diff options
Diffstat (limited to 'gfx/harfbuzz/src/hb-subset.cc')
| -rw-r--r-- | gfx/harfbuzz/src/hb-subset.cc | 269 |
1 files changed, 269 insertions, 0 deletions
diff --git a/gfx/harfbuzz/src/hb-subset.cc b/gfx/harfbuzz/src/hb-subset.cc new file mode 100644 index 0000000000..8b77ecd45a --- /dev/null +++ b/gfx/harfbuzz/src/hb-subset.cc @@ -0,0 +1,269 @@ +/* + * 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-os2-table.hh" +#include "hb-ot-post-table.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" + + +static unsigned +_plan_estimate_subset_table_size (hb_subset_plan_t *plan, unsigned table_len) +{ + unsigned src_glyphs = plan->source->get_num_glyphs (); + unsigned dst_glyphs = plan->glyphset ()->get_population (); + + if (unlikely (!src_glyphs)) + return 512 + table_len; + + return 512 + (unsigned) (table_len * sqrt ((double) dst_glyphs / src_glyphs)); +} + +template<typename TableType> +static bool +_subset (hb_subset_plan_t *plan) +{ + bool result = false; + hb_blob_t *source_blob = hb_sanitize_context_t ().reference_table<TableType> (plan->source); + const TableType *table = source_blob->as<TableType> (); + + hb_tag_t tag = TableType::tableTag; + if (source_blob->data) + { + hb_vector_t<char> buf; + /* TODO Not all tables are glyph-related. 'name' table size for example should not be + * affected by number of glyphs. Accommodate that. */ + unsigned buf_size = _plan_estimate_subset_table_size (plan, source_blob->length); + 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); + hb_blob_destroy (source_blob); + return false; + } + retry: + hb_serialize_context_t serializer ((void *) buf, buf_size); + serializer.start_serialize<TableType> (); + hb_subset_context_t c (source_blob, plan, &serializer, tag); + bool needed = table->subset (&c); + if (serializer.ran_out_of_room) + { + buf_size += (buf_size >> 1) + 32; + DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c ran out of room; reallocating to %u bytes.", HB_UNTAG (tag), buf_size); + if (unlikely (!buf.alloc (buf_size))) + { + DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c failed to reallocate %u bytes.", HB_UNTAG (tag), buf_size); + hb_blob_destroy (source_blob); + return false; + } + goto retry; + } + serializer.end_serialize (); + + result = !serializer.in_error (); + + if (result) + { + if (needed) + { + hb_blob_t *dest_blob = serializer.copy_blob (); + DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c final subset table size: %u bytes.", HB_UNTAG (tag), dest_blob->length); + result = c.plan->add_table (tag, dest_blob); + hb_blob_destroy (dest_blob); + } + else + { + DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c::subset table subsetted to empty.", HB_UNTAG (tag)); + } + } + } + else + DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c::subset sanitize failed on source table.", HB_UNTAG (tag)); + + hb_blob_destroy (source_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) +{ + hb_tag_t table_tags[32]; + unsigned offset = 0, num_tables = ARRAY_LENGTH (table_tags); + while ((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 */ + 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->drop_hints; + +#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 + + default: + return false; + } +} + +static bool +_subset_table (hb_subset_plan_t *plan, hb_tag_t tag) +{ + DEBUG_MSG (SUBSET, nullptr, "subset %c%c%c%c", HB_UNTAG (tag)); + switch (tag) + { + case HB_OT_TAG_glyf: return _subset<const OT::glyf> (plan); + case HB_OT_TAG_hdmx: return _subset<const OT::hdmx> (plan); + case HB_OT_TAG_name: return _subset<const OT::name> (plan); + 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<const OT::head> (plan); + case HB_OT_TAG_hhea: return true; /* skip hhea, handled by hmtx */ + case HB_OT_TAG_hmtx: return _subset<const OT::hmtx> (plan); + case HB_OT_TAG_vhea: return true; /* skip vhea, handled by vmtx */ + case HB_OT_TAG_vmtx: return _subset<const OT::vmtx> (plan); + case HB_OT_TAG_maxp: return _subset<const OT::maxp> (plan); + case HB_OT_TAG_sbix: return _subset<const OT::sbix> (plan); + case HB_OT_TAG_loca: return true; /* skip loca, handled by glyf */ + case HB_OT_TAG_cmap: return _subset<const OT::cmap> (plan); + case HB_OT_TAG_OS2 : return _subset<const OT::OS2 > (plan); + case HB_OT_TAG_post: return _subset<const OT::post> (plan); + case HB_OT_TAG_COLR: return _subset<const OT::COLR> (plan); + case HB_OT_TAG_CBLC: return _subset<const OT::CBLC> (plan); + case HB_OT_TAG_CBDT: return true; /* skip CBDT, handled by CBLC */ + +#ifndef HB_NO_SUBSET_CFF + case HB_OT_TAG_cff1: return _subset<const OT::cff1> (plan); + case HB_OT_TAG_cff2: return _subset<const OT::cff2> (plan); + case HB_OT_TAG_VORG: return _subset<const OT::VORG> (plan); +#endif + +#ifndef HB_NO_SUBSET_LAYOUT + case HB_OT_TAG_GDEF: return _subset<const OT::GDEF> (plan); + case HB_OT_TAG_GSUB: return _subset<const OT::GSUB> (plan); + case HB_OT_TAG_GPOS: return _subset<const OT::GPOS> (plan); + case HB_OT_TAG_gvar: return _subset<const OT::gvar> (plan); + case HB_OT_TAG_HVAR: return _subset<const OT::HVAR> (plan); + case HB_OT_TAG_VVAR: return _subset<const OT::VVAR> (plan); +#endif + + default: + 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; + } +} + +/** + * hb_subset: + * @source: font face data to be subset. + * @input: input to use for the subsetting. + * + * Subsets a font according to provided input. + **/ +hb_face_t * +hb_subset (hb_face_t *source, hb_subset_input_t *input) +{ + if (unlikely (!input || !source)) return hb_face_get_empty (); + + hb_subset_plan_t *plan = hb_subset_plan_create (source, input); + if (unlikely (plan->in_error ())) + return hb_face_get_empty (); + + hb_set_t tags_set; + bool success = true; + hb_tag_t table_tags[32]; + unsigned offset = 0, num_tables = ARRAY_LENGTH (table_tags); + while ((hb_face_get_table_tags (source, 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, tag); + if (unlikely (!success)) goto end; + } + offset += num_tables; + } +end: + + hb_face_t *result = success ? hb_face_reference (plan->dest) : hb_face_get_empty (); + + hb_subset_plan_destroy (plan); + return result; +} |