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-subset-private.hh"
  28
  29 #include "hb-subset-plan.hh"
  30 #include "hb-ot-cmap-table.hh"
  31 #include "hb-ot-glyf-table.hh"
  32
  33 static int
  34 _hb_codepoint_t_cmp (const void *pa, const void *pb)
  35 {
  36   hb_codepoint_t a = * (hb_codepoint_t *) pa;
  37   hb_codepoint_t b = * (hb_codepoint_t *) pb;
  38
  39   return a < b ? -1 : a > b ? +1 : 0;
  40 }
  41
  42 hb_bool_t
  43 hb_subset_plan_new_gid_for_codepoint (hb_subset_plan_t *plan,
  44                                       hb_codepoint_t codepoint,
  45                                       hb_codepoint_t *new_gid)
  46 {
  47   // TODO actual map, delete this garbage.
  48   for (unsigned int i = 0; i < plan->codepoints.len; i++)
  49   {
  50     if (plan->codepoints[i] != codepoint) continue;
  51     if (!hb_subset_plan_new_gid_for_old_id(plan, plan->gids_to_retain[i], new_gid))
  52     {
  53       return false;
  54     }
  55     return true;
  56   }
  57   return false;
  58 }
  59
  60 hb_bool_t
  61 hb_subset_plan_new_gid_for_old_id (hb_subset_plan_t *plan,
  62                                    hb_codepoint_t old_gid,
  63                                    hb_codepoint_t *new_gid)
  64 {
  65   // the index in old_gids is the new gid; only up to codepoints.len are valid
  66   for (unsigned int i = 0; i < plan->gids_to_retain_sorted.len; i++)
  67   {
  68     if (plan->gids_to_retain_sorted[i] == old_gid)
  69     {
  70       *new_gid = i;
  71       return true;
  72     }
  73   }
  74   return false;
  75 }
  76
  77 hb_bool_t
  78 hb_subset_plan_add_table (hb_subset_plan_t *plan,
  79                           hb_tag_t tag,
  80                           hb_blob_t *contents)
  81 {
  82   hb_blob_t *source_blob = plan->source->reference_table (tag);
  83   DEBUG_MSG(SUBSET, nullptr, "add table %c%c%c%c, dest %d bytes, source %d bytes", HB_UNTAG(tag), hb_blob_get_length (contents), hb_blob_get_length (source_blob));
  84   hb_blob_destroy (source_blob);
  85   return hb_subset_face_add_table(plan->dest, tag, contents);
  86 }
  87
  88 static void
  89 _populate_codepoints (hb_set_t *input_codepoints,
  90                       hb_prealloced_array_t<hb_codepoint_t>& plan_codepoints)
  91 {
  92   plan_codepoints.alloc (hb_set_get_population (input_codepoints));
  93   hb_codepoint_t cp = -1;
  94   while (hb_set_next (input_codepoints, &cp)) {
  95     hb_codepoint_t *wr = plan_codepoints.push();
  96     *wr = cp;
  97   }
  98   plan_codepoints.qsort (_hb_codepoint_t_cmp);
  99 }
 100
 101 static void
 102 _add_gid_and_children (const OT::glyf::accelerator_t &glyf,
 103                        hb_codepoint_t gid,
 104                        hb_set_t *gids_to_retain)
 105 {
 106   if (hb_set_has (gids_to_retain, gid))
 107     // Already visited this gid, ignore.
 108     return;
 109
 110   hb_set_add (gids_to_retain, gid);
 111
 112   OT::glyf::CompositeGlyphHeader::Iterator composite;
 113   if (glyf.get_composite (gid, &composite))
 114   {
 115     do
 116     {
 117       _add_gid_and_children (glyf, (hb_codepoint_t) composite.current->glyphIndex, gids_to_retain);
 118     } while (composite.move_to_next());
 119   }
 120 }
 121
 122 static void
 123 _populate_gids_to_retain (hb_face_t *face,
 124                           hb_prealloced_array_t<hb_codepoint_t>& codepoints,
 125                           hb_prealloced_array_t<hb_codepoint_t>& old_gids,
 126                           hb_prealloced_array_t<hb_codepoint_t>& old_gids_sorted)
 127 {
 128   OT::cmap::accelerator_t cmap;
 129   OT::glyf::accelerator_t glyf;
 130   cmap.init (face);
 131   glyf.init (face);
 132
 133   hb_auto_array_t<unsigned int> bad_indices;
 134
 135   old_gids.alloc (codepoints.len);
 136   for (unsigned int i = 0; i < codepoints.len; i++)
 137   {
 138     hb_codepoint_t gid;
 139     if (!cmap.get_nominal_glyph (codepoints[i], &gid))
 140     {
 141       gid = -1;
 142       *(bad_indices.push ()) = i;
 143     }
 144     *(old_gids.push ()) = gid;
 145   }
 146
 147   /* Generally there shouldn't be any */
 148   while (bad_indices.len > 0)
 149   {
 150     unsigned int i = bad_indices[bad_indices.len - 1];
 151     bad_indices.pop ();
 152     DEBUG_MSG(SUBSET, nullptr, "Drop U+%04X; no gid", codepoints[i]);
 153     codepoints.remove (i);
 154     old_gids.remove (i);
 155   }
 156
 157   // Populate a full set of glyphs to retain by adding all referenced
 158   // composite glyphs.
 159   // TODO expand with glyphs reached by G*
 160   hb_set_t * all_gids_to_retain = hb_set_create ();
 161   _add_gid_and_children (glyf, 0, all_gids_to_retain);
 162   for (unsigned int i = 0; i < old_gids.len; i++)
 163     _add_gid_and_children (glyf, old_gids[i], all_gids_to_retain);
 164
 165   // Transfer to a sorted list.
 166   old_gids_sorted.alloc (hb_set_get_population (all_gids_to_retain));
 167   hb_codepoint_t gid = HB_SET_VALUE_INVALID;
 168   while (hb_set_next (all_gids_to_retain, &gid))
 169     *(old_gids_sorted.push ()) = gid;
 170
 171   hb_set_destroy (all_gids_to_retain);
 172   glyf.fini ();
 173   cmap.fini ();
 174 }
 175
 176 /**
 177  * hb_subset_plan_create:
 178  * Computes a plan for subsetting the supplied face according
 179  * to a provide profile and input. The plan describes
 180  * which tables and glyphs should be retained.
 181  *
 182  * Return value: New subset plan.
 183  *
 184  * Since: 1.7.5
 185  **/
 186 hb_subset_plan_t *
 187 hb_subset_plan_create (hb_face_t           *face,
 188                        hb_subset_profile_t *profile,
 189                        hb_subset_input_t   *input)
 190 {
 191   hb_subset_plan_t *plan = hb_object_create<hb_subset_plan_t> ();
 192
 193   plan->codepoints.init();
 194   plan->gids_to_retain.init();
 195   plan->gids_to_retain_sorted.init();
 196   plan->source = hb_face_reference (face);
 197   plan->dest = hb_subset_face_create ();
 198   plan->drop_hints = input->drop_hints;
 199
 200   _populate_codepoints (input->unicodes, plan->codepoints);
 201   _populate_gids_to_retain (face,
 202                             plan->codepoints,
 203                             plan->gids_to_retain,
 204                             plan->gids_to_retain_sorted);
 205
 206   return plan;
 207 }
 208
 209 /**
 210  * hb_subset_plan_destroy:
 211  *
 212  * Since: 1.7.5
 213  **/
 214 void
 215 hb_subset_plan_destroy (hb_subset_plan_t *plan)
 216 {
 217   if (!hb_object_destroy (plan)) return;
 218
 219   plan->codepoints.finish ();
 220   plan->gids_to_retain.finish ();
 221   plan->gids_to_retain_sorted.finish ();
 222
 223   hb_face_destroy (plan->source);
 224   hb_face_destroy (plan->dest);
 225
 226   free (plan);
 227 }