src/hb-subset-plan.cc

   1 /*
   2  * Copyright © 2018  Google, Inc.
   3  *
   4  *  This is part of HarfBuzz, a text shaping library.
   5  *
   6  * Permission is hereby granted, without written agreement and without
   7  * license or royalty fees, to use, copy, modify, and distribute this
   8  * software and its documentation for any purpose, provided that the
   9  * above copyright notice and the following two paragraphs appear in
  10  * all copies of this software.
  11  *
  12  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  13  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  14  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  15  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  16  * DAMAGE.
  17  *
  18  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  19  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  20  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  21  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  22  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  23  *
  24  * Google Author(s): Garret Rieger, Roderick Sheeter
  25  */
  26
  27 #include "hb-map-private.hh"
  28 #include "hb-subset-private.hh"
  29 #include "hb-set-private.hh"
  30
  31 #include "hb-subset-plan.hh"
  32 #include "hb-ot-cmap-table.hh"
  33 #include "hb-ot-glyf-table.hh"
  34
  35 static void
  36 _add_gid_and_children (const OT::glyf::accelerator_t &glyf,
  37                        hb_codepoint_t gid,
  38                        hb_set_t *gids_to_retain)
  39 {
  40   if (hb_set_has (gids_to_retain, gid))
  41     // Already visited this gid, ignore.
  42     return;
  43
  44   hb_set_add (gids_to_retain, gid);
  45
  46   OT::glyf::CompositeGlyphHeader::Iterator composite;
  47   if (glyf.get_composite (gid, &composite))
  48   {
  49     do
  50     {
  51       _add_gid_and_children (glyf, (hb_codepoint_t) composite.current->glyphIndex, gids_to_retain);
  52     } while (composite.move_to_next());
  53   }
  54 }
  55
  56 static void
  57 _gsub_closure (hb_face_t *face, hb_set_t *gids_to_retain)
  58 {
  59   // TODO(grieger): This uses all lookups, instead collect
  60   //                the set of lookups that are relevant.
  61   //                See fontTools implementation.
  62   hb_ot_layout_lookups_substitute_closure (face,
  63                                            nullptr,
  64                                            gids_to_retain);
  65 }
  66
  67
  68 static void
  69 _populate_gids_to_retain (hb_face_t *face,
  70                           const hb_set_t *unicodes,
  71                           bool close_over_gsub,
  72                           hb_set_t *unicodes_to_retain,
  73                           hb_map_t *codepoint_to_glyph,
  74                           hb_vector_t<hb_codepoint_t> *glyphs)
  75 {
  76   OT::cmap::accelerator_t cmap;
  77   OT::glyf::accelerator_t glyf;
  78   cmap.init (face);
  79   glyf.init (face);
  80
  81   hb_set_t *initial_gids_to_retain = hb_set_create ();
  82   initial_gids_to_retain->add (0); // Not-def
  83
  84   hb_codepoint_t cp = HB_SET_VALUE_INVALID;
  85   while (unicodes->next (&cp))
  86   {
  87     hb_codepoint_t gid;
  88     if (!cmap.get_nominal_glyph (cp, &gid))
  89     {
  90       DEBUG_MSG(SUBSET, nullptr, "Drop U+%04X; no gid", cp);
  91       continue;
  92     }
  93     unicodes_to_retain->add (cp);
  94     codepoint_to_glyph->set (cp, gid);
  95     initial_gids_to_retain->add (gid);
  96   }
  97
  98   if (close_over_gsub)
  99     // Add all glyphs needed for GSUB substitutions.
 100     _gsub_closure (face, initial_gids_to_retain);
 101
 102   // Populate a full set of glyphs to retain by adding all referenced
 103   // composite glyphs.
 104   hb_codepoint_t gid = HB_SET_VALUE_INVALID;
 105   hb_set_t *all_gids_to_retain = hb_set_create ();
 106   while (initial_gids_to_retain->next (&gid))
 107   {
 108     _add_gid_and_children (glyf, gid, all_gids_to_retain);
 109   }
 110   hb_set_destroy (initial_gids_to_retain);
 111
 112   glyphs->alloc (all_gids_to_retain->get_population ());
 113   gid = HB_SET_VALUE_INVALID;
 114   while (all_gids_to_retain->next (&gid))
 115     glyphs->push (gid);
 116
 117   hb_set_destroy (all_gids_to_retain);
 118   glyf.fini ();
 119   cmap.fini ();
 120 }
 121
 122 static void
 123 _create_old_gid_to_new_gid_map (const hb_vector_t<hb_codepoint_t> &glyphs,
 124                                 hb_map_t *glyph_map)
 125 {
 126   for (unsigned int i = 0; i < glyphs.len; i++) {
 127     glyph_map->set (glyphs[i], i);
 128   }
 129 }
 130
 131 /**
 132  * hb_subset_plan_create:
 133  * Computes a plan for subsetting the supplied face according
 134  * to a provide profile and input. The plan describes
 135  * which tables and glyphs should be retained.
 136  *
 137  * Return value: New subset plan.
 138  *
 139  * Since: 1.7.5
 140  **/
 141 hb_subset_plan_t *
 142 hb_subset_plan_create (hb_face_t           *face,
 143                        hb_subset_profile_t *profile,
 144                        hb_subset_input_t   *input)
 145 {
 146   hb_subset_plan_t *plan = hb_object_create<hb_subset_plan_t> ();
 147
 148   plan->drop_hints = input->drop_hints;
 149   plan->drop_ot_layout = input->drop_ot_layout;
 150   plan->unicodes = hb_set_create();
 151   plan->glyphs.init();
 152   plan->source = hb_face_reference (face);
 153   plan->dest = hb_subset_face_create ();
 154   plan->codepoint_to_glyph = hb_map_create();
 155   plan->glyph_map = hb_map_create();
 156
 157   _populate_gids_to_retain (face,
 158                             input->unicodes,
 159                             !plan->drop_ot_layout,
 160                             plan->unicodes,
 161                             plan->codepoint_to_glyph,
 162                             &plan->glyphs);
 163   _create_old_gid_to_new_gid_map (plan->glyphs,
 164                                   plan->glyph_map);
 165
 166   return plan;
 167 }
 168
 169 /**
 170  * hb_subset_plan_destroy:
 171  *
 172  * Since: 1.7.5
 173  **/
 174 void
 175 hb_subset_plan_destroy (hb_subset_plan_t *plan)
 176 {
 177   if (!hb_object_destroy (plan)) return;
 178
 179   hb_set_destroy (plan->unicodes);
 180   plan->glyphs.fini();
 181   hb_face_destroy (plan->source);
 182   hb_face_destroy (plan->dest);
 183   hb_map_destroy (plan->codepoint_to_glyph);
 184   hb_map_destroy (plan->glyph_map);
 185
 186   free (plan);
 187 }