harfbuzz/src/hb-ot-var-avar-table.hh

153 lines
4.1 KiB
C++

/*
* 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_OT_VAR_AVAR_TABLE_HH
#define HB_OT_VAR_AVAR_TABLE_HH
#include "hb-open-type.hh"
/*
* avar -- Axis Variations
* https://docs.microsoft.com/en-us/typography/opentype/spec/avar
*/
#define HB_OT_TAG_avar HB_TAG('a','v','a','r')
namespace OT {
struct AxisValueMap
{
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this));
}
public:
F2DOT14 fromCoord; /* A normalized coordinate value obtained using
* default normalization. */
F2DOT14 toCoord; /* The modified, normalized coordinate value. */
public:
DEFINE_SIZE_STATIC (4);
};
struct SegmentMaps : ArrayOf<AxisValueMap>
{
int map (int value) const
{
/* The following special-cases are not part of OpenType, which requires
* that at least -1, 0, and +1 must be mapped. But we include these as
* part of a better error recovery scheme. */
if (len < 2)
{
if (!len)
return value;
else /* len == 1*/
return value - arrayZ[0].fromCoord + arrayZ[0].toCoord;
}
if (value <= arrayZ[0].fromCoord)
return value - arrayZ[0].fromCoord + arrayZ[0].toCoord;
unsigned int i;
unsigned int count = len;
for (i = 1; i < count && value > arrayZ[i].fromCoord; i++)
;
if (value >= arrayZ[i].fromCoord)
return value - arrayZ[i].fromCoord + arrayZ[i].toCoord;
if (unlikely (arrayZ[i-1].fromCoord == arrayZ[i].fromCoord))
return arrayZ[i-1].toCoord;
int denom = arrayZ[i].fromCoord - arrayZ[i-1].fromCoord;
return arrayZ[i-1].toCoord +
((arrayZ[i].toCoord - arrayZ[i-1].toCoord) *
(value - arrayZ[i-1].fromCoord) + denom/2) / denom;
}
public:
DEFINE_SIZE_ARRAY (2, *this);
};
struct avar
{
static constexpr hb_tag_t tableTag = HB_OT_TAG_avar;
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
if (unlikely (!(version.sanitize (c) &&
version.major == 1 &&
c->check_struct (this))))
return_trace (false);
const SegmentMaps *map = &firstAxisSegmentMaps;
unsigned int count = axisCount;
for (unsigned int i = 0; i < count; i++)
{
if (unlikely (!map->sanitize (c)))
return_trace (false);
map = &StructAfter<SegmentMaps> (*map);
}
return_trace (true);
}
void map_coords (int *coords, unsigned int coords_length) const
{
unsigned int count = hb_min (coords_length, axisCount);
const SegmentMaps *map = &firstAxisSegmentMaps;
for (unsigned int i = 0; i < count; i++)
{
coords[i] = map->map (coords[i]);
map = &StructAfter<SegmentMaps> (*map);
}
}
protected:
FixedVersion<>version; /* Version of the avar table
* initially set to 0x00010000u */
HBUINT16 reserved; /* This field is permanently reserved. Set to 0. */
HBUINT16 axisCount; /* The number of variation axes in the font. This
* must be the same number as axisCount in the
* 'fvar' table. */
SegmentMaps firstAxisSegmentMaps;
public:
DEFINE_SIZE_MIN (8);
};
} /* namespace OT */
#endif /* HB_OT_VAR_AVAR_TABLE_HH */