harfbuzz/src/hb-subset-plan.cc

/*
 * 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, Roderick Sheeter
 */

#include "hb-subset-plan.hh"
#include "hb-map.hh"
#include "hb-set.hh"

#include "hb-ot-cmap-table.hh"
#include "hb-ot-glyf-table.hh"
#include "hb-ot-layout-gdef-table.hh"
#include "hb-ot-layout-gpos-table.hh"
#include "hb-ot-layout-gsub-table.hh"
#include "hb-ot-cff1-table.hh"
#include "hb-ot-color-colr-table.hh"
#include "hb-ot-color-colrv1-closure.hh"
#include "hb-ot-var-fvar-table.hh"
#include "hb-ot-stat-table.hh"


typedef hb_hashmap_t<unsigned, hb_set_t *, (unsigned)-1, nullptr> script_langsys_map;
#ifndef HB_NO_SUBSET_CFF
static inline void
_add_cff_seac_components (const OT::cff1::accelerator_t &cff,
			  hb_codepoint_t gid,
			  hb_set_t *gids_to_retain)
{
  hb_codepoint_t base_gid, accent_gid;
  if (cff.get_seac_components (gid, &base_gid, &accent_gid))
  {
    gids_to_retain->add (base_gid);
    gids_to_retain->add (accent_gid);
  }
}
#endif

static void
_remap_palette_indexes (const hb_set_t *palette_indexes,
			hb_map_t       *mapping /* OUT */)
{
  unsigned new_idx = 0;
  for (unsigned palette_index : palette_indexes->iter ())
  {
    if (palette_index == 0xFFFF)
    {
      mapping->set (palette_index, palette_index);
      continue;
    }
    mapping->set (palette_index, new_idx);
    new_idx++;
  }
}

static void
_remap_indexes (const hb_set_t *indexes,
		hb_map_t       *mapping /* OUT */)
{
  unsigned count = indexes->get_population ();

  for (auto _ : + hb_zip (indexes->iter (), hb_range (count)))
    mapping->set (_.first, _.second);

}

#ifndef HB_NO_SUBSET_LAYOUT
typedef void (*layout_collect_func_t) (hb_face_t *face, hb_tag_t table_tag, const hb_tag_t *scripts, const hb_tag_t *languages, const hb_tag_t *features, hb_set_t *lookup_indexes /* OUT */);

static void _collect_subset_layout (hb_face_t		 *face,
				    hb_tag_t		  table_tag,
				    const hb_set_t	 *layout_features_to_retain,
				    bool		  retain_all_features,
				    layout_collect_func_t layout_collect_func,
				    hb_set_t		 *lookup_indices /* OUT */)
{
  if (retain_all_features)
  {
    layout_collect_func (face,
			 table_tag,
			 nullptr,
			 nullptr,
			 nullptr,
			 lookup_indices);
    return;
  }

  if (hb_set_is_empty (layout_features_to_retain)) return;
  unsigned num = layout_features_to_retain->get_population () + 1;
  hb_tag_t *features = (hb_tag_t *) hb_malloc (num * sizeof (hb_tag_t));
  if (!features) return;

  unsigned i = 0;
  for (hb_tag_t f : layout_features_to_retain->iter ())
    features[i++] = f;

  features[i] = 0;

  layout_collect_func (face,
		       table_tag,
		       nullptr,
		       nullptr,
		       features,
		       lookup_indices);

  hb_free (features);
}

template <typename T>
static inline void
_closure_glyphs_lookups_features (hb_face_t	     *face,
				  hb_set_t	     *gids_to_retain,
				  const hb_set_t     *layout_features_to_retain,
				  bool		      retain_all_features,
				  hb_map_t	     *lookups,
				  hb_map_t	     *features,
				  script_langsys_map *langsys_map)
{
  hb_blob_ptr_t<T> table = hb_sanitize_context_t ().reference_table<T> (face);
  hb_tag_t table_tag = table->tableTag;
  hb_set_t lookup_indices;
  _collect_subset_layout (face,
			  table_tag,
			  layout_features_to_retain,
			  retain_all_features,
			  hb_ot_layout_collect_lookups,
			  &lookup_indices);

  if (table_tag == HB_OT_TAG_GSUB)
    hb_ot_layout_lookups_substitute_closure (face,
					    &lookup_indices,
					     gids_to_retain);
  table->closure_lookups (face,
			  gids_to_retain,
			 &lookup_indices);
  _remap_indexes (&lookup_indices, lookups);

  // Collect and prune features
  hb_set_t feature_indices;
  _collect_subset_layout (face,
			  table_tag,
			  layout_features_to_retain,
			  retain_all_features,
			  hb_ot_layout_collect_features,
			  &feature_indices);

  table->prune_features (lookups, &feature_indices);
  hb_map_t duplicate_feature_map;
  table->find_duplicate_features (lookups, &feature_indices, &duplicate_feature_map);

  feature_indices.clear ();
  table->prune_langsys (&duplicate_feature_map, langsys_map, &feature_indices);
  _remap_indexes (&feature_indices, features);

  table.destroy ();
}

#endif

#ifndef HB_NO_VAR
static inline void
  _collect_layout_variation_indices (hb_face_t *face,
				     const hb_set_t *glyphset,
				     const hb_map_t *gpos_lookups,
				     hb_set_t  *layout_variation_indices,
				     hb_map_t  *layout_variation_idx_map)
{
  hb_blob_ptr_t<OT::GDEF> gdef = hb_sanitize_context_t ().reference_table<OT::GDEF> (face);
  hb_blob_ptr_t<OT::GPOS> gpos = hb_sanitize_context_t ().reference_table<OT::GPOS> (face);

  if (!gdef->has_data ())
  {
    gdef.destroy ();
    gpos.destroy ();
    return;
  }
  OT::hb_collect_variation_indices_context_t c (layout_variation_indices, glyphset, gpos_lookups);
  gdef->collect_variation_indices (&c);

  if (hb_ot_layout_has_positioning (face))
    gpos->collect_variation_indices (&c);

  gdef->remap_layout_variation_indices (layout_variation_indices, layout_variation_idx_map);

  gdef.destroy ();
  gpos.destroy ();
}
#endif

static inline void
_cmap_closure (hb_face_t	   *face,
	       const hb_set_t	   *unicodes,
	       hb_set_t		   *glyphset)
{
  OT::cmap::accelerator_t cmap;
  cmap.init (face);
  cmap.table->closure_glyphs (unicodes, glyphset);
  cmap.fini ();
}

static inline void
_remove_invalid_gids (hb_set_t *glyphs,
		      unsigned int num_glyphs)
{
  hb_codepoint_t gid = HB_SET_VALUE_INVALID;
  while (glyphs->next (&gid))
  {
    if (gid >= num_glyphs)
      glyphs->del (gid);
  }
}

static void
_populate_unicodes_to_retain (const hb_set_t *unicodes,
                              const hb_set_t *glyphs,
                              hb_subset_plan_t *plan)
{
  OT::cmap::accelerator_t cmap;
  cmap.init (plan->source);

  for (hb_codepoint_t cp : *unicodes)
  {
    hb_codepoint_t gid;
    if (!cmap.get_nominal_glyph (cp, &gid))
    {
      DEBUG_MSG(SUBSET, nullptr, "Drop U+%04X; no gid", cp);
      continue;
    }
    plan->unicodes->add (cp);
    plan->codepoint_to_glyph->set (cp, gid);
    plan->_glyphset_gsub->add (gid);
  }

  if (glyphs->is_empty ())
  {
    cmap.fini ();
    return;
  }

  hb_map_t unicode_glyphid_map;
  cmap.collect_mapping (hb_set_get_empty (), &unicode_glyphid_map);
  cmap.fini ();

  for (hb_pair_t<hb_codepoint_t, hb_codepoint_t> cp_gid :
       + unicode_glyphid_map.iter () | hb_filter (glyphs, hb_second))
  {
    plan->unicodes->add (cp_gid.first);
    plan->codepoint_to_glyph->set (cp_gid.first, cp_gid.second);
  }
}

static void
_populate_gids_to_retain (hb_subset_plan_t* plan,
			  const hb_set_t *unicodes,
			  const hb_set_t *input_glyphs_to_retain,
			  bool close_over_gsub,
			  bool close_over_gpos,
			  bool close_over_gdef)
{
  OT::glyf::accelerator_t glyf;
#ifndef HB_NO_SUBSET_CFF
  OT::cff1::accelerator_t cff;
#endif
  OT::COLR::accelerator_t colr;
  glyf.init (plan->source);
#ifndef HB_NO_SUBSET_CFF
  cff.init (plan->source);
#endif
  colr.init (plan->source);

  plan->_glyphset_gsub->add (0); // Not-def
  hb_set_union (plan->_glyphset_gsub, input_glyphs_to_retain);

  _cmap_closure (plan->source, plan->unicodes, plan->_glyphset_gsub);

#ifndef HB_NO_SUBSET_LAYOUT
  if (close_over_gsub)
    // closure all glyphs/lookups/features needed for GSUB substitutions.
    _closure_glyphs_lookups_features<OT::GSUB> (plan->source, plan->_glyphset_gsub, plan->layout_features, plan->retain_all_layout_features, plan->gsub_lookups, plan->gsub_features, plan->gsub_langsys);

  if (close_over_gpos)
    _closure_glyphs_lookups_features<OT::GPOS> (plan->source, plan->_glyphset_gsub, plan->layout_features, plan->retain_all_layout_features, plan->gpos_lookups, plan->gpos_features, plan->gpos_langsys);
#endif
  _remove_invalid_gids (plan->_glyphset_gsub, plan->source->get_num_glyphs ());

  // Collect all glyphs referenced by COLRv0
  hb_set_t* cur_glyphset = plan->_glyphset_gsub;
  hb_set_t glyphset_colrv0;
  if (colr.is_valid ())
  {
    glyphset_colrv0.union_ (*cur_glyphset);
    for (hb_codepoint_t gid : cur_glyphset->iter ())
      colr.closure_glyphs (gid, &glyphset_colrv0);
    cur_glyphset = &glyphset_colrv0;
  }

  hb_set_t palette_indices;
  colr.closure_V0palette_indices (cur_glyphset, &palette_indices);

  hb_set_t layer_indices;
  colr.closure_forV1 (cur_glyphset, &layer_indices, &palette_indices);
  _remap_indexes (&layer_indices, plan->colrv1_layers);
  _remap_palette_indexes (&palette_indices, plan->colr_palettes);
  colr.fini ();
  _remove_invalid_gids (cur_glyphset, plan->source->get_num_glyphs ());

  // Populate a full set of glyphs to retain by adding all referenced
  // composite glyphs.
  for (hb_codepoint_t gid : cur_glyphset->iter ())
  {
    glyf.add_gid_and_children (gid, plan->_glyphset);
#ifndef HB_NO_SUBSET_CFF
    if (cff.is_valid ())
      _add_cff_seac_components (cff, gid, plan->_glyphset);
#endif
  }

  _remove_invalid_gids (plan->_glyphset, plan->source->get_num_glyphs ());


#ifndef HB_NO_VAR
  if (close_over_gdef)
    _collect_layout_variation_indices (plan->source,
				       plan->_glyphset_gsub,
				       plan->gpos_lookups,
				       plan->layout_variation_indices,
				       plan->layout_variation_idx_map);
#endif

#ifndef HB_NO_SUBSET_CFF
  cff.fini ();
#endif
  glyf.fini ();
}

static void
_create_old_gid_to_new_gid_map (const hb_face_t *face,
				bool		 retain_gids,
				const hb_set_t	*all_gids_to_retain,
				hb_map_t	*glyph_map, /* OUT */
				hb_map_t	*reverse_glyph_map, /* OUT */
				unsigned int	*num_glyphs /* OUT */)
{
  if (!retain_gids)
  {
    + hb_enumerate (hb_iter (all_gids_to_retain), (hb_codepoint_t) 0)
    | hb_sink (reverse_glyph_map)
    ;
    *num_glyphs = reverse_glyph_map->get_population ();
  } else {
    + hb_iter (all_gids_to_retain)
    | hb_map ([] (hb_codepoint_t _) {
		return hb_pair_t<hb_codepoint_t, hb_codepoint_t> (_, _);
	      })
    | hb_sink (reverse_glyph_map)
    ;

    unsigned max_glyph =
    + hb_iter (all_gids_to_retain)
    | hb_reduce (hb_max, 0u)
    ;
    *num_glyphs = max_glyph + 1;
  }

  + reverse_glyph_map->iter ()
  | hb_map (&hb_pair_t<hb_codepoint_t, hb_codepoint_t>::reverse)
  | hb_sink (glyph_map)
  ;
}

static void
_nameid_closure (hb_face_t *face,
		 hb_set_t  *nameids)
{
#ifndef HB_NO_STYLE
  face->table.STAT->collect_name_ids (nameids);
#endif
#ifndef HB_NO_VAR
  face->table.fvar->collect_name_ids (nameids);
#endif
}

/**
 * hb_subset_plan_create:
 * @face: font face to create the plan for.
 * @input: a subset input.
 *
 * Computes a plan for subsetting the supplied face according
 * to a provided input. The plan describes
 * which tables and glyphs should be retained.
 *
 * Return value: New subset plan.
 *
 * Since: 1.7.5
 **/
hb_subset_plan_t *
hb_subset_plan_create (hb_face_t	 *face,
		       const hb_subset_input_t *input)
{
  hb_subset_plan_t *plan;
  if (unlikely (!(plan = hb_object_create<hb_subset_plan_t> ())))
    return const_cast<hb_subset_plan_t *> (&Null (hb_subset_plan_t));

  plan->successful = true;
  plan->drop_hints = input->drop_hints;
  plan->desubroutinize = input->desubroutinize;
  plan->retain_gids = input->retain_gids;
  plan->name_legacy = input->name_legacy;
  plan->overlaps_flag = input->overlaps_flag;
  plan->notdef_outline = input->notdef_outline;
  plan->prune_unicode_ranges = !input->no_prune_unicode_ranges;
  plan->retain_all_layout_features = input->retain_all_layout_features;
  plan->passthrough_unrecognized = input->passthrough_unrecognized;
  plan->unicodes = hb_set_create ();
  plan->name_ids = hb_set_copy (input->name_ids);
  _nameid_closure (face, plan->name_ids);
  plan->name_languages = hb_set_copy (input->name_languages);
  plan->layout_features = hb_set_copy (input->layout_features);
  plan->glyphs_requested = hb_set_copy (input->glyphs);
  plan->drop_tables = hb_set_copy (input->drop_tables);
  plan->no_subset_tables = hb_set_copy (input->no_subset_tables);
  plan->source = hb_face_reference (face);
  plan->dest = hb_face_builder_create ();

  plan->_glyphset = hb_set_create ();
  plan->_glyphset_gsub = hb_set_create ();
  plan->codepoint_to_glyph = hb_map_create ();
  plan->glyph_map = hb_map_create ();
  plan->reverse_glyph_map = hb_map_create ();
  plan->gsub_lookups = hb_map_create ();
  plan->gpos_lookups = hb_map_create ();

  if (plan->check_success (plan->gsub_langsys = hb_object_create<script_langsys_map> ()))
    plan->gsub_langsys->init_shallow ();
  if (plan->check_success (plan->gpos_langsys = hb_object_create<script_langsys_map> ()))
    plan->gpos_langsys->init_shallow ();

  plan->gsub_features = hb_map_create ();
  plan->gpos_features = hb_map_create ();
  plan->colrv1_layers = hb_map_create ();
  plan->colr_palettes = hb_map_create ();
  plan->layout_variation_indices = hb_set_create ();
  plan->layout_variation_idx_map = hb_map_create ();

  if (plan->in_error ()) {
    return plan;
  }

  _populate_unicodes_to_retain (input->unicodes, input->glyphs, plan);

  _populate_gids_to_retain (plan,
			    input->unicodes,
			    input->glyphs,
			    !input->drop_tables->has (HB_OT_TAG_GSUB),
			    !input->drop_tables->has (HB_OT_TAG_GPOS),
			    !input->drop_tables->has (HB_OT_TAG_GDEF));

  _create_old_gid_to_new_gid_map (face,
				  input->retain_gids,
				  plan->_glyphset,
				  plan->glyph_map,
				  plan->reverse_glyph_map,
				  &plan->_num_output_glyphs);

  return plan;
}

/**
 * hb_subset_plan_destroy:
 *
 * Since: 1.7.5
 **/
void
hb_subset_plan_destroy (hb_subset_plan_t *plan)
{
  if (!hb_object_destroy (plan)) return;

  hb_set_destroy (plan->unicodes);
  hb_set_destroy (plan->name_ids);
  hb_set_destroy (plan->name_languages);
  hb_set_destroy (plan->layout_features);
  hb_set_destroy (plan->glyphs_requested);
  hb_set_destroy (plan->drop_tables);
  hb_set_destroy (plan->no_subset_tables);
  hb_face_destroy (plan->source);
  hb_face_destroy (plan->dest);
  hb_map_destroy (plan->codepoint_to_glyph);
  hb_map_destroy (plan->glyph_map);
  hb_map_destroy (plan->reverse_glyph_map);
  hb_set_destroy (plan->_glyphset);
  hb_set_destroy (plan->_glyphset_gsub);
  hb_map_destroy (plan->gsub_lookups);
  hb_map_destroy (plan->gpos_lookups);
  hb_map_destroy (plan->gsub_features);
  hb_map_destroy (plan->gpos_features);
  hb_map_destroy (plan->colrv1_layers);
  hb_map_destroy (plan->colr_palettes);
  hb_set_destroy (plan->layout_variation_indices);
  hb_map_destroy (plan->layout_variation_idx_map);

  if (plan->gsub_langsys)
  {
    for (auto _ : plan->gsub_langsys->iter ())
      hb_set_destroy (_.second);

    hb_object_destroy (plan->gsub_langsys);
    plan->gsub_langsys->fini_shallow ();
    hb_free (plan->gsub_langsys);
  }

  if (plan->gpos_langsys)
  {
    for (auto _ : plan->gpos_langsys->iter ())
      hb_set_destroy (_.second);

    hb_object_destroy (plan->gpos_langsys);
    plan->gpos_langsys->fini_shallow ();
    hb_free (plan->gpos_langsys);
  }

  hb_free (plan);
}