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harfbuzz/src/hb-ot-hmtx-table.hh

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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, Roderick Sheeter
*/
#ifndef HB_OT_HMTX_TABLE_HH
#define HB_OT_HMTX_TABLE_HH
#include "hb-open-type.hh"
#include "hb-ot-hhea-table.hh"
#include "hb-ot-os2-table.hh"
#include "hb-ot-var-hvar-table.hh"
/*
* hmtx -- Horizontal Metrics
* https://docs.microsoft.com/en-us/typography/opentype/spec/hmtx
* vmtx -- Vertical Metrics
* https://docs.microsoft.com/en-us/typography/opentype/spec/vmtx
*/
#define HB_OT_TAG_hmtx HB_TAG('h','m','t','x')
#define HB_OT_TAG_vmtx HB_TAG('v','m','t','x')
namespace OT {
struct LongMetric
{
UFWORD advance; /* Advance width/height. */
FWORD lsb; /* Leading (left/top) side bearing. */
public:
DEFINE_SIZE_STATIC (4);
};
template <typename T, typename H>
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);
}
inline bool subset_update_header (hb_subset_plan_t *plan,
unsigned int num_hmetrics) const
{
hb_blob_t *src_blob = hb_sanitize_context_t().reference_table<H> (plan->source, H::tableTag);
hb_blob_t *dest_blob = hb_blob_copy_writable_or_fail(src_blob);
hb_blob_destroy (src_blob);
if (unlikely (!dest_blob)) {
return false;
}
unsigned int length;
H *table = (H *) hb_blob_get_data (dest_blob, &length);
table->numberOfLongMetrics.set (num_hmetrics);
bool result = plan->add_table (H::tableTag, dest_blob);
hb_blob_destroy (dest_blob);
return result;
}
inline bool subset (hb_subset_plan_t *plan) const
{
typename T::accelerator_t _mtx;
_mtx.init (plan->source);
/* All the trailing glyphs with the same advance can use one LongMetric
* and just keep LSB */
hb_vector_t<hb_codepoint_t> &gids = plan->glyphs;
unsigned int num_advances = gids.len;
unsigned int last_advance = _mtx.get_advance (gids[num_advances - 1]);
while (num_advances > 1
&& last_advance == _mtx.get_advance (gids[num_advances - 2]))
{
num_advances--;
}
/* alloc the new table */
size_t dest_sz = num_advances * 4
+ (gids.len - num_advances) * 2;
void *dest = (void *) malloc (dest_sz);
if (unlikely (!dest))
{
return false;
}
DEBUG_MSG(SUBSET, nullptr, "%c%c%c%c in src has %d advances, %d lsbs", HB_UNTAG(T::tableTag), _mtx.num_advances, _mtx.num_metrics - _mtx.num_advances);
DEBUG_MSG(SUBSET, nullptr, "%c%c%c%c in dest has %d advances, %d lsbs, %u bytes", HB_UNTAG(T::tableTag), num_advances, gids.len - num_advances, (unsigned int) dest_sz);
const char *source_table = hb_blob_get_data (_mtx.blob, nullptr);
// Copy everything over
LongMetric * old_metrics = (LongMetric *) source_table;
FWORD *lsbs = (FWORD *) (old_metrics + _mtx.num_advances);
char * dest_pos = (char *) dest;
bool failed = false;
for (unsigned int i = 0; i < gids.len; i++)
{
/* the last metric or the one for gids[i] */
LongMetric *src_metric = old_metrics + MIN ((hb_codepoint_t) _mtx.num_advances - 1, gids[i]);
if (gids[i] < _mtx.num_advances)
{
/* src is a LongMetric */
if (i < num_advances)
{
/* dest is a LongMetric, copy it */
*((LongMetric *) dest_pos) = *src_metric;
}
else
{
/* dest just lsb */
*((FWORD *) dest_pos) = src_metric->lsb;
}
}
else
{
if (gids[i] >= _mtx.num_metrics)
{
DEBUG_MSG(SUBSET, nullptr, "gid %d is >= number of source metrics %d",
gids[i], _mtx.num_metrics);
failed = true;
break;
}
FWORD src_lsb = *(lsbs + gids[i] - _mtx.num_advances);
if (i < num_advances)
{
/* dest needs a full LongMetric */
LongMetric *metric = (LongMetric *)dest_pos;
metric->advance = src_metric->advance;
metric->lsb = src_lsb;
}
else
{
/* dest just needs an lsb */
*((FWORD *) dest_pos) = src_lsb;
}
}
dest_pos += (i < num_advances ? 4 : 2);
}
_mtx.fini ();
// Amend header num hmetrics
if (failed || unlikely (!subset_update_header (plan, num_advances)))
{
free (dest);
return false;
}
hb_blob_t *result = hb_blob_create ((const char *)dest,
dest_sz,
HB_MEMORY_MODE_READONLY,
dest,
free);
bool success = plan->add_table (T::tableTag, result);
hb_blob_destroy (result);
return success;
}
struct accelerator_t
{
friend struct hmtxvmtx;
inline void init (hb_face_t *face,
unsigned int default_advance_ = 0)
{
default_advance = default_advance_ ? default_advance_ : hb_face_get_upem (face);
bool got_font_extents = false;
if (T::os2Tag)
{
hb_blob_t *os2_blob = hb_sanitize_context_t().reference_table<os2> (face);
const os2 *os2_table = os2_blob->as<os2> ();
#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 = hb_sanitize_context_t().reference_table<H> (face);
const H *_hea_table = _hea_blob->as<H> ();
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 = hb_sanitize_context_t().reference_table<hmtxvmtx> (face, 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 = blob->as<hmtxvmtx> ();
var_blob = hb_sanitize_context_t().reference_table<HVARVVAR> (face, T::variationsTag);
var_table = var_blob->as<HVARVVAR> ();
}
inline void fini (void)
{
hb_blob_destroy (blob);
hb_blob_destroy (var_blob);
}
inline unsigned int get_advance (hb_codepoint_t glyph) 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->longMetricZ[MIN (glyph, (uint32_t) num_advances - 1)].advance;
}
inline unsigned int get_advance (hb_codepoint_t glyph,
hb_font_t *font) const
{
unsigned int advance = get_advance (glyph);
if (likely(glyph < num_metrics))
{
advance += (font->num_coords ? var_table->get_advance_var (glyph, font->coords, font->num_coords) : 0); // TODO Optimize?!
}
return advance;
}
public:
bool has_font_extents;
unsigned short ascender;
unsigned short descender;
unsigned short line_gap;
protected:
unsigned int num_metrics;
unsigned int num_advances;
unsigned int default_advance;
private:
const hmtxvmtx *table;
hb_blob_t *blob;
const HVARVVAR *var_table;
hb_blob_t *var_blob;
};
protected:
UnsizedArrayOf<LongMetric>longMetricZ;/* 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. */
/*UnsizedArrayOf<FWORD> leadingBearingX;*//* 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_ARRAY (0, longMetricZ);
};
struct hmtx : hmtxvmtx<hmtx, hhea> {
static const hb_tag_t tableTag = HB_OT_TAG_hmtx;
static const hb_tag_t variationsTag = HB_OT_TAG_HVAR;
static const hb_tag_t os2Tag = HB_OT_TAG_os2;
};
struct vmtx : hmtxvmtx<vmtx, vhea> {
static const hb_tag_t tableTag = HB_OT_TAG_vmtx;
static const hb_tag_t variationsTag = HB_OT_TAG_VVAR;
static const hb_tag_t os2Tag = HB_TAG_NONE;
};
struct hmtx_accelerator_t : hmtx::accelerator_t {};
struct vmtx_accelerator_t : vmtx::accelerator_t {};
} /* namespace OT */
#endif /* HB_OT_HMTX_TABLE_HH */
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