/* * 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-open-file.hh" #include "hb-subset.hh" #include "hb-subset-table.hh" #include "hb-subset-accelerator.hh" #include "hb-ot-cmap-table.hh" #include "hb-ot-var-cvar-table.hh" #include "hb-ot-head-table.hh" #include "hb-ot-stat-table.hh" #include "hb-ot-post-table-v2subset.hh" /** * 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. */ hb_user_data_key_t _hb_subset_accelerator_user_data_key = {}; /* * 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_TAG('B','A','S','E'), HB_TAG('C','B','D','T'), HB_TAG('C','B','L','C'), HB_TAG('C','F','F',' '), HB_TAG('C','F','F','2'), HB_TAG('c','m','a','p'), HB_TAG('C','O','L','R'), HB_TAG('C','P','A','L'), 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_TAG('G','D','E','F'), HB_TAG('g','l','y','f'), HB_TAG('G','P','O','S'), HB_TAG('G','S','U','B'), HB_TAG('g','v','a','r'), HB_TAG('h','d','m','x'), HB_TAG('h','e','a','d'), HB_TAG('h','h','e','a'), HB_TAG('h','m','t','x'), HB_TAG('H','V','A','R'), HB_TAG('J','S','T','F'), HB_TAG('k','e','r','n'), HB_TAG('l','o','c','a'), HB_TAG('L','T','S','H'), HB_TAG('M','A','T','H'), HB_TAG('m','a','x','p'), 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_TAG('p','o','s','t'), HB_TAG('p','r','e','p'), HB_TAG('s','b','i','x'), HB_TAG('S','T','A','T'), HB_TAG('S','V','G',' '), HB_TAG('V','D','M','X'), HB_TAG('v','h','e','a'), HB_TAG('v','m','t','x'), HB_TAG('V','O','R','G'), HB_TAG('V','V','A','R'), HB_TAG('n','a','m','e'), HB_TAG('O','S','/','2') }; 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 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_TAG('G','D','E','F'): case HB_TAG('G','P','O','S'): case HB_TAG('G','S','U','B'): 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_TAG('H','V','A','R'): case HB_TAG('V','V','A','R'): case HB_TAG('M','V','A','R'): return plan->all_axes_pinned; default: return false; } } static bool _dependencies_satisfied (hb_subset_plan_t *plan, hb_tag_t tag, const hb_set_t &subsetted_tags, const hb_set_t &pending_subset_tags) { switch (tag) { case HB_TAG('h','m','t','x'): case HB_TAG('v','m','t','x'): case HB_TAG('m','a','x','p'): case HB_TAG('O','S','/','2'): return !plan->normalized_coords || !pending_subset_tags.has (HB_TAG('g','l','y','f')); case HB_TAG('G','P','O','S'): return plan->all_axes_pinned || !pending_subset_tags.has (HB_TAG('G','D','E','F')); default: return true; } } 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 _hb_subset_table_passthrough (plan, tag); } DEBUG_MSG (SUBSET, nullptr, "subset %c%c%c%c", HB_UNTAG (tag)); bool success; if (_hb_subset_table_layout (plan, buf, tag, &success) || _hb_subset_table_var (plan, buf, tag, &success) || _hb_subset_table_cff (plan, buf, tag, &success) || _hb_subset_table_color (plan, buf, tag, &success) || _hb_subset_table_other (plan, buf, tag, &success)) return success; switch (tag) { case HB_TAG('h','e','a','d'): if (_is_table_present (plan->source, HB_TAG('g','l','y','f')) && !_should_drop_table (plan, HB_TAG('g','l','y','f'))) return true; /* skip head, handled by glyf */ return _hb_subset_table (plan, buf); case HB_TAG('S','T','A','T'): if (!plan->user_axes_location.is_empty ()) return _hb_subset_table (plan, buf); else return _hb_subset_table_passthrough (plan, tag); case HB_TAG('c','v','t',' '): #ifndef HB_NO_VAR if (_is_table_present (plan->source, HB_TAG('c','v','a','r')) && plan->normalized_coords && !plan->pinned_at_default) { auto &cvar = *plan->source->table.cvar; return OT::cvar::add_cvt_and_apply_deltas (plan, cvar.get_tuple_var_data (), &cvar); } #endif return _hb_subset_table_passthrough (plan, tag); } if (plan->flags & HB_SUBSET_FLAGS_PASSTHROUGH_UNRECOGNIZED) return _hb_subset_table_passthrough (plan, tag); // Drop table return true; } static void _attach_accelerator_data (hb_subset_plan_t* plan, hb_face_t* face /* IN/OUT */) { if (!plan->inprogress_accelerator) return; // Transfer the accelerator from the plan to us. hb_subset_accelerator_t* accel = plan->inprogress_accelerator; plan->inprogress_accelerator = nullptr; if (accel->in_error ()) { hb_subset_accelerator_t::destroy (accel); return; } // Populate caches that need access to the final tables. hb_blob_ptr_t cmap_ptr (hb_sanitize_context_t ().reference_table (face)); accel->cmap_cache = OT::cmap::create_filled_cache (cmap_ptr); accel->destroy_cmap_cache = OT::SubtableUnicodesCache::destroy; if (!hb_face_set_user_data(face, hb_subset_accelerator_t::user_data_key(), accel, hb_subset_accelerator_t::destroy, true)) hb_subset_accelerator_t::destroy (accel); } /** * 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 or the face has no glyphs. * * 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 nullptr; if (unlikely (!source->get_num_glyphs ())) { DEBUG_MSG (SUBSET, nullptr, "No glyphs in source font."); return nullptr; } 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_tag_t table_tags[32]; unsigned offset = 0, num_tables = ARRAY_LENGTH (table_tags); hb_set_t subsetted_tags, pending_subset_tags; 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)) continue; pending_subset_tags.add (tag); } offset += num_tables; } bool success = true; { // Grouping to deallocate buf before calling hb_face_reference (plan->dest). hb_vector_t buf; buf.alloc (8192 - 16); while (!pending_subset_tags.is_empty ()) { if (subsetted_tags.in_error () || pending_subset_tags.in_error ()) { success = false; goto end; } bool made_changes = false; for (hb_tag_t tag : pending_subset_tags) { if (!_dependencies_satisfied (plan, tag, subsetted_tags, pending_subset_tags)) { // delayed subsetting for some tables since they might have dependency on other tables // in some cases: e.g: during instantiating glyf tables, hmetrics/vmetrics are updated // and saved in subset plan, hmtx/vmtx subsetting need to use these updated metrics values continue; } pending_subset_tags.del (tag); subsetted_tags.add (tag); made_changes = true; success = _subset_table (plan, buf, tag); if (unlikely (!success)) goto end; } if (!made_changes) { DEBUG_MSG (SUBSET, nullptr, "Table dependencies unable to be satisfied. Subset failed."); success = false; goto end; } } } if (success && plan->attach_accelerator_data) { _attach_accelerator_data (plan, plan->dest); } end: return success ? hb_face_reference (plan->dest) : nullptr; }