340 lines
9.5 KiB
C++
340 lines
9.5 KiB
C++
/*
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* Copyright © 2011,2012 Google, Inc.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* Google Author(s): Behdad Esfahbod, Roderick Sheeter
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*/
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#ifndef HB_OT_HMTX_TABLE_HH
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#define HB_OT_HMTX_TABLE_HH
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#include "hb-open-type.hh"
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#include "hb-ot-hhea-table.hh"
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#include "hb-ot-var-hvar-table.hh"
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#include "hb-ot-metrics.hh"
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/*
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* hmtx -- Horizontal Metrics
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* https://docs.microsoft.com/en-us/typography/opentype/spec/hmtx
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* vmtx -- Vertical Metrics
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* https://docs.microsoft.com/en-us/typography/opentype/spec/vmtx
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*/
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#define HB_OT_TAG_hmtx HB_TAG('h','m','t','x')
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#define HB_OT_TAG_vmtx HB_TAG('v','m','t','x')
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HB_INTERNAL int
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_glyf_get_side_bearing_var (hb_font_t *font, hb_codepoint_t glyph, bool is_vertical);
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HB_INTERNAL unsigned
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_glyf_get_advance_var (hb_font_t *font, hb_codepoint_t glyph, bool is_vertical);
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namespace OT {
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struct LongMetric
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{
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UFWORD advance; /* Advance width/height. */
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FWORD sb; /* Leading (left/top) side bearing. */
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public:
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DEFINE_SIZE_STATIC (4);
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};
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template <typename T, typename H>
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struct hmtxvmtx
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{
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bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const
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{
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TRACE_SANITIZE (this);
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/* We don't check for anything specific here. The users of the
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* struct do all the hard work... */
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return_trace (true);
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}
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bool subset_update_header (hb_subset_plan_t *plan,
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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);
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hb_blob_t *dest_blob = hb_blob_copy_writable_or_fail (src_blob);
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hb_blob_destroy (src_blob);
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if (unlikely (!dest_blob)) {
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return false;
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}
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unsigned int length;
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H *table = (H *) hb_blob_get_data (dest_blob, &length);
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table->numberOfLongMetrics = num_hmetrics;
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bool result = plan->add_table (H::tableTag, dest_blob);
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hb_blob_destroy (dest_blob);
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return result;
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}
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template<typename Iterator,
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hb_requires (hb_is_iterator (Iterator))>
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void serialize (hb_serialize_context_t *c,
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Iterator it,
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unsigned num_advances)
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{
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unsigned idx = 0;
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for (auto _ : it)
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{
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if (idx < num_advances)
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{
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LongMetric lm;
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lm.advance = _.first;
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lm.sb = _.second;
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if (unlikely (!c->embed<LongMetric> (&lm))) return;
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}
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else
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{
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FWORD *sb = c->allocate_size<FWORD> (FWORD::static_size);
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if (unlikely (!sb)) return;
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*sb = _.second;
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}
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idx++;
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}
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}
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bool subset (hb_subset_context_t *c) const
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{
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TRACE_SUBSET (this);
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T *table_prime = c->serializer->start_embed <T> ();
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if (unlikely (!table_prime)) return_trace (false);
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accelerator_t _mtx;
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_mtx.init (c->plan->source);
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unsigned num_advances = _mtx.num_advances_for_subset (c->plan);
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auto it =
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+ hb_range (c->plan->num_output_glyphs ())
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| hb_map ([c, &_mtx] (unsigned _)
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{
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hb_codepoint_t old_gid;
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if (!c->plan->old_gid_for_new_gid (_, &old_gid))
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return hb_pair (0u, 0);
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return hb_pair (_mtx.get_advance (old_gid), _mtx.get_side_bearing (old_gid));
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})
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;
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table_prime->serialize (c->serializer, it, num_advances);
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_mtx.fini ();
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if (unlikely (c->serializer->ran_out_of_room || c->serializer->in_error ()))
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return_trace (false);
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// Amend header num hmetrics
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if (unlikely (!subset_update_header (c->plan, num_advances)))
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return_trace (false);
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return_trace (true);
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}
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struct accelerator_t
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{
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friend struct hmtxvmtx;
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void init (hb_face_t *face,
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unsigned int default_advance_ = 0)
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{
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default_advance = default_advance_ ? default_advance_ : hb_face_get_upem (face);
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num_advances = T::is_horizontal ? face->table.hhea->numberOfLongMetrics : face->table.vhea->numberOfLongMetrics;
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table = hb_sanitize_context_t ().reference_table<hmtxvmtx> (face, T::tableTag);
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/* Cap num_metrics() and num_advances() based on table length. */
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unsigned int len = table.get_length ();
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if (unlikely (num_advances * 4 > len))
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num_advances = len / 4;
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num_metrics = num_advances + (len - 4 * num_advances) / 2;
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/* We MUST set num_metrics to zero if num_advances is zero.
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* Our get_advance() depends on that. */
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if (unlikely (!num_advances))
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{
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num_metrics = num_advances = 0;
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table.destroy ();
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table = hb_blob_get_empty ();
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}
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var_table = hb_sanitize_context_t ().reference_table<HVARVVAR> (face, T::variationsTag);
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}
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void fini ()
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{
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table.destroy ();
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var_table.destroy ();
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}
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int get_side_bearing (hb_codepoint_t glyph) const
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{
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if (glyph < num_advances)
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return table->longMetricZ[glyph].sb;
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if (unlikely (glyph >= num_metrics))
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return 0;
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const FWORD *bearings = (const FWORD *) &table->longMetricZ[num_advances];
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return bearings[glyph - num_advances];
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}
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int get_side_bearing (hb_font_t *font, hb_codepoint_t glyph) const
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{
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int side_bearing = get_side_bearing (glyph);
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#ifndef HB_NO_VAR
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if (unlikely (glyph >= num_metrics) || !font->num_coords)
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return side_bearing;
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if (var_table.get_length ())
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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
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return side_bearing;
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#endif
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}
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unsigned int get_advance (hb_codepoint_t glyph) const
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{
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if (unlikely (glyph >= num_metrics))
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{
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/* If num_metrics is zero, it means we don't have the metrics table
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* for this direction: return default advance. Otherwise, it means that the
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* glyph index is out of bound: return zero. */
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if (num_metrics)
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return 0;
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else
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return default_advance;
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}
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return table->longMetricZ[hb_min (glyph, (uint32_t) num_advances - 1)].advance;
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}
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unsigned int get_advance (hb_codepoint_t glyph,
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hb_font_t *font) const
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{
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unsigned int advance = get_advance (glyph);
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#ifndef HB_NO_VAR
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if (unlikely (glyph >= num_metrics) || !font->num_coords)
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return advance;
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if (var_table.get_length ())
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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
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return advance;
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#endif
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}
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unsigned int num_advances_for_subset (const hb_subset_plan_t *plan) const
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{
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unsigned int num_advances = plan->num_output_glyphs ();
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unsigned int last_advance = _advance_for_new_gid (plan,
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num_advances - 1);
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while (num_advances > 1 &&
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last_advance == _advance_for_new_gid (plan,
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num_advances - 2))
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{
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num_advances--;
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}
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return num_advances;
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}
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private:
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unsigned int _advance_for_new_gid (const hb_subset_plan_t *plan,
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hb_codepoint_t new_gid) const
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{
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hb_codepoint_t old_gid;
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if (!plan->old_gid_for_new_gid (new_gid, &old_gid))
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return 0;
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return get_advance (old_gid);
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}
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protected:
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unsigned int num_metrics;
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unsigned int num_advances;
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unsigned int default_advance;
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private:
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hb_blob_ptr_t<hmtxvmtx> table;
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hb_blob_ptr_t<HVARVVAR> var_table;
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};
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protected:
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UnsizedArrayOf<LongMetric>
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longMetricZ; /* Paired advance width and leading
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* bearing values for each glyph. The
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* value numOfHMetrics comes from
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* the 'hhea' table. If the font is
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* monospaced, only one entry need
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* be in the array, but that entry is
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* required. The last entry applies to
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* all subsequent glyphs. */
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/*UnsizedArrayOf<FWORD> leadingBearingX;*/
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/* Here the advance is assumed
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* to be the same as the advance
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* for the last entry above. The
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* number of entries in this array is
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* derived from numGlyphs (from 'maxp'
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* table) minus numberOfLongMetrics.
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* This generally is used with a run
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* of monospaced glyphs (e.g., Kanji
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* fonts or Courier fonts). Only one
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* run is allowed and it must be at
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* the end. This allows a monospaced
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* font to vary the side bearing
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* values for each glyph. */
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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> {
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static constexpr hb_tag_t tableTag = HB_OT_TAG_hmtx;
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static constexpr hb_tag_t variationsTag = HB_OT_TAG_HVAR;
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static constexpr bool is_horizontal = true;
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};
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struct vmtx : hmtxvmtx<vmtx, vhea> {
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static constexpr hb_tag_t tableTag = HB_OT_TAG_vmtx;
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static constexpr hb_tag_t variationsTag = HB_OT_TAG_VVAR;
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static constexpr bool is_horizontal = false;
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};
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struct hmtx_accelerator_t : hmtx::accelerator_t {};
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struct vmtx_accelerator_t : vmtx::accelerator_t {};
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} /* namespace OT */
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#endif /* HB_OT_HMTX_TABLE_HH */
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