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/*
* Copyright © 2011,2012 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_HMTX_TABLE_HH
#define HB_OT_HMTX_TABLE_HH
#include "hb-open-type-private.hh"
#include "hb-ot-hhea-table.hh"
#include "hb-ot-os2-table.hh"
#include "hb-ot-var-hvar-table.hh"
namespace OT {
/*
* hmtx -- The Horizontal Metrics Table
* vmtx -- The Vertical Metrics Table
*/
#define HB_OT_TAG_hmtx HB_TAG('h','m','t','x')
#define HB_OT_TAG_vmtx HB_TAG('v','m','t','x')
struct LongMetric
{
UFWORD advance; /* Advance width/height. */
FWORD lsb; /* Leading (left/top) side bearing. */
public:
DEFINE_SIZE_STATIC (4);
};
template <typename T>
struct hmtxvmtx
{
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
/* We don't check for anything specific here. The users of the
* struct do all the hard work... */
return_trace (true);
}
struct accelerator_t
{
inline void init (hb_face_t *face,
unsigned int default_advance_ = 0)
{
default_advance = default_advance_ ? default_advance_ : face->get_upem ();
bool got_font_extents = false;
if (T::os2Tag)
{
hb_blob_t *os2_blob = Sanitizer<os2>::sanitize (face->reference_table (T::os2Tag));
const os2 *os2_table = Sanitizer<os2>::lock_instance (os2_blob);
#define USE_TYPO_METRICS (1u<<7)
if (0 != (os2_table->fsSelection & USE_TYPO_METRICS))
{
ascender = os2_table->sTypoAscender;
descender = os2_table->sTypoDescender;
line_gap = os2_table->sTypoLineGap;
got_font_extents = (ascender | descender) != 0;
}
hb_blob_destroy (os2_blob);
}
hb_blob_t *_hea_blob = Sanitizer<_hea>::sanitize (face->reference_table (T::headerTag));
const _hea *_hea_table = Sanitizer<_hea>::lock_instance (_hea_blob);
num_advances = _hea_table->numberOfLongMetrics;
if (!got_font_extents)
{
ascender = _hea_table->ascender;
descender = _hea_table->descender;
line_gap = _hea_table->lineGap;
got_font_extents = (ascender | descender) != 0;
}
hb_blob_destroy (_hea_blob);
has_font_extents = got_font_extents;
blob = Sanitizer<hmtxvmtx>::sanitize (face->reference_table (T::tableTag));
/* Cap num_metrics() and num_advances() based on table length. */
unsigned int len = hb_blob_get_length (blob);
if (unlikely (num_advances * 4 > len))
num_advances = len / 4;
num_metrics = num_advances + (len - 4 * num_advances) / 2;
/* We MUST set num_metrics to zero if num_advances is zero.
* Our get_advance() depends on that. */
if (unlikely (!num_advances))
{
num_metrics = num_advances = 0;
hb_blob_destroy (blob);
blob = hb_blob_get_empty ();
}
table = Sanitizer<hmtxvmtx>::lock_instance (blob);
var_blob = Sanitizer<HVARVVAR>::sanitize (face->reference_table (T::variationsTag));
var_table = Sanitizer<HVARVVAR>::lock_instance (var_blob);
}
inline void fini (void)
{
hb_blob_destroy (blob);
hb_blob_destroy (var_blob);
}
inline unsigned int get_advance (hb_codepoint_t glyph,
hb_font_t *font) const
{
if (unlikely (glyph >= num_metrics))
{
/* If num_metrics is zero, it means we don't have the metrics table
* for this direction: return default advance. Otherwise, it means that the
* glyph index is out of bound: return zero. */
if (num_metrics)
return 0;
else
return default_advance;
}
return table->longMetric[MIN (glyph, (uint32_t) num_advances - 1)].advance
+ var_table->get_advance_var (glyph, font->coords, font->num_coords); // TODO Optimize?!
}
public:
bool has_font_extents;
unsigned short ascender;
unsigned short descender;
unsigned short line_gap;
private:
unsigned int num_metrics;
unsigned int num_advances;
unsigned int default_advance;
const hmtxvmtx *table;
hb_blob_t *blob;
const HVARVVAR *var_table;
hb_blob_t *var_blob;
};
protected:
LongMetric longMetric[VAR]; /* Paired advance width and leading
* bearing values for each glyph. The
* value numOfHMetrics comes from
* the 'hhea' table. If the font is
* monospaced, only one entry need
* be in the array, but that entry is
* required. The last entry applies to
* all subsequent glyphs. */
FWORD leadingBearingX[VAR]; /* Here the advance is assumed
* to be the same as the advance
* for the last entry above. The
* number of entries in this array is
* derived from numGlyphs (from 'maxp'
* table) minus numberOfLongMetrics.
* This generally is used with a run
* of monospaced glyphs (e.g., Kanji
* fonts or Courier fonts). Only one
* run is allowed and it must be at
* the end. This allows a monospaced
* font to vary the side bearing
* values for each glyph. */
public:
DEFINE_SIZE_ARRAY2 (0, longMetric, leadingBearingX);
};
struct hmtx : hmtxvmtx<hmtx> {
static const hb_tag_t tableTag = HB_OT_TAG_hmtx;
static const hb_tag_t headerTag = HB_OT_TAG_hhea;
static const hb_tag_t variationsTag = HB_OT_TAG_HVAR;
static const hb_tag_t os2Tag = HB_OT_TAG_os2;
};
struct vmtx : hmtxvmtx<vmtx> {
static const hb_tag_t tableTag = HB_OT_TAG_vmtx;
static const hb_tag_t headerTag = HB_OT_TAG_vhea;
static const hb_tag_t variationsTag = HB_OT_TAG_VVAR;
static const hb_tag_t os2Tag = HB_TAG_NONE;
};
} /* namespace OT */
#endif /* HB_OT_HMTX_TABLE_HH */
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