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

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/*
* Copyright © 2011,2012 Google, Inc.
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*
* 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.
*
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* Google Author(s): Behdad Esfahbod, Roderick Sheeter
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*/
#ifndef HB_OT_HMTX_TABLE_HH
#define HB_OT_HMTX_TABLE_HH
#include "hb-open-type.hh"
#include "hb-ot-maxp-table.hh"
#include "hb-ot-hhea-table.hh"
#include "hb-ot-var-hvar-table.hh"
#include "hb-ot-metrics.hh"
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/*
* 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
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*/
#define HB_OT_TAG_hmtx HB_TAG('h','m','t','x')
#define HB_OT_TAG_vmtx HB_TAG('v','m','t','x')
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HB_INTERNAL int
_glyf_get_side_bearing_var (hb_font_t *font, hb_codepoint_t glyph, bool is_vertical);
HB_INTERNAL unsigned
_glyf_get_advance_var (hb_font_t *font, hb_codepoint_t glyph, bool is_vertical);
namespace OT {
struct LongMetric
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{
UFWORD advance; /* Advance width/height. */
FWORD sb; /* Leading (left/top) side bearing. */
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public:
DEFINE_SIZE_STATIC (4);
};
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template <typename T, typename H>
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struct hmtxvmtx
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{
bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const
{
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TRACE_SANITIZE (this);
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/* We don't check for anything specific here. The users of the
* struct do all the hard work... */
return_trace (true);
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}
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bool subset_update_header (hb_subset_plan_t *plan,
unsigned int num_hmetrics) const
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{
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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);
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if (unlikely (!dest_blob)) {
return false;
}
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unsigned int length;
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H *table = (H *) hb_blob_get_data (dest_blob, &length);
table->numberOfLongMetrics = num_hmetrics;
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bool result = plan->add_table (H::tableTag, dest_blob);
hb_blob_destroy (dest_blob);
return result;
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}
template<typename Iterator,
hb_requires (hb_is_iterator (Iterator))>
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void serialize (hb_serialize_context_t *c,
Iterator it,
unsigned num_long_metrics)
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{
unsigned idx = 0;
for (auto _ : it)
{
if (idx < num_long_metrics)
{
LongMetric lm;
lm.advance = _.first;
lm.sb = _.second;
if (unlikely (!c->embed<LongMetric> (&lm))) return;
}
else
{
FWORD *sb = c->allocate_size<FWORD> (FWORD::static_size);
if (unlikely (!sb)) return;
*sb = _.second;
}
idx++;
}
}
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bool subset (hb_subset_context_t *c) const
{
TRACE_SUBSET (this);
T *table_prime = c->serializer->start_embed <T> ();
if (unlikely (!table_prime)) return_trace (false);
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accelerator_t _mtx (c->plan->source);
unsigned num_long_metrics;
{
/* Determine num_long_metrics to encode. */
auto& plan = c->plan;
num_long_metrics = plan->num_output_glyphs ();
hb_codepoint_t old_gid = 0;
unsigned int last_advance = plan->old_gid_for_new_gid (num_long_metrics - 1, &old_gid) ? _mtx.get_advance (old_gid) : 0;
while (num_long_metrics > 1 &&
last_advance == (plan->old_gid_for_new_gid (num_long_metrics - 2, &old_gid) ? _mtx.get_advance (old_gid) : 0))
{
num_long_metrics--;
}
}
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auto it =
+ hb_range (c->plan->num_output_glyphs ())
| hb_map ([c, &_mtx] (unsigned _)
{
hb_codepoint_t old_gid;
if (!c->plan->old_gid_for_new_gid (_, &old_gid))
return hb_pair (0u, 0);
return hb_pair (_mtx.get_advance (old_gid), _mtx.get_side_bearing (old_gid));
})
;
table_prime->serialize (c->serializer, it, num_long_metrics);
if (unlikely (c->serializer->in_error ()))
return_trace (false);
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// Amend header num hmetrics
if (unlikely (!subset_update_header (c->plan, num_long_metrics)))
return_trace (false);
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return_trace (true);
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}
struct accelerator_t
{
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friend struct hmtxvmtx;
accelerator_t (hb_face_t *face)
{
table = hb_sanitize_context_t ().reference_table<hmtxvmtx> (face, T::tableTag);
var_table = hb_sanitize_context_t ().reference_table<HVARVVAR> (face, T::variationsTag);
default_advance = T::is_horizontal ? hb_face_get_upem (face) / 2 : hb_face_get_upem (face);
/* Populate count variables and sort them out as we go */
unsigned int len = table.get_length ();
if (len & 1)
len--;
num_long_metrics = T::is_horizontal ?
face->table.hhea->numberOfLongMetrics :
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#ifndef HB_NO_VERTICAL
face->table.vhea->numberOfLongMetrics
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#else
0
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#endif
;
if (unlikely (num_long_metrics * 4 > len))
num_long_metrics = len / 4;
len -= num_long_metrics * 4;
num_bearings = face->table.maxp->get_num_glyphs ();
if (unlikely (num_bearings < num_long_metrics))
num_bearings = num_long_metrics;
if (unlikely ((num_bearings - num_long_metrics) * 2 > len))
num_bearings = num_long_metrics + len / 2;
len -= (num_bearings - num_long_metrics) * 2;
/* We MUST set num_bearings to zero if num_long_metrics is zero.
* Our get_advance() depends on that. */
if (unlikely (!num_long_metrics))
num_bearings = num_long_metrics = 0;
num_advances = num_bearings + len / 2;
num_glyphs = face->get_num_glyphs ();
if (num_glyphs < num_advances)
num_glyphs = num_advances;
}
~accelerator_t ()
{
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table.destroy ();
var_table.destroy ();
}
bool has_data () const { return (bool) num_bearings; }
int get_side_bearing (hb_codepoint_t glyph) const
{
if (glyph < num_long_metrics)
return table->longMetricZ[glyph].sb;
if (unlikely (glyph >= num_bearings))
return 0;
const FWORD *bearings = (const FWORD *) &table->longMetricZ[num_long_metrics];
return bearings[glyph - num_long_metrics];
}
int get_side_bearing (hb_font_t *font, hb_codepoint_t glyph) const
{
int side_bearing = get_side_bearing (glyph);
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#ifndef HB_NO_VAR
if (unlikely (glyph >= num_bearings) || !font->num_coords)
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return side_bearing;
if (var_table.get_length ())
return side_bearing + var_table->get_side_bearing_var (glyph, font->coords, font->num_coords); // TODO Optimize?!
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return _glyf_get_side_bearing_var (font, glyph, T::tableTag == HB_OT_TAG_vmtx);
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#else
return side_bearing;
#endif
}
unsigned int get_advance (hb_codepoint_t glyph) const
{
/* OpenType case. */
if (glyph < num_bearings)
return table->longMetricZ[hb_min (glyph, (uint32_t) num_long_metrics - 1)].advance;
/* If num_advances is zero, it means we don't have the metrics table
* for this direction: return default advance. Otherwise, there's a
* well-defined answer. */
if (unlikely (!num_advances))
return default_advance;
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#ifdef HB_NO_BORING_EXPANSION
return 0;
#endif
if (unlikely (glyph >= num_glyphs))
return 0;
/* num_bearings <= glyph < num_glyphs;
* num_bearings <= num_advances */
/* TODO Optimize */
if (num_bearings == num_advances)
return get_advance (num_bearings - 1);
const FWORD *bearings = (const FWORD *) &table->longMetricZ[num_long_metrics];
const UFWORD *advances = (const UFWORD *) &bearings[num_bearings - num_long_metrics];
return advances[hb_min (glyph - num_bearings, num_advances - num_bearings - 1)];
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}
unsigned int get_advance (hb_codepoint_t glyph,
hb_font_t *font) const
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{
unsigned int advance = get_advance (glyph);
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#ifndef HB_NO_VAR
if (unlikely (glyph >= num_bearings) || !font->num_coords)
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return advance;
if (var_table.get_length ())
return advance + roundf (var_table->get_advance_var (glyph, font)); // TODO Optimize?!
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return _glyf_get_advance_var (font, glyph, T::tableTag == HB_OT_TAG_vmtx);
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#else
return advance;
#endif
}
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protected:
// 0 <= num_long_metrics <= num_bearings <= num_advances <= num_glyphs
unsigned num_long_metrics;
unsigned num_bearings;
unsigned num_advances;
unsigned num_glyphs;
unsigned int default_advance;
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private:
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hb_blob_ptr_t<hmtxvmtx> table;
hb_blob_ptr_t<HVARVVAR> var_table;
};
protected:
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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. */
/*UnsizedArrayOf<UFWORD>advancesX;*/
/* TODO Document. */
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public:
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DEFINE_SIZE_ARRAY (0, longMetricZ);
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};
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struct hmtx : hmtxvmtx<hmtx, hhea> {
static constexpr hb_tag_t tableTag = HB_OT_TAG_hmtx;
static constexpr hb_tag_t variationsTag = HB_OT_TAG_HVAR;
static constexpr bool is_horizontal = true;
};
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struct vmtx : hmtxvmtx<vmtx, vhea> {
static constexpr hb_tag_t tableTag = HB_OT_TAG_vmtx;
static constexpr hb_tag_t variationsTag = HB_OT_TAG_VVAR;
static constexpr bool is_horizontal = false;
};
struct hmtx_accelerator_t : hmtx::accelerator_t {
hmtx_accelerator_t (hb_face_t *face) : hmtx::accelerator_t (face) {}
};
struct vmtx_accelerator_t : vmtx::accelerator_t {
vmtx_accelerator_t (hb_face_t *face) : vmtx::accelerator_t (face) {}
};
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} /* namespace OT */
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#endif /* HB_OT_HMTX_TABLE_HH */