/* * Copyright © 2018 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): Garret Rieger, Rod Sheeter, Behdad Esfahbod */ #include "hb.hh" #include "hb-open-type.hh" #include "hb-subset.hh" #include "hb-open-file.hh" #include "hb-ot-cmap-table.hh" #include "hb-ot-glyf-table.hh" #include "hb-ot-hdmx-table.hh" #include "hb-ot-head-table.hh" #include "hb-ot-hhea-table.hh" #include "hb-ot-hmtx-table.hh" #include "hb-ot-maxp-table.hh" #include "hb-ot-color-sbix-table.hh" #include "hb-ot-color-colr-table.hh" #include "hb-ot-color-cpal-table.hh" #include "hb-ot-os2-table.hh" #include "hb-ot-post-table.hh" #include "hb-ot-post-table-v2subset.hh" #include "hb-ot-cff1-table.hh" #include "hb-ot-cff2-table.hh" #include "hb-ot-vorg-table.hh" #include "hb-ot-name-table.hh" #include "hb-ot-color-cbdt-table.hh" #include "hb-ot-layout-gsub-table.hh" #include "hb-ot-layout-gpos-table.hh" #include "hb-ot-var-gvar-table.hh" #include "hb-ot-var-hvar-table.hh" #include "hb-ot-math-table.hh" #include "hb-ot-stat-table.hh" #include "hb-repacker.hh" using OT::Layout::GSUB; using OT::Layout::GPOS; /** * SECTION:hb-subset * @title: hb-subset * @short_description: Subsets font files. * @include: hb-subset.h * * Subsetting reduces the codepoint coverage of font files and removes all data * that is no longer needed. A subset input describes the desired subset. The input is * provided along with a font to the subsetting operation. Output is a new font file * containing only the data specified in the input. * * Currently most outline and bitmap tables are supported: glyf, CFF, CFF2, sbix, * COLR, and CBDT/CBLC. This also includes fonts with variable outlines via OpenType * variations. Notably EBDT/EBLC and SVG are not supported. Layout subsetting is supported * only for OpenType Layout tables (GSUB, GPOS, GDEF). Notably subsetting of graphite or AAT tables * is not yet supported. * * Fonts with graphite or AAT tables may still be subsetted but will likely need to use the * retain glyph ids option and configure the subset to pass through the layout tables untouched. */ /* * The list of tables in the open type spec. Used to check for tables that may need handling * if we are unable to list the tables in a face. */ static hb_tag_t known_tables[] { HB_TAG ('a', 'v', 'a', 'r'), HB_OT_TAG_BASE, HB_OT_TAG_CBDT, HB_OT_TAG_CBLC, HB_OT_TAG_cff1, HB_OT_TAG_cff2, HB_OT_TAG_cmap, HB_OT_TAG_COLR, HB_OT_TAG_CPAL, HB_TAG ('c', 'v', 'a', 'r'), HB_TAG ('c', 'v', 't', ' '), HB_TAG ('D', 'S', 'I', 'G'), HB_TAG ('E', 'B', 'D', 'T'), HB_TAG ('E', 'B', 'L', 'C'), HB_TAG ('E', 'B', 'S', 'C'), HB_TAG ('f', 'p', 'g', 'm'), HB_TAG ('f', 'v', 'a', 'r'), HB_TAG ('g', 'a', 's', 'p'), HB_OT_TAG_GDEF, HB_OT_TAG_glyf, HB_OT_TAG_GPOS, HB_OT_TAG_GSUB, HB_OT_TAG_gvar, HB_OT_TAG_hdmx, HB_OT_TAG_head, HB_OT_TAG_hhea, HB_OT_TAG_hmtx, HB_OT_TAG_HVAR, HB_OT_TAG_JSTF, HB_TAG ('k', 'e', 'r', 'n'), HB_OT_TAG_loca, HB_TAG ('L', 'T', 'S', 'H'), HB_OT_TAG_MATH, HB_OT_TAG_maxp, HB_TAG ('M', 'E', 'R', 'G'), HB_TAG ('m', 'e', 't', 'a'), HB_TAG ('M', 'V', 'A', 'R'), HB_TAG ('P', 'C', 'L', 'T'), HB_OT_TAG_post, HB_TAG ('p', 'r', 'e', 'p'), HB_OT_TAG_sbix, HB_TAG ('S', 'T', 'A', 'T'), HB_TAG ('S', 'V', 'G', ' '), HB_TAG ('V', 'D', 'M', 'X'), HB_OT_TAG_vhea, HB_OT_TAG_vmtx, HB_OT_TAG_VORG, HB_OT_TAG_VVAR, HB_OT_TAG_name, HB_OT_TAG_OS2 }; static bool _table_is_empty (const hb_face_t *face, hb_tag_t tag) { hb_blob_t* blob = hb_face_reference_table (face, tag); bool result = (blob == hb_blob_get_empty ()); hb_blob_destroy (blob); return result; } static unsigned int _get_table_tags (const hb_subset_plan_t* plan, unsigned int start_offset, unsigned int *table_count, /* IN/OUT */ hb_tag_t *table_tags /* OUT */) { unsigned num_tables = hb_face_get_table_tags (plan->source, 0, nullptr, nullptr); if (num_tables) return hb_face_get_table_tags (plan->source, start_offset, table_count, table_tags); // If face has 0 tables associated with it, assume that it was built from // hb_face_create_tables and thus is unable to list its tables. Fallback to // checking each table type we can handle for existence instead. auto it = hb_concat ( + hb_array (known_tables) | hb_filter ([&] (hb_tag_t tag) { return !_table_is_empty (plan->source, tag) && !plan->no_subset_tables->has (tag); }) | hb_map ([] (hb_tag_t tag) -> hb_tag_t { return tag; }), plan->no_subset_tables->iter () | hb_filter([&] (hb_tag_t tag) { return !_table_is_empty (plan->source, tag); })); it += start_offset; unsigned num_written = 0; while (bool (it) && num_written < *table_count) table_tags[num_written++] = *it++; *table_count = num_written; return num_written; } static unsigned _plan_estimate_subset_table_size (hb_subset_plan_t *plan, unsigned table_len, bool same_size) { unsigned src_glyphs = plan->source->get_num_glyphs (); unsigned dst_glyphs = plan->glyphset ()->get_population (); if (unlikely (!src_glyphs) || same_size) return 512 + table_len; return 512 + (unsigned) (table_len * sqrt ((double) dst_glyphs / src_glyphs)); } /* * Repack the serialization buffer if any offset overflows exist. */ static hb_blob_t* _repack (hb_tag_t tag, const hb_serialize_context_t& c) { if (tag != HB_OT_TAG_GPOS && tag != HB_OT_TAG_GSUB) { // Check for overflow in a non-handled table. return c.successful () ? c.copy_blob () : nullptr; } if (!c.offset_overflow ()) return c.copy_blob (); hb_blob_t* result = hb_resolve_overflows (c.object_graph (), tag); if (unlikely (!result)) { DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c offset overflow resolution failed.", HB_UNTAG (tag)); return nullptr; } return result; } template static bool _try_subset (const TableType *table, hb_vector_t* buf, hb_subset_context_t* c /* OUT */) { c->serializer->start_serialize (); if (c->serializer->in_error ()) return false; bool needed = table->subset (c); if (!c->serializer->ran_out_of_room ()) { c->serializer->end_serialize (); return needed; } unsigned buf_size = buf->allocated; buf_size = buf_size * 2 + 16; DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c ran out of room; reallocating to %u bytes.", HB_UNTAG (c->table_tag), buf_size); if (unlikely (buf_size > c->source_blob->length * 16 || !buf->alloc (buf_size))) { DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c failed to reallocate %u bytes.", HB_UNTAG (c->table_tag), buf_size); return needed; } c->serializer->reset (buf->arrayZ, buf->allocated); return _try_subset (table, buf, c); } template static bool _subset (hb_subset_plan_t *plan, hb_vector_t &buf) { hb_blob_ptr_t source_blob = plan->source_table (); const TableType *table = source_blob.get (); hb_tag_t tag = TableType::tableTag; if (!source_blob.get_blob()->data) { DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c::subset sanitize failed on source table.", HB_UNTAG (tag)); source_blob.destroy (); return false; } /* Tables that we want to allocate same space as the source table. For GSUB/GPOS it's * because those are expensive to subset, so giving them more room is fine. */ bool same_size_table = TableType::tableTag == HB_OT_TAG_GSUB || TableType::tableTag == HB_OT_TAG_GPOS || TableType::tableTag == HB_OT_TAG_name; unsigned buf_size = _plan_estimate_subset_table_size (plan, source_blob.get_length (), same_size_table); DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c initial estimated table size: %u bytes.", HB_UNTAG (tag), buf_size); if (unlikely (!buf.alloc (buf_size))) { DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c failed to allocate %u bytes.", HB_UNTAG (tag), buf_size); source_blob.destroy (); return false; } bool needed = false; hb_serialize_context_t serializer (buf.arrayZ, buf.allocated); { hb_subset_context_t c (source_blob.get_blob (), plan, &serializer, tag); needed = _try_subset (table, &buf, &c); } source_blob.destroy (); if (serializer.in_error () && !serializer.only_offset_overflow ()) { DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c::subset FAILED!", HB_UNTAG (tag)); return false; } if (!needed) { DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c::subset table subsetted to empty.", HB_UNTAG (tag)); return true; } bool result = false; hb_blob_t *dest_blob = _repack (tag, serializer); if (dest_blob) { DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c final subset table size: %u bytes.", HB_UNTAG (tag), dest_blob->length); result = plan->add_table (tag, dest_blob); hb_blob_destroy (dest_blob); } DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c::subset %s", HB_UNTAG (tag), result ? "success" : "FAILED!"); return result; } static bool _is_table_present (hb_face_t *source, hb_tag_t tag) { if (!hb_face_get_table_tags (source, 0, nullptr, nullptr)) { // If face has 0 tables associated with it, assume that it was built from // hb_face_create_tables and thus is unable to list its tables. Fallback to // checking if the blob associated with tag is empty. return !_table_is_empty (source, tag); } hb_tag_t table_tags[32]; unsigned offset = 0, num_tables = ARRAY_LENGTH (table_tags); while (((void) hb_face_get_table_tags (source, offset, &num_tables, table_tags), num_tables)) { for (unsigned i = 0; i < num_tables; ++i) if (table_tags[i] == tag) return true; offset += num_tables; } return false; } static bool _should_drop_table (hb_subset_plan_t *plan, hb_tag_t tag) { if (plan->drop_tables->has (tag)) return true; switch (tag) { case HB_TAG ('c','v','a','r'): /* hint table, fallthrough */ return plan->all_axes_pinned || (plan->flags & HB_SUBSET_FLAGS_NO_HINTING); case HB_TAG ('c','v','t',' '): /* hint table, fallthrough */ case HB_TAG ('f','p','g','m'): /* hint table, fallthrough */ case HB_TAG ('p','r','e','p'): /* hint table, fallthrough */ case HB_TAG ('h','d','m','x'): /* hint table, fallthrough */ case HB_TAG ('V','D','M','X'): /* hint table, fallthrough */ return plan->flags & HB_SUBSET_FLAGS_NO_HINTING; #ifdef HB_NO_SUBSET_LAYOUT // Drop Layout Tables if requested. case HB_OT_TAG_GDEF: case HB_OT_TAG_GPOS: case HB_OT_TAG_GSUB: case HB_TAG ('m','o','r','x'): case HB_TAG ('m','o','r','t'): case HB_TAG ('k','e','r','x'): case HB_TAG ('k','e','r','n'): return true; #endif case HB_TAG ('a','v','a','r'): case HB_TAG ('f','v','a','r'): case HB_TAG ('g','v','a','r'): case HB_OT_TAG_HVAR: case HB_OT_TAG_VVAR: case HB_TAG ('M','V','A','R'): return plan->all_axes_pinned; default: return false; } } static bool _passthrough (hb_subset_plan_t *plan, hb_tag_t tag) { hb_blob_t *source_table = hb_face_reference_table (plan->source, tag); bool result = plan->add_table (tag, source_table); hb_blob_destroy (source_table); return result; } static bool _subset_table (hb_subset_plan_t *plan, hb_vector_t &buf, hb_tag_t tag) { if (plan->no_subset_tables->has (tag)) { return _passthrough (plan, tag); } DEBUG_MSG (SUBSET, nullptr, "subset %c%c%c%c", HB_UNTAG (tag)); switch (tag) { case HB_OT_TAG_glyf: return _subset (plan, buf); case HB_OT_TAG_hdmx: return _subset (plan, buf); case HB_OT_TAG_name: return _subset (plan, buf); case HB_OT_TAG_head: if (_is_table_present (plan->source, HB_OT_TAG_glyf) && !_should_drop_table (plan, HB_OT_TAG_glyf)) return true; /* skip head, handled by glyf */ return _subset (plan, buf); case HB_OT_TAG_hhea: return true; /* skip hhea, handled by hmtx */ case HB_OT_TAG_hmtx: return _subset (plan, buf); case HB_OT_TAG_vhea: return true; /* skip vhea, handled by vmtx */ case HB_OT_TAG_vmtx: return _subset (plan, buf); case HB_OT_TAG_maxp: return _subset (plan, buf); case HB_OT_TAG_sbix: return _subset (plan, buf); case HB_OT_TAG_loca: return true; /* skip loca, handled by glyf */ case HB_OT_TAG_cmap: return _subset (plan, buf); case HB_OT_TAG_OS2 : return _subset (plan, buf); case HB_OT_TAG_post: return _subset (plan, buf); case HB_OT_TAG_COLR: return _subset (plan, buf); case HB_OT_TAG_CPAL: return _subset (plan, buf); case HB_OT_TAG_CBLC: return _subset (plan, buf); case HB_OT_TAG_CBDT: return true; /* skip CBDT, handled by CBLC */ case HB_OT_TAG_MATH: return _subset (plan, buf); #ifndef HB_NO_SUBSET_CFF case HB_OT_TAG_cff1: return _subset (plan, buf); case HB_OT_TAG_cff2: return _subset (plan, buf); case HB_OT_TAG_VORG: return _subset (plan, buf); #endif #ifndef HB_NO_SUBSET_LAYOUT case HB_OT_TAG_GDEF: return _subset (plan, buf); case HB_OT_TAG_GSUB: return _subset (plan, buf); case HB_OT_TAG_GPOS: return _subset (plan, buf); case HB_OT_TAG_gvar: return _subset (plan, buf); case HB_OT_TAG_HVAR: return _subset (plan, buf); case HB_OT_TAG_VVAR: return _subset (plan, buf); #endif case HB_OT_TAG_STAT: /*TODO(qxliu): change the condition as we support more complex * instancing operation*/ if (plan->all_axes_pinned) return _subset (plan, buf); else return _passthrough (plan, tag); default: if (plan->flags & HB_SUBSET_FLAGS_PASSTHROUGH_UNRECOGNIZED) return _passthrough (plan, tag); // Drop table return true; } } /** * hb_subset_or_fail: * @source: font face data to be subset. * @input: input to use for the subsetting. * * Subsets a font according to provided input. Returns nullptr * if the subset operation fails. * * Since: 2.9.0 **/ hb_face_t * hb_subset_or_fail (hb_face_t *source, const hb_subset_input_t *input) { if (unlikely (!input || !source)) return hb_face_get_empty (); hb_subset_plan_t *plan = hb_subset_plan_create_or_fail (source, input); if (unlikely (!plan)) { return nullptr; } hb_face_t * result = hb_subset_plan_execute_or_fail (plan); hb_subset_plan_destroy (plan); return result; } /** * hb_subset_plan_execute_or_fail: * @plan: a subsetting plan. * * Executes the provided subsetting @plan. * * Return value: * on success returns a reference to generated font subset. If the subsetting operation fails * returns nullptr. * * Since: 4.0.0 **/ hb_face_t * hb_subset_plan_execute_or_fail (hb_subset_plan_t *plan) { if (unlikely (!plan || plan->in_error ())) { return nullptr; } hb_set_t tags_set; bool success = true; hb_tag_t table_tags[32]; unsigned offset = 0, num_tables = ARRAY_LENGTH (table_tags); hb_vector_t buf; buf.alloc (4096 - 16); while (((void) _get_table_tags (plan, offset, &num_tables, table_tags), num_tables)) { for (unsigned i = 0; i < num_tables; ++i) { hb_tag_t tag = table_tags[i]; if (_should_drop_table (plan, tag) && !tags_set.has (tag)) continue; tags_set.add (tag); success = _subset_table (plan, buf, tag); if (unlikely (!success)) goto end; } offset += num_tables; } end: return success ? hb_face_reference (plan->dest) : nullptr; }