264 lines
8.7 KiB
C++
264 lines
8.7 KiB
C++
/*
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* Copyright © 2018 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): Garret Rieger, Rod Sheeter, Behdad Esfahbod
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*/
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#include "hb.hh"
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#include "hb-open-type.hh"
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#include "hb-subset.hh"
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#include "hb-open-file.hh"
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#include "hb-ot-cmap-table.hh"
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#include "hb-ot-glyf-table.hh"
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#include "hb-ot-hdmx-table.hh"
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#include "hb-ot-head-table.hh"
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#include "hb-ot-hhea-table.hh"
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#include "hb-ot-hmtx-table.hh"
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#include "hb-ot-maxp-table.hh"
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#include "hb-ot-color-sbix-table.hh"
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#include "hb-ot-color-colr-table.hh"
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#include "hb-ot-os2-table.hh"
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#include "hb-ot-post-table.hh"
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#include "hb-ot-cff1-table.hh"
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#include "hb-ot-cff2-table.hh"
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#include "hb-ot-vorg-table.hh"
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#include "hb-ot-name-table.hh"
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#include "hb-ot-layout-gsub-table.hh"
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#include "hb-ot-layout-gpos-table.hh"
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#include "hb-ot-var-gvar-table.hh"
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#include "hb-ot-var-hvar-table.hh"
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static unsigned
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_plan_estimate_subset_table_size (hb_subset_plan_t *plan, unsigned table_len)
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{
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unsigned src_glyphs = plan->source->get_num_glyphs ();
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unsigned dst_glyphs = plan->glyphset ()->get_population ();
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if (unlikely (!src_glyphs))
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return 512 + table_len;
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return 512 + (unsigned) (table_len * sqrt ((double) dst_glyphs / src_glyphs));
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}
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template<typename TableType>
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static bool
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_subset (hb_subset_plan_t *plan)
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{
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bool result = false;
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hb_blob_t *source_blob = hb_sanitize_context_t ().reference_table<TableType> (plan->source);
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const TableType *table = source_blob->as<TableType> ();
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hb_tag_t tag = TableType::tableTag;
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if (source_blob->data)
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{
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hb_vector_t<char> buf;
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/* TODO Not all tables are glyph-related. 'name' table size for example should not be
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* affected by number of glyphs. Accommodate that. */
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unsigned buf_size = _plan_estimate_subset_table_size (plan, source_blob->length);
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DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c initial estimated table size: %u bytes.", HB_UNTAG (tag), buf_size);
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if (unlikely (!buf.alloc (buf_size)))
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{
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DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c failed to allocate %u bytes.", HB_UNTAG (tag), buf_size);
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hb_blob_destroy (source_blob);
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return false;
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}
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retry:
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hb_serialize_context_t serializer ((void *) buf, buf_size);
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serializer.start_serialize<TableType> ();
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hb_subset_context_t c (plan, &serializer);
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bool needed = table->subset (&c);
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if (serializer.ran_out_of_room)
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{
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buf_size += (buf_size >> 1) + 32;
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DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c ran out of room; reallocating to %u bytes.", HB_UNTAG (tag), buf_size);
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if (unlikely (!buf.alloc (buf_size)))
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{
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DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c failed to reallocate %u bytes.", HB_UNTAG (tag), buf_size);
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hb_blob_destroy (source_blob);
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return false;
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}
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goto retry;
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}
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serializer.end_serialize ();
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result = !serializer.in_error ();
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if (result)
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{
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if (needed)
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{
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hb_blob_t *dest_blob = serializer.copy_blob ();
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DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c final subset table size: %u bytes.", HB_UNTAG (tag), dest_blob->length);
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result = c.plan->add_table (tag, dest_blob);
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hb_blob_destroy (dest_blob);
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}
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else
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{
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DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c::subset table subsetted to empty.", HB_UNTAG (tag));
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}
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}
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}
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else
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DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c::subset sanitize failed on source table.", HB_UNTAG (tag));
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hb_blob_destroy (source_blob);
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DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c::subset %s", HB_UNTAG (tag), result ? "success" : "FAILED!");
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return result;
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}
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static bool
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_is_table_present (hb_face_t *source, hb_tag_t tag)
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{
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hb_tag_t table_tags[32];
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unsigned offset = 0, num_tables = ARRAY_LENGTH (table_tags);
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while ((hb_face_get_table_tags (source, offset, &num_tables, table_tags), num_tables))
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{
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for (unsigned i = 0; i < num_tables; ++i)
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if (table_tags[i] == tag)
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return true;
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offset += num_tables;
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}
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return false;
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}
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static bool
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_should_drop_table (hb_subset_plan_t *plan, hb_tag_t tag)
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{
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if (plan->drop_tables->has (tag))
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return true;
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switch (tag)
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{
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case HB_TAG ('c','v','a','r'): /* hint table, fallthrough */
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case HB_TAG ('c','v','t',' '): /* hint table, fallthrough */
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case HB_TAG ('f','p','g','m'): /* hint table, fallthrough */
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case HB_TAG ('p','r','e','p'): /* hint table, fallthrough */
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case HB_TAG ('h','d','m','x'): /* hint table, fallthrough */
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case HB_TAG ('V','D','M','X'): /* hint table, fallthrough */
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return plan->drop_hints;
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#ifdef HB_NO_SUBSET_LAYOUT
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// Drop Layout Tables if requested.
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case HB_OT_TAG_GDEF:
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case HB_OT_TAG_GPOS:
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case HB_OT_TAG_GSUB:
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case HB_TAG ('m','o','r','x'):
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case HB_TAG ('m','o','r','t'):
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case HB_TAG ('k','e','r','x'):
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case HB_TAG ('k','e','r','n'):
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return true;
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#endif
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default:
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return false;
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}
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}
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static bool
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_subset_table (hb_subset_plan_t *plan, hb_tag_t tag)
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{
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DEBUG_MSG (SUBSET, nullptr, "subset %c%c%c%c", HB_UNTAG (tag));
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switch (tag)
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{
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case HB_OT_TAG_glyf: return _subset<const OT::glyf> (plan);
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case HB_OT_TAG_hdmx: return _subset<const OT::hdmx> (plan);
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case HB_OT_TAG_name: return _subset<const OT::name> (plan);
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case HB_OT_TAG_head:
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if (_is_table_present (plan->source, HB_OT_TAG_glyf) && !_should_drop_table (plan, HB_OT_TAG_glyf))
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return true; /* skip head, handled by glyf */
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return _subset<const OT::head> (plan);
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case HB_OT_TAG_hhea: return true; /* skip hhea, handled by hmtx */
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case HB_OT_TAG_hmtx: return _subset<const OT::hmtx> (plan);
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case HB_OT_TAG_vhea: return true; /* skip vhea, handled by vmtx */
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case HB_OT_TAG_vmtx: return _subset<const OT::vmtx> (plan);
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case HB_OT_TAG_maxp: return _subset<const OT::maxp> (plan);
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case HB_OT_TAG_sbix: return _subset<const OT::sbix> (plan);
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case HB_OT_TAG_loca: return true; /* skip loca, handled by glyf */
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case HB_OT_TAG_cmap: return _subset<const OT::cmap> (plan);
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case HB_OT_TAG_OS2 : return _subset<const OT::OS2 > (plan);
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case HB_OT_TAG_post: return _subset<const OT::post> (plan);
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case HB_OT_TAG_COLR: return _subset<const OT::COLR> (plan);
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#ifndef HB_NO_SUBSET_CFF
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case HB_OT_TAG_cff1: return _subset<const OT::cff1> (plan);
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case HB_OT_TAG_cff2: return _subset<const OT::cff2> (plan);
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case HB_OT_TAG_VORG: return _subset<const OT::VORG> (plan);
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#endif
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#ifndef HB_NO_SUBSET_LAYOUT
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case HB_OT_TAG_GDEF: return _subset<const OT::GDEF> (plan);
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case HB_OT_TAG_GSUB: return _subset<const OT::GSUB> (plan);
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case HB_OT_TAG_GPOS: return _subset<const OT::GPOS> (plan);
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case HB_OT_TAG_gvar: return _subset<const OT::gvar> (plan);
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case HB_OT_TAG_HVAR: return _subset<const OT::HVAR> (plan);
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case HB_OT_TAG_VVAR: return _subset<const OT::VVAR> (plan);
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#endif
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default:
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hb_blob_t *source_table = hb_face_reference_table (plan->source, tag);
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bool result = plan->add_table (tag, source_table);
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hb_blob_destroy (source_table);
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return result;
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}
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}
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/**
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* hb_subset:
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* @source: font face data to be subset.
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* @input: input to use for the subsetting.
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*
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* Subsets a font according to provided input.
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**/
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hb_face_t *
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hb_subset (hb_face_t *source, hb_subset_input_t *input)
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{
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if (unlikely (!input || !source)) return hb_face_get_empty ();
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hb_subset_plan_t *plan = hb_subset_plan_create (source, input);
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hb_set_t tags_set;
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bool success = true;
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hb_tag_t table_tags[32];
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unsigned offset = 0, num_tables = ARRAY_LENGTH (table_tags);
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while ((hb_face_get_table_tags (source, offset, &num_tables, table_tags), num_tables))
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{
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for (unsigned i = 0; i < num_tables; ++i)
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{
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hb_tag_t tag = table_tags[i];
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if (_should_drop_table (plan, tag) && !tags_set.has (tag)) continue;
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tags_set.add (tag);
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success = _subset_table (plan, tag);
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if (unlikely (!success)) goto end;
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}
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offset += num_tables;
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}
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end:
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hb_face_t *result = success ? hb_face_reference (plan->dest) : hb_face_get_empty ();
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hb_subset_plan_destroy (plan);
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return result;
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}
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