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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 #ifndef HB_SUBSET_PLAN_HH
28 #define HB_SUBSET_PLAN_HH
29 
30 #include "hb.hh"
31 
32 #include "hb-subset.h"
33 #include "hb-subset-input.hh"
34 
35 #include "hb-map.hh"
36 #include "hb-set.hh"
37 
38 struct hb_subset_plan_t
39 {
40   hb_object_header_t header;
41 
42   bool successful;
43   unsigned flags;
44 
45   // For each cp that we'd like to retain maps to the corresponding gid.
46   hb_set_t *unicodes;
47 
48   // name_ids we would like to retain
49   hb_set_t *name_ids;
50 
51   // name_languages we would like to retain
52   hb_set_t *name_languages;
53 
54   //layout features which will be preserved
55   hb_set_t *layout_features;
56 
57   //glyph ids requested to retain
58   hb_set_t *glyphs_requested;
59 
60   // Tables which should not be processed, just pass them through.
61   hb_set_t *no_subset_tables;
62 
63   // Tables which should be dropped.
64   hb_set_t *drop_tables;
65 
66   // The glyph subset
67   hb_map_t *codepoint_to_glyph;
68 
69   // Old -> New glyph id mapping
70   hb_map_t *glyph_map;
71   hb_map_t *reverse_glyph_map;
72 
73   // Plan is only good for a specific source/dest so keep them with it
74   hb_face_t *source;
75   hb_face_t *dest;
76 
77   unsigned int _num_output_glyphs;
78   hb_set_t *_glyphset;
79   hb_set_t *_glyphset_gsub;
80   hb_set_t *_glyphset_mathed;
81 
82   //active lookups we'd like to retain
83   hb_map_t *gsub_lookups;
84   hb_map_t *gpos_lookups;
85 
86   //active langsys we'd like to retain
87   hb_hashmap_t<unsigned, hb_set_t *> *gsub_langsys;
88   hb_hashmap_t<unsigned, hb_set_t *> *gpos_langsys;
89 
90   //active features after removing redundant langsys and prune_features
91   hb_map_t *gsub_features;
92   hb_map_t *gpos_features;
93 
94   //active layers/palettes we'd like to retain
95   hb_map_t *colrv1_layers;
96   hb_map_t *colr_palettes;
97 
98   //The set of layout item variation store delta set indices to be retained
99   hb_set_t *layout_variation_indices;
100   //Old -> New layout item variation store delta set index mapping
101   hb_map_t *layout_variation_idx_map;
102 
103  public:
104 
in_errorhb_subset_plan_t105   bool in_error () const { return !successful; }
106 
check_successhb_subset_plan_t107   bool check_success(bool success)
108   {
109     successful = (successful && success);
110     return successful;
111   }
112 
113   /*
114    * The set of input glyph ids which will be retained in the subset.
115    * Does NOT include ids kept due to retain_gids. You probably want to use
116    * glyph_map/reverse_glyph_map.
117    */
118   inline const hb_set_t *
glyphsethb_subset_plan_t119   glyphset () const
120   {
121     return _glyphset;
122   }
123 
124   /*
125    * The set of input glyph ids which will be retained in the subset.
126    */
127   inline const hb_set_t *
glyphset_gsubhb_subset_plan_t128   glyphset_gsub () const
129   {
130     return _glyphset_gsub;
131   }
132 
133   /*
134    * The total number of output glyphs in the final subset.
135    */
136   inline unsigned int
num_output_glyphshb_subset_plan_t137   num_output_glyphs () const
138   {
139     return _num_output_glyphs;
140   }
141 
142   /*
143    * Given an output gid , returns true if that glyph id is an empty
144    * glyph (ie. it's a gid that we are dropping all data for).
145    */
is_empty_glyphhb_subset_plan_t146   inline bool is_empty_glyph (hb_codepoint_t gid) const
147   {
148     return !_glyphset->has (gid);
149   }
150 
new_gid_for_codepointhb_subset_plan_t151   inline bool new_gid_for_codepoint (hb_codepoint_t codepoint,
152 				     hb_codepoint_t *new_gid) const
153   {
154     hb_codepoint_t old_gid = codepoint_to_glyph->get (codepoint);
155     if (old_gid == HB_MAP_VALUE_INVALID)
156       return false;
157 
158     return new_gid_for_old_gid (old_gid, new_gid);
159   }
160 
new_gid_for_old_gidhb_subset_plan_t161   inline bool new_gid_for_old_gid (hb_codepoint_t old_gid,
162 				   hb_codepoint_t *new_gid) const
163   {
164     hb_codepoint_t gid = glyph_map->get (old_gid);
165     if (gid == HB_MAP_VALUE_INVALID)
166       return false;
167 
168     *new_gid = gid;
169     return true;
170   }
171 
old_gid_for_new_gidhb_subset_plan_t172   inline bool old_gid_for_new_gid (hb_codepoint_t  new_gid,
173 				   hb_codepoint_t *old_gid) const
174   {
175     hb_codepoint_t gid = reverse_glyph_map->get (new_gid);
176     if (gid == HB_MAP_VALUE_INVALID)
177       return false;
178 
179     *old_gid = gid;
180     return true;
181   }
182 
183   inline bool
add_tablehb_subset_plan_t184   add_table (hb_tag_t tag,
185 	     hb_blob_t *contents)
186   {
187     if (HB_DEBUG_SUBSET)
188     {
189       hb_blob_t *source_blob = source->reference_table (tag);
190       DEBUG_MSG(SUBSET, nullptr, "add table %c%c%c%c, dest %d bytes, source %d bytes",
191 		HB_UNTAG(tag),
192 		hb_blob_get_length (contents),
193 		hb_blob_get_length (source_blob));
194       hb_blob_destroy (source_blob);
195     }
196     return hb_face_builder_add_table (dest, tag, contents);
197   }
198 };
199 
200 typedef struct hb_subset_plan_t hb_subset_plan_t;
201 
202 HB_INTERNAL hb_subset_plan_t *
203 hb_subset_plan_create (hb_face_t           *face,
204 		       const hb_subset_input_t   *input);
205 
206 HB_INTERNAL void
207 hb_subset_plan_destroy (hb_subset_plan_t *plan);
208 
209 #endif /* HB_SUBSET_PLAN_HH */
210