nullptr;
for (unsigned int i = 0; i < sizes; ++i)
// For now we only seek for track entries with zero tracking value
if (trackTable[i].get_track_value () == 0.)
trackTableEntry = &trackTable[0];
// We couldn't match any, exit
if (!trackTableEntry) return 0.;
/* TODO bfind() */
unsigned int size_index;
UnsizedArrayOf<Fixed> size_table = base+sizeTable;
for (size_index = 0; size_index < sizes; ++size_index)
if (size_table[size_index] >= fixed_size)
break;
// TODO(ebraminio): We don't attempt to extrapolate to larger or
// smaller values for now but we should do, per spec
if (size_index == sizes)
return trackTableEntry->get_value (base, sizes - 1);
if (size_index == 0 || size_table[size_index] == fixed_size)
return trackTableEntry->get_value (base, size_index);
float s0 = size_table[size_index - 1].to_float ();
float s1 = size_table[size_index].to_float ();
float t = (csspx - s0) / (s1 - s0);
return t * trackTableEntry->get_value (base, size_index) +
(1.0 - t) * trackTableEntry->get_value (base, size_index - 1);
}
protected:
HBUINT16 nTracks; /* Number of separate tracks included in this table. */
HBUINT16 nSizes; /* Number of point sizes included in this table. */
LOffsetTo<UnsizedArrayOf<Fixed> > /* Offset to array[nSizes] of size values. */
sizeTable;
UnsizedArrayOf<TrackTableEntry>
trackTable; /* Array[nTracks] of TrackTableEntry records. */
public:
DEFINE_SIZE_ARRAY (8, trackTable);
};
struct trak
{
static const hb_tag_t tableTag = HB_AAT_TAG_trak;
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) &&
horizData.sanitize (c, this, this) &&
vertData.sanitize (c, this, this));
}
inline bool apply (hb_aat_apply_context_t *c) const
{
TRACE_APPLY (this);
const float ptem = c->font->ptem;
if (ptem <= 0.f)
return_trace (false);
hb_buffer_t *buffer = c->buffer;
if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction))
{
const TrackData &trackData = this+horizData;
float tracking = trackData.get_tracking (this, ptem);
hb_position_t advance_to_add = c->font->em_scalef_x (tracking / 2);
foreach_grapheme (buffer, start, end)
{
/* TODO This is wrong. */
buffer->pos[start].x_advance += advance_to_add;
buffer->pos[end].x_advance += advance_to_add;
}
}
else
{
const TrackData &trackData = this+vertData;
float tracking = trackData.get_tracking (this, ptem);
hb_position_t advance_to_add = c->font->em_scalef_y (tracking / 2);
foreach_grapheme (buffer, start, end)
{
/* TODO This is wrong. */
buffer->pos[start].y_advance += advance_to_add;
buffer->pos[end].y_advance += advance_to_add;
}
}
return_trace (true);
}
protected:
FixedVersion<> version; /* Version of the tracking table--currently
* 0x00010000u for version 1.0. */
HBUINT16 format; /* Format of the tracking table */
OffsetTo<TrackData> horizData; /* TrackData for horizontal text */
OffsetTo<TrackData> vertData; /* TrackData for vertical text */
HBUINT16 reserved; /* Reserved. Set to 0. */
public:
DEFINE_SIZE_MIN (12);
};
} /* namespace AAT */
#endif /* HB_AAT_LAYOUT_TRAK_TABLE_HH */
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