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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 drop_hints : 1;
43   bool desubroutinize : 1;
44   bool retain_gids : 1;
45 
46   // For each cp that we'd like to retain maps to the corresponding gid.
47   hb_set_t *unicodes;
48 
49   // name_ids we would like to retain
50   hb_set_t *name_ids;
51 
52   // Tables which should be dropped.
53   hb_set_t *drop_tables;
54 
55   // The glyph subset
56   hb_map_t *codepoint_to_glyph;
57 
58   // Old -> New glyph id mapping
59   hb_map_t *glyph_map;
60   hb_map_t *reverse_glyph_map;
61 
62   // Plan is only good for a specific source/dest so keep them with it
63   hb_face_t *source;
64   hb_face_t *dest;
65 
66   unsigned int _num_output_glyphs;
67   hb_set_t *_glyphset;
68   hb_set_t *_glyphset_gsub;
69 
70  public:
71 
72   /*
73    * The set of input glyph ids which will be retained in the subset.
74    * Does NOT include ids kept due to retain_gids. You probably want to use
75    * glyph_map/reverse_glyph_map.
76    */
77   inline const hb_set_t *
glyphsethb_subset_plan_t78   glyphset () const
79   {
80     return _glyphset;
81   }
82 
83   /*
84    * The set of input glyph ids which will be retained in the subset.
85    */
86   inline const hb_set_t *
glyphset_gsubhb_subset_plan_t87   glyphset_gsub () const
88   {
89     return _glyphset_gsub;
90   }
91 
92   /*
93    * The total number of output glyphs in the final subset.
94    */
95   inline unsigned int
num_output_glyphshb_subset_plan_t96   num_output_glyphs () const
97   {
98     return _num_output_glyphs;
99   }
100 
101   /*
102    * Given an output gid , returns true if that glyph id is an empty
103    * glyph (ie. it's a gid that we are dropping all data for).
104    */
is_empty_glyphhb_subset_plan_t105   inline bool is_empty_glyph (hb_codepoint_t gid) const
106   {
107     return !_glyphset->has (gid);
108   }
109 
new_gid_for_codepointhb_subset_plan_t110   inline bool new_gid_for_codepoint (hb_codepoint_t codepoint,
111 				     hb_codepoint_t *new_gid) const
112   {
113     hb_codepoint_t old_gid = codepoint_to_glyph->get (codepoint);
114     if (old_gid == HB_MAP_VALUE_INVALID)
115       return false;
116 
117     return new_gid_for_old_gid (old_gid, new_gid);
118   }
119 
new_gid_for_old_gidhb_subset_plan_t120   inline bool new_gid_for_old_gid (hb_codepoint_t old_gid,
121 				   hb_codepoint_t *new_gid) const
122   {
123     hb_codepoint_t gid = glyph_map->get (old_gid);
124     if (gid == HB_MAP_VALUE_INVALID)
125       return false;
126 
127     *new_gid = gid;
128     return true;
129   }
130 
old_gid_for_new_gidhb_subset_plan_t131   inline bool old_gid_for_new_gid (hb_codepoint_t  new_gid,
132 				   hb_codepoint_t *old_gid) const
133   {
134     hb_codepoint_t gid = reverse_glyph_map->get (new_gid);
135     if (gid == HB_MAP_VALUE_INVALID)
136       return false;
137 
138     *old_gid = gid;
139     return true;
140   }
141 
142   inline bool
add_tablehb_subset_plan_t143   add_table (hb_tag_t tag,
144 	     hb_blob_t *contents)
145   {
146     hb_blob_t *source_blob = source->reference_table (tag);
147     DEBUG_MSG(SUBSET, nullptr, "add table %c%c%c%c, dest %d bytes, source %d bytes",
148 	      HB_UNTAG(tag),
149 	      hb_blob_get_length (contents),
150 	      hb_blob_get_length (source_blob));
151     hb_blob_destroy (source_blob);
152     return hb_face_builder_add_table (dest, tag, contents);
153   }
154 };
155 
156 typedef struct hb_subset_plan_t hb_subset_plan_t;
157 
158 HB_INTERNAL hb_subset_plan_t *
159 hb_subset_plan_create (hb_face_t           *face,
160 		       hb_subset_input_t   *input);
161 
162 HB_INTERNAL void
163 hb_subset_plan_destroy (hb_subset_plan_t *plan);
164 
165 #endif /* HB_SUBSET_PLAN_HH */
166